Record successful remote vanity verification

README.md

@@ -9,15 +9,18 @@ ConfigKit's simple `Load` accepts one strict YAML source (or explicit
 defaults-only input). `LoadLayered` additionally combines explicit lower-priority
 source groups with an independently selected main input. Sources can be host
 files, native `fs.FS` files, labeled bytes or readers, or snapshotted mappings.
-Enabled path and glob imports compose strictly within their group; precedence
+Enabled explicit imports compose strictly within their group; precedence
 between groups combines mappings recursively. Both entry points return a complete,
-validated configuration with detached metadata and safe diagnostics.
+validated configuration with detached metadata and safe diagnostics. Successful
+results and load errors also provide passive `Source(id)` lookups alongside source
+enumeration.
 Applications may perform audited defaulting and normalization through a resolver,
 then report domain errors and warnings through read-only semantic validation. Secret
 tags and a path predicate drive deterministic redacted effective YAML. Typed secret
 references resolve environment names before validation, and explicit
 secrets-directory bootstrap is available as a separate startup operation. Explicit
-CLI override records apply above overlays. Value explanation is available through
+CLI override records apply after inheritance and typed decoding, before application
+resolution. Value explanation is available through
 detached structured records and deterministic redacted output. Built-in
 `extends` relationships let a mapping inherit from a named sibling during the
 same load, retaining explicit presence and source/derivation history. The root
@@ -26,7 +29,32 @@ the [configuration contract](docs/config.md#effective-configuration-diffs) and
 [consumer guide](docs/consumers/README.md#effective-configuration-diffs) describe
 its safe changed-region records and maintained workflows.
 
+Sources can also be explicitly placed as sequence items. Configuration
+declarations and application registrations can give selected sequences scalar
+identities and choose how they combine across precedence and inheritance.
+Strict peers combine distinct records, while higher-priority collections can
+replace, append, or upsert whole records. See the
+[sequence contract](docs/config.md#strict-document-composition),
+[maintained catalog examples](docs/consumers/README.md#identified-prompt-sequences),
+and [ADR 0017](docs/adr/0017-collection-sequence-policy.md).
+
+Imports are also explicit: a source may name files, search declared directories,
+or select files with path globs. Applications can set load-wide import defaults
+while keeping declaration-specific exceptions. Files are acquired in authored
+declaration order; dependency-ready composition uses a shared stable scheduler.
+ConfigKit does not search conventional application paths implicitly. See the
+[import contract](docs/config.md#explicit-imports), [consumer examples](docs/consumers/README.md),
+and [ADR 0015](docs/adr/0015-shared-dependency-ready-ordering.md) and
+[ADR 0016](docs/adr/0016-independent-import-controls.md).
+
+Main-file discovery is explicit too: applications choose and order `Search`
+descriptions and pass `SearchConfig` to the existing load APIs. See the
+[discovery contract](docs/config.md#configuration-discovery), [consumer guide](docs/consumers/README.md#explicit-main-file-discovery),
+and [ADR 0019](docs/adr/0019-explicit-configuration-discovery.md).
+
 ```go
+import "go.maximumdirect.net/configkit"
+
 type Config struct {
     Enabled bool `yaml:"enabled"`
     Workers int  `yaml:"workers"`
@@ -41,6 +69,9 @@ func ReadConfig(path string) (Config, error) {
 }
 ```
 
+Existing consumers should follow the
+[module-path migration guidance](docs/consumers/README.md#vanity-module-path-migration).
+
 ## Design philosophy
 
 ConfigKit favors one coherent, predictable configuration model over flexibility
@@ -60,20 +91,29 @@ mappings combine, while overlapping non-mapping definitions are errors. Between
 precedence tiers, mappings combine recursively, retaining omitted lower-priority
 children; other values replace lower-priority values. The main document and its
 imports form one strictly composed tier. Explicit underlay groups sit below it
-and above typed defaults; a selected overlay and explicit CLI overrides sit
-above it. The [configuration contract](docs/config.md#strict-document-composition)
-owns the detailed combination rules and input-specific constraints.
+and above typed defaults; a selected overlay applies before inheritance, while
+explicit CLI overrides apply after decoding and before application resolution.
+The [configuration contract](docs/config.md#strict-document-composition) owns
+the detailed combination rules and input-specific constraints. Declared or
+registered collections combine distinct identified records within strict tiers
+and use their selected operation at precedence boundaries; other sequences keep
+their strict-conflict and whole-value-replacement behavior.
 
 The [architecture goals](docs/policy/architecture.md#success-criteria) explain
 these priorities and how genuine new needs can justify extending the shared
-model. The [deferred scope](docs/roadmap/deferred.md) records deliberate exclusions.
+model. The [future feature list](docs/roadmap/future.md) preserves candidates for
+consideration in future releases.
 
-The [configuration contract](docs/config.md) describes implemented behavior. The
-[consumer adoption guide](docs/consumers/README.md) provides maintained simple
-native-filesystem, layered, and sibling-inheritance examples alongside the migration shapes.
-See the [development guide](docs/development.md) for repository orientation and the
-[release procedure](docs/release.md) for maintainer-only candidate and publication
-steps.
+The [configuration contract](docs/config.md) describes implemented behavior,
+including [input destinations](docs/config.md#input-destinations). The
+[consumer adoption guide](docs/consumers/README.md) provides maintained simple,
+layered, mounted-collection, and identified-prompt examples alongside the
+migration shapes. Input placement decisions are recorded in
+[ADR 0011](docs/adr/0011-input-destinations.md) and sequence placement and
+composition in [ADR 0014](docs/adr/0014-sequence-placement-and-composition.md).
+See the [development guide](docs/development.md) for repository orientation and
+the [release procedure](docs/release.md) for maintainer-only candidate and
+publication steps.
 
 ConfigKit code is licensed under the [LGPL v3.0 or later](COPYRIGHT).
 

conversion.go

@@ -1,6 +1,6 @@
 package configkit
 
-import "gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+import "go.maximumdirect.net/configkit/internal/engine"
 
 func fromEngineLocation(value engine.Location) Location {
 	return Location{SourceID: value.SourceID, Line: value.Line, Column: value.Column}
@@ -43,10 +43,61 @@ func toEngineLocations(values []Location) []engine.Location {
 	return result
 }
 func fromEngineSourceInfo(value engine.SourceInfo) SourceInfo {
-	return SourceInfo{ID: value.ID, Label: value.Label, Path: value.Path, Layer: Layer(value.Layer), Kind: SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex, ImportedFrom: fromEngineLocationPointer(value.ImportedFrom)}
+	return SourceInfo{
+		ID: value.ID, Label: value.Label, Path: value.Path, Destination: fromEnginePath(value.Destination),
+		PlacementMode:         PlacementMode(engine.SourceInfoPlacementModeForFacade(value)),
+		DestinationIsFallback: engine.SourceInfoDestinationUnresolvedForFacade(value),
+		Layer:                 Layer(value.Layer), Kind: SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex,
+		ImportedFrom: fromEngineLocationPointer(value.ImportedFrom), VersionEvidence: fromEngineSourceVersionEvidence(value.VersionCheck),
+		EmptyImportSelections: fromEngineEmptyImportSelections(engine.SourceInfoImportSelectionsForFacade(value)),
+	}
 }
-func toEngineSourceInfo(value SourceInfo) engine.SourceInfo {
-	return engine.SourceInfo{ID: value.ID, Label: value.Label, Path: value.Path, Layer: engine.Layer(value.Layer), Kind: engine.SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex, ImportedFrom: toEngineLocationPointer(value.ImportedFrom)}
+func fromEngineEmptyImportSelections(values []engine.ImportSelectionForFacade) []EmptyImportSelection {
+	if values == nil {
+		return nil
+	}
+	result := make([]EmptyImportSelection, len(values))
+	for index, value := range values {
+		result[index] = EmptyImportSelection{
+			Path: fromEnginePath(value.Path), Location: fromEngineLocation(value.Location),
+			Selector: ImportSelector(value.Selector),
+		}
+	}
+	return result
+}
+
+func toEngineOverrides(values []Override) []engine.Override {
+	if values == nil {
+		return nil
+	}
+	result := make([]engine.Override, len(values))
+	for index, value := range values {
+		result[index] = engine.Override{
+			Path: toEnginePath(value.Path), Value: value.Value, Flag: value.Flag,
+		}
+	}
+	return result
+}
+
+func toEngineImportDefaults(value ImportDefaults) engine.ImportDefaults {
+	return engine.ImportDefaults{
+		Required:  value.Required,
+		Follow:    value.FollowSymlinks,
+		Hidden:    value.IncludeHidden,
+		Recursive: value.Recursive,
+		Pattern:   value.Pattern,
+	}
+}
+
+func fromEngineSourceVersionEvidence(value *engine.SourceVersionCheck) *SourceVersionEvidence {
+	if value == nil {
+		return nil
+	}
+	return &SourceVersionEvidence{
+		Path:     fromEnginePath(value.Path),
+		Version:  Version{Present: value.Version.Present, Null: value.Version.Null, Text: value.Version.Text},
+		Location: fromEngineLocationPointer(value.Location), Redacted: value.Redacted,
+	}
 }
 func fromEngineOrigin(value engine.Origin) Origin {
 	result := Origin{Layer: Layer(value.Layer), Locations: fromEngineLocations(value.Locations), Operation: ChangeKind(value.Operation)}
@@ -61,19 +112,6 @@ func fromEngineOrigin(value engine.Origin) Origin {
 	}
 	return result
 }
-func toEngineOrigin(value Origin) engine.Origin {
-	result := engine.Origin{Layer: engine.Layer(value.Layer), Locations: toEngineLocations(value.Locations), Operation: engine.ChangeKind(value.Operation)}
-	if value.Inheritance != nil {
-		result.Inheritance = make([]engine.InheritanceStep, len(value.Inheritance))
-		for index, step := range value.Inheritance {
-			result.Inheritance[index] = engine.InheritanceStep{
-				From: toEnginePath(step.From), To: toEnginePath(step.To), Reference: toEnginePath(step.Reference),
-				Locations: toEngineLocations(step.Locations),
-			}
-		}
-	}
-	return result
-}
 func fromEngineDiagnostic(value engine.Diagnostic) Diagnostic {
 	return Diagnostic{Code: Code(value.Code), Severity: Severity(value.Severity), Path: fromEnginePath(value.Path), Message: value.Message, Primary: fromEngineLocationPointer(value.Primary), Related: fromEngineLocations(value.Related)}
 }

diagnostic.go

@@ -3,7 +3,7 @@ package configkit
 import (
 	"io"
 
-	"gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+	"go.maximumdirect.net/configkit/internal/engine"
 )
 
 // LoadError reports safe structured diagnostics for a failed configuration load.
@@ -50,6 +50,21 @@ func (e *LoadError) Sources() []SourceInfo {
 	return result
 }
 
+// Source returns a detached record from the sanitized source evidence retained
+// before loading failed, including placement evidence available at that point.
+// IDs are local to the failed load. It does not acquire sources or access the
+// filesystem. Empty or unknown IDs return false.
+func (e *LoadError) Source(id string) (SourceInfo, bool) {
+	if e == nil || e.value == nil {
+		return SourceInfo{}, false
+	}
+	value, ok := e.value.Source(id)
+	if !ok {
+		return SourceInfo{}, false
+	}
+	return fromEngineSourceInfo(value), true
+}
+
 // WriteDiagnostics writes diagnostics in canonical order. It escapes terminal
 // control characters and propagates writer errors, including short writes.
 func WriteDiagnostics(output io.Writer, diagnostics []Diagnostic) error {

diff.go

@@ -1,6 +1,6 @@
 package configkit
 
-import "gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+import "go.maximumdirect.net/configkit/internal/engine"
 
 // Difference describes one canonical changed region between two successful
 // loads. Left is the earlier value and Right is the later value. Each snapshot

discovery.go

@@ -0,0 +1,90 @@
+package configkit
+
+import "go.maximumdirect.net/configkit/internal/engine"
+
+// Search is an immutable ordered description of possible host-file inputs.
+// It is consumed only when passed to SearchConfig and used by a load.
+type Search struct{ value engine.Search }
+
+// FilenameGroup selects filenames in order for a directory search.
+// Construct groups with NamedFilenames, GenericFilenames, or CustomFilenames.
+type FilenameGroup struct{ value engine.FilenameGroup }
+
+// SearchOptions controls whether a search must select a file.
+type SearchOptions struct {
+	// Required reports a missing-source error if the complete search is exhausted.
+	Required bool
+}
+
+// DirectorySearchOptions selects the filename groups used by SearchDirectory.
+type DirectorySearchOptions struct {
+	// Filenames concatenates groups in order. A nil slice uses Named then Generic;
+	// a non-nil empty slice selects no filenames.
+	Filenames []FilenameGroup
+}
+
+// NamedFilenames selects <application>.yml followed by <application>.yaml.
+func NamedFilenames() FilenameGroup { return FilenameGroup{value: engine.NamedFilenames()} }
+
+// GenericFilenames selects config.yml, config.yaml, main.yml, and main.yaml.
+func GenericFilenames() FilenameGroup { return FilenameGroup{value: engine.GenericFilenames()} }
+
+// CustomFilenames selects literal filename components in the supplied order.
+// Names cannot be empty or contain a directory component.
+func CustomFilenames(names ...string) FilenameGroup {
+	return FilenameGroup{value: engine.CustomFilenames(names...)}
+}
+
+// SearchDirectory describes a search within directory. Omitted options or a nil
+// Filenames slice uses Named then Generic groups. Explicitly empty Filenames
+// selects no names and does not resolve the directory base.
+func SearchDirectory(directory string, supplied ...DirectorySearchOptions) Search {
+	options := make([]engine.DirectorySearchOptions, len(supplied))
+	for index, option := range supplied {
+		if option.Filenames == nil {
+			continue
+		}
+		options[index].Filenames = make([]engine.FilenameGroup, len(option.Filenames))
+		for groupIndex, group := range option.Filenames {
+			options[index].Filenames[groupIndex] = group.value
+		}
+	}
+	return Search{value: engine.SearchDirectory(directory, options...)}
+}
+
+// SearchPaths describes literal host-file candidates in the supplied order.
+func SearchPaths(paths ...string) Search { return Search{value: engine.Paths(paths...)} }
+
+// Searches concatenates descriptions in order and snapshots their entries.
+func Searches(searches ...Search) Search {
+	values := make([]engine.Search, len(searches))
+	for index, search := range searches {
+		values[index] = search.value
+	}
+	return Search{value: engine.Searches(values...)}
+}
+
+// UnixSystemDirectories describes the conventional Unix system directories.
+// Loading on an unsupported platform fails if this preset is reached.
+func UnixSystemDirectories() Search { return Search{value: engine.UnixSystemDirectories()} }
+
+// UserConfigDirectory describes searches rooted at the Go user-config directory.
+func UserConfigDirectory() Search { return Search{value: engine.UserConfigDirectory()} }
+
+// HomeDirectory describes searches rooted at the Go home directory.
+func HomeDirectory() Search { return Search{value: engine.HomeDirectory()} }
+
+// WorkingDirectory describes application-named files in the current directory.
+func WorkingDirectory() Search { return Search{value: engine.WorkingDirectory()} }
+
+// SearchConfig creates a source that selects the first matching host file when
+// consumed by Load or LoadLayered. Without Required, exhausting the search uses
+// the absent-input lifecycle. Description and option errors are reported while
+// loading.
+func SearchConfig(application string, search Search, supplied ...SearchOptions) Source {
+	options := make([]engine.SearchOptions, len(supplied))
+	for index, option := range supplied {
+		options[index] = engine.SearchOptions{Required: option.Required}
+	}
+	return Source{value: engine.SearchConfig(application, search.value, options...)}
+}

docs/adr/0005-explicit-overrides-and-safe-explanation.md

@@ -1,6 +1,8 @@
 # ADR 0005: Record explicit CLI overrides and safe value explanation
 
-Status: accepted
+Status: Partially superseded by
+[ADR 0018](0018-cli-after-structural-resolution.md) for override-before-decoding
+ordering. The remaining ownership and safe explanation decisions remain accepted.
 
 Date: 2026-09-06
 

docs/adr/0007-source-backed-underlays.md

@@ -2,7 +2,9 @@
 
 ## Status
 
-Proposed draft for review. Completed planning and remediation records are
+Proposed draft for review; its whole-sequence precedence replacement rule is
+superseded by [ADR 0017](0017-collection-sequence-policy.md). The remainder
+retains its proposed status. Completed planning and remediation records are
 preserved in Git history at `b604aa1` under `docs/roadmap/`; the
 [configuration contract](../config.md#layered-loading) owns current behavior.
 

docs/adr/0009-sibling-inheritance.md

@@ -2,8 +2,14 @@
 
 ## Status
 
-Accepted and implemented. The [configuration contract](../config.md#sibling-inheritance)
-owns current behavior. The completed implementation plan is preserved in Git
+Partially superseded by [ADR 0017](0017-collection-sequence-policy.md) for
+sequence combination and the addition of identified-sequence sibling scopes,
+and [ADR 0018](0018-cli-after-structural-resolution.md) for CLI-before-inheritance
+ordering. Existing mapping-sibling scopes and the remaining ownership and
+inspection decisions remain accepted.
+
+The [configuration contract](../config.md#sibling-inheritance) owns implemented
+behavior. The completed implementation plan is preserved in Git
 history at `83c59ea`.
 
 ## Date

docs/adr/0011-input-destinations.md

@@ -0,0 +1,74 @@
+# ADR 0011: Place Configuration Inputs at Mapping Destinations
+
+## Status
+
+Accepted and implemented. Current placement behavior is owned by the
+[configuration contract](../config.md#input-destinations). The accepted
+relative-import extension is recorded in
+[ADR 0012](0012-relative-import-destinations.md). The completed roadmap, consumer
+request, and review records are preserved at `e4270c9` under `docs/roadmap/` in
+Git history; the original input-destination implementation plan remains at
+`315f464:docs/roadmap/implementation.md`.
+
+## Date
+
+2026-10-14
+
+## Context
+
+Consumers assembling collections of independently authored configuration
+fragments need each source to contribute beneath a selected application path.
+Requiring consumers to rewrite source documents or merge completed values would
+separate placement from ConfigKit's existing composition, precedence, source
+identity, and inspection behavior. Placement should remain part of the ordinary
+loading lifecycle and preserve the root-owned public facade.
+
+## Decision
+
+Add an optional `Destination Path` to root-owned `Input` and expose the effective
+destination on existing `SourceInfo` records. The empty path means the existing
+application root. A non-empty destination is a sequence of literal mapping keys;
+explicit sequence-index segments are invalid. Existing reserved structural keys
+remain reserved, while keys that merely contain their spelling remain ordinary
+keys.
+
+Acquire and interpret each source using its original physical identity and
+source-local directives, then place its application body before strict
+composition and the existing final lifecycle. Imported application bodies
+inherit the input destination. Placement applies to main and underlay inputs;
+ordinary root loading, selected overlays, and CLI inputs retain root placement.
+The main-owned version rule continues to check its effective application path
+at its existing lifecycle point.
+
+Placement preserves authored node locations and source identity. Introduced
+mapping structure belongs to the contributing source and uses that document's
+root location as its source-coordinate fallback. A present empty mapping
+materializes its destination; an absent `NoSource` contributes nothing. The
+result continues through the existing strict composition, overlay, inheritance,
+typed loading, diagnostics, provenance, history, sensitivity, and resource
+context mechanisms.
+
+The added exported fields preserve keyed and zero-value struct use. Callers
+using unkeyed composite literals for `Input` or `SourceInfo` must migrate to
+keyed literals. Treat this feature as minor-release work; select the version and
+document the compatibility impact during separately authorized release
+preparation, consistent with the release policy.
+
+## Alternatives considered
+
+- **Rewrite or merge sources in consumers.** This makes each consumer reproduce
+  placement, strict composition, source attribution, and inspection semantics.
+- **Add a separate loading entry point or public wrapper type.** This creates a
+  parallel API for a behavior that belongs to existing per-input loading.
+- **Load each fragment as a complete application before placement.** This runs
+  defaults, decoding, resolution, and validation on incomplete fragments rather
+  than once on the assembled application.
+
+## Consequences
+
+Consumers can assemble contributions at effective mapping paths in one ordinary
+layered load and inspect each source's placement through existing source
+records. Paths, conflicts, and later application operations use the placed
+structure while source coordinates and relative-resource contexts continue to
+identify their original sources. Public field additions require release-note
+guidance for callers using unkeyed literals.

docs/adr/0012-relative-import-destinations.md

@@ -0,0 +1,78 @@
+# ADR 0012: Place Imported Configuration at Relative Destinations
+
+## Status
+
+Accepted and implemented. The
+[configuration contract](../config.md#input-destinations) owns current behavior.
+The completed roadmap and review records are preserved at `e4270c9` under
+`docs/roadmap/` in Git history; the relative-import implementation plan remains
+at `d9f08ff:docs/roadmap/implementation.md`.
+
+## Date
+
+2026-10-14
+
+## Context
+
+ConfigKit can place an input document at a literal mapping path while retaining
+source identity, composition, and inspection in its normal loading lifecycle.
+An importing document can currently bring in other documents, but those
+contributions inherit only the importing input's destination. Consumers that
+assemble a collection therefore cannot declare the layout of imported
+fragments alongside the import itself without rewriting source documents or
+performing another merge outside ConfigKit.
+
+The extension should reuse input placement and the existing import lifecycle.
+Logical application placement must remain independent from physical path
+resolution, source identity, precedence, and resource ownership.
+
+## Decision
+
+Add an optional `destination` field to each YAML import declaration. Its value
+is a sequence of strings representing literal mapping-key segments. Omission
+and an empty sequence add no segments. A non-empty destination appends to the
+effective destination of the immediately importing document; nested imports
+continue from the resulting child destination. Every match of one glob
+declaration receives the same computed destination.
+
+Use the existing input-destination validation and reserved-key rules. Do not
+interpret destination segments as filesystem paths, separators, sequence
+indices, or root-reset instructions. Physical import paths continue to resolve
+from their declaring source under existing containment rules.
+
+Imports remain in their existing strict-composition group. A destination does
+not grant precedence, bypass cycle or repeated-source rules, or change source
+identity. Existing placement, version ownership, source records, diagnostics,
+resource contexts, inheritance, history, and inspection mechanisms continue to
+govern the placed contributions. No public Go entry point or independent
+specification-header behavior is introduced.
+
+This is additive YAML functionality and is minor-release work. Version
+selection, release notes, roadmap retirement, and publication remain separate
+release-preparation work.
+
+## Alternatives Considered
+
+- **Require complete application-root destinations on every import.** This
+  avoids inherited context but repeats collection prefixes in nested source
+  declarations and does not express placement relative to the importing
+  document.
+- **Encode destinations as dotted or slash-delimited strings.** This introduces
+  separator and escaping rules even though existing paths already represent
+  literal mapping keys as segments.
+- **Rewrite or merge imported documents in consumers.** This duplicates source
+  placement, strict composition, attribution, and inspection behavior outside
+  ConfigKit's loading lifecycle.
+- **Add independent specification headers or collection-specific validation.**
+  These are separate design questions and are not required to declare relative
+  placement.
+
+## Consequences
+
+Import declarations can describe the logical placement of their contributions
+while preserving the physical source and existing composition lifecycle.
+Placement is immediate-parent-relative, so nested imports accumulate their
+declared segments and sibling declarations remain independent. The feature is
+implemented behind the existing public loading surface; detailed validation,
+diagnostic, accounting, and inspection requirements are tracked by the
+implementation roadmap.

docs/adr/0013-shared-source-version-checks.md

@@ -0,0 +1,92 @@
+# ADR 0013: Check Source Versions with One Shared Policy
+
+## Status
+
+Accepted and implemented. The
+[configuration contract](../config.md#shared-source-version-checks) owns current
+behavior. The completed roadmap, implementation plan, consumer request, and
+resolved review findings are preserved at `e4270c9` under `docs/roadmap/` in
+Git history; the [development guide](../development.md#baseline-validation)
+provides retrieval examples.
+
+## Date
+
+2026-10-15
+
+## Context
+
+Applications that assemble one configuration from independently authored
+documents need a way to require that each contributing document declares a
+version accepted by the application's existing `Definition.Version` checker.
+Checking only the eventual composed value lets another source hide a rejected
+declaration, while separate consumer-side parsing duplicates ConfigKit's source
+handling and diagnostics.
+
+The extension must preserve one application-owned acceptance policy and the
+existing loading lifecycle. Source declarations are compatibility evidence, not
+independent fragment schemas or values to compare for equality. Existing
+composition, placement, precedence, source identity, diagnostics, and
+sensitivity rules remain authoritative.
+
+## Decision
+
+Provide a load-wide source-version mode for ordinary and layered loading. The
+zero-value mode preserves current behavior. The enabled modes check declarations
+when present or require them, using the existing `Definition.Version` path and
+checker. Interpret the configured path relative to each participating source
+before placement or composition. Different declarations may be accepted by the
+same checker; ConfigKit adds no equality, SemVer, or expected-version rule.
+
+Apply the selected policy to the actual main document, direct underlays,
+imports, and selected overlays. Missing non-main declarations are skipped in
+if-present mode and rejected in required mode. Existing main absence behavior
+remains, with required mode additionally rejecting an absent declaration on an
+actual main document. `NoSource`, unmatched optional inputs, synthetic field
+operations, and empty groups do not become documents that need declarations.
+
+Reuse the existing version vocabulary and validation boundary: absence, null,
+exact strings, and strict decimal integers retain their established meanings;
+unsupported present values fail version-type validation. Warnings remain
+nonfatal, and source declarations do not replace final application decoding or
+domain validation.
+
+After an accepted non-main declaration is checked, consume exactly that node
+before its remaining application content is composed or overlaid. Preserve the
+main declaration and its value semantics. Keep the declaration, source-local
+path, physical location, and checked absence as detached source evidence,
+separate from effective application values and history. Apply established
+sensitivity rules to that evidence, including original mounted paths and
+ancestors; retain existing safe failure disclosure.
+
+In enabled modes, the main declaration remains source-local while its protected
+application path is derived from the main input's destination. This distinction
+does not change default-mode path interpretation or weaken protection of
+remaining payload and synthetic operations.
+
+Public option-field additions and the enabled-mode interpretation for mounted
+main inputs are compatibility considerations for separately authorized minor-
+release preparation. This decision does not select a release version or
+authorize release notes or publication.
+
+## Alternatives Considered
+
+- **Check only the final composed value.** Later sources can hide an earlier
+  rejected declaration, so this does not validate every contributing document.
+- **Let consumers parse and check each source.** This duplicates acquisition,
+  source attribution, safe diagnostics, and lifecycle coordination in every
+  application.
+- **Require declarations to be equal or impose a universal version grammar.**
+  Consumers already own the acceptance policy; ConfigKit need not invent an
+  expected value or a domain-specific compatibility rule.
+- **Keep accepted non-main declarations in application payload.** A selected
+  source-local declaration is metadata for this policy and cannot also remain
+  an ordinary field at the same path without ambiguity.
+
+## Consequences
+
+Consumers can apply one existing version policy across contributing documents
+and select gradual or required adoption per load. Accepted non-main headers no
+longer participate in application composition; their inspectable evidence is
+kept separate and subject to sensitivity classification. Default callers retain
+current behavior. The implementation plan records the concrete API names,
+integration order, and validation evidence.

docs/adr/0014-sequence-placement-and-composition.md

@@ -0,0 +1,81 @@
+# ADR 0014: Place and Compose Sequence Items Explicitly
+
+## Status
+
+Partially superseded by [ADR 0017](0017-collection-sequence-policy.md) for
+identity ownership and sequence combination. Explicit source placement remains
+accepted.
+
+The [configuration contract](../config.md#strict-document-composition)
+defines implemented behavior, and the [consumer guide](../consumers/README.md#identified-prompt-sequences)
+shows the maintained example. The completed roadmap, implementation plan, and
+resolved remediation record are preserved in Git history at `008d2ba` under
+`docs/roadmap/`; see the [development guide](../development.md) for retrieval
+commands.
+
+## Date
+
+2026-10-16
+
+## Context
+
+ConfigKit strictly composes independent documents by recursively combining
+mappings and rejecting other overlapping values. This makes two independently
+authored sequence fragments conflict, even when their records are distinct.
+Precedence assembly has a different purpose: a higher-priority present sequence
+replaces the lower-priority sequence as one value. Those existing rules are
+predictable, but they do not express the separate operation of collecting
+independent records while rejecting duplicate identities.
+
+Likewise, mapping destinations place a source beneath literal mapping keys, but
+there is no explicit way to state that a source mapping represents one item in a
+sequence. Inferring that intent from document shape or fields would make source
+meaning implicit and change existing placement behavior.
+
+## Decision
+
+Keep mapping placement as the zero-value behavior and add an explicit item
+placement choice for a source whose mapping should become one element at a
+non-root sequence destination. Item placement provides structure only; it does
+not infer or synthesize identity values.
+
+Allow a definition to register literal mapping paths and one literal identity
+field for sequences at those paths. Within each strict composition tier, a
+registered sequence accepts mapping records with a present string identity,
+appends distinct records in contribution order, and rejects repeated exact
+identity strings. Identical registrations coalesce; conflicting identity fields
+for the same path are invalid. Registration does not recursively select paths
+inside sequence records.
+
+Keep precedence assembly unchanged. A present higher-priority sequence replaces
+the lower-priority value wholesale, including at a registered path. Registration
+changes strict composition only; it does not turn precedence into append or
+identity-based merging.
+
+This decision preserves ConfigKit's distinction between independent
+same-priority contributions and intentional precedence. Explicit source
+placement and definition-owned composition policy make the two required choices
+visible while keeping the existing zero-value load behavior.
+
+## Alternatives Considered
+
+- **Infer item placement from a source mapping or identity field.** Shape-based
+  inference would make ordinary mapping placement depend on document contents
+  and would leave the intended destination ambiguous.
+- **Append all overlapping sequences during strict composition.** This would
+  change existing conflict semantics at unregistered paths and would not detect
+  duplicate records.
+- **Merge matching records recursively by identity.** This would add a second
+  recursive merge rule with different conflict and precedence behavior from
+  ConfigKit's existing mapping composition and overlay operations.
+- **Use identity to merge sequences across precedence tiers.** This would
+  change established whole-value replacement semantics and conflate strict
+  composition with precedence.
+
+## Consequences
+
+Consumers can explicitly place mappings as sequence items and opt selected
+sequences into duplicate-rejecting strict composition. Unregistered sequences
+retain their current strict-conflict behavior, and higher-priority sequences
+continue to replace lower-priority ones. The implementation plan owns the exact
+API, YAML syntax, diagnostics, and implementation status.

docs/adr/0015-shared-dependency-ready-ordering.md

@@ -0,0 +1,68 @@
+# ADR 0015: Share Dependency-Ready Ordering Across Imports and Inheritance
+
+## Status
+
+Accepted. Implemented behavior is described in the
+[configuration contract](../config.md#explicit-imports) and
+[internal import overview](../internal/imports.md).
+
+## Date
+
+2026-10-19
+
+## Context
+
+Imports and sibling inheritance both resolve relationships between configuration
+contributions. Their existing resolvers use different traversal rules, making
+ordering depend on which mechanism expresses a dependency. Ordering affects
+sequence contributions, provenance, and diagnostics, so a consistent rule is
+part of ConfigKit's configuration model.
+
+The resolvers also serve distinct purposes. Imports strictly compose sources;
+inheritance overlays a child on its resolved parent after source assembly.
+Item-local contributions and nested inheritance introduce scope boundaries that
+resolution must preserve.
+
+## Decision
+
+ConfigKit owns one shared dependency-ready scheduler for imports and sibling
+inheritance. Both resolvers use Kahn's algorithm with a stable ordering key,
+selecting the smallest currently eligible node after its dependencies have
+completed. The shared scheduler owns eligibility, deterministic tie-breaking,
+and dependency-cycle identification. Each resolver owns construction of its
+dependency relationships and application of its domain operations.
+
+Apply the common scheduling rule within the scopes where dependencies are
+available. Complete item-local contributions before item placement and resolve
+enclosing inheritance before relationships in the resulting nested scopes.
+Source discovery supplies the import graph; the scheduler determines resolution
+order.
+
+Strict composition, inheritance overlay, and precedence tiers retain their
+existing ownership and meanings under [ADR 0001](0001-separate-composition-and-overlay.md).
+The lifecycle and scope decisions in
+[ADR 0009](0009-sibling-inheritance.md) continue to govern inheritance. Import
+admission retains its cycle and repeated-source rules.
+
+## Alternatives Considered
+
+- **Deterministic depth-first postorder.** Keeps dependency branches together,
+  but gives traversal branch selection an additional role in ordering.
+- **Dependency rounds.** Groups nodes by readiness rounds, but delays newly
+  eligible nodes until the current round finishes.
+- **Descending longest-path depth.** Prioritizes the furthest dependencies,
+  but adds distance from the root as an ordering policy.
+- **Separate resolver algorithms.** Allows local specialization, but leaves
+  consumers and maintainers with different rules for analogous dependencies.
+
+## Consequences
+
+Both resolvers follow one deterministic ordering model and share responsibility
+for maintaining that model. Resolver-specific scopes, combination semantics,
+and source-admission rules remain explicit at their integration boundaries.
+
+Independent branches may interleave as nodes become eligible. Adopting this
+rule changes existing traversal-dependent sequence positions and reporting
+order, requiring coordinated review of source assembly, provenance, and
+inheritance behavior. The configuration contract owns the implemented ordering
+details.

docs/adr/0016-independent-import-controls.md

@@ -0,0 +1,83 @@
+# ADR 0016: Separate Import Selection, Traversal, and Presence Requirements
+
+## Status
+
+Accepted. Implemented behavior is described in the
+[configuration contract](../config.md#explicit-imports), the
+[public API declarations](../../lifecycle.go), and the
+[internal import overview](../internal/imports.md).
+
+## Date
+
+2026-10-19
+
+## Context
+
+Consumers assemble configurations from named files and collections whose layout
+varies between installations. Simple imports should require little setup, while
+larger collections need control over discovery, recursion, filtering, and
+required contributions. Combining those choices implicitly makes declarations
+harder to interpret and pushes source-selection work into applications.
+
+Discovery can also reach a candidate through overlapping searches or encounter
+different names for one canonical source. Selection and source admission need
+distinct identities to support useful search unions while preserving ConfigKit's
+existing source-integrity rules.
+
+## Decision
+
+ConfigKit owns import discovery and selection within its source-loading
+lifecycle. Support explicit files, directory searches, and path globs as
+distinct selection forms. Keep traversal, filename filtering, and presence
+requirements independently expressible. Discovery determines the selected
+contributions; the shared scheduler in
+[ADR 0015](0015-shared-dependency-ready-ordering.md) determines their resolution
+order.
+
+Use optional-by-default imports with explicit requiredness controls. Selected
+sources remain subject to ConfigKit's validity, containment, resource, and
+composition contracts. This applies the library's
+[simplicity and defaults principles](../policy/architecture.md#simplicity-defaults-and-explicit-controls)
+to import absence while retaining meaningful errors for invalid contributions.
+
+Applications own their selected import defaults. Authored declaration values
+take precedence over application defaults, which take precedence over library
+defaults. Each declaration resolves applicable controls independently,
+including declarations in imported sources. This gives applications a shared
+baseline while preserving explicit choices in individual declarations.
+
+Keep declaration-local candidate identity separate from canonical source
+identity. Search unions coalesce repeated candidate paths within a source
+namespace before symlink resolution; filename filtering uses the selected or
+discovered name. Source admission continues to use canonical identity and the
+existing repeated-source rules. Distinct aliases retain their separate
+inclusion routes.
+
+## Alternatives Considered
+
+- **Use path globs for all discovery.** Offers one selection form, but makes
+  collection traversal depend on path-pattern structure and complicates
+  independently controlling recursion and filename filtering.
+- **Offer only explicit files and directory searches.** Reduces the selector
+  vocabulary, but moves wildcard directory selection into repeated declarations
+  or application-side discovery.
+- **Require every import by default.** Detects absent contributions immediately,
+  but requires repeated opt-outs for installations with optional components.
+- **Make application settings override authored declarations.** Provides central
+  enforcement, but prevents declarations from expressing local exceptions.
+- **Deduplicate selections globally by canonical source identity.** Coalesces
+  aliases and separate inclusion routes, but changes the existing repeated-source
+  contract and obscures independently authored contributions.
+
+## Consequences
+
+Consumers can express simple imports and more selective collection searches
+through the same loading lifecycle. Applications choose defaults and validate
+their required effective configuration; ConfigKit owns consistent selection,
+source admission, composition, and inspection.
+
+Optional absence can conceal misspelled selectors, so requiredness and
+inspection provide explicit ways to detect and explain missing contributions.
+Declaration-local deduplication requires the loader to preserve candidate
+identity alongside canonical source identity. The configuration and public API
+contracts own the implemented behavior.

docs/adr/0017-collection-sequence-policy.md

@@ -0,0 +1,143 @@
+# ADR 0017: Define Identity and Merge Rules for Each Collection
+
+## Status
+
+Accepted.
+
+This supersedes the decisions about who declares identity and how
+sequences combine in [ADR 0014](0014-sequence-placement-and-composition.md),
+and the rule that inheritance always replaces sequences in
+[ADR 0009](0009-sibling-inheritance.md). It also extends that ADR's sibling
+scopes to identified sequences. Existing mapping-sibling scopes and source
+placement continue to apply. It supersedes the whole-sequence
+precedence replacement rule in the proposed
+[ADR 0007](0007-source-backed-underlays.md).
+
+## Date
+
+2026-10-22
+
+## Context
+
+ConfigKit can load separate files as records in a sequence. Applications can
+register an identity key so records with different identities combine and
+duplicates fail. However, a higher configuration layer or an inheriting mapping
+currently replaces the whole sequence. Applications that need to extend a
+catalog across layers must write their own merging code and keep source and
+history information consistent with its results.
+
+Configuration authors need to choose how records are identified and whether a
+layer adds records, updates records, or replaces the collection. Applications
+also need a way to require unique identities in the final loaded configuration.
+These rules must work consistently for imported records, inline sequences,
+overlays, and inheritance.
+
+Records in a sequence may also share settings. Authors need to reuse those
+settings through inheritance while keeping each record's own identity.
+
+## Decision
+
+ConfigKit manages identity and merge rules for each collection during loading.
+Configuration files can declare those rules for imported and inline sequences,
+including sequences in selected overlays. Applications can require a particular
+identity definition, and configuration declarations must agree with it. Source
+placement determines where each contribution enters the configuration.
+
+Keep the distinction between contributions at the same priority and overrides
+from a higher layer, as established in
+[ADR 0001](0001-separate-composition-and-overlay.md). Within one tier, records
+with distinct identities combine; duplicate identities and conflicting
+declarations fail. Determine the applicable rules before combining those
+contributions, including any identity established in lower tiers.
+
+Across layers, support three operations: replace the whole sequence, append
+records while rejecting duplicate identities, or replace whole records by
+identity (`upsert`). Source layering and sibling inheritance use the same
+operations. For inheritance, the rules at the inheriting destination determine
+which operation applies.
+
+An identified sequence is also a sibling scope for inheritance. A record may
+inherit from one other record in the same sequence, selected by its complete
+identity. Each record supplies its own identity before inheritance. The child
+keeps that identity and combines its settings with the parent's other fields,
+using the existing mapping and collection rules. Parents remain ordinary records
+subject to normal validation.
+
+Resolve these relationships after source assembly, using the same dependency
+ordering as mapping-sibling inheritance. Resolve nested relationships at each
+inheriting destination. Preserve the assembled sequence order. Whole-record
+upsert keeps its existing meaning; inheritance then uses the records that remain.
+Typed defaults, CLI overrides, and application resolution follow the lifecycle
+in [ADR 0018](0018-cli-after-structural-resolution.md).
+
+An explicitly selected operation remains in effect at its destination until a
+higher layer changes it. When no explicit operation applies, use upsert if an
+identity definition is available; otherwise replace the whole sequence. Authors
+can declare identity and an operation before supplying any records. Keep source
+acquisition order separate from layer priority and the dependency ordering
+established by [ADR 0015](0015-shared-dependency-ready-ordering.md).
+
+Rules declared inside a record belong to that record. Retaining the record
+retains its local rules; replacing it discards them. Replacing a whole collection
+can discard its previous YAML identity definition, while application requirements
+still apply. Inheritance can copy collection identity, but the inheriting
+destination chooses its operation. Application registrations continue to govern
+the paths where they were registered. The same ownership rules apply to
+declarations made before a sequence exists.
+
+Check YAML-declared identity when combining collections during source assembly
+and inheritance. Application registrations also require the final loaded
+sequences to satisfy their identity rules, including after typed defaults, CLI
+overrides, and application resolution. This guarantee checks sequences that
+exist; the application schema and validation decide whether a collection must
+exist and which value types are allowed. The guarantee applies when loading
+completes, rather than to every intermediate callback state or changes made by
+the caller afterward.
+
+Preserve explicit presence, source attribution, history, sensitivity, and
+resource context through these operations, following
+[ADR 0003](0003-preserve-presence-and-resolution-history.md). Typed defaults,
+CLI assignments, and application resolution keep their own rules for changing
+values. The public API provides registration and inspection; the implementation
+chooses how to store and track collection rules internally.
+
+## Alternatives Considered
+
+- **Keep identity application-owned and always replace sequences across layers.**
+  Keeps the current design small, but reusable catalogs require application
+  changes or custom merging code.
+- **Put merge rules on each import.** Keeps the rules beside the imported source,
+  but inline sequences and overlays need a separate way to declare them. It also
+  makes rules for a collection spread across several imports harder to reconcile.
+- **Merge individual fields of records with matching identities.** Allows partial
+  record updates, but adds rules for field conflicts and retained values.
+  Replacing the whole record makes the update's scope clear.
+- **Keep inheritance limited to mapping siblings.** Keeps parent lookup simpler,
+  but authors of sequence records must duplicate shared settings or applications
+  must implement inheritance themselves. Collection identity provides a way to
+  select a parent within the existing loading process.
+- **Check every YAML identity again at the end of loading.** Gives YAML declarations
+  authority over values changed by defaults, CLI assignments, and application
+  resolution. This extends the lifetime of those declarations; application
+  registration provides that final guarantee when needed.
+
+## Consequences
+
+Consumers can build and customize catalogs in one load while retaining useful
+inspection information. Configuration authors choose how collections combine
+within application requirements. Duplicate identities among contributions at
+the same priority remain errors.
+
+Existing registered collections use upsert across layers by default unless an
+explicit operation selects otherwise. Correct loading now requires tracking
+which declarations still apply as records are replaced, copied, or moved to new
+positions. Lower-tier identity must be available before combining higher-tier
+contributions.
+
+Record inheritance also requires parent lookup by identity and checking for
+missing parents and cycles. Copied settings retain the same source, history,
+and sensitivity information as mapping-sibling inheritance.
+
+The [configuration contract](../config.md#strict-document-composition) defines
+declaration syntax, identity comparison, omission and empty-value behavior, and
+diagnostics for the implemented feature.

docs/adr/0018-cli-after-structural-resolution.md

@@ -0,0 +1,84 @@
+# ADR 0018: Apply CLI Overrides After Inheritance and Decoding
+
+## Status
+
+Accepted.
+
+This supersedes the rule that CLI overrides apply before decoding in
+[ADR 0005](0005-explicit-overrides-and-safe-explanation.md) and the
+rule that they apply before inheritance in [ADR 0009](0009-sibling-inheritance.md).
+Their remaining ownership, inheritance scope, and safe inspection decisions
+continue to apply.
+
+## Date
+
+2026-10-22
+
+## Context
+
+Explicit command-line values are the operator's highest-priority input. If they
+apply before inheritance, a sequence supplied as a replacement could gain
+inherited records afterward. Its final contents would then differ from the
+operator's assignment.
+
+The application also needs these values when it fills missing settings,
+normalizes values, or computes derived settings. ConfigKit needs a clear loading
+order that preserves both CLI precedence and the application's role in resolving
+the final configuration.
+
+## Decision
+
+ConfigKit uses this loading order:
+
+1. Combine sources within tiers and apply precedence between layers.
+2. Resolve sibling inheritance, apply typed defaults, and decode the configuration
+   into the application's types.
+3. Apply explicit CLI overrides and check them against the application schema.
+4. Run application resolution using the overridden configuration.
+5. Look up effective secret references, validate the final configuration, and
+   return it.
+
+CLI overrides are the highest-priority input to application resolution. A CLI
+sequence replaces the whole sequence; mappings combine recursively. Collection
+merge rules apply during the earlier source and inheritance steps. Inheritance
+and typed defaulting do not run again after CLI overrides.
+
+Keep track of which values were explicitly supplied and which CLI input supplied
+them. Applications continue to parse command-line arguments; ConfigKit applies
+and validates the overrides and makes their effects inspectable. Reject
+structural directives in override paths and values, so instructions such as
+inheritance relationships remain part of source processing.
+
+Application resolution keeps its existing rules for defaults and recorded
+changes under [ADR 0003](0003-preserve-presence-and-resolution-history.md).
+It receives CLI values together with their presence and source information.
+Defaults that only fill missing settings preserve explicit CLI values.
+Application normalization and derived-value calculations can still change them,
+with those changes recorded. Secret lookup and final validation use the resulting
+configuration.
+
+## Alternatives Considered
+
+- **Apply CLI overrides before inheritance.** Preserves existing ordering, but
+  later merging needs special handling to preserve CLI replacement intent while
+  still combining ordinary source contributions.
+- **Apply CLI overrides after inheritance but before typed decoding.** Allows an
+  override to fix a source value that would otherwise fail decoding, but leaves
+  typed defaulting after the operator's assignment. Completing defaulting and
+  decoding first gives CLI overrides an already resolved configuration to modify.
+- **Apply CLI overrides after application resolution.** Applies assignments after
+  the application's changes, but derived settings still reflect earlier values
+  unless resolution runs again.
+
+## Consequences
+
+CLI overrides change a configuration whose inheritance and typed defaults are
+already resolved. The application can then derive settings from the operator's
+values. The final values, source information, history, and sensitivity handling
+must remain consistent throughout loading.
+
+CLI input can no longer add or cancel inheritance relationships or bypass an
+earlier error in source assembly or inheritance. It also cannot fix a value that
+fails the earlier decoding step. Semantic validation still runs after overrides
+and application resolution. The [configuration contract](../config.md#explicit-cli-overrides)
+and [consumer guidance](../consumers/README.md) describe this behavior.

docs/adr/0019-explicit-configuration-discovery.md

@@ -0,0 +1,68 @@
+# ADR 0019: Keep Configuration Discovery Explicit and Inside Loading
+
+## Status
+
+Accepted.
+
+## Date
+
+2026-10-24
+
+## Context
+
+Applications often need a small ordered convention for choosing a main
+configuration file. Keeping that choice entirely in each application repeats
+path selection and file-loading plumbing. Moving the convention into ConfigKit
+without an explicit declaration would make ordinary loads search paths that a
+consumer did not choose, obscuring both precedence and filesystem access.
+
+ConfigKit already owns synchronous source acquisition, parsing, composition,
+decoding, validation, and inspection. A selected host file can therefore enter
+that lifecycle as the existing file source, preserving its source identity,
+resource context, and diagnostics. Optional exhaustion can use the same absent
+main lifecycle as an explicitly absent source.
+
+## Decision
+
+Consumers choose and order the main-file conventions they want to use. They may
+describe literal paths, directory filename groups, and supported directory
+presets, and may mark the complete search as required. Search descriptions are
+explicit inputs to loading; no preset or convention is activated implicitly.
+
+During synchronous loading, ConfigKit resolves the description to one real host
+file or to absence before parsing. The selected file follows the existing source
+acquisition and processing rules. A selected-file access, parse, version,
+composition, decode, or validation failure is terminal and does not resume the
+search. Optional exhaustion shares the absent-main lifecycle; required
+exhaustion reports a missing-source diagnostic. No candidate-attempt history is
+added to public metadata.
+
+This keeps convention choice with applications while moving repeated selection
+and loading plumbing into the library's established lifecycle. It preserves
+explicit control, ordinary source behavior, and complete-on-return ownership.
+
+## Alternatives Considered
+
+- **Keep all search and fallback loading in each application.** This preserves
+  consumer ownership but repeats the file-selection and load coordination that
+  ConfigKit already owns, and risks divergent handling of selected-file errors.
+- **Search conventional locations implicitly during every load.** This reduces
+  setup, but activates filesystem access and precedence the consumer did not
+  select and makes ordinary source behavior less predictable.
+- **Return candidate paths for the application to load one by one.** This keeps
+  selection outside the load lifecycle and encourages repeated complete loads,
+  potentially rerunning defaults, callbacks, and validation during fallback.
+
+## Consequences
+
+The public search description must be immutable and root-owned, with private
+engine conversion and selection. The contract documents candidate ordering,
+selection, exhaustion, context, and provenance; the API declaration documents
+the public symbols. Dynamic bases and file availability are observed when each
+load consumes the description. Applications remain responsible for selecting
+conventions and for their schema and domain requirements.
+
+The [configuration contract](../config.md) owns implemented behavior, and the
+[component overview](../internal/overview.md) describes implementation ownership.
+The completed implementation plan and remediation record are preserved in Git
+history at `0369111` under `docs/roadmap/`.

docs/consumers/README.md

@@ -6,6 +6,33 @@ applications. Consumers still own their configuration structs, defaults, semanti
 validation, schema-version policy, CLI parsing, runtime matching and conversion,
 resource checks, remote acquisition, and service initialization.
 
+Import the public root package as `"go.maximumdirect.net/configkit"`; its package
+name remains `configkit`.
+
+## Choosing a loading entry point
+
+- Use [`Load`](../../lifecycle.go) with one source for an ordinary configuration.
+  [`SearchConfig`](../../discovery.go) is also a source, so its explicit
+  discovery result can be passed to `Load` or used as the main input to
+  [`LoadLayered`](../../layered.go).
+- Use `LoadLayered` when inputs must be composed in underlay groups before the
+  main source. Each [`Input`](../../layered.go) owns its source, filesystem,
+  destination, and import choice. The overlay filesystem context is selected
+  independently in [`LayeredOptions`](../../layered.go).
+- Load-wide rules belong to [`Options`](../../lifecycle.go) or
+  [`LayeredOptions`](../../layered.go): the application definition (including
+  version policy), import defaults, and explicit overrides. These do not turn
+  on imports or discovery by themselves. See the
+  [configuration contract](../config.md#layered-loading) and
+  [discovery contract](../config.md#configuration-discovery) for exact rules.
+
+The root [README example](../../README.md) shows the small `Load` path.
+[`layered.go`](../../examples/consumers/layered.go) demonstrates the bundled
+file and layered cases. For import-focused adoption, see the
+[prompt catalog](../../examples/consumers/prompt_catalog.go); for explicit
+discovery composed with sequences, see the
+[sequence catalog](../../examples/consumers/sequence_catalog.go).
+
 The maintained [`examples/consumers`](../../examples/consumers) package demonstrates
 sanitized shapes using only ConfigKit and the Go standard library:
 
@@ -17,8 +44,11 @@ sanitized shapes using only ConfigKit and the Go standard library:
 | Seriatim-like | Independent strict ordered speaker and autocorrect rule files | First-match and ordered replacement algorithms; no central application configuration file |
 | Bundled file | Simple native `fs.FS` source through ordinary `Load` | Selection and lifetime of the application-owned embedded filesystem |
 | Layered catalog | Embedded defaults with an import, a mapping underlay, an independent host main file, explicit false/zero input, and source-relative resource access | Domain validation and opening/interpreting the template resource |
+| Mounted collections | Entry-declared relative destinations, nested metadata/prompt/profile imports, local inheritance, and a version-only higher-tier override | Collection IDs, profile meaning, and opening/interpreting prompt resources |
 | Named presets | One-load sibling inheritance, explicit false, nested destination resolution, and source/derivation inspection | Choosing and executing a preset |
 | Effective configuration diff | Same-type frozen effective comparisons for two selected files or base-versus-overlay impact | Source/options selection and consumer-owned safe presentation |
+| Shared source-version checks | One `Definition.Version` policy for accepted declarations across participating source documents, with optional or required declarations and sanitized evidence | Choosing which declarations the application accepts; final assembled schema and domain validation |
+| Sequence catalogs | Declared collection operations, record inheritance, typed CLI and resolution, inspection, exact and wildcard application registrations | Catalog meaning and final domain validation |
 
 The YAML under [`testdata`](../../examples/consumers/testdata) is loaded by the
 executable examples and ordinary tests. It contains no private application data,
@@ -52,6 +82,56 @@ both without redefining their syntax. ConfigKit overlays are configuration overl
 they do not select or replace an application's LLM, model, pipeline, report, or
 execution profile concepts.
 
+## Explicit main-file discovery
+
+Applications choose the search conventions and their precedence, then pass the
+resulting `SearchConfig` source to the same `Load` or `LoadLayered` entry point.
+For example, the maintained sequence catalog puts a caller-selected file before
+a custom directory fallback while keeping its underlay and overlay choices
+independent. See [`sequence_catalog.go`](../../examples/consumers/sequence_catalog.go)
+and its [behavior tests](../../examples/consumers/sequence_catalog_test.go), plus
+the [working-directory executable example](../../examples/consumers/discovery_test.go).
+Together, the root-owned [discovery API](../../discovery.go) and [configuration
+discovery contract](../config.md#configuration-discovery) define ordered
+concatenation, directory-first Cartesian expansion, optional exhaustion, and
+selected-file behavior. [ADR 0019](../adr/0019-explicit-configuration-discovery.md)
+records why discovery is explicitly selected.
+
+## Import defaults and selection inspection
+
+`Options.ImportDefaults` and `LayeredOptions.ImportDefaults` apply one
+load-wide policy to enabled main, underlay, and transitive imports. Each field
+is resolved independently: a declaration's explicit value wins, then the
+application default, then the library default. `Required`, `FollowSymlinks`,
+`IncludeHidden`, and `Recursive` use nil pointers for unspecified values.
+`Pattern` applies to
+directory searches: nil leaves filenames unrestricted, while a non-nil empty
+slice selects no files. A declaration's own `pattern` replaces the application
+default. The defaults do not enable imports or change selected-overlay behavior.
+The Go fields `FollowSymlinks` and `IncludeHidden` correspond to the unchanged
+YAML keys `follow` and `hidden`.
+
+`Result.Sources`, `LoadError.Sources`, and `Resolution.Source` expose each
+declaring source's `EmptyImportSelections`. `Result.Source(id)` and
+`LoadError.Source(id)` retrieve one retained record directly when its load-local
+ID is known. These records identify the source-local declaration path, its
+authored location and selector;
+they do not include candidate names or a guessed reason for absence. Returned
+records are detached snapshots. The [configuration contract](../config.md#explicit-imports)
+owns selector applicability and exact absence semantics.
+
+## Shared source-version checks
+
+[`LoadVersionedService`](../../examples/consumers/source_version.go) demonstrates
+if-present and required modes with one `Definition.Version` rule across a mounted
+main input and an underlay. The example reads only sanitized
+`SourceInfo.VersionEvidence` fields; its executable test is in
+[`layered_test.go`](../../examples/consumers/layered_test.go). The
+[configuration contract](../config.md#shared-source-version-checks) defines
+participation, source-local lookup and diagnostics, non-main header consumption,
+main-path protection, default behavior, and evidence disclosure. Accepted
+declarations do not replace final assembled decoding or application validation.
+
 ## Effective configuration diffs
 
 [`CompareFiles`](../../examples/consumers/diff.go) loads two caller-selected files
@@ -108,6 +188,79 @@ and may fail independently of the completed configuration load. The
 [configuration contract](../config.md#source-resource-contexts) owns exact
 lifetime and precedence rules.
 
+[`LoadPromptBundle`](../../examples/consumers/layered.go) is the ordinary-root
+counterpart: its entry opts into imports through `Load`, imports metadata at the
+root, and places a prompt beneath `prompts` using YAML. The executable example
+and behavior test are in
+[`layered_test.go`](../../examples/consumers/layered_test.go).
+
+## Input destinations and mounted collections
+
+Main and underlay inputs use the same destination field. An import without a
+`destination` inherits its declaring document's effective destination; an
+explicit sequence of key strings appends a relative suffix. Nested imports
+append to their immediate parent's effective destination, while filesystem
+paths remain relative to the declaring file. Destinations are application
+mapping paths, independent of filesystem context. The configuration contract
+owns the complete behavior and validation rules.
+
+The small [`Example_inputDestination`](../../examples/consumers/destinations_test.go)
+mounts one mapping source beneath literal collection/prompt keys and loads a
+second input without a destination to show that root placement remains the
+default. Consumers pass paths, not filenames or namespace strings for ConfigKit
+to interpret.
+
+[`LoadCollectionBundle`](../../examples/consumers/destinations.go) assembles an
+embedded collection manifest mounted beneath a literal collection path. The
+entry's YAML places nested metadata imports at the collection root and prompt
+and profile peers beneath their own keys. A higher-priority input changes only
+one prompt's ordinary `version` field. The main document alone supplies the
+application schema version. A prompt's local `extends` relationship resolves
+after all tiers, so `custom` inherits the final `brief` content and fields while
+retaining its own profile selection.
+
+The resolver follows each effective `content_file` origin to its declaring
+source context. This also works for `custom`'s inherited resource. The
+application-owned [`ReadCollectionPromptContent`](../../examples/consumers/destinations.go)
+demonstrates the same lookup after loading; ConfigKit does not open or interpret
+the resource. [`destinations_test.go`](../../examples/consumers/destinations_test.go)
+checks source destinations and authored coordinates, presence, inherited values,
+relative resources, and strict peer conflicts. The
+[configuration contract](../config.md#input-destinations) owns shared placement,
+import, source-location, and ownership behavior.
+
+## Identified prompt sequences
+
+[`LoadPromptCatalog`](../../examples/consumers/prompt_catalog.go) shows the
+smaller import-focused adoption path: a registered `prompts.id` identity,
+directory and glob selection, a helper import that supplies an item's ID, and
+resource lookup through the effective source context. Its executable examples
+and tests are in
+[`prompt_catalog_test.go`](../../examples/consumers/prompt_catalog_test.go), with
+complete [catalog](../../examples/consumers/testdata/prompt-catalog/config.yml)
+and [required-file](../../examples/consumers/testdata/prompt-catalog/simple.yml)
+fixtures.
+
+[`LoadSequenceCatalog`](../../examples/consumers/sequence_catalog.go) integrates
+an underlay declaration, imported main fragments, identified-record inheritance,
+selected overlay `append`, `upsert`, and `replace`, a typed CLI override, and
+recorded application resolution. Its tests and runnable example demonstrate
+stable output order, whole-record upsert, provenance/history inspection,
+resource lookup for inherited records, and secret-safe explanation in
+[`sequence_catalog_test.go`](../../examples/consumers/sequence_catalog_test.go).
+[`LoadNamespacedMapCatalog`](../../examples/consumers/sequence_catalog.go) adds
+an exact root registration and a wildcard namespace registration, showing that
+each concrete sequence has an independent identity scope. The same tests show
+that a YAML identity declaration without an application registration does not
+create final-result identity enforcement.
+
+The examples keep prompt meaning and domain checks in the consuming application.
+The [configuration contract](../config.md#strict-document-composition) owns
+declaration, identity, operation, ownership, and final-validation semantics;
+[sibling inheritance](../config.md#sibling-inheritance) defines record
+relationships, and the [CLI contract](../config.md#explicit-cli-overrides) owns
+override ordering.
+
 Known module catalogs should use canonical object entries with a module identifier
 and typed options. A small union struct is sufficient when the available option
 fields are known; validation selects which fields apply to each module. Runtime-
@@ -119,7 +272,7 @@ conversion API.
 ## Source-aware application path policy
 
 [`LoadNotariusPaths`](../../examples/consumers/consumers.go) is the maintained
-path-bearing example. Its application resolver uses `Resolution.InputInfo` and
+path-bearing example. Its application resolver uses `Resolution.EntryInfo` and
 `Resolution.Source` before normalizing: relative CLI input uses an explicitly
 supplied invocation directory, retained defaults use the canonical main source,
 and a file-authored scalar uses its one declaring source. Absolute paths remain
@@ -156,10 +309,67 @@ The examples preserve domain meaning while adopting one configuration convention
   parsers translate only explicitly set configuration flags into `Override` records.
   Separate invocation state remains outside configuration.
 - Credential fields migrate to environment-name `Secret` references. Applications
-  explicitly call `LoadSecretsDir` before `Load` when they choose file bootstrap;
+  explicitly call `LoadSecretsIntoEnvironment` before `Load` when they choose
+  file bootstrap;
   blocked empty variables remain blocked, and ordinary `Load` never changes the
   process environment.
 
+### Vanity module path migration
+
+ConfigKit's module identifier changed from
+`gitea.maximumdirect.net/eric/ConfigKit` to `go.maximumdirect.net/configkit` before
+v1.0.0. Update the dependency requirement in your application's `go.mod` and its
+Go imports together, selecting a revision or release that declares the new module
+path. The package name remains `configkit`; the configuration model and public
+symbol names are unchanged by this identity migration.
+
+Old and new import paths identify distinct Go packages, including distinct named
+types. Coordinate adoption with any dependencies that exchange ConfigKit values
+with your application; changing a requirement alone does not make those types
+interchangeable. The maintained examples use the new path, but other repositories
+must manage their own migrations.
+
+Historical tags keep their original module declarations and contents. Older
+releases such as v0.10.2 still use the old path and cannot be installed under the
+vanity identifier simply because discovery can find their repository. A matching
+migrated revision is needed; no old-path compatibility module is supplied here.
+
+### Pre-v1 public API cleanup
+
+The pre-v1 API cleanup replaces these names outright; it does not retain
+compatibility aliases:
+
+| Previous API | Current API |
+| --- | --- |
+| `Resolution.InputInfo(path)` | `Resolution.EntryInfo(path)` |
+| `Definition.Secret` | `Definition.Sensitive` |
+| `SourceVersionModeDefault` | `SourceVersionModeMainOnly` |
+| `SourceVersionCheck` | `SourceVersionEvidence` |
+| `SourceInfo.VersionCheck` | `SourceInfo.VersionEvidence` |
+| `ImportSelection` | `EmptyImportSelection` |
+| `SourceInfo.ImportSelections` | `SourceInfo.EmptyImportSelections` |
+| `SourceInfo.DestinationUnresolved` | `SourceInfo.DestinationIsFallback` |
+| `ImportDefaults.Follow` / `.Hidden` | `FollowSymlinks` / `IncludeHidden` |
+| `Paths(paths...)` | `SearchPaths(paths...)` |
+| `LoadSecretsDir(directory)` | `LoadSecretsIntoEnvironment(directory)` |
+| `LayerBase` | `LayerMain` |
+| `CodeExplainLimitExceeded` | `CodeHistoryLimitExceeded` |
+| `CodeResolveInvalidKind` / `CodeOptionsUnavailable` | Removed; no replacement |
+| `ImportSelection.Outcome`, `ImportSelectionOutcome`, `ImportSelectionNone` | Removed; empty-selection records no longer carry an outcome |
+| `Resolution.Record(path, ChangeDerivedDefault, reason, deps...)` | `Resolution.RecordDerivedDefault(path, reason, deps...)` |
+| `Resolution.Record(path, ChangeNormalization, reason, deps...)` | `Resolution.RecordNormalization(path, reason, deps...)` |
+| Enumerating `Result.Sources()` / `LoadError.Sources()` to find one ID | `Result.Source(id)` / `LoadError.Source(id)` |
+| Provenance string `"base"` | `"main"` |
+| History diagnostic string `"explain.limit_exceeded"` | `"history.limit_exceeded"` |
+
+The YAML import keys `follow` and `hidden`, the `configkit:"secret"` tag, and
+typed `Secret` references are unchanged. Consumers that compare literal strings
+or keep serialized diagnostic/provenance expectations may need to update those
+alongside Go references. This repository guidance does not claim that downstream
+applications have migrated and does not select a release version for this
+breaking pre-v1 change. `ChangeKind` and its inspection constants remain; use
+`Default` and `Normalize` when the helper should both assign and record a value.
+
 ### Selected-overlay migration
 
 To adopt the current selected-overlay API, rename `Options.Profile`,
@@ -185,8 +395,9 @@ focused behavioral owner:
 | `Load`, `NoSource`, validation, versions, resolution, `SecretEnv`, overrides, and explanation | Executable examples in [`example_test.go`](../../example_test.go) |
 | Source/import/selected-overlay pipeline rules and artifact defaults | Narratio-shaped executable example and fixture |
 | Canonical module objects and dynamic option handling | WeatherReporter- and Notarius-shaped examples and migration tests |
-| `LoadSecretsDir`, bootstrap reporting, typed lookup, CLI explanation | `Example_weatherStartup` |
+| `LoadSecretsIntoEnvironment`, bootstrap reporting, typed lookup, CLI explanation | `Example_weatherStartup` |
 | Native filesystem, grouped underlays, programmatic mapping, retained resource context | `Example_nativeFilesystem`, `Example_layeredCatalog`, and their focused consumer tests |
+| Literal input destinations, root-default compatibility, and mounted peer collections | `Example_inputDestination`, `LoadCollectionBundle`, and `destinations_test.go` |
 | Named sibling inheritance, presence, and derivation | `Example_inheritedPresets` and `TestPresetCatalogOneLoadAndDerivation` |
 | Effective configuration diffs and consumer-owned presentation | `ExampleDiff`, `ExampleCompareFiles`, and `ExampleCompareRolloutOverlay` |
 | Results, metadata, diagnostics, effective output, and writer failures | Focused root-package load, provenance, rendering, and explanation tests |

docs/development.md

@@ -39,9 +39,11 @@ public behavior.
 | Task | Read |
 | --- | --- |
 | Repository orientation or component responsibility | [Component overview](internal/overview.md) |
+| Input destinations | [Configuration contract](config.md#input-destinations), [ADR 0011](adr/0011-input-destinations.md), and the destination tests below |
+| Shared source-version checks | [Configuration contract](config.md#shared-source-version-checks), [ADR 0013](adr/0013-shared-source-version-checks.md), and the version/source-version tests below |
 | Documentation changes | The owning document |
 | Licensing, dependencies, attribution, or release-document changes | [Project grant](../COPYRIGHT) and [attribution](oss/attribution.md); release changes also follow the release procedure |
-| Architecture decisions or future work | [Deferred scope](roadmap/deferred.md) and relevant ADRs listed below |
+| Architecture decisions or future work | [Future features](roadmap/future.md) and relevant ADRs listed below |
 | Code and test changes | The owning contract and tests from the map below |
 | Examples or copyable assets | The owning implemented contract and [consumer adoption guide](consumers/README.md) |
 | Release preparation | [Release procedure](release.md) |
@@ -49,12 +51,19 @@ public behavior.
 Accepted decisions:
 
 - [Separate composition and overlay](adr/0001-separate-composition-and-overlay.md)
+- [Check source versions with one shared policy](adr/0013-shared-source-version-checks.md)
 - [Own YAML semantics behind a private parser boundary](adr/0002-own-yaml-semantics.md)
 - [Preserve presence and record application resolution](adr/0003-preserve-presence-and-resolution-history.md)
 - [Secret references and explicit bootstrap](adr/0004-secret-references-and-explicit-bootstrap.md)
 - [Explicit overrides and safe explanation](adr/0005-explicit-overrides-and-safe-explanation.md)
 - [Keep the public facade root-owned](adr/0006-public-facade.md)
 - [Compare frozen effective configuration snapshots](adr/0010-effective-configuration-diff.md)
+- [Place inputs at literal application mapping paths](adr/0011-input-destinations.md)
+- [Share dependency-ready ordering](adr/0015-shared-dependency-ready-ordering.md)
+- [Separate import selection controls](adr/0016-independent-import-controls.md)
+- [Define identity and merge rules for each collection](adr/0017-collection-sequence-policy.md)
+- [Apply CLI overrides after inheritance and decoding](adr/0018-cli-after-structural-resolution.md)
+- [Keep main-file discovery explicit and composable](adr/0019-explicit-configuration-discovery.md)
 
 For cross-cutting changes, follow every applicable row. Completed implementation
 and remediation plans are preserved in Git history at `cb5b435`; use current
@@ -104,7 +113,7 @@ git show 8e91a2b:docs/roadmap/startup-benchmark.md
 ```
 
 Remaining optimization candidates belong to
-[deferred scope](roadmap/deferred.md#deferred-performance-experiments).
+[future performance experiments](roadmap/future.md#5-performance-experiments).
 
 The completed effective-configuration diff roadmap, implementation plan, and
 resolved review findings are preserved in Git history at `1c2610c` under
@@ -113,6 +122,110 @@ resolved review findings are preserved in Git history at `1c2610c` under
 comparison and disclosure behavior, and
 [ADR 0010](adr/0010-effective-configuration-diff.md) records the decision.
 
+The completed input-destination, relative-import-destination, and shared
+source-version roadmaps, associated consumer request, implementation plan, and
+resolved review findings are preserved in Git history at `e4270c9` under
+`docs/roadmap/`. For example:
+
+```sh
+git show e4270c9:docs/roadmap/implementation.md
+git show e4270c9:docs/roadmap/remediation.md
+```
+
+Current behavior belongs to the configuration contract's
+[input destinations](config.md#input-destinations),
+[imports](config.md#explicit-imports), and
+[shared source-version checks](config.md#shared-source-version-checks) sections.
+Explicit sequence-item placement, collection operations, identity registration,
+and final registered-identity validation are owned by the
+[strict composition](config.md#strict-document-composition) section;
+[imports](config.md#explicit-imports) owns acquisition and scheduling. The
+[maintained sequence catalog](consumers/README.md#identified-prompt-sequences)
+shows the consumer boundary, and [ADR 0017](adr/0017-collection-sequence-policy.md)
+records the collection decision.
+
+The completed sequence-composition roadmap, implementation plan, and resolved
+remediation record are preserved in Git history at `008d2ba` under
+`docs/roadmap/`. For example:
+
+```sh
+git show 008d2ba:docs/roadmap/sequence-composition.md
+git show 008d2ba:docs/roadmap/implementation.md
+git show 008d2ba:docs/roadmap/remediation.md
+```
+
+The completed import-discovery roadmap, implementation plan, and resolved
+remediation record are preserved in Git history at `5747ec4` under
+`docs/roadmap/`. For example:
+
+```sh
+git show 5747ec4:docs/roadmap/imports.md
+git show 5747ec4:docs/roadmap/implementation.md
+git show 5747ec4:docs/roadmap/remediation.md
+```
+
+The subsequent import-integration audit and completed remediation record are
+preserved at `6903c9e:docs/roadmap/remediation.md`; retrieve them with
+`git show 6903c9e:docs/roadmap/remediation.md`.
+
+The completed sequence-identity/collection-policy roadmap and implementation
+plan are preserved in Git history at `d0a605a`:
+
+```sh
+git show d0a605a:docs/roadmap/sequences.md
+git show d0a605a:docs/roadmap/implementation.md
+```
+
+Current behavior belongs to the configuration contract's
+[strict composition](config.md#strict-document-composition),
+[sibling inheritance](config.md#sibling-inheritance), and
+[CLI overrides](config.md#explicit-cli-overrides) sections.
+The completed remediation record, including the algorithm-audit findings, is
+preserved at `ea46001:docs/roadmap/remediation.md`.
+
+The completed configuration-discovery roadmap, implementation plan, and
+remediation record are preserved in Git history at `0369111`, for example
+`git show 0369111:docs/roadmap/remediation.md`. Current behavior belongs to
+[configuration discovery](config.md#configuration-discovery); the public
+[discovery declarations](../discovery.go) own the Go API.
+
+The completed consolidation proposal, implementation plan, and resolved audit
+findings are preserved in Git history at `34cbc0d` under `docs/roadmap/`. For
+example:
+
+```sh
+git show 34cbc0d:docs/roadmap/implementation.md
+git show 34cbc0d:docs/roadmap/remediation.md
+```
+
+Potential enhancements are tracked in [future features](roadmap/future.md).
+The completed audit-remediation, internal-boundary simplification, shared-history,
+and public API cleanup roadmaps, reviews, and resolved findings are preserved at
+`68400ff` under `docs/roadmap/`. For example:
+
+```sh
+git show 68400ff:docs/roadmap/api.md
+git show 68400ff:docs/roadmap/remediation.md
+```
+
+Their earlier completed implementation plans are preserved at
+`bb5540b:docs/roadmap/implementation.md` (audit remediation),
+`f6d54a0:docs/roadmap/implementation.md` (internal-boundary simplification), and
+`07e4ae5:docs/roadmap/implementation.md` (shared history). The plan at
+`68400ff:docs/roadmap/implementation.md` records the public API cleanup.
+Current behavior and migration information belong to the
+[configuration contract](config.md), public declaration comments, and
+[consumer guide](consumers/README.md#pre-v1-public-api-cleanup).
+
+The consolidated audit, including
+findings, evidence, and settled scope decisions, is preserved at
+`453da68:docs/roadmap/audit.md`; the original nine reports are preserved at
+`ecd5d5d` under `docs/roadmap/`. Retrieve the consolidated record with:
+
+```sh
+git show 453da68:docs/roadmap/audit.md
+```
+
 Install the Go version required by `go.mod` or a compatible newer toolchain.
 Acquire declared dependencies explicitly before entering an offline
 development or validation environment:
@@ -159,19 +272,25 @@ code changes. Use the component overview to find the corresponding implementatio
 | Task | Behavioral test owners | Focused command |
 | --- | --- | --- |
 | YAML syntax, diagnostics, parser limits | [Adapter tests](../internal/yaml/parse_test.go), [source translation](../internal/engine/parse_test.go) | `go test ./internal/yaml` and `go test ./internal/engine -run '^TestParseSource'` |
-| File/reader access, imports, globs, containment | [Sources](../internal/engine/source_test.go), [FIFO](../internal/engine/source_fifo_test.go), [imports](../internal/engine/imports_test.go), [globs](../internal/engine/glob_test.go) | `go test ./internal/engine -run 'Source\|Import\|Glob\|Filesystem\|Nonregular\|RegularFile'` |
+| File/reader access, imports, globs, containment | [Import internals](internal/imports.md), [source acquisition](../internal/engine/source_test.go), [FIFO](../internal/engine/source_fifo_test.go), [import traversal](../internal/engine/imports_test.go), [import evidence](../internal/engine/import_evidence_test.go), [relative destinations](../internal/engine/destination_import_test.go), [globs](../internal/engine/glob_test.go) | `go test ./internal/engine -run 'Source\|Import\|Glob\|Filesystem\|Nonregular\|RegularFile'` |
+| Explicit main-file discovery and absent-input loading | [Candidate selection](../internal/engine/discovery_test.go), [load integration](../internal/engine/discovery_load_test.go), [public facade](../facade_discovery_test.go), and maintained [catalog](../examples/consumers/sequence_catalog_test.go) and [preset](../examples/consumers/discovery_test.go) examples | `go test ./internal/engine -run 'Discovery|Search'`, `go test . -run 'Search'`, and `go test ./examples/consumers -run 'WorkingDirectoryPreset|SequenceCatalog'` |
+| Import defaults, empty-selection evidence, and dependency-ready ordering | [Defaults and facade evidence](../facade_import_defaults_test.go), [engine import evidence](../internal/engine/import_evidence_test.go), [scheduler](../internal/engine/dependency_order_test.go), [scheduling integrations](../internal/engine/imports_test.go) | `go test ./internal/engine -run 'Import|ScheduleDependencies|Inheritance'`, `go test . -run 'ImportDefaults|FacadeImport'`, and `go test ./examples/consumers` |
 | Native filesystem and mapping sources | [Native acquisition](../internal/engine/native_filesystem_test.go), [filesystem facade](../facade_filesystem_test.go), [mapping facade](../facade_mapping_test.go) | `go test ./internal/engine -run 'NativeFilesystem'` and `go test . -run 'TestFacade'` |
 | Composition, selected overlays, CLI precedence | [Composition](../internal/engine/compose_test.go), [overlay](../internal/engine/overlay_test.go), [selected overlays](../internal/engine/selected_overlay_test.go), [overrides](../internal/engine/override_test.go) | `go test ./internal/engine -run 'Compose\|Overlay\|Override'` |
-| Sibling inheritance, provenance, history, sensitivity | [Expansion](../internal/engine/inheritance_test.go), [destination scopes](../internal/engine/inheritance_walk_test.go), [origins](../internal/engine/inheritance_origin_test.go), [history](../internal/engine/inheritance_history_test.go), [secrets](../internal/engine/inheritance_secret_test.go), [public loading](../facade_inheritance_test.go) | `go test ./internal/engine -run 'Inheritance\|Inherited'` and `go test . -run '^TestFacadeInheritance\|^TestFacadeInheritedSecrets'` |
+| Sequence identity, declarations, and operations | [Identity](../internal/engine/sequence_identity_test.go), [registrations](../internal/engine/sequence_registration_test.go), [declarations](../internal/engine/sequence_declaration_test.go), [combination](../internal/engine/sequence_combine_test.go), [final facade validation](../facade_final_sequence_identity_test.go), and [consumer catalog](../examples/consumers/sequence_catalog_test.go) | `go test ./internal/engine -run 'Sequence\|Collection'`, `go test . -run 'SequenceIdentity\|SequenceRegistration'`, and `go test ./examples/consumers` |
+| Sibling inheritance, provenance, history, sensitivity | [Implementation flow](internal/overview.md#implementation-flow), [expansion](../internal/engine/inheritance_test.go), [destination scopes](../internal/engine/inheritance_walk_test.go), [origins](../internal/engine/inheritance_origin_test.go), [history](../internal/engine/inheritance_history_test.go), [secrets](../internal/engine/inheritance_secret_test.go), [public loading](../facade_inheritance_test.go) | `go test ./internal/engine -run 'Inheritance\|Inherited'` and `go test . -run '^TestFacadeInheritance\|^TestFacadeInheritedSecrets'` |
 | Layered loading and source equivalence | [Grouped lifecycle](../internal/engine/load_request_test.go), [layered facade](../facade_layered_test.go), [equivalence](../facade_equivalence_test.go) | `go test ./internal/engine -run '^TestGrouped'`, `go test . -run '^TestFacadeLayered'`, and `go test . -run '^TestEquivalentSourceForms'` |
-| Schema, defaults, projection, cloning | [Schema](../internal/engine/schema_test.go), [decoding](../internal/engine/decode_test.go), [projection](../internal/engine/projection_test.go) | `go test ./internal/engine -run 'Schema\|Decode\|Projection\|Clone\|Inline\|CompareDocument'` |
+| Input and relative-import destinations, mounted sources, and source ownership | [Destination engine tests](../internal/engine/destination_test.go), [tier tests](../internal/engine/destination_tiers_test.go), [import traversal and version tests](../internal/engine/destination_import_test.go), [accounting tests](../internal/engine/destination_accounting_test.go), [lifecycle inspection tests](../internal/engine/destination_import_lifecycle_test.go), [public source/error tests](../facade_destination_test.go), [resource contexts](../facade_resource_context_test.go), and [consumer examples](../examples/consumers/destinations_test.go) | `go test ./internal/engine -run 'Destination|Import|Glob|Mounted'`, `go test . -run 'Destination|Import|SourceContext|FacadeMounted'`, and `go test ./examples/consumers` |
+| Shared source-version modes and evidence | [Engine source-version tests](../internal/engine/source_version_test.go), [public facade tests](../facade_source_version_mode_test.go), and [consumer example tests](../examples/consumers/layered_test.go) | `go test ./internal/engine -run 'SourceVersion'`, `go test . -run 'SourceVersion'`, and `go test ./examples/consumers` |
+| Schema, defaults, projection, cloning | [Implementation flow](internal/overview.md#implementation-flow), [schema](../internal/engine/schema_test.go), [decoding](../internal/engine/decode_test.go), [projection and typed cloning](../internal/engine/projection_test.go) | `go test ./internal/engine -run 'Schema\|Decode\|Projection\|Clone\|Inline\|CompareDocument'` |
 | Lifecycle, resolution, validation, callback ownership | [Loading](../internal/engine/load_test.go), [resolution](../internal/engine/resolution_test.go), [validation](../internal/engine/validation_test.go), [ownership](../internal/engine/callback_ownership_test.go), [independence](../internal/engine/independence_test.go) | `go test ./internal/engine -run 'Load\|Resolution\|Validation\|Validator\|Hook\|Callback\|Parallel'` |
 | Paths, metadata, provenance | [Paths](../internal/engine/path_test.go), [metadata](../internal/engine/metadata_test.go), [provenance](../internal/engine/provenance_test.go) | `go test ./internal/engine -run 'Path\|Metadata\|Provenance\|Queries'` |
 | Passive resource contexts | [Engine contexts](../internal/engine/resource_context_test.go), [public contexts](../facade_resource_context_test.go) | `go test ./internal/engine -run 'Resource'` and `go test . -run 'SourceContext'` |
 | Secrets, bootstrap, redaction, explanation | [References](../internal/engine/secret_reference_test.go), [bootstrap](../internal/engine/secrets_test.go), [rendering](../internal/engine/render_test.go), [explanation](../internal/engine/explain_test.go) | `go test ./internal/engine -run 'Secret\|Bootstrap\|Effective\|Explain\|Explanation\|History\|Sensitivity'` |
 | Effective configuration diff | [Engine comparison and masking tests](../internal/engine/diff_test.go), [engine operation tests](../internal/engine/diff_operation_test.go), [root facade tests](../facade_diff_test.go), and [consumer examples](../examples/consumers/diff_test.go) | `go test ./internal/engine -run 'Diff|Explain|History|Secret|Independent'`, `go test . -run 'Diff|FacadeInspection|PublicFacadeBoundary|DependencyImportBoundary'`, `go test ./examples/consumers`, and `go test . -run '^ExampleDiff$'` |
-| Consumer examples and migration fixtures | [Consumer tests](../examples/consumers/consumers_test.go), [native and layered examples](../examples/consumers/layered_test.go), [API examples](../example_test.go) | `go test ./examples/consumers` and `go test . -run '^Example'` |
+| Consumer examples and migration fixtures | [Consumer tests](../examples/consumers/consumers_test.go), [native, layered, and ordinary relative-import examples](../examples/consumers/layered_test.go), [mounted collection examples](../examples/consumers/destinations_test.go), [API examples](../example_test.go) | `go test ./examples/consumers` and `go test . -run '^Example'` |
 | Assembly and layered scaling evidence | [Assembly benchmarks](../internal/engine/assembly_bench_test.go), [layered benchmarks](../internal/engine/underlay_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkUnderlay' -benchmem`; repeat with `^BenchmarkCompose` and `^BenchmarkOverlay` |
+| Identified-sequence scaling evidence | [Mixed-upsert benchmark](../internal/engine/sequence_combine_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkSequenceMixedUpsert$' -benchmem` |
 | Inheritance scaling evidence | [Expansion benchmarks](../internal/engine/inheritance_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkInheritance' -benchmem` |
 | Documentation links and dependency isolation | [Link checks](../documentation_test.go), [import boundary](../import_boundary_test.go), [public boundary](../public_boundary_test.go) | `go test . -run 'TestLocalDocumentationLinks\|TestDependencyImportBoundary\|TestPublicFacadeBoundary'` |
 | Development check behavior | [Development checker test](../development_check_test.go) | `go test . -run '^TestDevelopmentCheckHandlesFilenamesAndStopsOnFailure$'` |

docs/internal/imports.md

@@ -0,0 +1,125 @@
+# Import Discovery and Scheduling Internals
+
+The [configuration contract](../config.md#explicit-imports) owns selector syntax,
+defaults, requiredness, placement, inspection evidence, and observable ordering.
+This note records implementation flow and private identities for maintainers.
+
+## Discovery and acquisition
+
+Each source's root directive is parsed into presence-aware declarations and
+resolved against load-wide defaults. `acquisition.go` owns shared acquisition
+policy, load-wide accounting, and tier-scoped repetition/namespace state;
+`import_acquisition.go` owns reading candidate bytes, declaration traversal,
+and import admission. Candidate
+selection in `import_selection.go` preserves a normalized
+namespace path separately from canonical access identity: overlapping roots
+coalesce the same candidate spelling in that namespace, while aliases reached
+through distinct spellings retain separate inclusion routes for admission.
+Directory searches walk each distinct normalized root once, apply all filename
+patterns to discovered names, and form a set union of matching candidates across
+overlapping roots. Exclusions are applied as set difference after discovery and
+candidate normalization. They do not suppress discovery or resource errors.
+
+Directory traversal tracks canonical directories on the active traversal path.
+It adds an identity when descending and removes it when the frame is popped, so
+only a back-edge to an active directory is a traversal cycle; a later alias is
+not mistaken for one. This is separate from import dependency-cycle detection.
+For host sources, discovery uses rooted `Lstat` and canonical containment.
+`filesystem_context.go` owns resolved access facts and live access setup; the
+acquisition operation closes its live handles before composition. Native sources
+use `fs.ReadLinkFS` inspection when supplied; otherwise traversal follows the
+capabilities and behavior of the provided `fs.FS`, without claiming a general
+sandbox guarantee. `source_context.go` derives passive resource contexts from
+resolved sources for later caller-owned reads; those records do not retain live
+acquisition handles.
+
+Host and native link bindings share one iterative link-frame evaluator. It
+tracks active links for cycle detection and reuses successfully completed link
+targets while resolving the remaining path components; each binding retains its
+own namespace and target-containment rules. Directory reads distinguish an
+initial-open failure from failures after opening: only an initial missing
+directory can be treated as optional, while enumeration and close failures
+remain selection errors, including errors from the standard `fs.ReadDir`
+fallback.
+
+Glob selection keeps traversal coordination in `selectGlobImportCandidates`:
+it advances literal and patterned segments, reads directories, unions and sorts
+candidates, validates final targets, then applies exclusions and requiredness.
+For each patterned directory entry, `prepareGlobEntry` handles matching and
+hidden filtering, containment, target and link inspection, intermediate-directory
+eligibility, host/native access-path selection, and candidate identity and label.
+It returns a candidate, an ordinary skip, or a diagnostic without mutating the
+selector's candidate set or traversal state. Directory entry preparation remains
+separate because its matching, absence, recursion, and traversal-state rules
+differ.
+
+Acquisition remains authored: declarations are visited in source order and each
+selected candidate set in namespace-path lexical order. This preserves source
+records, IDs, source-local version checks, and callback ordering. The acquired
+inclusion graph is retained separately from composition scopes so cycles that
+cross item boundaries remain detectable. Source discovery does not itself choose
+sequence assembly order.
+
+## Stable keys and scheduling
+
+The shared scheduler compares immutable tuples component by component using Go's
+bytewise string order; if one tuple is a prefix of another, the shorter tuple
+sorts first. The import key is
+`(namespace-kind, namespace-anchor, resource-kind, resource-path)`:
+
+- Namespace kind is `host` or `native`. Host resource paths are canonical
+  absolute paths rendered with slash separators; native paths retain their
+  namespace-relative identity.
+- Anchors come from explicit input positions, not discovery order: main is
+  `(0,0)` and underlay/input positions are `(group+1,input+1)`, each encoded as
+  fixed-width decimal. Host accesses in one scheduled tier share its host anchor.
+  A native filesystem namespace uses its earliest explicit selecting position
+  in that tier. Filesystem tokens distinguish namespace equality, not sort order,
+  so separately constructed filesystems with the same label remain distinct.
+- Resource kind is `file` or `synthetic`. A synthetic root uses its explicit
+  input anchor and an empty resource path rather than a display label or token
+  address.
+
+Inheritance keys are
+`("definition", scope-pointer, definition-pointer)`, where both pointers use
+canonical escaped semantic path spelling. Source IDs are not part of the key.
+
+Both integrations use the same Kahn scheduler: it deduplicates dependency edges,
+keeps currently ready nodes in a min-heap, and selects the smallest ready key
+after every completion. Its scheduling cost is `O(E + V log V)` time and
+`O(V + E)` additional memory, excluding key construction, tuple copying, and
+tuple comparisons. On a stalled graph, deterministic DFS over the residual graph
+returns a closed cycle rotated to its smallest key; blocked dependents are not
+reported as cycle members.
+
+Import edge preparation builds an importer-to-target adjacency index once for
+an acquisition's outer and item-local scheduling, and once for grouped
+scheduling. Each scope gathers edges from its participating identities and
+retains only edges with both endpoints in its local slots. The retained
+inclusion graph still owns cycle diagnostics and source relationships.
+
+Import composition schedules a main tier or one underlay group as a single
+strict-scope graph. Applicable collection declarations are gathered for the
+scope before peer composition, including identity inherited from lower tiers.
+Identified peer sequences then combine distinct records in assembled source and
+list order; after the strict scope completes, layered assembly applies the
+resolved collection operation against the lower value, as defined by the
+[configuration contract](../config.md#strict-document-composition). Item
+contributions own nested local strict-mapping scopes; their helpers complete
+before the item is placed in its outer scope. Inheritance uses the same
+ready-node rule inside each sibling mapping scope, while preserving the authored
+mapping order in its output.
+These scopes do not flatten into one global graph, and independent precedence
+tiers remain separate.
+
+The owners are [`acquisition.go`](../../internal/engine/acquisition.go),
+[`import_selection.go`](../../internal/engine/import_selection.go),
+[`import_acquisition.go`](../../internal/engine/import_acquisition.go),
+[`directory_walk.go`](../../internal/engine/directory_walk.go),
+[`import_graph.go`](../../internal/engine/import_graph.go),
+[`import_projection.go`](../../internal/engine/import_projection.go),
+[`dependency_order.go`](../../internal/engine/dependency_order.go), and
+[`inheritance_schedule.go`](../../internal/engine/inheritance_schedule.go).
+Their focused behavior is covered by import-selection, acquisition, scheduler,
+and scheduling integration tests under `internal/engine`; see the
+[development test map](../development.md#task-to-test-map).

docs/internal/overview.md

@@ -7,21 +7,41 @@ private state; public signatures and fields do not expose engine types.
 
 Implemented component owners:
 
-- `internal/engine` owns host and native-filesystem source acquisition,
-  grouped strict composition, recursive precedence assembly, and destination-local
-  sibling inheritance before typed decoding. It also owns schema
+- `internal/engine` owns host and native-filesystem source acquisition and
+  explicitly selected configuration discovery. A search resolves once during
+  shared acquisition; the selected concrete file or absent-input state then
+  follows the existing composition, metadata, and resource-context lifecycle.
+  It also owns grouped strict composition, recursive precedence assembly,
+  per-input mapping and sequence-item placement, YAML collection declarations
+  and operations for identified sequences, and application identity registrations for strict
+  composition, inheritance, and final validation. It applies the selected
+  collection operation at precedence boundaries and owns dependency-ready,
+  destination-local inheritance before typed decoding. CLI assignment follows
+  inheritance and decoding, before application resolution. The engine also owns
+  shared source-version checking with sanitized declaration evidence.
+  Explicit import discovery supports declared paths, directory searches, and
+  globs; root-owned defaults are converted to the engine's single defaults input
+  and snapshotted during load preflight before acquisition, while source-local
+  empty-selection evidence crosses the facade without changing acquisition
+  order. The root constructs placement directly on engine options and inputs
+  using explicit enum conversion; public types and fields remain root-owned.
+  Import and inheritance resolution share dependency-ready scheduling within
+  their composition scopes.
+  It retains each source's effective placement alongside physical source
+  identity and owns schema
   inspection, lifecycle coordination, callback auditing,
   provenance/history, passive source-context retention, secret resolution and
-  bootstrap, safe inspection rendering, and effective-value comparison over
+  bootstrap, operation-local secret failure-location attribution, safe
+  inspection rendering, and effective-value comparison over
   frozen inspection snapshots. It never imports the root package.
 - Root `Source`, `Filesystem`, `Input`, `Underlay`, `Path`, `Secret`, records,
   lifecycle callbacks, results, and bootstrap reports are root-defined wrappers
   or records. Callback wrappers pass only live engine context during a callback;
   `Result.Config` is detached and its private inspection remains frozen
   independently.
-- Root conversion files explicitly cross the path, record, callback, secret, and
-  error boundaries. There are no public aliases, anonymous engine embeddings, or
-  public engine bridge methods.
+- Root conversion files explicitly cross the path, record, callback, secret,
+  search-description, and error boundaries. There are no public aliases,
+  anonymous engine embeddings, or public engine bridge methods.
 - Root `Diff` and `Difference` provide the public comparison boundary and
   convert detached engine records to root-owned paths and snapshots; consumer
   examples own presentation of the safe changed regions.
@@ -41,12 +61,121 @@ these constraints and rejects exported aliases, fields, or signatures involving
 internal types.
 
 The [configuration contract](../config.md) owns implemented YAML and lifecycle
-semantics, including [effective configuration diffs](../config.md#effective-configuration-diffs).
+semantics, including
+[configuration discovery](../config.md#configuration-discovery),
+[input destinations](../config.md#input-destinations),
+[shared source-version checks](../config.md#shared-source-version-checks), and
+[effective configuration diffs](../config.md#effective-configuration-diffs).
+The [strict composition contract](../config.md#strict-document-composition)
+owns sequence declarations, identity, operations, ownership, and final
+validation; [CLI overrides](../config.md#explicit-cli-overrides) own override
+ordering. The [consumer guide](../consumers/README.md#identified-prompt-sequences)
+links maintained workflow examples.
 The [consumer adoption guide](../consumers/README.md) owns application guidance.
 The [architecture policy](../policy/architecture.md) owns contributor
 boundaries; [ADR 0006](../adr/0006-public-facade.md) records the facade decision
 and [ADR 0010](../adr/0010-effective-configuration-diff.md) records the diff
+decision; [ADR 0011](../adr/0011-input-destinations.md) records the placement
 decision. See the [development guide](../development.md) for validation commands
 and [release procedure](../release.md) for source-candidate gates. [ADR
 0009](../adr/0009-sibling-inheritance.md) records why inheritance is a built-in
-post-assembly structural operation.
+post-assembly structural operation. [ADR 0012](../adr/0012-relative-import-destinations.md)
+records the relative-import extension; [ADR 0013](../adr/0013-shared-source-version-checks.md)
+records the source-version decision.
+[ADR 0014](../adr/0014-sequence-placement-and-composition.md) records explicit
+sequence placement and composition. [ADR 0015](../adr/0015-shared-dependency-ready-ordering.md)
+records the shared dependency-ready ordering decision; [ADR
+0016](../adr/0016-independent-import-controls.md) records the independent
+selection controls. [ADR 0017](../adr/0017-collection-sequence-policy.md) and
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md) record collection
+operations and CLI ordering. [ADR 0019](../adr/0019-explicit-configuration-discovery.md)
+records explicit main-file discovery. The [import internals](imports.md)
+document candidate and namespace identities, discovery and scheduling, and the
+bounded algorithms.
+
+## Implementation flow
+
+The root facade converts caller-owned values into engine-owned requests. Its
+`ImportDefaults` conversion maps fields without taking ownership; engine load
+preflight snapshots the defaults once before source acquisition or callbacks.
+Ordinary and grouped loading then carry that read-only value through their
+normalized `loadRequest` and acquisition policy, while declaration resolution
+copies values needed by its independently owned effective policy. Placement is
+constructed directly on the engine's options and input records after explicit
+root-to-engine enum conversion. See
+[`lifecycle.go`](../../lifecycle.go), [`layered.go`](../../layered.go), and
+[`load_request.go`](../../internal/engine/load_request.go). Load-wide definition,
+version, default-import, and override policy stays distinct from each input's
+source, filesystem, destination, and import settings.
+
+[`acquisition.go`](../../internal/engine/acquisition.go) defines acquisition
+policy, load-wide accounting, and tier-scoped repetition/namespace state. Each
+input is acquired under that policy; grouped requests retain acquired underlay
+scopes until their tier is composed in
+[`load_request.go`](../../internal/engine/load_request.go). Completed tiers then
+share one assembly handoff that applies collection declarations and projects
+only that tier's source/version evidence; the caller keeps main-version
+protection and its projection explicit. Live
+filesystem access handles are confined to acquisition and closed there. Resolved
+filesystem facts used to authorize access are separate from passively retained
+resource contexts. Non-import validation retains those facts on `assembledInput`
+for passive-context construction and ordinary-overlay handling: see
+[`filesystem_context.go`](../../internal/engine/filesystem_context.go) and
+[`source_context.go`](../../internal/engine/source_context.go).
+
+Import responsibilities are split across candidate selection and path
+normalization in [`import_selection.go`](../../internal/engine/import_selection.go),
+source reading and traversal admission in
+[`import_acquisition.go`](../../internal/engine/import_acquisition.go),
+directory walking in [`directory_walk.go`](../../internal/engine/directory_walk.go),
+dependency graph scheduling in [`import_graph.go`](../../internal/engine/import_graph.go),
+and projection of acquired evidence into final source coordinates in
+[`import_projection.go`](../../internal/engine/import_projection.go). The
+[import internals](imports.md) page describes the boundaries and identities.
+
+After acquisition handles are closed, grouped composition and inheritance run on
+the retained ordered documents. `inheritance.go` coordinates traversal and
+[`inheritance_schedule.go`](../../internal/engine/inheritance_schedule.go) applies
+dependency-ready templates;
+[`inheritance_prepare.go`](../../internal/engine/inheritance_prepare.go)
+prepares child and parent inputs,
+[`inheritance_combine.go`](../../internal/engine/inheritance_combine.go)
+returns the combined value with its origin, policy, sequence, and diagnostic
+evidence, and [`inheritance_finalize.go`](../../internal/engine/inheritance_finalize.go)
+accounts for and finalizes the result. Projection and schema work have separate
+operation owners: [`value_operation.go`](../../internal/engine/value_operation.go)
+holds per-operation state, [`projection.go`](../../internal/engine/projection.go)
+builds projected values, [`schema.go`](../../internal/engine/schema.go) owns
+descriptor caching and type policy, and
+[`schema_fields.go`](../../internal/engine/schema_fields.go) owns ordinary and
+inline field assembly. [`decode.go`](../../internal/engine/decode.go) consumes
+those descriptors for typed decoding.
+
+History and inspection use one private evidence owner. The
+[`history_model.go`](../../internal/engine/history_model.go) builder receives
+baseline, source-composition, inheritance, typed-checkpoint, and CLI evidence
+in [`preparePostDecodeOverrideContext`](../../internal/engine/override_context.go),
+before application resolution begins. The callback retains its separate fixed
+entry view; it does not read a builder that continues to change. After successful
+resolution auditing, [`resolveLoadInput`](../../internal/engine/load_result.go)
+adds the original resolution records and their net replay groups. At the existing
+pre-secret admission boundary, [`prepareInspectionHistory`](../../internal/engine/load_result.go)
+freezes that builder and counts the retained document roots before secret lookup
+and validation.
+
+The frozen model is shared by `Metadata` and `Inspection`. Its shape-aware
+selection in [`history_select.go`](../../internal/engine/history_select.go)
+drives metadata history, explanation, and historical-path membership; the model
+also supplies historical diagnostic locations and sensitivity/dependency
+evidence. `Inspection` replays selected payloads to produce detached, safely
+rendered values, while metadata queries return detached attribution records.
+History and explanation behavior is covered by focused `history_*_test.go`
+tests alongside metadata, secret, inheritance, and facade integration tests.
+
+Behavioral ownership follows the same handoffs: imports and grouped lifetimes are
+covered by `imports_test.go`, `load_request_test.go`, and focused source,
+discovery, and destination tests; inheritance by the inheritance test files;
+reflection behavior by `schema_test.go`, `projection_test.go`, and
+`decode_test.go`. The [development test map](../development.md#task-to-test-map)
+links focused commands. [`clone.go`](../../internal/engine/clone.go) owns typed
+copying, using the shared descriptors and per-operation traversal helpers.

docs/policy/architecture.md

@@ -2,7 +2,7 @@
 
 **Base Policy Version:** 1.3
 
-**Last Updated**: 2026-09-29
+**Last Updated**: 2026-10-22
 
 **Upstream Source:** [Standard Repository Policies](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/docs/policy/architecture.md)
 
@@ -19,8 +19,8 @@ to ADRs for decision rationale.
 ConfigKit is an opinionated Go library for consistent YAML configuration loading
 and resolution across consuming applications. The [component overview](../internal/overview.md)
 owns implementation inventory, the [configuration contract](../config.md) owns
-implemented behavior, and the [deferred scope](../roadmap/deferred.md) preserves
-deferred scope.
+implemented behavior, and the [future feature list](../roadmap/future.md) preserves
+candidates for future consideration.
 
 ## Adopted Constraints And Implemented Structure
 
@@ -32,6 +32,12 @@ structure as implemented when its changes land.
 Constraints must reflect deliberately selected requirements and decisions.
 Do not promote incidental implementation choices into architectural invariants.
 
+The implemented collection-policy and CLI-ordering constraints below reflect
+accepted [ADR 0017](../adr/0017-collection-sequence-policy.md) and
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md). The configuration
+contract owns their current behavior; these architectural constraints describe
+the system boundaries and guarantees that guide changes to that behavior.
+
 ## Success Criteria
 
 ConfigKit prioritizes a coherent configuration model: consistency and
@@ -91,17 +97,82 @@ boundaries, and keep simple consumers independent of optional composition
 features. The [consumer adoption guide](../consumers/README.md) demonstrates the
 implemented surface against representative simple and complex shapes.
 
+## Simplicity, Defaults, And Explicit Controls
+
+These principles apply throughout ConfigKit: to configuration syntax, the public
+Go API, defaults, and feature design. Evaluate their effects on both configuration
+authors and consuming applications.
+
+**Keep straightforward workflows straightforward.** Common configuration
+workflows should require little configuration text and minimal API setup.
+Support more demanding workflows through explicit, composable options, without
+requiring simple consumers to understand or configure those options.
+
+**Prefer simple, permissive defaults with explicit controls.** Choose predictable
+defaults that minimize required setup and accommodate valid configurations
+without unnecessary restrictions. Provide selectable options for workflows that
+need additional capabilities, narrower behavior, or stronger requirements.
+
+Measure simplicity by what consumers must understand and maintain, including
+configuration text and application-side plumbing. Concise syntax is useful, but
+hidden inference and interacting meanings can make a shorter declaration harder
+to understand. Prefer explicitness where it makes behavior more predictable.
+A terse configuration format that requires substantial application-side
+infrastructure does not satisfy the simplicity principle.
+
+Define what permissiveness means for each behavior. Allowing an optional
+contribution to be absent or accepting valid inputs without an unnecessary
+filename restriction can reduce required setup. Invalid declarations, ambiguous
+composition, and unreadable selected sources must still produce meaningful
+errors under the applicable contracts. Permissiveness does not authorize silent
+recovery from invalid supplied configuration or weaken configuration integrity.
+
+Options should express coherent choices with understandable purposes and fit
+ConfigKit's shared configuration model. Support powerful controls when they
+serve concrete needs; these principles do not require a switch for every
+implementation behavior or conceivable consumer preference.
+
+Defaults require judgment when simplicity and permissiveness pull in different
+directions. Broader discovery can accommodate more layouts while increasing the
+implicit search scope. Evaluate such tradeoffs explicitly; these principles do
+not mechanically select the broadest behavior for every option. Changes to
+existing defaults remain subject to compatibility review, and proposed behavior
+remains in the roadmap until implemented.
+
 ## Responsibility Boundaries
 
 ConfigKit owns configuration input processing and the coordination of decoding,
 resolution, validation, and inspection. Applications own their configuration
 types, field meanings, defaults, normalization, semantic validation, and schema
-version policy. Applications also own main-file search conventions, CLI wiring,
-remote acquisition, runtime initialization, and resource checks.
+version policy. Applications choose and order their main-file search conventions;
+ConfigKit provides explicitly selected search descriptions that resolve during
+loading. Applications also own CLI wiring, remote acquisition, runtime
+initialization, and resource checks. See the [configuration discovery
+contract](../config.md#configuration-discovery) and [ADR
+0019](../adr/0019-explicit-configuration-discovery.md).
+
+The engine applies each input's mapping destination within the existing source
+assembly, applies immediate-parent-relative YAML destinations to imports, and
+retains each effective placement with source identity and inspection records;
+the root facade owns the public fields and conversions. The
+[configuration contract](../config.md#input-destinations) defines the observable
+placement behavior. [ADR 0011](../adr/0011-input-destinations.md) records input
+placement, and [ADR 0012](../adr/0012-relative-import-destinations.md) records
+the import extension.
 
 Library code must not depend on consuming applications or initialize their
-runtime resources. It must not perform implicit network access, discover
-application-specific paths, or change process-global state during ordinary `Load`.
+runtime resources. It must not perform implicit network access, implicitly
+discover application-specific paths, or change process-global state during
+ordinary `Load`.
+Import discovery is available only through declarations in selected sources:
+explicit `path`, `dir`, and `glob` selectors may search their declared scope, but
+ConfigKit does not search conventional application paths unless the application
+explicitly supplies a discovery description, and it never discovers a main
+configuration file implicitly. Imports and sibling inheritance share
+dependency-ready scheduling within their existing scopes; acquisition order and
+precedence-tier boundaries remain distinct. The [configuration contract](../config.md#explicit-imports)
+owns observable behavior; [ADR 0015](../adr/0015-shared-dependency-ready-ordering.md)
+and [ADR 0016](../adr/0016-independent-import-controls.md) record the decisions.
 The explicit secrets-directory bootstrap is a narrow, opt-in exception: applications
 invoke it during startup, and it reports writes, skips and partial failures. It
 must never run implicitly as part of configuration loading.
@@ -124,6 +195,29 @@ The [configuration contract](../config.md#completion-and-resource-lifetime) owns
 the precise completion and ownership behavior. The proposed decision record is
 [ADR 0008](../adr/0008-complete-on-return-loading.md).
 
+### Accepted Processing Order
+
+Complete source composition and precedence, including selected overlays, before
+sibling inheritance. Then apply typed defaults and decode the configuration.
+Apply explicit CLI overrides to that configuration and check their types before
+running application resolution. Effective secret lookup and final validation
+follow resolution, before publication. [ADR 0018](../adr/0018-cli-after-structural-resolution.md)
+records this ordering.
+
+CLI overrides are the highest-priority input to application resolution. Supplied
+sequences replace whole sequences, and mappings combine recursively. Inheritance
+and typed defaulting do not run again after CLI application. CLI paths and values
+must not introduce structural directives; earlier source, inheritance, and
+decoding failures remain errors even if a CLI assignment would replace the value.
+Semantic validation assesses the final configuration after overrides and resolution.
+
+Applications own flag parsing and domain resolution. ConfigKit owns override
+application, validation, and source attribution. Resolution receives CLI values
+with their explicit-presence and source information. Absence-based defaults
+preserve explicit values; recorded normalization and derivation can still change
+them. Typed defaults and application resolution retain their own assignment
+semantics, independently of collection operations during source assembly.
+
 ## Public API And Dependency Direction
 
 Keep one small, coherent public surface for the supported lifecycle. Simple
@@ -152,31 +246,44 @@ framework on this library.
 
 ## Configuration Integrity
 
-Within a configuration tier, independent contributions use strict composition:
-shared mappings combine recursively, while overlapping non-mapping definitions
-are conflicts, including equal values. Between precedence tiers, intentional
-overlay combines mappings recursively, retains omitted lower-priority children,
-and replaces other present values according to the existing overlay rules.
-Tier precedence is explicit; traversal order within a tier establishes stable
-reporting, not permission to override. The distinction and its rationale are
-recorded in [ADR 0001](../adr/0001-separate-composition-and-overlay.md).
+Within a configuration tier, independent contributions use strict composition.
+Shared mappings combine recursively. Sequences with an applicable identity
+combine distinct records and reject duplicate identities, including equal
+records. Other overlapping non-mapping values remain conflicts, including equal
+values. Conflicting identity or operation declarations among peers also fail.
+Traversal order establishes stable reporting and record order; it does not grant
+precedence to peers. [ADR 0001](../adr/0001-separate-composition-and-overlay.md)
+records the distinction between strict composition and intentional overrides.
 
 The main document and its imports form a strictly composed tier. Explicit
-underlay groups compose strictly within each group, then combine recursively
-from lowest to highest beneath the main tier. Source acquisition kind does not
-determine its precedence role. Input-specific constraints, including CLI path
-rules and opt-in version ownership, remain part of the configuration contract. Consistent combination
-semantics do not require identical acquisition or lifetime behavior from every
-source kind.
+underlay groups compose strictly within each group, then combine from lowest to
+highest beneath the main tier. Between tiers, mappings combine recursively and
+retain omitted lower-priority children. Sequence values follow collection policy;
+other present values retain the established replacement rules. Source acquisition
+kind does not determine precedence. Input-specific constraints, including version
+ownership and path protections, remain part of the configuration contract.
+Consistent combination semantics do not require identical acquisition or lifetime
+behavior from every source kind.
 
-After source precedence is complete, built-in sibling `extends` relationships
-resolve structurally in the same parser-independent representation, using the
-existing recursive overlay rules. This adds neither an acquired source nor a
-consumer registration mechanism. Enclosing relationships precede nested
-destination-local resolution; typed defaults, application resolution, and
-secret lookup retain their existing lifecycle roles. The [configuration
-contract](../config.md#sibling-inheritance) owns the exact syntax and presence
-rules, and [ADR 0009](../adr/0009-sibling-inheritance.md) records the rationale.
+Built-in sibling `extends` relationships resolve after source precedence in the
+parser-independent document representation. Preserve existing mapping-sibling
+scopes and allow an identified sequence to provide a sibling scope for its
+records. A record may inherit from one parent in that sequence, selected by
+complete identity. The child supplies and keeps its own identity while inheriting
+the parent's other settings. Parents remain ordinary records subject to normal
+validation.
+
+Use the shared dependency ordering and preserve assembled sequence order.
+Resolve enclosing relationships before nested destination-local relationships.
+Mappings combine recursively; sequences use the inheriting collection's policy.
+Whole-record upsert replaces records during combination; explicit inheritance
+uses the records that remain. Inheritance remains built-in and creates no
+acquired source.
+[ADR 0009](../adr/0009-sibling-inheritance.md) records the
+original scope and continuing ownership decisions, with sequence combination
+and identified-sequence inheritance defined by
+[ADR 0017](../adr/0017-collection-sequence-policy.md) and CLI ordering by
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md).
 
 ConfigKit must define supported YAML semantics explicitly rather than inherit
 parser defaults. Processing order and diagnostics must be deterministic for the
@@ -185,13 +292,14 @@ configuration. Do not run application hooks on invalid typed configuration.
 
 User-controlled precedence is application defaults, ordered underlays, composed
 main input, selected overlay, then explicitly supplied CLI overrides.
-Applications own flag parsing; ConfigKit owns overlay semantics and provenance.
-Domain resolution follows these
-inputs and must remain recorded, not become a hidden override channel.
+This priority order is distinct from processing order: typed defaults are applied
+at decoding, and application resolution follows CLI input under the lifecycle
+rules above.
 
-Preserve node-based composition until the effective input is ready for typed
-decoding. Preserve presence and source information through processing. Ordinary Go zero
-values must not be used to infer whether input was absent. Final configuration,
+Preserve node-based composition through source assembly and inheritance until
+typed decoding. Preserve presence and source information through later CLI and
+application-resolution changes as well. Ordinary Go zero values must not be used
+to infer whether input was absent. Final configuration,
 metadata, and effective inspection must agree, including application resolution
 changes; see [ADR 0003](../adr/0003-preserve-presence-and-resolution-history.md).
 Safe historical values and an explanation renderer are part of the implemented contract,
@@ -208,6 +316,72 @@ comparison and disclosure behavior, the [component overview](../internal/overvie
 owns implementation responsibility, and [ADR 0010](../adr/0010-effective-configuration-diff.md)
 records the accepted decision.
 
+## Collection Identity And Combination
+
+ConfigKit owns a common collection policy for imported records, inline sequences,
+selected overlays, and sibling inheritance. Configuration authors may declare
+identity and combination rules; applications may register authoritative identity
+constraints. Configuration declarations must agree with application constraints.
+Keep source placement explicit and separate from policy, retaining the placement
+decision in [ADR 0014](../adr/0014-sequence-placement-and-composition.md).
+[ADR 0017](../adr/0017-collection-sequence-policy.md) owns the rationale for
+collection policy and its relationship to application authority.
+
+Gather declarations for the relevant destination and source or item-local scope
+before strict composition. Applicable identity from accumulated lower tiers must
+be available when composing higher-tier peers. Higher-tier declarations cannot
+repair invalid lower-tier composition. Preserve the distinction between source
+acquisition, dependency-ready scheduling within scopes, and precedence order.
+
+Strictly compose each tier's contributions before applying one operation for the
+collection against its lower value. Support whole-sequence replacement,
+duplicate-rejecting append, and whole-record replacement by identity (`upsert`).
+Append and upsert require identity; do not infer it from record fields or position.
+Duplicate identities among peers fail under every mode. Source precedence and
+inheritance use the same operations and deterministic ordering rules. Whole-record
+upsert replaces the matching record's fields together; recursive record merging
+and unkeyed sequence concatenation are outside this operation model.
+
+An explicit mode persists at its applicable destination until a higher explicit
+mode changes it. With no explicit mode, effective identity selects upsert and
+its absence selects whole-sequence replacement. Inferred defaults do not become
+persistent instructions. The inheriting destination chooses its operation; copying
+a parent collection does not automatically copy its mode to that destination.
+
+Track YAML identity and explicit modes according to their separate lifetimes.
+Actual whole-value replacement discards lower YAML identity while preserving
+application constraints and any new identity declaration. Item-local policies
+belong to their records: retaining a record retains its rules, and discarding it
+discards those rules. Policies independently applicable at a destination remain
+in effect. Inheritance can copy YAML identity subject to agreement and replacement
+rules; application registrations continue to constrain their registered paths.
+Numeric positions alone do not establish policy ownership.
+
+Allow declarations without accompanying records. A key declaration validates a
+retained sequence immediately or remains pending in its owning scope when no
+sequence exists. A mode-only declaration affects later combinations without
+recombining earlier tiers. Neither declaration alone clears a collection, and
+declaring replace alone does not authorize changing a retained collection's
+identity. These rules do not independently impose path-existence or shape
+requirements.
+
+Enforce YAML identity during source composition, precedence, and identified
+inheritance operations. Application registrations additionally constrain final
+effective sequences after defaults, CLI overrides, and application resolution.
+The application schema and validation own existence, nullability, and allowed
+shape. The final identity guarantee covers actual sequences on successful load;
+it does not cover every intermediate callback state or later caller mutations.
+YAML-only declarations carry no such final guarantee through defaults, CLI
+assignments, or application resolution.
+
+Preserve source attribution, presence, history, sensitivity, and resource context
+as records survive, move, or are replaced. Identity diagnostics use paths and
+available origin information without exposing identity values. The guarantee
+requires no new mutation-history system or exact reconstruction of causes for
+records supplied by defaults or callbacks. Exact identity equality, declaration
+syntax, presence cases, and operation tables belong in the
+[configuration contract](../config.md#strict-document-composition).
+
 ## Ownership And Confidentiality
 
 Returned configuration and metadata must not share mutable state across loads.
@@ -234,7 +408,7 @@ for safe messages supplied by their hooks.
 Do not introduce automatic directory discovery, network providers, arbitrary
 merge strategies, additional configuration languages, or application runtime
 management without concrete consumer evidence and an explicit design decision.
-The [deferred scope](../roadmap/deferred.md#explicit-non-goals-and-deferred-scope)
-owns the deferred-feature inventory. Significant boundary
-changes require an ADR and corresponding policy/contract updates; implementation
-convenience alone is not a reason to broaden the public API.
+Record significant decisions to exclude capabilities, and their rationale, in
+ADRs. Significant boundary changes require an ADR and corresponding
+policy/contract updates; implementation convenience alone is not a reason to
+broaden the public API.

docs/policy/documentation.md

@@ -2,7 +2,7 @@
 
 **Base Policy Version:** 1.11
 
-**Last Updated**: 2026-09-28
+**Last Updated**: 2026-10-16
 
 **Upstream Source:** [Standard Repository Policies](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/docs/policy/documentation.md)
 
@@ -38,9 +38,10 @@ roadmap owns implementation status and sequencing until the decision is
 implemented. Current architecture, user, operator, integration, and internal
 documentation are updated when the behavior lands.
 
-`docs/roadmap/deferred.md` owns deliberate exclusions; task-specific plans
-own execution order and progress. Completed plans retire during release
-preparation.
+`docs/roadmap/future.md` owns potential enhancements and their open questions;
+task-specific plans own execution order and progress. Record significant
+architectural exclusions and their rationale in ADRs. Do not maintain a roadmap
+inventory of rejected proposals. Completed plans retire during release preparation.
 
 ### Audience And Detail
 
@@ -91,7 +92,7 @@ secret values.
 | Inventory of implemented internal packages | `docs/internal/overview.md` | Implemented packages and components, responsibilities, and links to focused internal docs. | Normative architecture, contributor reading policy, external contracts. |
 | Behavior and architecture of internal packages | Other files under `docs/internal/` | Implementation flow, collaborators, state transitions, package-local guarantees and failures, and relevant tests. | Global architecture invariants, configuration definitions and defaults, external schemas, operator procedures. |
 | Architectural decision records | `docs/adr/` | Significant decisions, context, alternatives, rationale, consequences, and supersession history. | Current behavior reference, implementation status, task sequencing. |
-| Deferred scope | `docs/roadmap/deferred.md` | Deliberate exclusions and conditions for reconsideration. | Task execution and current behavior. |
+| Potential future features | `docs/roadmap/future.md` | Candidate enhancements and open questions for future consideration. | Rejected proposals, architectural decisions, task execution, and current behavior. |
 | Future implementation plans | Task-specific files under `docs/roadmap/` | Unfinished work, sequencing, acceptance, and progress; completed plans retire during release preparation. | Implemented behavior and ADR rationale. |
 | Release-note history | `docs/releases/` | One checked-in summary per source release under the procedure; the note at its immutable tag is the release record. | Current commands, behavior, contracts, and compatibility definitions. |
 | Complete examples | `examples/` and executable Go examples | Maintained copyable artifacts and Go API examples. | Configuration reference, symbol contracts, and prose explanation. |
@@ -156,8 +157,10 @@ Use sequentially numbered ADR filenames such as
 
 Treat the decision content of an accepted ADR as immutable. When a decision
 changes, create a new ADR and update the earlier ADR's status to superseded.
-Rejected architectural alternatives belong in the ADR; rejected product ideas
-belong in the roadmap. Routine choices need no ADR.
+Rejected architectural alternatives and significant architectural exclusions
+belong in ADRs. Roadmaps preserve plausible future work, not rejected product
+ideas. Routine choices and rejected suggestions need no ADR unless they
+represent a significant architectural decision.
 
 ## Maintenance
 

docs/release.md

@@ -7,10 +7,10 @@ container image, generated package, or separate registry publication.
 
 ## Release identity and support
 
-- Module: `gitea.maximumdirect.net/eric/ConfigKit`
+- Module: `go.maximumdirect.net/configkit`
 - Primary branch: `main`
 - Authoritative remote: `origin`
-- Authoritative push URL: `https://gitea.maximumdirect.net/eric/ConfigKit.git`
+- Authoritative push URL: `ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git`
 - Tags: stable Semantic Versions such as `v0.5.0`; no prereleases
 - Minimum Go version: the first stable patch of the selected Go series, or a
   higher patch when required by a dependency or specific correctness fix, as
@@ -24,6 +24,9 @@ Release validation runs one offline race-enabled Go suite, one full vet pass,
 and CGO-disabled package compilation for both Linux targets. macOS and CI are
 not release gates; do not wait for or poll CI.
 
+The vanity module path identifies Go imports. Source/tag browser links and public
+Go retrieval use the Forge HTTPS repository independently of SSH publication.
+
 ## 1. Select Go and prepare the tool
 
 Use a clean checkout with Git, Bash 3.2 or newer, and a native compiler for race
@@ -82,7 +85,7 @@ go list -m gitea.maximumdirect.net/eric/ReleaseKit
 "$releasekit_bin" version
 ```
 
-The module-selected executable is ReleaseKit v0.3.0. Use the built executable
+The module-selected executable is ReleaseKit v0.4.2. Use the built executable
 for publication to preserve its exit status and publication-state diagnostics.
 `go run` maps a nonzero child exit status to 1. ReleaseKit's child Go commands
 use the `go` found on `PATH` with `GOTOOLCHAIN=local`; keep the selected
@@ -91,7 +94,7 @@ executable first on `PATH` through the publication command.
 Verify access to the authoritative remote without displaying credentials:
 
 ```sh
-git ls-remote https://gitea.maximumdirect.net/eric/ConfigKit.git HEAD refs/heads/main
+git ls-remote ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git HEAD refs/heads/main
 ```
 
 Publication requires explicit authorization. Local implementation commits do
@@ -111,7 +114,7 @@ Create `docs/releases/<version>.md`. Its first line must be exactly
 `# ConfigKit <version>`, and it must end with the license and attribution footer:
 
 ```markdown
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/docs/oss/attribution.md)
+[COPYRIGHT](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/COPYRIGHT) | [LICENSE](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/LICENSE) | [ATTRIBUTION](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/docs/oss/attribution.md)
 ```
 
 Replace `VERSION` with the full tag and confirm the three target files exist in
@@ -127,7 +130,7 @@ Push only that committed candidate to the literal authoritative URL. This does
 not follow local tags:
 
 ```sh
-git push --no-follow-tags https://gitea.maximumdirect.net/eric/ConfigKit.git HEAD:refs/heads/main
+git push --no-follow-tags ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git HEAD:refs/heads/main
 ```
 
 ReleaseKit requires authoritative `main` to equal this candidate before it
@@ -228,8 +231,8 @@ consumer_dir=$(mktemp -d)
 (
   cd "$consumer_dir"
   go mod init example.invalid/configkit-release-check
-  GOPRIVATE=gitea.maximumdirect.net GOPROXY=direct go get "gitea.maximumdirect.net/eric/ConfigKit@$release_version"
-  go list -m -f '{{.Path}} {{.Version}}' gitea.maximumdirect.net/eric/ConfigKit
+  GOWORK=off GOPROXY=direct go get "go.maximumdirect.net/configkit@$release_version"
+  GOWORK=off go list -m -f '{{.Path}} {{.Version}}' go.maximumdirect.net/configkit
 )
 ```
 

docs/releases/v0.10.0.md

@@ -0,0 +1,77 @@
+# ConfigKit v0.10.0
+
+This minor release adds explicit, composable discovery of a configuration file.
+Applications choose the search conventions and their order; ConfigKit selects one
+file during loading and returns the final configuration with its normal metadata.
+Optional searches that find no file share the expanded `NoSource()` lifecycle.
+
+## Changes
+
+- Add `SearchConfig`, immutable `Search` and `FilenameGroup` descriptions, and
+  search-wide requiredness through `SearchOptions`. Compose explicit `Paths`,
+  custom `SearchDirectory` descriptions, and built-in Unix system, user-config,
+  home, or working-directory presets with `Searches`. See the
+  [public declarations](../../discovery.go) and
+  [discovery contract](../config.md#configuration-discovery).
+- Expand searches in supplied order, trying a directory's filename groups before
+  moving to the next directory. Named and generic groups provide conventional
+  YAML filenames; custom groups provide literal names. Directory searches
+  distinguish omitted filename selection from an explicitly empty selection.
+  Constructors perform no filesystem access, and each load observes current
+  directory bases and file availability.
+- Select the first existing candidate. Access errors and failures while loading
+  the selected file terminate the load rather than trying another configuration.
+  Selected files retain physical source identity, placement, provenance, imports,
+  and relative-resource context. Discovery works with ordinary loading and
+  layered inputs, including underlays, without adding a precedence tier.
+- Permit enabled imports with an absent main input: there are no main import
+  declarations to traverse, while actual underlay sources retain normal imports.
+  Support ordinary selected overlays with an absent main and explicit filesystem
+  context, including a root-only host context. Layered overlays retain their
+  independent `OverlayFilesystem` requirement. See
+  [single-source loading](../config.md#single-source-loading) and
+  [layered loading](../config.md#layered-loading).
+- Preserve ordinary file-context behavior after discovery and include the
+  failing candidate's file identity in access diagnostics. Use Go's
+  platform-aware Windows component rules and native drive-root-relative path
+  resolution. Isolate user-config tests according to the host Go conventions.
+
+## Compatibility and upgrade
+
+Existing explicit source constructors and loading APIs remain available.
+`File(path)` remains an exclusive selection that fails for a missing file;
+discovery is activated only by explicitly supplying `SearchConfig`.
+
+Searches are optional by default. Set `SearchOptions{Required: true}` when the
+application must find a file. An exhausted optional search contributes no main
+document or source record; application version checks, defaults, resolution,
+and validation still run under their existing rules and may reject incomplete
+configuration. A selected overlay is still required to exist.
+
+The former `NoSource()` rejections of enabled imports and explicit filesystem
+context are relaxed. An active ordinary overlay with no main file now loads
+when explicit context is supplied. Applications that relied on those combinations
+being rejected should review their option handling. Selected host files derive
+their own base directory; do not supply an explicit `BaseDir` or native filesystem
+context for a search that selects a host file.
+
+Applications may replace their own fallback-loading loops with the new search
+descriptions. The maintained [consumer examples](../consumers/README.md#explicit-main-file-discovery)
+show simple preset selection and custom-first discovery alongside existing
+configuration tiers. Composition, collection operations, inheritance, CLI
+precedence, and the complete-on-return ownership model retain their existing
+semantics.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.0
+```
+
+The consumer minimum remains Go 1.26.0. Release validation uses Go 1.26.10.
+The YAML dependency remains `go.yaml.in/yaml/v4 v4.0.0-rc.6`, and the maintainer
+tool remains ReleaseKit v0.4.1. Linux amd64 and arm64 remain release-validated
+targets; macOS remains best-effort. Publication follows the existing
+[release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/docs/oss/attribution.md)

docs/releases/v0.10.1.md

@@ -0,0 +1,42 @@
+# ConfigKit v0.10.1
+
+This patch release consolidates ConfigKit's internal loading machinery and
+reduces repeated import bookkeeping. Public APIs and configuration semantics
+remain unchanged from v0.10.0.
+
+## Changes
+
+- Consolidate ordinary and layered input acquisition, including import requests
+  and selected-overlay handling, while retaining their distinct context and
+  precedence rules. Remove unused private reverse conversions.
+- Separate import acquisition, scoped composition, and evidence projection;
+  clarify inheritance preparation, combination, and finalization; and simplify
+  reflective projection and schema-field assembly responsibilities.
+- Retain resolved filesystem facts from non-import validation for later passive
+  resource contexts and ordinary overlays. Remove duplicate absent-host context
+  derivation while preserving validation timing and handle cleanup.
+- Record empty optional-import selections directly against their declaring
+  source, avoiding repeated searches through acquired sources. Index import
+  dependencies for scope-local edge preparation instead of scanning the whole
+  inclusion graph for every item scope. Stable dependency-ready ordering,
+  provenance, and source destinations are preserved.
+- Expand regression coverage for import evidence ownership, scope boundaries,
+  and broad main/underlay item imports. Improve
+  [consumer loading guidance](../consumers/README.md) and internal documentation.
+
+## Compatibility and upgrade
+
+No consumer code or configuration migration is required. Composition, collection
+operations, inheritance, discovery, CLI precedence, source-version checks, and
+inspection retain their existing contracts.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.1
+```
+
+The consumer minimum remains Go 1.26.0. Dependencies and platform support are
+unchanged. Publication follows the existing [release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/docs/oss/attribution.md)

docs/releases/v0.10.2.md

@@ -0,0 +1,70 @@
+# ConfigKit v0.10.2
+
+This patch release fixes edge-case loading failures, resource cleanup, and limit
+accounting, and simplifies ConfigKit's internal loading machinery. Public APIs
+and documented configuration semantics remain unchanged from v0.10.1.
+
+## Fixes
+
+- Terminate pointer-only recursive type traversal safely during decoding and
+  schema-path resolution, preserving nullable values and supported recursive
+  structures. Roll back failed dynamic descriptor construction so subsequent
+  operations do not reuse incomplete state or panic.
+- Accept finite, non-cyclic slice views that share backing storage while
+  retaining cycle detection and detached output.
+- Deactivate resolution, validation, and version-check contexts when callbacks
+  panic, and close library-owned import roots during panic unwinding. The
+  original application panic continues to propagate.
+- Report directory enumeration and close failures instead of treating them as
+  optional absence, including failures reported as not-exist after a successful
+  open. Genuinely missing optional directories retain their existing behavior.
+- Reuse completed symlink dependencies during host and native import discovery,
+  avoiding exponential repeated expansion of finite link graphs while retaining
+  cycle detection and containment checks.
+- Check existing projection budgets before bulk container allocation and account
+  for the complete retained inspection-history graph, including replay and
+  separately copied inheritance evidence.
+- Apply the documented append/upsert sequence requirements to non-sequence
+  contributions at retained collection-policy destinations.
+
+## Internal improvements
+
+- Index collection-policy retirement and prepare sparse incoming policy changes
+  instead of repeatedly scanning or copying unrelated retained policy.
+- Reuse successful dynamic-type eligibility checks within an operation and index
+  tier-history lookups, compound identity restoration, and secret-failure source
+  attribution to avoid repeated scans.
+- Remove unused snapshots, evidence, helpers, fields, and test-only production
+  paths. Clarify acquisition handoffs and separate collection preparation,
+  application, and finalization while sharing sequence-history construction.
+- Separate patterned glob entry preparation from traversal. Consolidate engine
+  import defaults, snapshot them during load preflight, and construct placement
+  directly across the facade while keeping public types root-owned.
+- Add regression coverage for the corrected failures, public historical paths,
+  defaults snapshots, and resource ownership. Strengthen fuzz detachment checks
+  and replace redundant or implementation-coupled assertions.
+- Update release tooling from ReleaseKit v0.4.1 to v0.4.2.
+
+These changes remove redundant work and improve scaling in the identified paths;
+no end-to-end performance improvement has been quantified.
+
+## Compatibility and upgrade
+
+No consumer API or configuration-format migration is required. The
+[configuration contract](../config.md) remains authoritative.
+
+Loads that previously succeeded despite directory acquisition failures, invalid
+append/upsert contributions, or incomplete retained-history accounting may now
+return the documented structured errors. These corrections enforce existing
+requirements and limits rather than introducing new ones.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.2
+```
+
+The consumer minimum remains Go 1.26.0. The YAML dependency and platform support
+are unchanged. Publication follows the existing [release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/docs/oss/attribution.md)

docs/releases/v0.6.0.md

@@ -30,7 +30,7 @@ adopts ReleaseKit for source publication, and raises the consumer Go minimum to
   successful-tag-push completion point remain unchanged; CI is not a gate.
 - Adopt release policy 1.6, distinguishing the consumer Go minimum from the
   validation toolchain. Retire completed planning and measurement records into
-  Git history while preserving [deferred work](../roadmap/deferred.md).
+  Git history while preserving [performance candidates](../roadmap/future.md#5-performance-experiments).
 
 ## Compatibility and upgrade
 

docs/releases/v0.7.1.md

@@ -0,0 +1,22 @@
+# ConfigKit v0.7.1
+
+This patch updates the maintainer release tool to ReleaseKit v0.4.1. ConfigKit's
+runtime behavior and public API are unchanged.
+
+## Compatibility and upgrade
+
+No application-code or configuration migration is required from v0.7.0. The
+consumer minimum remains Go 1.26.0, and the YAML dependency is unchanged.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.7.1
+```
+
+ReleaseKit v0.4.1 is a maintainer tool dependency and does not change consumer
+configuration or runtime behavior. Linux amd64 and arm64 remain
+release-validated targets; macOS remains best-effort. Publication follows the
+existing [release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.7.1/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.7.1/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.7.1/docs/oss/attribution.md)

docs/releases/v0.8.0.md

@@ -0,0 +1,70 @@
+# ConfigKit v0.8.0
+
+This minor release adds explicit input placement, relative import destinations,
+shared source-version checking, and opt-in composition of identified sequence
+records. Applications can assemble independently authored configuration fragments
+into one final configuration while retaining source locations, provenance,
+history, and sensitivity information.
+
+## Changes
+
+- Add `Destination` to ordinary load options and layered inputs. A source mapping
+  can contribute beneath literal application keys without being rewritten by the
+  consumer. Imports inherit that destination or append a relative YAML
+  `destination`. Physical import paths and resource contexts remain relative to
+  their declaring sources. See [input destinations](../config.md#input-destinations),
+  [import syntax](../config.md#explicit-imports), and the
+  [mounted collection example](../consumers/README.md#input-destinations-and-mounted-collections).
+- Add `SourceVersionModeIfPresent` and `SourceVersionModeRequired` to apply one
+  application-owned version checker across main, underlay, imported, and selected
+  overlay documents. Enabled modes check source-local declarations and consume
+  accepted non-main headers before composition. Detached, sensitivity-aware
+  evidence is available through `SourceInfo.VersionCheck`. Acceptance remains
+  application policy; ConfigKit does not require declarations to equal the main
+  version. See [shared source-version checks](../config.md#shared-source-version-checks).
+- Add explicit `PlacementModeSequenceItem` placement for ordinary and layered
+  inputs, and `placement: sequence-item` for path and glob imports. A source
+  mapping becomes one item at its destination; ordinary helper imports compose
+  within that item and can supply its identity. See
+  [imports](../config.md#explicit-imports).
+- Add `Definition.SequenceCompositions` registrations for strict composition at
+  selected literal paths using one string identity field. Distinct records append
+  in contribution order, while duplicate identities conflict. Higher-priority
+  sequences still replace lower-priority sequences wholesale. Registration does
+  not add identity-based overlays or final identity validation after defaults and
+  application resolution. See the [composition contract](../config.md#strict-document-composition)
+  and [maintained prompt catalog](../consumers/README.md#identified-prompt-sequences).
+- Extend source inspection with destination and placement evidence, including
+  whether a nested destination is unresolved in an intermediate or failed-load
+  snapshot. Preserve source-specific history, consumed-header sensitivity, and
+  explanations of descendants removed by sequence replacement as records are
+  assembled. Source locations continue to identify authored coordinates.
+
+## Compatibility and upgrade
+
+The new behavior is opt-in: zero-valued destinations retain root placement,
+mapping placement remains the default, unregistered sequences retain strict
+conflict behavior, and the default source-version mode preserves the existing
+main-only version policy. Recursive mapping precedence, whole-sequence
+replacement between tiers, and application-owned final validation remain intact.
+
+Public option, definition, input, and source-information structs gain fields.
+Consumers using unkeyed literals for affected structs must switch to keyed
+literals or update them. `SourceInfo` now contains a `Path` and is no longer
+comparable with `==` or usable directly as a map key; compare the relevant fields
+or select an application-appropriate key instead. Existing keyed literals need
+no changes to retain the previous loading behavior.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.8.0
+```
+
+The consumer minimum remains Go 1.26.0. The YAML dependency remains
+`go.yaml.in/yaml/v4 v4.0.0-rc.6`, and the maintainer tool dependency remains
+ReleaseKit v0.4.1. Linux amd64 and arm64 remain release-validated targets;
+macOS remains best-effort. Publication follows the existing
+[release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.8.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.8.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.8.0/docs/oss/attribution.md)

docs/releases/v0.9.0.md

@@ -0,0 +1,111 @@
+# ConfigKit v0.9.0
+
+This minor release expands import selection, adds author-declared collection
+identity and operations, and supports inheritance between identified records.
+It also moves CLI assignments after inheritance and typed decoding. These changes
+include breaking API and configuration behavior changes from v0.8.0; review the
+migration guidance below before upgrading.
+
+## Changes
+
+- Extend imports with named-file and directory lists, directory filename patterns,
+  exclusions, recursion and depth controls, and explicit hidden-file and symlink
+  discovery controls. Add `ImportDefaults` to ordinary and layered options, with
+  authored declarations taking precedence over application defaults. Imports are
+  optional by default. `SourceInfo.ImportSelections` exposes completed optional
+  declarations that selected no sources. See the
+  [import contract](../config.md#explicit-imports) and
+  [consumer guidance](../consumers/README.md#import-defaults-and-selection-inspection).
+- Use shared dependency-ready ordering for import composition and sibling
+  inheritance. Dependencies complete before dependents, with deterministic
+  selection among currently eligible contributions. Source acquisition and
+  callback order remain separate from assembly order. See the
+  [ordering decision](../adr/0015-shared-dependency-ready-ordering.md).
+- Add root `configkit.sequences` declarations for collection identity and
+  `replace`, `append`, or `upsert` operations, including in selected overlays.
+  Strict peers combine distinct identities and reject duplicates; precedence
+  and inheritance apply the destination's collection operation. Upsert replaces
+  a whole matching record at its retained position. Identity supports compound
+  field sets and scalar strings, numbers, booleans, and null. See the
+  [collection contract](../config.md#strict-document-composition).
+- Add `Definition.SequenceIdentities`, exact `SequenceIdentityAt` registrations,
+  and dynamic `SequenceIdentityMatching` selectors. Application registrations
+  govern structural collection operations and check existing matching final
+  typed sequences, including values from defaults, CLI assignments, and
+  application resolution. YAML-only declarations govern structural operations
+  without adding that final-result check.
+- Support record inheritance within an identified sequence using an `extends`
+  mapping containing the parent's complete identity. The child retains its own
+  identity, relationships use surviving assembled records, and output sequence
+  order is preserved. See [sibling inheritance](../config.md#sibling-inheritance)
+  and the maintained [sequence catalog](../consumers/README.md#identified-prompt-sequences).
+- Apply explicit CLI overrides to the decoded configuration before application
+  resolution. Mappings retain omitted fields and their presence metadata;
+  sequences replace whole lists independently of collection operations. See the
+  [CLI contract](../config.md#explicit-cli-overrides).
+- Correct native import alias and contained-symlink handling, source-version
+  path projection, and provenance/history through collection movement,
+  replacement, inheritance, and CLI assignment. Reduce repeated scans,
+  accumulated policy copying, and sparse-projection storage during construction.
+
+## Compatibility and upgrade
+
+This pre-v1 minor release intentionally changes the v0.8.0 contracts:
+
+1. **Migrate import requiredness.** The YAML `optional` field is removed and is
+   rejected. Replace `optional: true` with `required: false`; omission is equivalent
+   when the application does not default imports to required. Replace
+   `optional: false` with `required: true`. Imports that previously relied on
+   implicit requiredness now need `required: true`, or an application
+   `ImportDefaults.Required` default set to true. Review discovery filters:
+   `follow` and `hidden` default to true, and directory searches select all
+   filenames unless a pattern is supplied.
+2. **Replace sequence registrations.** `SequenceComposition` and
+   `Definition.SequenceCompositions` are removed without compatibility aliases.
+   For a previous registration at `prompts` using `id`, use:
+
+   ```go
+   rules.SequenceIdentities = []configkit.SequenceIdentity{
+       configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+   }
+   ```
+
+   These registrations now also enforce identity in final typed sequences. Fix
+   missing or duplicate identities introduced by defaults, CLI assignments, or
+   application resolution. Registration does not require a collection to exist
+   or determine its allowed shape; schema and application validation retain
+   those responsibilities.
+3. **Review collection precedence and ordering.** An identified collection now
+   defaults to upsert across layers and inheritance when no explicit mode
+   applies, rather than unconditional whole-sequence replacement. Declare
+   `mode: replace` at the relevant destination where replacement is intended.
+   With append or upsert, `[]` contributes no records and does not clear the
+   collection; null is invalid. Use `mode: replace` with `[]` to clear it.
+   An explicit mode persists at its destination until changed; a parent's mode
+   does not transfer to a different inheriting destination. Unidentified
+   sequences retain strict peer conflicts and whole-value precedence
+   replacement. Dependency-ready assembly can change sequence positions and
+   diagnostic or history order compared with the former traversal order.
+4. **Review CLI recovery and inheritance assumptions.** CLI overrides can no
+   longer repair values that fail earlier decoding, bypass source or inheritance
+   errors, or add or cancel inheritance relationships. Supply structural
+   directives in source configuration. Application resolution still receives
+   explicit CLI values and may record subsequent normalization or derivation.
+5. **Update affected Go literals and diagnostic handling.** Use keyed literals
+   for expanded option and source-information structs. Collection validation adds
+   `CodeSequenceInvalid` (`sequence.invalid`) and `CodeSequenceConflict`
+   (`sequence.conflict`); update diagnostic handling where applicable.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.9.0
+```
+
+The consumer minimum remains Go 1.26.0. The YAML dependency remains
+`go.yaml.in/yaml/v4 v4.0.0-rc.6`, and the maintainer tool dependency remains
+ReleaseKit v0.4.1. Linux amd64 and arm64 remain release-validated targets;
+macOS remains best-effort. Publication follows the existing
+[release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/docs/oss/attribution.md)

docs/roadmap/deferred.md

@@ -1,57 +0,0 @@
-# Deferred Scope
-
-This document owns intentionally excluded features, not a committed delivery plan.
-The [architecture policy](../policy/architecture.md) governs changes to these
-boundaries. Implemented behavior belongs in the [configuration contract](../config.md)
-and consumer adoption in the [consumer guide](../consumers/README.md).
-
-## Explicit non-goals and deferred scope
-
-General environment-variable configuration overlays are not supported. Typed secret
-references and explicit directory bootstrap are the environment convention. Literal
-credential configuration and implicit secret-directory discovery are unsupported.
-
-The following remain deliberately excluded:
-
-- automatic `conf.d` discovery;
-- remote imports, arbitrary providers, and additional configuration formats;
-- custom merge strategies, sequence merging, reset operators, multiple-parent
-  inheritance, and cross-scope references;
-- named overlay inheritance;
-- parser-specific or custom structural-decoding extension APIs;
-- generic dynamic-subtree conversion and module-registry APIs;
-- automatic schema migrations;
-- hot reload, runtime resource replacement, and remote resource validation;
-- a bundled CLI framework or application commands; and
-- configuration fingerprints.
-
-Applications may build their own validate, effective-value, source, bootstrap, and
-explanation commands around the library. Broadening these boundaries requires
-concrete consumer evidence, compatibility review, and an explicit design change.
-
-Effective configuration diffs are implemented over frozen successful-load
-inspections; their current comparison and disclosure contract is in the
-[configuration contract](../config.md#effective-configuration-diffs), with
-consumer workflows in the [adoption guide](../consumers/README.md#effective-configuration-diffs).
-Fingerprints remain deferred.
-
-Built-in sibling inheritance using `extends` is implemented as described in the
-[configuration contract](../config.md#sibling-inheritance). It is distinct from
-inheritance between selected overlay files, which remains excluded above.
-
-## Deferred performance experiments
-
-The completed performance audit left these internal optimization candidates for
-separate investigation:
-
-- branch-local explanation replay instead of the current whole-tree replay;
-- redesigning the private metadata-copy handoff while preserving detached public
-  records;
-- caching schema descriptors across loads; and
-- indexing complex contributor-trace membership while preserving its equality
-  rules and compact linked traces.
-
-These are not committed implementation work. Reconsider them with evidence that
-the benefit justifies the ownership, retained-memory, or equivalence risks. The
-completed audit and implementation evidence are preserved in Git history at
-`8e91a2b` under `docs/roadmap/`.

docs/roadmap/future.md

@@ -0,0 +1,104 @@
+# Potential Future Work
+
+This document lists potential enhancements and maintenance work for consideration
+in future ConfigKit releases. Entries are not accepted contracts, implementation
+plans, or release commitments. Adopting a candidate requires an explicit design
+decision and a separate plan. Significant architectural exclusions and their rationale belong
+in ADRs; this document does not maintain a list of rejected proposals.
+
+## 3. Recursive body merging for identified records
+
+Status: deferred. The implemented
+[collection policy](../config.md#strict-document-composition) uses `upsert` to
+replace a complete matched record. Recursive merging of fields inside matching
+records remains a separate candidate and would revisit the whole-record update
+boundary selected by [ADR 0017](../adr/0017-collection-sequence-policy.md).
+
+Consider this only in response to a concrete consumer need. A proposal would need
+to define conflicts for overlapping body fields, removal of omitted fields,
+presence and ordering, and how provenance, history, sensitivity, and resource
+context follow partially retained records. Any change requires a new decision and
+implementation plan; this entry does not alter current upsert behavior.
+
+## 4. Required version declarations for selected sources
+
+Status: deferred. PromptKit requested a way to require version declarations on
+a selected subset of source files while permitting other fragments to omit them.
+
+### Motivation and proposed behavior
+
+PromptKit could require each collection's root file (for example,
+`collection.yml` or `meta.yml`, with naming still undecided) to declare an
+accepted specification version. Other files would use the existing
+[check-when-present behavior](../config.md#shared-source-version-checks).
+This would enforce a rule that otherwise remains a documentation convention.
+
+All declarations would use the same application-owned `Definition.Version`
+path and acceptance policy. The proposal concerns where declarations are
+required; it does not introduce independently versioned collections or subtrees.
+A root declaration would not prove that headerless descendants declare a
+compatible version or replace final configuration validation.
+
+### Questions to resolve before implementation
+
+- **Selection API:** should callers mark explicit inputs, select sources by
+  path or predicate, or annotate imports? An input-level requirement is simpler,
+  but cannot by itself select a root reached only through an import.
+- **Scope:** does a requirement apply only to the selected document or also to
+  its imports? Applying it only to that document best fits PromptKit's request;
+  imported fragments could still declare versions checked by the shared policy.
+- **Mode interaction:** how should selection interact with disabled source
+  checks? Require an enabled mode, or activate checking for selected sources?
+  Selection would strengthen check-when-present behavior and add no requirement
+  beyond the load-wide required mode.
+- **Source handling and evidence:** how should selection work across file,
+  reader, byte, and mapping inputs, glob matches, and repeated imports? Define
+  behavior for absent optional inputs and preserve source-local diagnostics,
+  inspection evidence, and existing sensitivity handling.
+
+## 5. Performance experiments
+
+Status: deferred pending evidence. The completed performance audit identified
+four internal optimization candidates for separate investigation:
+
+- Branch-local explanation replay instead of the current whole-tree replay.
+- Redesigning the private metadata-copy handoff while preserving detached public
+  records.
+- Caching schema descriptors across loads.
+- Indexing complex contributor-trace membership while preserving its equality
+  rules and compact linked traces.
+
+These are experiments, not committed implementation work or promised speedups.
+Reconsider them with evidence that the benefit justifies the ownership,
+retained-memory, or equivalence risks. The completed audit and implementation
+evidence are preserved in Git history at `8e91a2b` under `docs/roadmap/`.
+
+### Questions to resolve before implementation
+
+- Which representative workloads show enough remaining cost to justify each
+  optimization, and what measurements would establish a useful improvement?
+- Can narrower replay and membership indexes preserve explanation results,
+  ordering, provenance, and sensitivity behavior?
+- Can metadata handoff changes preserve detached public records and ownership
+  across loads without introducing aliasing?
+- What cache lifetime and concurrency design would make schema reuse worthwhile
+  without excessive retained memory?
+
+## 6. Public path comparison
+
+Status: deferred pending a concrete consumer need. This preserves A2 from the
+completed API review at `68400ff:docs/roadmap/review.md`.
+
+`Path.String()` is a JSON Pointer spelling, not a complete semantic identity:
+an explicit numeric mapping key and a sequence index can share it. The public
+type is opaque and currently non-comparable.
+
+If consumers need comparison, consider a small exact-representation operation
+rather than exposing mutable segments or introducing a pattern language. A
+proposal must distinguish exact segment representation, including parsed versus
+explicit segments and invalid state, from resolution against a document. Pointer
+string equality must not be presented as semantic equality.
+
+Keeping `Path` solely as an opaque query/building value remains an alternative.
+No current contract changes or implementation commitment follow from this entry;
+a comparison operation can be added compatibly later.

docs/roadmap/migration.md

@@ -0,0 +1,268 @@
+# Vanity Module Path Migration
+
+Status: repository implementation and exact-revision remote consumer verification
+complete.
+Planning baseline: `21c9bc0ad0315c4ac96268b487a52376558a18d7`.
+
+This roadmap defines the target and work needed to adopt
+`go.maximumdirect.net/configkit` before ConfigKit's initial v1.0.0 release.
+It is not a staged implementation plan or authorization to push or publish.
+The [configuration contract](../config.md), public declaration comments, and
+[release policy](../policy/release.md) continue to own behavior outside the
+module-identity migration.
+
+## Purpose And Scope
+
+Give ConfigKit a stable, project-owned Go module identifier independent of its
+repository host, while retaining its existing package name, public facade,
+configuration behavior, and implementation boundaries.
+
+The migration changes the module path and therefore Go package/type identities.
+It also brings ConfigKit's release endpoint references into agreement with its
+current Forge hosting. These are related identity updates, not changes to the
+loading lifecycle, YAML syntax, composition, provenance, history, or secrets.
+No runtime API redesign or compatibility-shim system is needed for this scope.
+
+## Current Baseline
+
+| Area | Baseline | Target |
+| --- | --- | --- |
+| Module declaration | `gitea.maximumdirect.net/eric/ConfigKit` in [go.mod](../../go.mod) | `go.maximumdirect.net/configkit` |
+| Self-imports | Old module prefix throughout production packages, tests, benchmarks, and examples | New module prefix with the same package layout |
+| Public package | Root-owned `configkit` facade over private internal packages | Same name and ownership under the new module identifier |
+| Vanity discovery | Root and nested requests already advertise the Forge repository | Existing discovery continues to locate the migrated module |
+| Git remote | `origin` uses `ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git` | Retain this SSH endpoint and align release configuration with it |
+| Release configuration | [releasekit.json](../../releasekit.json), its test, and [runbook](../release.md) still name the old Gitea HTTPS endpoint | Consistent Forge publication references and vanity-path consumer commands |
+
+Path-sensitive test expectations include
+[import_boundary_test.go](../../import_boundary_test.go),
+[facade_candidate_test.go](../../facade_candidate_test.go), and
+[releasekit_profile_test.go](../../releasekit_profile_test.go). Compilation alone
+will not identify every stale literal: a boundary test using the old prefix can
+silently stop checking the intended imports.
+
+### Preliminary External Verification
+
+Checks against the baseline, using Go 1.26.10 and disposable modules/caches
+outside the repository, established:
+
+- HTTPS discovery at the module root and a nested package path returns a
+  `go-import` mapping from `go.maximumdirect.net/configkit` to
+  `https://forge.maximumdirect.net/base-layer/configkit`.
+- Anonymous HTTPS Git access returns the expected `main` revision and release
+  tags, including v0.10.2.
+- Go resolves and downloads v0.10.2 through direct retrieval and the standard
+  public-proxy/fallback configuration, with checksum verification enabled.
+- A disposable consumer's `go get go.maximumdirect.net/configkit@v0.10.2`
+  reaches the repository but rejects its old module declaration. That is the
+  expected remaining mismatch, not a discovery failure.
+
+These observations demonstrate that discovery and retrieval infrastructure work;
+they do not establish that the migrated module builds or can be installed yet,
+nor promise continuing external-service availability. No vanity-service change
+was identified as necessary by these checks.
+
+## Targeted End State
+
+### Canonical Go Identity
+
+The module declares `go.maximumdirect.net/configkit`. Production imports,
+external-package tests, maintained examples, and path-sensitive expectations use
+that prefix consistently. The package name remains `configkit`, and the root
+remains the sole supported consumer import surface. Existing internal packages
+stay internal; the migration does not expose them or change dependency direction.
+
+The v1 module uses the unsuffixed path, with ordinary root-level release tags such
+as `v1.0.0`. There is no `/v1` import suffix or module subdirectory to introduce.
+The [Go module reference](https://go.dev/ref/mod#major-version-suffixes) owns the
+language/toolchain conventions behind that choice.
+
+Existing dependency and tool module identities are separate from ConfigKit's
+identity. In particular, this work does not automatically rename or upgrade the
+ReleaseKit requirement/tool declaration because the vanity service also advertises
+a ReleaseKit path. Any dependency-path change should be assessed separately
+against that upstream module's declared identity and available versions. The
+current Go minimum and dependency versions are not selected for change here.
+
+### Consumer Migration
+
+Current installation/import examples identify the vanity path. The consumer guide
+explains updating the module requirement and Go imports together, including
+transitive libraries that exchange ConfigKit types with an application. Packages
+loaded under the old and new prefixes have different Go identities; changing a
+requirement alone does not make those types interchangeable.
+
+This is a coordinated pre-v1 identity change. Old tags keep their original module
+declarations and contents. The migration does not rewrite them to make historical
+versions installable under the new path. Requesting an older tag through the
+vanity identifier can still produce the observed module-declaration mismatch
+even after this migration; consumers need a revision declaring the new path.
+
+Maintained examples in this repository migrate with the library. Updating other
+applications or maintaining a separate old-path compatibility module is outside
+this effort; neither is required to declare the repository changes complete.
+
+### Repository And Publication Identity
+
+The vanity path identifies Go packages. Forge URLs identify the source repository,
+browser pages, and publication transport. They remain distinct: Go HTTPS discovery
+can use the public Forge HTTPS repository while maintainers push through SSH.
+
+The authoritative publication endpoint remains
+`ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git`. Retaining the
+existing SSH `origin` avoids an unnecessary transport/credential change.
+ReleaseKit's exact `expected_push_url`, its existing profile test, and the
+runbook's literal publication/recovery commands agree with that endpoint.
+Browser/tag links in current release guidance refer to the Forge HTTPS project,
+not to the SSH transport or vanity import path. Public Go retrieval continues
+using the verified Forge HTTPS repository independently. Authenticated write
+capability still belongs to ordinary authorized release preparation; anonymous
+HTTPS read success does not prove push access.
+
+The existing release sequence, validation profile, permissions, immutable tags,
+and successful-publication completion point are unchanged. This migration does
+not introduce CI waiting, proxy-propagation waiting, native macOS checks, or
+consumer installation as permanent release gates.
+
+## Work Needed From The Baseline
+
+### Module Declaration, Imports, And Tests
+
+Update the module directive and all ConfigKit self-imports as one coordinated
+change across root wrappers, engine/document/YAML packages, tests, benchmarks,
+and maintained examples. Preserve the existing package layout and public symbol
+names. Do not mechanically replace every old-host URL: dependency identities,
+upstream attribution, and historical references have different owners.
+
+Review import-boundary predicates, reflection package-path assertions, and any
+other literal module checks alongside imports. Retain their existing protection
+with the new identity rather than removing assertions to make the migration pass.
+Review module metadata/tidiness as appropriate after changing the module path,
+without using that review to bundle unrelated upgrades or tool migrations.
+
+### Release Configuration And Current Guidance
+
+Align `releasekit.json`, its test, and the runbook's publication/recovery commands
+with the retained SSH endpoint. Update the runbook's module identity, HTTPS source
+links, and consumer verification examples accordingly. Reflect only necessary
+endpoint wording changes in the adopted release policy if its current text
+requires them; its release guarantees and gates remain the same.
+
+Review README, declaration documentation, the consumer guide, and applicable
+development/internal documentation for current identity references. Describe the
+consumer import/type-identity migration in the existing consumer migration
+guidance. New release documentation, when prepared through the normal procedure,
+should explain the change and use version-matched Forge source/license links.
+
+Preserve historical release records, accepted ADR decision content, revision-pinned
+audit evidence, upstream provenance links, and third-party module paths where
+they describe their original material. A historical old-host reference is not an
+unmigrated self-import. This roadmap does not authorize rewriting that history or
+changing licensing arrangements.
+
+### Proportionate Verification
+
+Use the existing [development checks](../development.md#baseline-validation)
+and [testing policy](../policy/testing.md). Verify the migrated module builds,
+the default suite and maintained examples pass, and public/dependency boundary
+checks still enforce the root/internal separation under the new prefix. The
+eventual release retains its existing validation, rather than acquiring a second
+validation framework or an expanded platform matrix.
+
+When the migrated commit is available remotely, a one-time disposable consumer
+check should retrieve that exact revision through the vanity path, without a
+local replacement or workspace override, and compile a small public-API use.
+An exact revision before tagging can exercise the migration without creating a
+test release. Report direct retrieval and default proxy/fallback results
+separately where both are checked; do not infer a successful install from
+`go list` or archive download alone.
+
+This remote check is migration evidence when the revised commit is available,
+not authorization to push and not a new publication-completion gate. Keep network
+checks outside the deterministic default suite, avoid polling external services,
+and preserve the policy that successful tag publication completes a release.
+After publication, retrieval of the exact released version remains optional and
+non-gating under the existing procedure. Record any unavailable verification
+honestly instead of claiming that baseline retrieval validates migrated code.
+
+## Completion Criteria
+
+- The repository consistently declares and imports the vanity module path,
+  while preserving the package name, facade ownership, and configuration behavior.
+- Current documentation, examples, path-sensitive tests, and Forge publication
+  references agree with the implemented identities.
+- Applicable local checks pass, without unrelated dependency or contract changes.
+- Migration evidence distinguishes the preliminary infrastructure checks from
+  any later successful consumer installation of the actual migrated revision.
+- Historical releases remain unchanged, and downstream migration guidance
+  explains both import changes and distinct Go type identities.
+
+Repository implementation completion, external retrieval evidence, downstream
+application adoption, and release publication are separate outcomes. No push,
+tag, or downstream change is authorized merely by completing this roadmap.
+
+No significant open decision remains for this migration.
+
+## Implementation And Verification
+
+The module declaration and all ConfigKit self-imports now use
+`go.maximumdirect.net/configkit`, including internal packages, external-package
+tests, maintained examples, and benchmarks. The import-boundary predicates and
+root-type reflection expectations use the new prefix. Review of every changed
+Go hunk confirmed only the intended module-prefix replacements and publication
+URL expectation; no loading behavior or public symbol names changed.
+
+`releasekit.json`, its profile test, and the runbook now use the retained Forge
+SSH publication endpoint, matching the existing effective `origin` push URL.
+The runbook distinguishes that transport from Forge HTTPS browser links and
+vanity-path consumer retrieval. README and the consumer guide identify the new
+import path; migration guidance covers named-type identity and historical tags.
+
+The Go minimum, dependency/tool versions, and `go.sum` are unchanged. Historical
+release records, accepted ADRs, adopted policies, and upstream attribution were
+left intact. Remaining old ConfigKit path references describe the migration's
+baseline, consumer upgrade instructions, or historical releases.
+
+Local validation passed on Linux with Go 1.26.10 and cached dependencies:
+
+```sh
+GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off ./scripts/check.sh
+GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go mod tidy -diff
+GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test -race ./...
+```
+
+The everyday check included maintained examples, documentation links, root type
+ownership, dependency boundaries, and the release profile. Module/package
+inspection reported the new main-module identity and no old ConfigKit imports
+in the assembled test dependency graph. The module-selected ReleaseKit built
+outside the checkout and reported v0.4.2. Module tidiness produced no diff.
+
+### Remote Consumer Verification
+
+With subsequent user authorization, migration commit
+`587f407a32dec1e00d2aa17d2790c293d994721d` was pushed to authoritative `main`
+through the retained Forge SSH endpoint. No release tag was created or published.
+
+Two disposable consumer modules outside the repository retrieved that exact
+revision through `go.maximumdirect.net/configkit`, using separate fresh module
+caches and Go 1.26.10:
+
+- Direct retrieval with `GOPROXY=direct` passed.
+- Retrieval with `GOPROXY=https://proxy.golang.org,direct` passed. This verifies
+  the standard proxy/fallback configuration, not a proxy-only availability claim.
+
+Checksum verification was enabled, `GOWORK=off` disabled workspace overrides, and
+neither consumer had a `replace` directive. Go selected
+`v0.10.3-0.20261101141937-587f407a32de`; the downloaded origin metadata identified
+the exact migration commit in the Forge HTTPS repository. Both consumers received
+the same module and module-file checksums.
+
+After retrieval, each consumer passed `GOPROXY=off go test -mod=readonly -v ./...`.
+The smoke test compiled and exercised the public API: explicit false/zero input
+over typed defaults, effective provenance with `LayerMain`, source lookup by an
+origin's source ID, and effective YAML rendering. Module inspection confirmed
+that ConfigKit came from the corresponding fresh download cache, not the checkout.
+
+This completes the one-time remote migration verification. The Go-generated
+pseudo-version identifies an untagged commit; it is not an additional release.
+No CI waiting or release gate was introduced.

example_test.go

@@ -6,7 +6,7 @@ import (
 	"os"
 	"strings"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func ExampleLoad() {
@@ -19,6 +19,28 @@ func ExampleLoad() {
 	// Output: {true 3} <nil>
 }
 
+func ExampleLoad_sequenceDeclaration() {
+	type Item struct {
+		ID string `yaml:"id"`
+	}
+	type Config struct {
+		Items []Item `yaml:"items"`
+	}
+	result, err := configkit.Load[Config](configkit.Bytes("catalog.yml", []byte(`configkit:
+  sequences:
+    - destination: [items]
+      key: id
+items:
+  - id: prompt
+`)))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	fmt.Println(result.Config.Items[0].ID)
+	// Output: prompt
+}
+
 func ExampleNoSource() {
 	type Config struct {
 		Workers int `yaml:"workers"`
@@ -154,10 +176,18 @@ func ExampleOverride() {
 		})
 	}
 	result, err := configkit.Load(configkit.NoSource(), configkit.Options[Config]{
-		Definition: configkit.Definition[Config]{Defaults: func() Config { return Config{Workers: 4} }},
-		Overrides:  overrides,
+		Definition: configkit.Definition[Config]{
+			Defaults: func() Config { return Config{Workers: 4} },
+			Resolve: func(configuration *Config, resolution *configkit.Resolution) error {
+				configkit.Default(resolution, configkit.Keys("workers"), &configuration.Workers, 100,
+					"preserve an explicitly supplied worker count")
+				return nil
+			},
+		},
+		Overrides: overrides,
 	})
-	fmt.Println(result.Config.Workers, result.Sources()[0].Label, err)
+	source, _ := result.Source("source-1")
+	fmt.Println(result.Config.Workers, source.Label, err)
 	// Output: 0 --workers <nil>
 }
 

examples/consumers/consumers.go

@@ -9,7 +9,7 @@ import (
 	"strings"
 	"time"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // Artifact is a Narratio-shaped generated output declaration.
@@ -167,7 +167,7 @@ func LoadNotariusPaths(path, invocationDir string, overrides ...configkit.Overri
 				resolveNotariusReference(configuration, resolution, invocationDir)
 				return nil
 			},
-			Secret: func(path configkit.Path) bool { return path.String() == "/sensitive" },
+			Sensitive: func(path configkit.Path) bool { return path.String() == "/sensitive" },
 		},
 	})
 }
@@ -177,7 +177,7 @@ func resolveNotariusReference(configuration *NotariusPathConfig, resolution *con
 	if configuration.Reference == "" || filepath.IsAbs(configuration.Reference) {
 		return
 	}
-	info, found := resolution.InputInfo(path)
+	info, found := resolution.EntryInfo(path)
 	if !found {
 		resolution.Warning(path, "relative reference has no entry provenance")
 		return

examples/consumers/consumers_test.go

@@ -11,8 +11,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_narratio() {
@@ -82,7 +82,7 @@ func Example_weatherStartup() {
 	defer os.RemoveAll(directory)
 	_ = os.WriteFile(filepath.Join(directory, blockedName), []byte("unused-example-value\n"), 0o600)
 	_ = os.WriteFile(filepath.Join(directory, tokenName), []byte("disposable-example-credential\n"), 0o600)
-	report, bootstrapErr := configkit.LoadSecretsDir(directory)
+	report, bootstrapErr := configkit.LoadSecretsIntoEnvironment(directory)
 	var reportOutput bytes.Buffer
 	_, reportWriteErr := report.WriteTo(&reportOutput)
 

examples/consumers/destinations.go

@@ -0,0 +1,154 @@
+package consumers
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"path"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+// CollectionBundleConfig is a representative application-owned collection
+// shape. Collection and prompt version labels remain ordinary domain fields.
+type CollectionBundleConfig struct {
+	Version     string                          `yaml:"version"`
+	Collections map[string]CollectionDefinition `yaml:"collections"`
+}
+
+type CollectionDefinition struct {
+	Name        string                       `yaml:"name"`
+	Version     string                       `yaml:"version"`
+	Description string                       `yaml:"description"`
+	Prompts     map[string]CollectionPrompt  `yaml:"prompts"`
+	Profiles    map[string]CollectionProfile `yaml:"profiles"`
+}
+
+type CollectionPrompt struct {
+	Version        string              `yaml:"version"`
+	DefaultProfile string              `yaml:"default_profile"`
+	ContentFile    string              `yaml:"content_file"`
+	ResourceText   string              `yaml:"resource_text"`
+	Messages       []CollectionMessage `yaml:"messages"`
+}
+
+type CollectionMessage struct {
+	Role    string `yaml:"role"`
+	Content string `yaml:"content"`
+}
+
+type CollectionProfile struct {
+	Format      string  `yaml:"format"`
+	Temperature float64 `yaml:"temperature"`
+}
+
+// LoadCollectionBundle demonstrates one layered collection load. Its main
+// document owns the application schema version; the mounted entry declares
+// relative destinations for collection metadata, prompt/profile peers, and
+// their nested imports. The operator version override remains a separate tier.
+func LoadCollectionBundle() (*configkit.Result[CollectionBundleConfig], error) {
+	files, err := fs.Sub(bundledFiles, "testdata/collection-bundle")
+	if err != nil {
+		return nil, err
+	}
+	bundle := configkit.NewFilesystem("collection bundle", files)
+	collectionDestination := configkit.Keys("collections", "weatherreporter")
+	promptDestination := collectionDestination.Key("prompts")
+	return configkit.LoadLayered(
+		configkit.Input{Source: configkit.Bytes("application main", []byte("version: 1\n"))},
+		configkit.LayeredOptions[CollectionBundleConfig]{
+			Definition: configkit.Definition[CollectionBundleConfig]{
+				Version: &configkit.VersionRule{Path: configkit.Keys("version"), Check: func(version configkit.Version, _ *configkit.Validation) error {
+					if !version.Present || version.Text != "1" {
+						return errors.New("unsupported application schema version")
+					}
+					return nil
+				}},
+				Resolve:  resolveCollectionResources,
+				Validate: validateCollectionBundle,
+			},
+			Underlays: []configkit.Underlay{
+				{Inputs: []configkit.Input{{
+					Source: bundle.File("collections/weather/collection.yml"), Imports: true, Destination: collectionDestination,
+				}}},
+				{Inputs: []configkit.Input{{
+					Source: bundle.File("operators/weather-prompt-version.yml"), Destination: promptDestination,
+				}}},
+			},
+		},
+	)
+}
+
+func resolveCollectionResources(configuration *CollectionBundleConfig, resolution *configkit.Resolution) error {
+	for collectionID, collection := range configuration.Collections {
+		for promptID, prompt := range collection.Prompts {
+			if prompt.ContentFile == "" {
+				continue
+			}
+			contentPath := configkit.Keys("collections", collectionID, "prompts", promptID, "content_file")
+			info, found := resolution.EntryInfo(contentPath)
+			if !found || len(info.Origin.Locations) != 1 {
+				return fmt.Errorf("prompt resource has no single declaring source")
+			}
+			resourceSource, found := resolution.Source(info.Origin.Locations[0].SourceID)
+			if !found {
+				return fmt.Errorf("prompt resource source is unavailable")
+			}
+			context, found := resolution.SourceContext(resourceSource.ID)
+			if !found {
+				return fmt.Errorf("prompt resource context is unavailable")
+			}
+			data, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, prompt.ContentFile))
+			if err != nil {
+				return fmt.Errorf("read prompt resource: %w", err)
+			}
+			prompt.ResourceText = string(data)
+			collection.Prompts[promptID] = prompt
+			resolution.RecordNormalization(
+				configkit.Keys("collections", collectionID, "prompts", promptID, "resource_text"),
+				"read source-relative prompt content", contentPath,
+			)
+		}
+		configuration.Collections[collectionID] = collection
+	}
+	return nil
+}
+
+func validateCollectionBundle(configuration *CollectionBundleConfig, validation *configkit.Validation) {
+	for collectionID, collection := range configuration.Collections {
+		for promptID, prompt := range collection.Prompts {
+			if prompt.DefaultProfile == "" {
+				continue
+			}
+			if _, found := collection.Profiles[prompt.DefaultProfile]; !found {
+				validation.Error(configkit.Keys("collections", collectionID, "prompts", promptID, "default_profile"), "must name a profile in this collection")
+			}
+		}
+	}
+}
+
+// ReadCollectionPromptContent follows the effective content field's physical
+// source, including when it was inherited from a peer prompt.
+func ReadCollectionPromptContent(result *configkit.Result[CollectionBundleConfig], collectionID, promptID string) (string, error) {
+	if result == nil {
+		return "", errors.New("collection result is nil")
+	}
+	contentPath := configkit.Keys("collections", collectionID, "prompts", promptID, "content_file")
+	info, found := result.Metadata().Lookup(contentPath)
+	if !found || len(info.Origin.Locations) != 1 {
+		return "", errors.New("prompt resource has no single declaring source")
+	}
+	context, found := result.SourceContext(info.Origin.Locations[0].SourceID)
+	if !found {
+		return "", errors.New("prompt resource context is unavailable")
+	}
+	prompt, found := result.Config.Collections[collectionID].Prompts[promptID]
+	if !found {
+		return "", errors.New("prompt is unavailable")
+	}
+	data, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, prompt.ContentFile))
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}

examples/consumers/destinations_test.go

@@ -0,0 +1,137 @@
+package consumers_test
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
+)
+
+func Example_inputDestination() {
+	mounted, err := configkit.LoadLayered[map[string]any](configkit.Input{
+		Source: configkit.Mapping("weather prompt", map[string]any{
+			"summarize.alerts": map[string]any{"version": "1"},
+		}),
+		Destination: configkit.Keys("collections", "weather.reporter", "prompts"),
+	})
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	root, err := configkit.LoadLayered[map[string]any](configkit.Input{
+		Source: configkit.Bytes("standalone", []byte("name: standalone\n")),
+	})
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	_, found := mounted.Config["collections"]
+	fmt.Println(found, root.Config["name"])
+	// Output: true standalone
+}
+
+func TestCollectionBundleAssemblesMountedPeersAndResources(t *testing.T) {
+	result, err := consumers.LoadCollectionBundle()
+	if err != nil {
+		t.Fatalf("LoadCollectionBundle: %v", err)
+	}
+	collection := result.Config.Collections["weatherreporter"]
+	if result.Config.Version != "1" || collection.Name != "Weather Reporter" || collection.Version != "2.4.0" {
+		t.Fatalf("main and collection versions = %q, %#v", result.Config.Version, collection)
+	}
+	brief := collection.Prompts["brief"]
+	custom := collection.Prompts["custom"]
+	if brief.Version != "2" || brief.DefaultProfile != "compact" || brief.ContentFile != "welcome.txt" || len(brief.Messages) != 1 {
+		t.Fatalf("version-only override replaced lower prompt fields: %#v", brief)
+	}
+	if custom.Version != "2" || custom.DefaultProfile != "weather" || custom.ContentFile != brief.ContentFile ||
+		len(custom.Messages) != 1 || custom.ResourceText != "Welcome to the weather collection.\n" {
+		t.Fatalf("inherited prompt = %#v", custom)
+	}
+	weatherProfile := collection.Profiles["weather"]
+	if weatherProfile.Format != "text" || weatherProfile.Temperature != 0.4 {
+		t.Fatalf("inherited profile = %#v", weatherProfile)
+	}
+	resource, err := consumers.ReadCollectionPromptContent(result, "weatherreporter", "custom")
+	if err != nil || resource != custom.ResourceText {
+		t.Fatalf("inherited prompt resource = %q, %v", resource, err)
+	}
+
+	versionInfo, ok := result.Metadata().Lookup(configkit.Keys("version"))
+	if !ok || !versionInfo.Explicit || versionInfo.Origin.Layer != configkit.LayerMain || len(versionInfo.Origin.Locations) != 1 {
+		t.Fatalf("main-owned version metadata = %#v, %v", versionInfo, ok)
+	}
+	collectionVersionPath := configkit.Keys("collections", "weatherreporter", "version")
+	collectionVersion, ok := result.Metadata().Lookup(collectionVersionPath)
+	if !ok || !collectionVersion.Explicit || collectionVersion.Origin.Layer != configkit.LayerUnderlay || len(collectionVersion.Origin.Locations) != 1 {
+		t.Fatalf("ordinary collection version metadata = %#v, %v", collectionVersion, ok)
+	}
+	var metadataSource configkit.SourceInfo
+	var collectionEntrySource configkit.SourceInfo
+	var versionSource configkit.SourceInfo
+	var parentPromptSource configkit.SourceInfo
+	var promptIndexSource configkit.SourceInfo
+	var profileIndexSource configkit.SourceInfo
+	var promptVersionSource configkit.SourceInfo
+	for _, source := range result.Sources() {
+		switch source.Path {
+		case "collections/weather/collection.yml":
+			collectionEntrySource = source
+		case "collections/weather/metadata.yml":
+			metadataSource = source
+		case "collections/weather/version.yml":
+			versionSource = source
+		case "collections/weather/prompts/index.yml":
+			promptIndexSource = source
+		case "collections/weather/prompts/brief.yml":
+			parentPromptSource = source
+		case "collections/weather/profiles/index.yml":
+			profileIndexSource = source
+		case "operators/weather-prompt-version.yml":
+			promptVersionSource = source
+		}
+	}
+	collectionVersionLocation := collectionVersion.Origin.Locations[0]
+	if collectionEntrySource.ID != "source-2" || collectionEntrySource.Destination.String() != "/collections/weatherreporter" ||
+		metadataSource.ID == "" || metadataSource.Destination.String() != "/collections/weatherreporter" ||
+		metadataSource.ImportedFrom == nil || metadataSource.ImportedFrom.SourceID != collectionEntrySource.ID ||
+		versionSource.ID == "" || collectionVersionLocation.SourceID != versionSource.ID || versionSource.Destination.String() != "/collections/weatherreporter" ||
+		versionSource.ImportedFrom == nil || versionSource.ImportedFrom.SourceID != metadataSource.ID || collectionVersionLocation.Line != 1 {
+		t.Fatalf("nested collection version provenance = entry %#v, metadata %#v, version %#v, location %#v", collectionEntrySource, metadataSource, versionSource, collectionVersionLocation)
+	}
+	if promptIndexSource.ID == "" || promptIndexSource.Destination.String() != "/collections/weatherreporter/prompts" ||
+		promptIndexSource.ImportedFrom == nil || promptIndexSource.ImportedFrom.SourceID != collectionEntrySource.ID ||
+		profileIndexSource.ID == "" || profileIndexSource.Destination.String() != "/collections/weatherreporter/profiles" ||
+		profileIndexSource.ImportedFrom == nil || profileIndexSource.ImportedFrom.SourceID != collectionEntrySource.ID {
+		t.Fatalf("nested prompt/profile placement = prompt %#v profile %#v", promptIndexSource, profileIndexSource)
+	}
+	if promptVersionSource.ID == "" || promptVersionSource.Destination.String() != "/collections/weatherreporter/prompts" || promptVersionSource.UnderlayIndex != 2 {
+		t.Fatalf("prompt version source = %#v", promptVersionSource)
+	}
+	contentPath := configkit.Keys("collections", "weatherreporter", "prompts", "custom", "content_file")
+	contentInfo, ok := result.Metadata().Lookup(contentPath)
+	if !ok || !contentInfo.Explicit || len(contentInfo.Origin.Inheritance) != 1 || len(contentInfo.Origin.Locations) != 1 {
+		t.Fatalf("inherited content field metadata = %#v, %v", contentInfo, ok)
+	}
+	contentLocation := contentInfo.Origin.Locations[0]
+	if parentPromptSource.ID == "" || contentLocation.SourceID != parentPromptSource.ID || contentLocation.Line != 4 ||
+		parentPromptSource.Destination.String() != "/collections/weatherreporter/prompts" {
+		t.Fatalf("inherited resource source coordinates = %#v, source %#v", contentLocation, parentPromptSource)
+	}
+}
+
+func TestCollectionPeerPromptConflictsRemainStrict(t *testing.T) {
+	destination := configkit.Keys("collections", "weatherreporter", "prompts")
+	_, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
+			{Source: configkit.Bytes("peer-a", []byte("brief: {version: '1'}\n")), Destination: destination},
+			{Source: configkit.Bytes("peer-b", []byte("brief: {version: '1'}\n")), Destination: destination},
+		}}},
+	})
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeComposeConflict {
+		t.Fatalf("duplicate peer prompt error = %v", err)
+	}
+}

examples/consumers/diff.go

@@ -5,7 +5,7 @@ import (
 	"strconv"
 	"strings"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // FileComparisonConfig is a small application-owned shape for comparing
@@ -101,8 +101,8 @@ func resolveRollout(configuration *RolloutConfig, resolution *configkit.Resoluti
 	url := fmt.Sprintf("https://%s:%d", endpoint.Host, endpoint.Port)
 	if endpoint.URL != url {
 		endpoint.URL = url
-		resolution.Record(configkit.Keys("service", "endpoint", "url"),
-			configkit.ChangeNormalization, "derived endpoint URL",
+		resolution.RecordNormalization(configkit.Keys("service", "endpoint", "url"),
+			"derived endpoint URL",
 			configkit.Keys("service", "endpoint", "host"),
 			configkit.Keys("service", "endpoint", "port"))
 	}

examples/consumers/diff_test.go

@@ -7,8 +7,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func ExampleCompareFiles() {

examples/consumers/discovery_test.go

@@ -0,0 +1,46 @@
+package consumers_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+type workingDirectoryPresetConfig struct {
+	Name string `yaml:"name"`
+}
+
+func Example_workingDirectoryPreset() {
+	original, err := os.Getwd()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer func() { _ = os.Chdir(original) }()
+	root, err := os.MkdirTemp("", "configkit-working-search-")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer os.RemoveAll(root)
+	if err := os.Chdir(root); err != nil {
+		fmt.Println(err)
+		return
+	}
+	if err := os.WriteFile(filepath.Join(root, "service.yml"), []byte("name: example\n"), 0o600); err != nil {
+		fmt.Println(err)
+		return
+	}
+	result, err := configkit.Load[workingDirectoryPresetConfig](
+		configkit.SearchConfig("service", configkit.WorkingDirectory()),
+	)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	source, _ := result.Source("source-1")
+	fmt.Println(result.Config.Name, filepath.Base(source.Path))
+	// Output: example service.yml
+}

examples/consumers/inheritance.go

@@ -1,6 +1,6 @@
 package consumers
 
-import configkit "gitea.maximumdirect.net/eric/ConfigKit"
+import configkit "go.maximumdirect.net/configkit"
 
 // PresetCatalog is ordinary application data; no inheritance fields or
 // registration hooks are required in the typed configuration.

examples/consumers/inheritance_test.go

@@ -3,8 +3,8 @@ package consumers_test
 import (
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func TestPresetCatalogOneLoadAndDerivation(t *testing.T) {

examples/consumers/layered.go

@@ -6,10 +6,10 @@ import (
 	"io/fs"
 	"path"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
-//go:embed testdata/native-source testdata/layered-bundle
+//go:embed testdata/native-source testdata/layered-bundle testdata/collection-bundle testdata/ordinary-imports testdata/source-version
 var bundledFiles embed.FS
 
 // BundledConfig is a small configuration loaded directly from an embedded file.
@@ -18,6 +18,30 @@ type BundledConfig struct {
 	Enabled bool   `yaml:"enabled"`
 }
 
+type PromptBundleConfig struct {
+	Name        string                  `yaml:"name"`
+	Version     string                  `yaml:"version"`
+	Description string                  `yaml:"description"`
+	Prompts     map[string]BundlePrompt `yaml:"prompts"`
+}
+
+type BundlePrompt struct {
+	Summary string `yaml:"summary"`
+}
+
+// LoadPromptBundle demonstrates ordinary Load with opt-in imports whose
+// destinations are declared relative to the entry document.
+func LoadPromptBundle() (*configkit.Result[PromptBundleConfig], error) {
+	files, err := fs.Sub(bundledFiles, "testdata/ordinary-imports")
+	if err != nil {
+		return nil, err
+	}
+	return configkit.Load[PromptBundleConfig](
+		configkit.NewFilesystem("prompt bundle", files).File("config.yml"),
+		configkit.Options[PromptBundleConfig]{Imports: true},
+	)
+}
+
 // LoadBundled demonstrates a native filesystem source without layered options.
 func LoadBundled() (*configkit.Result[BundledConfig], error) {
 	files, err := fs.Sub(bundledFiles, "testdata/native-source")

examples/consumers/layered_test.go

@@ -6,8 +6,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_nativeFilesystem() {
@@ -20,6 +20,34 @@ func Example_nativeFilesystem() {
 	// Output: embedded false
 }
 
+func Example_rootRelativeImports() {
+	result, err := consumers.LoadPromptBundle()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	source, _ := result.Source("source-3")
+	fmt.Println(result.Config.Name, result.Config.Version, result.Config.Prompts["brief"].Summary, source.Destination.String(), err)
+	// Output: Root import example 1.0 A root-loaded prompt. /prompts <nil>
+}
+
+func TestPromptBundleUsesRelativeImportDestinations(t *testing.T) {
+	result, err := consumers.LoadPromptBundle()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Config.Name != "Root import example" || result.Config.Version != "1.0" || result.Config.Prompts["brief"].Summary != "A root-loaded prompt." {
+		t.Fatalf("root import result = %#v", result.Config)
+	}
+	sources := result.Sources()
+	if len(sources) != 3 || sources[0].Destination.String() != configkit.Keys().String() ||
+		sources[1].Path != "metadata.yml" || sources[1].Destination.String() != configkit.Keys().String() ||
+		sources[2].Path != "prompts/brief.yml" || sources[2].Destination.String() != "/prompts" ||
+		sources[2].ImportedFrom == nil || sources[2].ImportedFrom.SourceID != sources[0].ID {
+		t.Fatalf("root import sources = %#v", sources)
+	}
+}
+
 func Example_layeredCatalog() {
 	result, err := consumers.LoadCatalog(fixture("layered-main", "config.yml"))
 	if err != nil {
@@ -32,6 +60,58 @@ func Example_layeredCatalog() {
 	// Output: production false 0 bundle example Welcome from the bundle. <nil>
 }
 
+func Example_sourceVersionAdoption() {
+	result, err := consumers.LoadVersionedService(configkit.SourceVersionModeIfPresent)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	checks, redacted := 0, true
+	for _, source := range result.Sources() {
+		if check := source.VersionEvidence; check != nil {
+			checks++
+			redacted = redacted && check.Redacted && check.Version.Text == ""
+		}
+	}
+	required, requiredErr := consumers.LoadVersionedService(configkit.SourceVersionModeRequired)
+	fmt.Println(result.Config.Service.Version, result.Config.Service.Metadata.Release,
+		checks, redacted, required != nil && requiredErr == nil)
+	// Output: service-v2 application-2026.10 2 true true
+}
+
+func TestVersionedServiceModesAndMountedProtection(t *testing.T) {
+	for _, mode := range []configkit.SourceVersionMode{
+		configkit.SourceVersionModeIfPresent,
+		configkit.SourceVersionModeRequired,
+	} {
+		result, err := consumers.LoadVersionedService(mode)
+		if err != nil || result == nil || result.Config.Service.Version != "service-v2" ||
+			result.Config.Service.Name != "example service" || result.Config.Service.Endpoint != "https://service.example.invalid" ||
+			result.Config.Service.Metadata.Release != "application-2026.10" {
+			t.Fatalf("versioned service mode %d = %#v, %v", mode, result, err)
+		}
+		sources := result.Sources()
+		if len(sources) != 2 {
+			t.Fatalf("versioned service sources = %#v", sources)
+		}
+		for _, source := range sources {
+			check := source.VersionEvidence
+			if check == nil || check.Path.String() != "/version" || !check.Version.Present ||
+				!check.Redacted || check.Version.Text != "" {
+				t.Fatalf("safe source version evidence = %#v", sources)
+			}
+		}
+	}
+	_, err := consumers.LoadVersionedService(configkit.SourceVersionModeIfPresent,
+		configkit.Override{Path: configkit.Keys("service", "version"), Value: "cli-v3", Flag: "--service-version"})
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 ||
+		loadError.Diagnostics()[0].Code != configkit.CodeOverrideVersion ||
+		loadError.Diagnostics()[0].Path.String() != "/service/version" {
+		t.Fatalf("mounted main version override error = %v", err)
+	}
+}
+
 func TestCatalogRetainsPresenceAndSourceContext(t *testing.T) {
 	result, err := consumers.LoadCatalog(fixture("layered-main", "config.yml"))
 	if err != nil {
@@ -39,7 +119,7 @@ func TestCatalogRetainsPresenceAndSourceContext(t *testing.T) {
 	}
 	for _, key := range []string{"enabled", "workers"} {
 		info, found := result.Metadata().Lookup(configkit.Keys(key))
-		if !found || !info.Explicit || info.Origin.Layer != configkit.LayerBase {
+		if !found || !info.Explicit || info.Origin.Layer != configkit.LayerMain {
 			t.Fatalf("%s presence = %#v, %v", key, info, found)
 		}
 	}

examples/consumers/prompt_catalog.go

@@ -0,0 +1,67 @@
+package consumers
+
+import (
+	"strings"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+// PromptCatalogConfig is an application-owned prompt collection shape.
+type PromptCatalogConfig struct {
+	Prompts []PromptRecord `yaml:"prompts"`
+}
+
+// PromptRecord keeps its identity and message meaning in the consumer.
+type PromptRecord struct {
+	ID       string   `yaml:"id"`
+	Name     string   `yaml:"name"`
+	Messages []string `yaml:"messages"`
+	Resource string   `yaml:"resource"`
+}
+
+// LoadPromptCatalog discovers explicitly registered prompt records in the main
+// tier and replaces the lower-priority default collection as a whole.
+func LoadPromptCatalog(mainPath string) (*configkit.Result[PromptCatalogConfig], error) {
+	return configkit.LoadLayered(configkit.Input{
+		Source:  configkit.File(mainPath),
+		Imports: true,
+	}, configkit.LayeredOptions[PromptCatalogConfig]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+			Source: configkit.Bytes("default prompts", []byte("prompts:\n  - id: default\n    name: Default prompt\n    messages: [Default message]\n")),
+		}}}},
+		ImportDefaults: configkit.ImportDefaults{
+			Pattern: []string{"curated*.yml", "generated-*.yml"},
+		},
+		Definition: promptCatalogDefinition(),
+	})
+}
+
+// LoadRequiredPromptCatalog keeps the common one-file import shape small.
+func LoadRequiredPromptCatalog(mainPath string) (*configkit.Result[PromptCatalogConfig], error) {
+	return configkit.Load(configkit.File(mainPath), configkit.Options[PromptCatalogConfig]{
+		Imports: true, Definition: promptCatalogDefinition(),
+	})
+}
+
+func promptCatalogDefinition() configkit.Definition[PromptCatalogConfig] {
+	return configkit.Definition[PromptCatalogConfig]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+		},
+		Validate: validatePromptCatalog,
+	}
+}
+
+func validatePromptCatalog(configuration *PromptCatalogConfig, validation *configkit.Validation) {
+	for index, prompt := range configuration.Prompts {
+		if strings.TrimSpace(prompt.Name) == "" {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("name"), "must not be empty")
+		}
+		if len(prompt.Messages) == 0 {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("messages"), "must contain at least one message")
+		}
+	}
+	if len(configuration.Prompts) == 0 {
+		validation.Error(configkit.Keys("prompts"), "must contain at least one prompt")
+	}
+}

examples/consumers/prompt_catalog_test.go

@@ -0,0 +1,135 @@
+package consumers_test
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	pathpkg "path"
+	"path/filepath"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
+)
+
+func Example_identifiedPromptCatalog() {
+	result, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "config.yml"))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	ids := make([]string, 0, len(result.Config.Prompts))
+	for _, prompt := range result.Config.Prompts {
+		ids = append(ids, prompt.ID)
+	}
+	emptySearches := 0
+	for _, source := range result.Sources() {
+		for _, selection := range source.EmptyImportSelections {
+			if selection.Selector == configkit.ImportSelectorDirectory {
+				emptySearches++
+			}
+		}
+	}
+	fmt.Println(ids, emptySearches, err)
+	// Output: [weather curated welcome main] 1 <nil>
+}
+
+func Example_requiredPromptCatalog() {
+	result, err := consumers.LoadRequiredPromptCatalog(fixture("prompt-catalog", "simple.yml"))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	fmt.Println(result.Config.Prompts[0].ID, err)
+	// Output: required <nil>
+}
+
+func TestPromptCatalogImportsRegisteredItemsAndReplacesDefaults(t *testing.T) {
+	result, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "config.yml"))
+	if err != nil {
+		var loadError *configkit.LoadError
+		if errors.As(err, &loadError) {
+			t.Fatalf("load prompt catalog: %v (%#v)", err, loadError.Diagnostics())
+		}
+		t.Fatal(err)
+	}
+	if len(result.Config.Prompts) != 4 {
+		t.Fatalf("prompt records = %#v", result.Config.Prompts)
+	}
+	ids := []string{"weather", "curated", "welcome", "main"}
+	for index, id := range ids {
+		if result.Config.Prompts[index].ID != id {
+			t.Fatalf("prompt %d ID = %q, want %q", index, result.Config.Prompts[index].ID, id)
+		}
+	}
+	for _, prompt := range result.Config.Prompts {
+		if prompt.ID == "default" {
+			t.Fatalf("lower-priority default survived main sequence replacement: %#v", result.Config.Prompts)
+		}
+		if prompt.ID == "ignored" {
+			t.Fatalf("excluded generated prompt was selected: %#v", result.Config.Prompts)
+		}
+	}
+
+	var itemImports, helperImports int
+	for _, source := range result.Sources() {
+		switch filepath.Base(source.Path) {
+		case "curated.yml", "weather-feature.yml", "generated-welcome.yml":
+			if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/prompts" {
+				t.Fatalf("item source placement = %#v", source)
+			}
+			itemImports++
+		case "curated-id.yml":
+			if source.PlacementMode != configkit.PlacementModeMapping || source.ImportedFrom == nil {
+				t.Fatalf("helper source = %#v", source)
+			}
+			helperImports++
+		}
+	}
+	if itemImports != 3 || helperImports != 1 {
+		t.Fatalf("item imports = %d, helper imports = %d, sources = %#v", itemImports, helperImports, result.Sources())
+	}
+	if result.Config.Prompts[1].ID != "curated" {
+		t.Fatalf("helper did not provide prompt ID: %#v", result.Config.Prompts[1])
+	}
+}
+
+func TestPromptCatalogMountsResourceFromScheduledPromptOrigin(t *testing.T) {
+	result, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "config.yml"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Config.Prompts[2].ID != "welcome" || result.Config.Prompts[2].Resource != "welcome.txt" {
+		t.Fatalf("scheduled resource prompt = %#v", result.Config.Prompts)
+	}
+	resourcePath := configkit.Keys("prompts").Index(2).Key("resource")
+	info, ok := result.Metadata().Lookup(resourcePath)
+	if !ok || len(info.Origin.Locations) != 1 {
+		t.Fatalf("resource origin = %#v, %v", info, ok)
+	}
+	context, ok := result.SourceContext(info.Origin.Locations[0].SourceID)
+	if !ok || context.FS == nil || filepath.Base(context.BaseDir) != "prompts" {
+		t.Fatalf("resource source context = %#v, %v", context, ok)
+	}
+	contents, err := fs.ReadFile(context.FS, pathpkg.Join(context.BaseDir, result.Config.Prompts[2].Resource))
+	if err != nil || string(contents) != "Welcome resource text.\n" {
+		t.Fatalf("mounted resource = %q, %v", contents, err)
+	}
+}
+
+func TestRequiredPromptCatalogUsesOneRequiredFile(t *testing.T) {
+	result, err := consumers.LoadRequiredPromptCatalog(fixture("prompt-catalog", "simple.yml"))
+	if err != nil || len(result.Config.Prompts) != 1 || result.Config.Prompts[0].ID != "required" {
+		t.Fatalf("simple required prompt = %#v, %v", result, err)
+	}
+}
+
+func TestPromptCatalogLeavesDomainValidationWithConsumer(t *testing.T) {
+	_, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "invalid.yml"))
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 ||
+		loadError.Diagnostics()[0].Code != configkit.CodeValidateError ||
+		loadError.Diagnostics()[0].Path.String() != "/prompts/0/messages" {
+		t.Fatalf("consumer domain validation error = %v", err)
+	}
+}

examples/consumers/sequence_catalog.go

@@ -0,0 +1,145 @@
+package consumers
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+// SequenceCatalogConfig is a source-backed prompt catalog with an application
+// supplied run label and a value derived from that label during resolution.
+type SequenceCatalogConfig struct {
+	RunLabel      string                 `yaml:"run_label"`
+	ResolvedLabel string                 `yaml:"resolved_label"`
+	Prompts       []SequenceCatalogEntry `yaml:"prompts"`
+}
+
+// SequenceCatalogEntry keeps prompt meaning, resources, and credentials in the
+// consuming application while ConfigKit handles collection assembly.
+type SequenceCatalogEntry struct {
+	ID          string           `yaml:"id"`
+	Name        string           `yaml:"name"`
+	Description string           `yaml:"description"`
+	Messages    []string         `yaml:"messages"`
+	Resource    string           `yaml:"resource"`
+	Credential  configkit.Secret `yaml:"credential"`
+}
+
+// LoadSequenceCatalog searches its caller-selected main path before a custom
+// fallback directory, assembles imported fragments over a file-backed underlay,
+// applies one selected collection overlay, then resolves and validates once.
+func LoadSequenceCatalog(mainPath, overlayName, runLabel string) (*configkit.Result[SequenceCatalogConfig], error) {
+	absoluteMain, err := filepath.Abs(mainPath)
+	if err != nil {
+		return nil, err
+	}
+	root := filepath.Dir(absoluteMain)
+	filesystem := configkit.NewFilesystem("sequence catalog", os.DirFS(root))
+	filesystemContext := &configkit.FilesystemContext{BaseDir: ".", Root: ".", FS: &filesystem}
+	mainSearch := configkit.SearchConfig("", configkit.Searches(
+		configkit.SearchPaths(absoluteMain),
+		configkit.SearchDirectory(filepath.Join(root, "fallback"), configkit.DirectorySearchOptions{
+			Filenames: []configkit.FilenameGroup{configkit.CustomFilenames(filepath.Base(absoluteMain))},
+		}),
+	), configkit.SearchOptions{Required: true})
+	definition := configkit.Definition[SequenceCatalogConfig]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+		},
+		Resolve: func(configuration *SequenceCatalogConfig, resolution *configkit.Resolution) error {
+			configuration.ResolvedLabel = "for:" + configuration.RunLabel
+			resolution.RecordNormalization(configkit.Keys("resolved_label"),
+				"derive the resolved label from the selected run label", configkit.Keys("run_label"))
+			return nil
+		},
+		Validate: validateSequenceCatalog,
+	}
+	return configkit.LoadLayered(configkit.Input{
+		Source:     mainSearch,
+		Imports:    true,
+		Filesystem: &configkit.FilesystemContext{Root: root},
+	}, configkit.LayeredOptions[SequenceCatalogConfig]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+			Source: filesystem.File("underlay.yml"),
+		}}}},
+		Overlay:           overlayName,
+		OverlayFilesystem: filesystemContext,
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("run_label"), Value: runLabel, Flag: "--run-label",
+		}},
+		Definition: definition,
+	})
+}
+
+// ReadSequenceCatalogResource follows the final prompt field's source context,
+// including when record inheritance retained a resource from an underlay.
+func ReadSequenceCatalogResource(result *configkit.Result[SequenceCatalogConfig], promptID string) (string, error) {
+	if result == nil {
+		return "", errors.New("sequence catalog result is nil")
+	}
+	for index, prompt := range result.Config.Prompts {
+		if prompt.ID != promptID {
+			continue
+		}
+		resourcePath := configkit.Keys("prompts").Index(index).Key("resource")
+		info, found := result.Metadata().Lookup(resourcePath)
+		if !found || len(info.Origin.Locations) != 1 {
+			return "", errors.New("prompt resource has no single declaring source")
+		}
+		context, found := result.SourceContext(info.Origin.Locations[0].SourceID)
+		if !found {
+			return "", errors.New("prompt resource source context is unavailable")
+		}
+		data, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, prompt.Resource))
+		if err != nil {
+			return "", fmt.Errorf("read prompt resource: %w", err)
+		}
+		return string(data), nil
+	}
+	return "", fmt.Errorf("prompt %q is unavailable", promptID)
+}
+
+func validateSequenceCatalog(configuration *SequenceCatalogConfig, validation *configkit.Validation) {
+	for index, prompt := range configuration.Prompts {
+		if strings.TrimSpace(prompt.Name) == "" {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("name"), "must not be empty")
+		}
+		if len(prompt.Messages) == 0 {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("messages"), "must contain at least one message")
+		}
+	}
+	if len(configuration.Prompts) == 0 {
+		validation.Error(configkit.Keys("prompts"), "must contain at least one prompt")
+	}
+}
+
+// NamespacedMapCatalogConfig demonstrates typed application maps whose
+// independent prompt sequences use root and dynamic namespace registrations.
+type NamespacedMapCatalogConfig struct {
+	Prompts     []map[string]any          `yaml:"prompts"`
+	Collections map[string]map[string]any `yaml:"collections"`
+}
+
+// LoadNamespacedMapCatalog applies the same scalar identity constraint to one
+// root collection and each namespace's independently scoped collection.
+func LoadNamespacedMapCatalog(source configkit.Source) (*configkit.Result[NamespacedMapCatalogConfig], error) {
+	selector := configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("prompts"),
+	}
+	return configkit.Load(source, configkit.Options[NamespacedMapCatalogConfig]{
+		Definition: configkit.Definition[NamespacedMapCatalogConfig]{
+			SequenceIdentities: []configkit.SequenceIdentity{
+				configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+				configkit.SequenceIdentityMatching(selector, "id"),
+			},
+		},
+	})
+}

examples/consumers/sequence_catalog_test.go

@@ -0,0 +1,239 @@
+package consumers_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
+)
+
+func Example_sequenceCatalog() {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	restoreOld, restoreNew := preserveEnvironment(oldSecret), preserveEnvironment(newSecret)
+	defer restoreOld()
+	defer restoreNew()
+	_ = os.Setenv(oldSecret, "disposable-old-example-credential")
+	_ = os.Setenv(newSecret, "disposable-new-example-credential")
+
+	result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), "upsert", "preview")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	ids := make([]string, 0, len(result.Config.Prompts))
+	for _, prompt := range result.Config.Prompts {
+		ids = append(ids, prompt.ID)
+	}
+	shared := configkit.Keys("prompts").Index(1).Key("name")
+	info, _ := result.Metadata().Lookup(shared)
+	resource, resourceErr := consumers.ReadSequenceCatalogResource(result, "concise")
+	fmt.Println(ids, result.Config.ResolvedLabel, info.Explicit, len(result.Metadata().History(shared)), resource, resourceErr == nil, err)
+	// Output: [foundation shared welcome concise extra] for:preview true 2 Foundation resource text.
+	//  true <nil>
+}
+
+func TestSequenceCatalogSelectedOverlayOperations(t *testing.T) {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	t.Setenv(oldSecret, "sequence-catalog-old-canary")
+	t.Setenv(newSecret, "sequence-catalog-new-canary")
+
+	tests := []struct {
+		name    string
+		wantIDs []string
+		shared  *consumers.SequenceCatalogEntry
+	}{
+		{name: "append", wantIDs: []string{"foundation", "shared", "welcome", "concise", "extra"}},
+		{name: "upsert", wantIDs: []string{"foundation", "shared", "welcome", "concise", "extra"}, shared: &consumers.SequenceCatalogEntry{ID: "shared", Name: "Shared replacement", Messages: []string{"Replacement message"}, Credential: configkit.SecretEnv(newSecret)}},
+		{name: "replace", wantIDs: []string{"replacement", "last"}},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), test.name, "test")
+			if err != nil {
+				var loadError *configkit.LoadError
+				if errors.As(err, &loadError) {
+					t.Fatalf("load selected overlay: %v (%#v)", err, loadError.Diagnostics())
+				}
+				t.Fatal(err)
+			}
+			gotIDs := make([]string, 0, len(result.Config.Prompts))
+			for _, prompt := range result.Config.Prompts {
+				gotIDs = append(gotIDs, prompt.ID)
+			}
+			if strings.Join(gotIDs, ",") != strings.Join(test.wantIDs, ",") {
+				t.Fatalf("prompt order = %v, want %v", gotIDs, test.wantIDs)
+			}
+			if test.shared == nil {
+				return
+			}
+			shared := result.Config.Prompts[1]
+			if shared.ID != test.shared.ID || shared.Name != test.shared.Name || len(shared.Messages) != 1 ||
+				shared.Messages[0] != test.shared.Messages[0] || shared.Description != "" || shared.Resource != "" || shared.Credential.EnvName() != newSecret {
+				t.Fatalf("upsert did not replace the complete matched record: %#v", shared)
+			}
+		})
+	}
+}
+
+func TestSequenceCatalogInspectionTracksResourcesAndSecretHistory(t *testing.T) {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	const oldCanary = "sequence-catalog-old-canary"
+	const newCanary = "sequence-catalog-new-canary"
+	t.Setenv(oldSecret, oldCanary)
+	t.Setenv(newSecret, newCanary)
+
+	result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), "upsert", "history")
+	if err != nil {
+		var loadError *configkit.LoadError
+		if errors.As(err, &loadError) {
+			t.Fatalf("load sequence catalog: %v (%#v)", err, loadError.Diagnostics())
+		}
+		t.Fatal(err)
+	}
+	resourcePath := configkit.Keys("prompts").Index(3).Key("resource")
+	resourceInfo, found := result.Metadata().Lookup(resourcePath)
+	if !found || len(resourceInfo.Origin.Locations) != 1 || len(resourceInfo.Origin.Inheritance) != 1 {
+		t.Fatalf("inherited resource inspection = %#v, %v", resourceInfo, found)
+	}
+	resource, err := consumers.ReadSequenceCatalogResource(result, "concise")
+	if err != nil || resource != "Foundation resource text.\n" {
+		t.Fatalf("resource from inherited source context = %q, %v", resource, err)
+	}
+	if len(result.Metadata().History(configkit.Keys("resolved_label"))) == 0 {
+		t.Fatal("recorded CLI-driven resolution was absent from final inspection")
+	}
+	credentialPath := configkit.Keys("prompts").Index(1).Key("credential")
+	credentialHistory := result.Metadata().History(credentialPath)
+	if len(credentialHistory) == 0 {
+		t.Fatal("upsert did not retain the replaced secret reference in history")
+	}
+	var explanation bytes.Buffer
+	if err := result.WriteExplanation(&explanation, credentialPath); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(explanation.String(), oldCanary) || strings.Contains(explanation.String(), newCanary) {
+		t.Fatalf("secret explanation exposed a credential value: %s", explanation.String())
+	}
+}
+
+func TestNamespacedTypedMapIdentityScopesAreIndependent(t *testing.T) {
+	source := configkit.Bytes("namespaced maps", []byte(`
+prompts:
+  - id: shared
+    text: root prompt
+collections:
+  team:
+    prompts:
+      - id: shared
+        text: team prompt
+  operations:
+    prompts:
+      - id: shared
+        text: operations prompt
+`))
+	result, err := consumers.LoadNamespacedMapCatalog(source)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Config.Prompts[0]["text"] != "root prompt" ||
+		result.Config.Collections["team"]["prompts"].([]any)[0].(map[string]any)["text"] != "team prompt" ||
+		result.Config.Collections["operations"]["prompts"].([]any)[0].(map[string]any)["text"] != "operations prompt" {
+		t.Fatalf("typed map collections = %#v", result.Config)
+	}
+}
+
+func TestNamespacedTypedMapIdentityFindsCollectionsIntroducedByInheritance(t *testing.T) {
+	result, err := consumers.LoadNamespacedMapCatalog(configkit.Bytes("inherited namespace", []byte(`
+collections:
+  source:
+    prompts:
+      - id: shared
+        text: inherited prompt
+  copied:
+    extends: source
+`)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	copied := result.Config.Collections["copied"]["prompts"].([]any)
+	if len(copied) != 1 || copied[0].(map[string]any)["text"] != "inherited prompt" {
+		t.Fatalf("inherited typed-map collection = %#v", result.Config.Collections["copied"])
+	}
+}
+
+func Example_yamlDeclaredIdentityOnly() {
+	result, err := configkit.Load(configkit.Bytes("YAML identity only", []byte(`
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+prompts:
+  - id: initial
+`)), configkit.Options[map[string]any]{
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("prompts"),
+			Value: []any{
+				map[string]any{"id": "same"},
+				map[string]any{"id": "same"},
+			},
+			Flag: "--prompts",
+		}},
+	})
+	fmt.Println(len(result.Config["prompts"].([]any)), err)
+	// Output: 2 <nil>
+}
+
+func TestYAMLDeclaredIdentityDoesNotRegisterFinalTypedConstraint(t *testing.T) {
+	result, err := configkit.Load(configkit.Bytes("YAML identity only", []byte(`
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+prompts:
+  - id: initial
+`)), configkit.Options[map[string]any]{
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("prompts"),
+			Value: []any{
+				map[string]any{"id": "same"},
+				map[string]any{"id": "same"},
+			},
+			Flag: "--prompts",
+		}},
+	})
+	if err != nil {
+		t.Fatalf("YAML-only identity incorrectly became an application constraint: %v", err)
+	}
+	prompts := result.Config["prompts"].([]any)
+	if len(prompts) != 2 || prompts[0].(map[string]any)["id"] != prompts[1].(map[string]any)["id"] {
+		t.Fatalf("CLI result = %#v", result.Config)
+	}
+}
+
+func TestNamespacedTypedMapRejectsDuplicatesWithinOneCollection(t *testing.T) {
+	_, err := consumers.LoadNamespacedMapCatalog(configkit.Bytes("duplicate namespace", []byte(`
+collections:
+  team:
+    prompts:
+      - id: duplicate
+      - id: duplicate
+`)))
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 ||
+		loadError.Diagnostics()[0].Code != configkit.CodeComposeConflict ||
+		loadError.Diagnostics()[0].Path.String() != "/collections/team/prompts" {
+		diagnostics := []configkit.Diagnostic(nil)
+		if loadError != nil {
+			diagnostics = loadError.Diagnostics()
+		}
+		t.Fatalf("duplicate namespaced identity error = %v (%#v)", err, diagnostics)
+	}
+}

examples/consumers/source_version.go

@@ -0,0 +1,64 @@
+package consumers
+
+import (
+	"errors"
+	"io/fs"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+// VersionedServiceConfig demonstrates a mounted main input whose source-local
+// schema version is retained at the effective service path.
+type VersionedServiceConfig struct {
+	Service struct {
+		Version  string `yaml:"version"`
+		Name     string `yaml:"name"`
+		Endpoint string `yaml:"endpoint"`
+		Metadata struct {
+			Release string `yaml:"release"`
+		} `yaml:"metadata"`
+	} `yaml:"service"`
+}
+
+// LoadVersionedService checks the main and underlay declarations with one
+// application policy. The local rule path is "version" for each source; the
+// main input's destination places its protected value at /service/version.
+// Optional CLI overrides are passed through to ConfigKit for normal protection.
+func LoadVersionedService(mode configkit.SourceVersionMode, overrides ...configkit.Override) (*configkit.Result[VersionedServiceConfig], error) {
+	files, err := fs.Sub(bundledFiles, "testdata/source-version")
+	if err != nil {
+		return nil, err
+	}
+	main, err := fs.ReadFile(files, "main.yml")
+	if err != nil {
+		return nil, err
+	}
+	underlay, err := fs.ReadFile(files, "underlay.yml")
+	if err != nil {
+		return nil, err
+	}
+	definition := configkit.Definition[VersionedServiceConfig]{
+		Version: &configkit.VersionRule{
+			Path: configkit.Keys("version"),
+			Check: func(version configkit.Version, _ *configkit.Validation) error {
+				if !version.Present || version.Null || version.Text == "" {
+					return errors.New("a nonempty source version is required")
+				}
+				return nil
+			},
+		},
+		Sensitive: func(path configkit.Path) bool {
+			return path.String() == "/service/version"
+		},
+	}
+	return configkit.LoadLayered(configkit.Input{
+		Source: configkit.Bytes("service main", main), Destination: configkit.Keys("service"),
+	}, configkit.LayeredOptions[VersionedServiceConfig]{
+		Definition:        definition,
+		SourceVersionMode: mode,
+		Overrides:         overrides,
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+			Source: configkit.Bytes("service defaults", underlay), Destination: configkit.Keys("service"),
+		}}}},
+	})
+}

examples/consumers/testdata/collection-bundle/collections/weather/collection.yml

@@ -0,0 +1,9 @@
+configkit:
+  imports:
+    - path: metadata.yml
+      destination: []
+    - path: prompts/index.yml
+      destination: [prompts]
+    - path: profiles/index.yml
+      destination: [profiles]
+name: Weather Reporter

examples/consumers/testdata/collection-bundle/collections/weather/metadata.yml

@@ -0,0 +1,4 @@
+configkit:
+  imports:
+    - path: version.yml
+description: Imported collection metadata.

examples/consumers/testdata/collection-bundle/collections/weather/profiles/compact.yml

@@ -0,0 +1,3 @@
+compact:
+  format: text
+  temperature: 0.2

examples/consumers/testdata/collection-bundle/collections/weather/profiles/index.yml

@@ -0,0 +1,4 @@
+configkit:
+  imports:
+    - path: compact.yml
+    - path: weather.yml

examples/consumers/testdata/collection-bundle/collections/weather/profiles/weather.yml

@@ -0,0 +1,3 @@
+weather:
+  extends: compact
+  temperature: 0.4

examples/consumers/testdata/collection-bundle/collections/weather/prompts/brief.yml

@@ -0,0 +1,7 @@
+brief:
+  version: "1"
+  default_profile: compact
+  content_file: welcome.txt
+  messages:
+    - role: user
+      content: Write a concise weather summary.

examples/consumers/testdata/collection-bundle/collections/weather/prompts/custom.yml

@@ -0,0 +1,3 @@
+custom:
+  extends: brief
+  default_profile: weather

examples/consumers/testdata/collection-bundle/collections/weather/prompts/index.yml

@@ -0,0 +1,4 @@
+configkit:
+  imports:
+    - path: brief.yml
+    - path: custom.yml

examples/consumers/testdata/collection-bundle/collections/weather/prompts/welcome.txt

@@ -0,0 +1 @@
+Welcome to the weather collection.

examples/consumers/testdata/collection-bundle/collections/weather/version.yml

@@ -0,0 +1 @@
+version: "2.4.0"

examples/consumers/testdata/collection-bundle/operators/weather-prompt-version.yml

@@ -0,0 +1,2 @@
+brief:
+  version: "2"

examples/consumers/testdata/ordinary-imports/config.yml

@@ -0,0 +1,6 @@
+configkit:
+  imports:
+    - path: metadata.yml
+    - path: prompts/brief.yml
+      destination: [prompts]
+name: Root import example

examples/consumers/testdata/ordinary-imports/metadata.yml

@@ -0,0 +1,2 @@
+version: "1.0"
+description: Metadata imported into the root document.

examples/consumers/testdata/ordinary-imports/prompts/brief.yml

@@ -0,0 +1,2 @@
+brief:
+  summary: A root-loaded prompt.

examples/consumers/testdata/prompt-catalog/config.yml

@@ -0,0 +1,19 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
+  imports:
+    - dir: prompts
+      exclude: [generated-ignored.yml]
+      destination: [prompts]
+      placement: sequence-item
+    - dir: featured
+      pattern: [weather-*.yml]
+      destination: [prompts]
+      placement: sequence-item
+    - dir: optional
+prompts:
+  - id: main
+    name: Main authored prompt
+    messages: [Use the main prompt.]

examples/consumers/testdata/prompt-catalog/featured/weather-feature.yml

@@ -0,0 +1,4 @@
+id: weather
+name: Weather forecast
+messages:
+  - Describe today's forecast.

examples/consumers/testdata/prompt-catalog/invalid.yml

@@ -0,0 +1,9 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
+prompts:
+  - id: invalid
+    name: Invalid prompt
+    messages: []

examples/consumers/testdata/prompt-catalog/optional/ignored.txt

@@ -0,0 +1 @@
+This file does not match the application import defaults.

examples/consumers/testdata/prompt-catalog/prompts/curated.yml

@@ -0,0 +1,6 @@
+configkit:
+  imports:
+    - path: helpers/curated-id.yml
+name: Curated summary
+messages:
+  - Summarize the supplied content.

examples/consumers/testdata/prompt-catalog/prompts/generated-ignored.yml

@@ -0,0 +1,3 @@
+id: ignored
+name: Excluded generated prompt
+messages: [This record is excluded.]

examples/consumers/testdata/prompt-catalog/prompts/generated-welcome.yml

@@ -0,0 +1,5 @@
+id: welcome
+name: Welcome
+messages:
+  - Welcome the user.
+resource: welcome.txt

examples/consumers/testdata/prompt-catalog/prompts/helpers/curated-id.yml

@@ -0,0 +1 @@
+id: curated

examples/consumers/testdata/prompt-catalog/prompts/required.yml

@@ -0,0 +1,3 @@
+id: required
+name: Required prompt
+messages: [Use the required prompt.]

examples/consumers/testdata/prompt-catalog/prompts/welcome.txt

@@ -0,0 +1 @@
+Welcome resource text.

examples/consumers/testdata/prompt-catalog/simple.yml

@@ -0,0 +1,7 @@
+configkit:
+  imports:
+    - path: prompts/required.yml
+      required: true
+      destination: [prompts]
+      placement: sequence-item
+prompts: []

examples/consumers/testdata/sequence-catalog/config.yml

@@ -0,0 +1,7 @@
+run_label: source-default
+configkit:
+  imports:
+    - dir: fragments
+      pattern: '*.yml'
+      destination: [prompts]
+      placement: sequence-item

examples/consumers/testdata/sequence-catalog/foundation.txt

@@ -0,0 +1 @@
+Foundation resource text.

examples/consumers/testdata/sequence-catalog/fragments/01-welcome.yml

@@ -0,0 +1,4 @@
+id: welcome
+name: Welcome
+messages: [Welcome message]
+credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/fragments/02-concise.yml

@@ -0,0 +1,3 @@
+id: concise
+extends: {id: foundation}
+name: Concise

examples/consumers/testdata/sequence-catalog/overlays/append.yml

@@ -0,0 +1,10 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: append
+prompts:
+  - id: extra
+    name: Extra
+    messages: [Extra message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/overlays/replace.yml

@@ -0,0 +1,14 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
+prompts:
+  - id: replacement
+    name: Replacement
+    messages: [Replacement message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET
+  - id: last
+    name: Last
+    messages: [Last message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/overlays/upsert.yml

@@ -0,0 +1,14 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: upsert
+prompts:
+  - id: shared
+    name: Shared replacement
+    messages: [Replacement message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET
+  - id: extra
+    name: Extra
+    messages: [Extra message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/underlay.yml

@@ -0,0 +1,18 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: append
+prompts:
+  - id: foundation
+    name: Foundation
+    description: Shared foundation instruction
+    messages: [Foundation message]
+    resource: foundation.txt
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET
+  - id: shared
+    name: Shared draft
+    description: This field must not survive a whole-record replacement
+    messages: [Draft message]
+    resource: shared.txt
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/source-version/main.yml

@@ -0,0 +1,4 @@
+version: service-v2
+name: example service
+metadata:
+  release: application-2026.10

examples/consumers/testdata/source-version/underlay.yml

@@ -0,0 +1,2 @@
+version: catalog-v1
+endpoint: https://service.example.invalid

facade_candidate_test.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 var (
@@ -23,7 +23,7 @@ var (
 
 func TestFacadeValuesRemainRootOwned(t *testing.T) {
 	t.Parallel()
-	const packagePath = "gitea.maximumdirect.net/eric/ConfigKit"
+	const packagePath = "go.maximumdirect.net/configkit"
 	for _, candidate := range []reflect.Type{
 		reflect.TypeFor[configkit.Path](), reflect.TypeFor[configkit.Source](),
 		reflect.TypeFor[configkit.Secret](), reflect.TypeFor[configkit.Diagnostic](),
@@ -140,7 +140,7 @@ func TestFacadeSecretsBootstrapUsesFacadeRecords(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	report, err := configkit.LoadSecretsDir(directory)
+	report, err := configkit.LoadSecretsIntoEnvironment(directory)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -164,7 +164,7 @@ func TestFacadeSecretsBootstrapUsesFacadeRecords(t *testing.T) {
 		t.Fatalf("report rendering = %q, %v", rendered.String(), err)
 	}
 
-	failedReport, err := configkit.LoadSecretsDir("")
+	failedReport, err := configkit.LoadSecretsIntoEnvironment("")
 	var secretsError *configkit.SecretsError
 	if failedReport == nil || !errors.As(err, &secretsError) || len(secretsError.Diagnostics()) != 1 || secretsError.Diagnostics()[0].Code != configkit.CodeSecretsInvalidPath {
 		t.Fatalf("bootstrap failure = %#v / %#v", failedReport, err)
@@ -203,7 +203,7 @@ func TestFacadeLoadBridgesLifecycleCallbacks(t *testing.T) {
 			if !resolution.IsExplicit(configkit.Keys("input")) {
 				resolution.Error(configkit.Keys("input"), "input is required")
 			}
-			input, ok := resolution.InputInfo(configkit.Keys("input"))
+			input, ok := resolution.EntryInfo(configkit.Keys("input"))
 			if !ok || !input.Explicit {
 				resolution.Error(configkit.Keys("input"), "missing input provenance")
 			}
@@ -245,6 +245,8 @@ func TestFacadeLoadBridgesLifecycleCallbacks(t *testing.T) {
 	}
 	for _, context := range []func(){
 		func() { retainedResolution.IsExplicit(configkit.Keys("input")) },
+		func() { retainedResolution.RecordDerivedDefault(configkit.Keys("input"), "too late") },
+		func() { retainedResolution.RecordNormalization(configkit.Keys("input"), "too late") },
 		func() { retainedValidation.Warning(configkit.Keys("input"), "too late") },
 	} {
 		func() {

facade_compatibility_test.go

@@ -5,10 +5,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"reflect"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 var (
@@ -27,23 +26,6 @@ type facadeCompatibilityConfig struct {
 func TestFacadeCompatibility(t *testing.T) {
 	t.Parallel()
 
-	const packagePath = "gitea.maximumdirect.net/eric/ConfigKit"
-	for _, candidate := range []struct {
-		name  string
-		type_ reflect.Type
-	}{
-		{"Path", reflect.TypeFor[configkit.Path]()},
-		{"Source", reflect.TypeFor[configkit.Source]()},
-		{"Secret", reflect.TypeFor[configkit.Secret]()},
-		{"Definition", reflect.TypeFor[configkit.Definition[facadeCompatibilityConfig]]()},
-		{"Options", reflect.TypeFor[configkit.Options[facadeCompatibilityConfig]]()},
-		{"Result", reflect.TypeFor[configkit.Result[facadeCompatibilityConfig]]()},
-	} {
-		if candidate.type_.PkgPath() != packagePath {
-			t.Errorf("%s belongs to %q, want %q", candidate.name, candidate.type_.PkgPath(), packagePath)
-		}
-	}
-
 	constructed := configkit.Options[facadeCompatibilityConfig]{
 		Definition: configkit.Definition[facadeCompatibilityConfig]{},
 		Filesystem: &configkit.FilesystemContext{BaseDir: "configs", Root: "configs"},
@@ -56,11 +38,6 @@ func TestFacadeCompatibility(t *testing.T) {
 	if got := constructed.Overrides[0].Path.String(); got != "/value" {
 		t.Fatalf("constructed override path = %q, want /value", got)
 	}
-	publicResult := configkit.Result[facadeCompatibilityConfig]{Config: facadeCompatibilityConfig{Value: "constructed"}}
-	if publicResult.Config.Value != "constructed" {
-		t.Fatal("constructed result lost its public configuration")
-	}
-
 	result, err := configkit.Load(configkit.Bytes("facade.yml", []byte("value: input\n")), configkit.Options[facadeCompatibilityConfig]{
 		Definition: configkit.Definition[facadeCompatibilityConfig]{
 			Resolve: func(configuration *facadeCompatibilityConfig, resolution *configkit.Resolution) error {

facade_container_origin_test.go

@@ -0,0 +1,41 @@
+package configkit_test
+
+import (
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestOverlayExplanationUsesQueryScopedOrigin(t *testing.T) {
+	t.Parallel()
+	filesystem := configkit.NewFilesystem("origin", fstest.MapFS{
+		"main.yml":         {Data: []byte("a: base\ngroup: {x: X, y: Y}\n")},
+		"overlays/dev.yml": {Data: []byte("a: overlay\ngroup: {x: O}\n")},
+	})
+	result, err := configkit.Load[map[string]any](filesystem.File("main.yml"), configkit.Options[map[string]any]{Overlay: "dev"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, test := range []struct {
+		path         configkit.Path
+		line, column int
+	}{
+		{configkit.Keys(), 1, 1},
+		{configkit.Keys("group"), 2, 8},
+		{configkit.Keys("group", "x"), 2, 12},
+	} {
+		explanation, found := result.Explain(test.path)
+		if !found || len(explanation.History) == 0 {
+			t.Fatalf("missing explanation for %s", test.path)
+		}
+		origin := explanation.History[len(explanation.History)-1].Origin
+		if origin.Layer != configkit.LayerOverlay || len(origin.Locations) != 1 {
+			t.Fatalf("overlay origin for %s = %#v", test.path, origin)
+		}
+		location := origin.Locations[0]
+		if location.SourceID != "source-2" || location.Line != test.line || location.Column != test.column {
+			t.Fatalf("overlay location for %s = %#v; want line %d column %d", test.path, location, test.line, test.column)
+		}
+	}
+}

facade_context_test.go

@@ -3,7 +3,7 @@ package configkit_test
 import (
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func TestFacadeInactiveContextsPreserveClosedFailure(t *testing.T) {
@@ -24,10 +24,11 @@ func TestFacadeInactiveContextsPreserveClosedFailure(t *testing.T) {
 				call func()
 			}{
 				{"IsExplicit", func() { state.resolution.IsExplicit(path) }},
-				{"InputInfo", func() { state.resolution.InputInfo(path) }},
+				{"EntryInfo", func() { state.resolution.EntryInfo(path) }},
 				{"Source", func() { state.resolution.Source("source") }},
 				{"SourceContext", func() { state.resolution.SourceContext("source") }},
-				{"Record", func() { state.resolution.Record(path, configkit.ChangeNormalization, "reason") }},
+				{"RecordDerivedDefault", func() { state.resolution.RecordDerivedDefault(path, "reason") }},
+				{"RecordNormalization", func() { state.resolution.RecordNormalization(path, "reason") }},
 				{"Resolution.Error", func() { state.resolution.Error(path, "message") }},
 				{"Resolution.Warning", func() { state.resolution.Warning(path, "message") }},
 				{"Default", func() { configkit.Default(state.resolution, path, &target, 1, "reason") }},

facade_destination_test.go

@@ -0,0 +1,705 @@
+package configkit_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeInputDestinationsAcrossSourceKinds(t *testing.T) {
+	directory := t.TempDir()
+	hostPath := filepath.Join(directory, "host.yml")
+	if err := os.WriteFile(hostPath, []byte("value: host\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	native := configkit.NewFilesystem("native", fstest.MapFS{
+		"main.yml": &fstest.MapFile{Data: []byte("value: native\n")},
+	})
+	const literalValuePath = "/collections/weather.reporter/profiles/a~1b/~0/0"
+	destination := configkit.Keys("collections", "weather.reporter", "profiles", "a/b", "~", "0")
+	for _, test := range []struct {
+		name   string
+		source configkit.Source
+		want   string
+		kind   configkit.SourceKind
+	}{
+		{name: "host file", source: configkit.File(hostPath), want: "host", kind: configkit.SourceKindFile},
+		{name: "native filesystem", source: native.File("main.yml"), want: "native", kind: configkit.SourceKindFilesystem},
+		{name: "bytes", source: configkit.Bytes("bytes", []byte("value: bytes\n")), want: "bytes", kind: configkit.SourceKindBytes},
+		{name: "reader", source: configkit.Reader("reader", strings.NewReader("value: reader\n")), want: "reader", kind: configkit.SourceKindReader},
+		{name: "mapping", source: configkit.Mapping("mapping", map[string]any{"value": "mapping"}), want: "mapping", kind: configkit.SourceKindMapping},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: test.source, Destination: destination})
+			if err != nil {
+				t.Fatalf("LoadLayered: %v", err)
+			}
+			if got := facadeDestinationValue(t, result.Config, "collections", "weather.reporter", "profiles", "a/b", "~", "0", "value"); got != test.want {
+				t.Fatalf("placed value = %#v, want %q", got, test.want)
+			}
+			sources := result.Sources()
+			if len(sources) != 1 || sources[0].Kind != test.kind || sources[0].Destination.String() != destination.String() || destination.String() != literalValuePath {
+				t.Fatalf("source placement = %#v, destination = %q", sources, destination.String())
+			}
+		})
+	}
+}
+
+func TestFacadeDestinationRootEmptyMappingNoSourceAndInvalidPaths(t *testing.T) {
+	for _, test := range []struct {
+		name        string
+		destination configkit.Path
+	}{
+		{name: "omitted destination"},
+		{name: "explicit empty destination", destination: configkit.Path{}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Bytes("root", []byte("value: root\n")), Destination: test.destination})
+			if err != nil {
+				t.Fatalf("root load: %v", err)
+			}
+			if result.Config["value"] != "root" || len(result.Sources()) != 1 || result.Sources()[0].Destination.String() != "" {
+				t.Fatalf("root placement = %#v, sources %#v", result.Config, result.Sources())
+			}
+		})
+	}
+
+	emptyPath := configkit.Keys("collections", "empty")
+	empty, err := configkit.LoadLayered[map[string]any](configkit.Input{
+		Source: configkit.Mapping("empty", map[string]any{}), Destination: emptyPath,
+	})
+	if err != nil {
+		t.Fatalf("empty mapping load: %v", err)
+	}
+	if value := facadeDestinationMap(t, empty.Config, "collections")["empty"]; value == nil {
+		t.Fatal("empty mapping did not materialize its destination")
+	}
+	if info, ok := empty.Metadata().Lookup(emptyPath); !ok || !info.Explicit {
+		t.Fatalf("empty destination metadata = %#v, %v", info, ok)
+	}
+
+	absentPath := configkit.Keys("collections", "absent")
+	absent, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource(), Destination: absentPath})
+	if err != nil {
+		t.Fatalf("NoSource with a destination: %v", err)
+	}
+	if len(absent.Sources()) != 0 {
+		t.Fatalf("NoSource created source records: %#v", absent.Sources())
+	}
+	if _, ok := absent.Metadata().Lookup(absentPath); ok {
+		t.Fatal("NoSource materialized its destination")
+	}
+
+	reader := &destinationCountingReader{}
+	for _, test := range []struct {
+		name        string
+		source      configkit.Source
+		destination configkit.Path
+		wantReads   int
+	}{
+		{name: "index segment", source: configkit.Reader("unread", reader), destination: configkit.Keys("catalog").Index(0)},
+		{name: "reserved configkit key", source: configkit.NoSource(), destination: configkit.Keys("configkit")},
+		{name: "reserved extends key", source: configkit.NoSource(), destination: configkit.Keys("catalog", "extends")},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			_, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: test.source, Destination: test.destination})
+			loadError, ok := err.(*configkit.LoadError)
+			if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeOptionsInvalid {
+				t.Fatalf("invalid destination error = %#v", err)
+			}
+			if reader.reads != test.wantReads {
+				t.Fatalf("reader calls = %d, want %d", reader.reads, test.wantReads)
+			}
+		})
+	}
+}
+
+func TestFacadeImportedSourcesRetainInputDestination(t *testing.T) {
+	directory := t.TempDir()
+	mainPath := filepath.Join(directory, "main.yml")
+	fragmentPath := filepath.Join(directory, "fragment.yml")
+	if err := os.WriteFile(mainPath, []byte("configkit: {imports: [{path: fragment.yml}]}\nmain: present\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(fragmentPath, []byte("imported: present\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	destination := configkit.Keys("collections", "weatherreporter")
+	result, err := configkit.LoadLayered[map[string]any](configkit.Input{
+		Source: configkit.File(mainPath), Imports: true, Destination: destination,
+	})
+	if err != nil {
+		t.Fatalf("mounted import load: %v", err)
+	}
+	collection := facadeDestinationMap(t, result.Config, "collections", "weatherreporter")
+	if collection["main"] != "present" || collection["imported"] != "present" {
+		t.Fatalf("mounted imported values = %#v", collection)
+	}
+	sources := result.Sources()
+	if len(sources) != 2 || sources[0].Destination.String() != destination.String() || sources[1].Destination.String() != destination.String() {
+		t.Fatalf("mounted import source destinations = %#v", sources)
+	}
+	if sources[1].ImportedFrom == nil {
+		t.Fatalf("imported source lacks its authored directive: %#v", sources[1])
+	}
+}
+
+func TestFacadeRelativeImportDestinationsForRootAndMountedLoads(t *testing.T) {
+	directory := t.TempDir()
+	write := func(relative, contents string) string {
+		t.Helper()
+		filename := filepath.Join(directory, filepath.FromSlash(relative))
+		if err := os.MkdirAll(filepath.Dir(filename), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(filename, []byte(contents), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		return filename
+	}
+
+	mainPath := write("main.yml", `configkit:
+  imports:
+    - path: metadata.yml
+      destination: [metadata]
+    - glob: prompts/*.yml
+      destination: [prompts]
+    - path: entries/main.yml
+      destination: [profiles]
+    - path: sibling.yml
+      destination: [sibling]
+root: main
+`)
+	write("metadata.yml", "name: imported\n")
+	write("prompts/a.yml", "a: {name: alpha}\n")
+	write("prompts/b.yml", "b: {name: beta}\n")
+	write("entries/main.yml", `configkit:
+  imports:
+    - path: nested/details.yml
+      destination: [details]
+name: profile
+`)
+	write("entries/nested/details.yml", "summary: nested\n")
+	write("sibling.yml", "name: separate\n")
+
+	root, err := configkit.Load(
+		configkit.File(mainPath), configkit.Options[map[string]any]{Imports: true},
+	)
+	if err != nil {
+		if loadError, ok := err.(*configkit.LoadError); ok {
+			t.Fatalf("ordinary root Load: %v, diagnostics %#v", err, loadError.Diagnostics())
+		}
+		t.Fatalf("ordinary root Load: %v", err)
+	}
+	mountedDestination := configkit.Keys("collections", "weatherreporter")
+	mounted, err := configkit.LoadLayered[map[string]any](configkit.Input{
+		Source: configkit.File(mainPath), Imports: true, Destination: mountedDestination,
+	})
+	if err != nil {
+		t.Fatalf("mounted layered Load: %v", err)
+	}
+
+	for _, test := range []struct {
+		name   string
+		result *configkit.Result[map[string]any]
+		prefix []string
+	}{
+		{name: "ordinary root", result: root},
+		{name: "mounted entry", result: mounted, prefix: []string{"collections", "weatherreporter"}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			at := func(keys ...string) []string {
+				return append(append([]string(nil), test.prefix...), keys...)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("root")...); got != "main" {
+				t.Fatalf("root value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("metadata", "name")...); got != "imported" {
+				t.Fatalf("metadata value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("prompts", "a", "name")...); got != "alpha" {
+				t.Fatalf("first glob value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("prompts", "b", "name")...); got != "beta" {
+				t.Fatalf("second glob value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("profiles", "name")...); got != "profile" {
+				t.Fatalf("entry value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("profiles", "details", "summary")...); got != "nested" {
+				t.Fatalf("nested import value = %#v", got)
+			}
+			if got := facadeDestinationValue(t, test.result.Config, at("sibling", "name")...); got != "separate" {
+				t.Fatalf("subsequent sibling value = %#v", got)
+			}
+
+			wantPaths := []string{
+				"main.yml", "metadata.yml", "a.yml", "b.yml", "main.yml", "details.yml", "sibling.yml",
+			}
+			wantPhysicalPaths := []string{
+				mainPath,
+				filepath.Join(directory, "metadata.yml"),
+				filepath.Join(directory, "prompts", "a.yml"),
+				filepath.Join(directory, "prompts", "b.yml"),
+				filepath.Join(directory, "entries", "main.yml"),
+				filepath.Join(directory, "entries", "nested", "details.yml"),
+				filepath.Join(directory, "sibling.yml"),
+			}
+			wantImportParents := []string{"", "source-1", "source-1", "source-1", "source-1", "source-5", "source-1"}
+			wantDestinations := []configkit.Path{configkit.Keys(test.prefix...)}
+			for _, suffix := range [][]string{{"metadata"}, {"prompts"}, {"prompts"}, {"profiles"}, {"profiles", "details"}, {"sibling"}} {
+				destination := append([]string(nil), test.prefix...)
+				for _, segment := range suffix {
+					destination = append(destination, segment)
+				}
+				wantDestinations = append(wantDestinations, configkit.Keys(destination...))
+			}
+			sources := test.result.Sources()
+			if len(sources) != len(wantPaths) {
+				t.Fatalf("sources = %#v, want %d", sources, len(wantPaths))
+			}
+			for index, source := range sources {
+				if filepath.Base(source.Path) != wantPaths[index] || source.Path != wantPhysicalPaths[index] || source.Destination.String() != wantDestinations[index].String() {
+					t.Errorf("source %d path/destination = (%q, %q), want physical path %q and destination %q", index, source.Path, source.Destination.String(), wantPhysicalPaths[index], wantDestinations[index].String())
+				}
+				if source.ID != fmt.Sprintf("source-%d", index+1) || source.Kind != configkit.SourceKindFile {
+					t.Errorf("source %d identity/kind = (%q, %q)", index, source.ID, source.Kind)
+				}
+				if wantImportParents[index] == "" {
+					if source.ImportedFrom != nil {
+						t.Errorf("entry source unexpectedly has an import location: %#v", source.ImportedFrom)
+					}
+				} else if source.ImportedFrom == nil || source.ImportedFrom.SourceID != wantImportParents[index] || source.ImportedFrom.Line == 0 || source.ImportedFrom.Column == 0 {
+					t.Errorf("source %d import location = %#v, want declaration in %s", index, source.ImportedFrom, wantImportParents[index])
+				}
+			}
+		})
+	}
+}
+
+func TestFacadeSameFragmentMountsAtSeparateCollectionDestinations(t *testing.T) {
+	weatherDestination := configkit.Keys("collections", "weather", "prompts")
+	homeDestination := configkit.Keys("collections", "homewatch", "prompts")
+	result, err := configkit.LoadLayered(
+		configkit.Input{Source: configkit.NoSource()},
+		configkit.LayeredOptions[map[string]any]{Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
+			{Source: configkit.Bytes("weather", []byte("summarize.alerts: {title: weather}\n")), Destination: weatherDestination},
+			{Source: configkit.Bytes("homewatch", []byte("summarize.alerts: {title: home}\n")), Destination: homeDestination},
+		}}}},
+	)
+	if err != nil {
+		t.Fatalf("LoadLayered: %v", err)
+	}
+	for _, test := range []struct {
+		path []string
+		want string
+	}{
+		{path: []string{"collections", "weather", "prompts", "summarize.alerts", "title"}, want: "weather"},
+		{path: []string{"collections", "homewatch", "prompts", "summarize.alerts", "title"}, want: "home"},
+	} {
+		if got := facadeDestinationValue(t, result.Config, test.path...); got != test.want {
+			t.Errorf("value at %v = %#v, want %q", test.path, got, test.want)
+		}
+	}
+	sources := result.Sources()
+	if len(sources) != 2 || sources[0].Destination.String() != weatherDestination.String() || sources[1].Destination.String() != homeDestination.String() {
+		t.Fatalf("independent collection source placements = %#v", sources)
+	}
+}
+
+type destinationCountingReader struct{ reads int }
+
+func (reader *destinationCountingReader) Read([]byte) (int, error) {
+	reader.reads++
+	return 0, io.EOF
+}
+
+func TestFacadeMountedMainAndUnderlayInspectionResourcesAndDiff(t *testing.T) {
+	t.Parallel()
+
+	filesystem := configkit.NewFilesystem("resources", fstest.MapFS{
+		"assets/summary.md": &fstest.MapFile{Data: []byte("source-relative summary")},
+	})
+	context := &configkit.FilesystemContext{Root: ".", BaseDir: "assets", FS: &filesystem}
+	destination := configkit.Keys("catalog", "entries")
+	tokenPath := configkit.Keys("catalog", "entries", "item", "token")
+	titlePath := configkit.Keys("catalog", "entries", "item", "title")
+	var callbacks struct{ resolve, validate int }
+	load := func(token string) *configkit.Result[map[string]any] {
+		t.Helper()
+		main := configkit.Input{
+			Source:      configkit.Bytes("main", []byte("item:\n  title: main\n  resource: summary.md\n  token: "+token+"\n")),
+			Destination: destination, Filesystem: context,
+		}
+		underlay := configkit.Input{
+			Source:      configkit.Bytes("underlay", []byte("item:\n  title: lower\n  retained: lower-value\n  token: LOWER-TOKEN-CANARY\n")),
+			Destination: destination,
+		}
+		result, err := configkit.LoadLayered(main, configkit.LayeredOptions[map[string]any]{
+			Underlays: []configkit.Underlay{{Inputs: []configkit.Input{underlay}}},
+			Definition: configkit.Definition[map[string]any]{
+				Resolve: func(configuration *map[string]any, resolution *configkit.Resolution) error {
+					callbacks.resolve++
+					resourcePath := configkit.Keys("catalog", "entries", "item", "resource")
+					input, ok := resolution.EntryInfo(resourcePath)
+					if !ok || len(input.Origin.Locations) != 1 {
+						return fmt.Errorf("mounted resource input has no single source origin")
+					}
+					source, ok := resolution.Source(input.Origin.Locations[0].SourceID)
+					if !ok || source.Destination.String() != destination.String() {
+						return fmt.Errorf("resolution source did not retain its destination")
+					}
+					resourceContext, ok := resolution.SourceContext(source.ID)
+					if !ok {
+						return fmt.Errorf("resolution source context is unavailable")
+					}
+					data, err := fs.ReadFile(resourceContext.FS, path.Join(resourceContext.BaseDir, "summary.md"))
+					if err != nil {
+						return fmt.Errorf("read source-relative resource: %w", err)
+					}
+					entry := facadeDestinationMap(t, facadeDestinationMap(t, facadeDestinationMap(t, *configuration, "catalog"), "entries"), "item")
+					entry["resource_text"] = string(data)
+					resolution.RecordNormalization(configkit.Keys("catalog", "entries", "item", "resource_text"), "read source-relative summary", resourcePath)
+					return nil
+				},
+				Validate:  func(*map[string]any, *configkit.Validation) { callbacks.validate++ },
+				Sensitive: func(candidate configkit.Path) bool { return candidate.String() == tokenPath.String() },
+			},
+		})
+		if err != nil {
+			t.Fatalf("mounted load: %v", err)
+		}
+		return result
+	}
+
+	first := load("FIRST-TOKEN-CANARY")
+	second := load("SECOND-TOKEN-CANARY")
+	if callbacks.resolve != 2 || callbacks.validate != 2 {
+		t.Fatalf("lifecycle callbacks = %#v", callbacks)
+	}
+	for _, result := range []*configkit.Result[map[string]any]{first, second} {
+		entry := facadeDestinationMap(t, facadeDestinationMap(t, facadeDestinationMap(t, result.Config, "catalog"), "entries"), "item")
+		if entry["title"] != "main" || entry["retained"] != "lower-value" || entry["resource_text"] != "source-relative summary" {
+			t.Fatalf("mounted main/underlay configuration = %#v", entry)
+		}
+		sources := result.Sources()
+		if len(sources) != 2 || sources[0].Destination.String() != destination.String() || sources[1].Destination.String() != destination.String() {
+			t.Fatalf("public source destinations = %#v", sources)
+		}
+		resource, ok := result.SourceContext(sources[0].ID)
+		if !ok || resource.BaseDir != "assets" {
+			t.Fatalf("completed source context = %#v, %v", resource, ok)
+		}
+		data, err := fs.ReadFile(resource.FS, path.Join(resource.BaseDir, "summary.md"))
+		if err != nil || string(data) != "source-relative summary" {
+			t.Fatalf("completed relative resource = %q, %v", data, err)
+		}
+		if info, ok := result.Metadata().Lookup(titlePath); !ok || info.Origin.Layer != configkit.LayerMain {
+			t.Fatalf("mounted title metadata = %#v, %v", info, ok)
+		}
+		if history := result.Metadata().History(titlePath); len(history) < 2 {
+			t.Fatalf("mounted title history = %#v", history)
+		}
+		if explanation, ok := result.Explain(tokenPath); !ok || !explanation.Effective.Redacted {
+			t.Fatalf("mounted secret explanation = %#v, %v", explanation, ok)
+		}
+		var effective, explanation bytes.Buffer
+		if err := result.WriteEffective(&effective); err != nil {
+			t.Fatal(err)
+		}
+		if err := result.WriteExplanation(&explanation, tokenPath); err != nil {
+			t.Fatal(err)
+		}
+		output := effective.String() + explanation.String()
+		for _, canary := range []string{"FIRST-TOKEN-CANARY", "SECOND-TOKEN-CANARY", "LOWER-TOKEN-CANARY"} {
+			if strings.Contains(output, canary) {
+				t.Fatalf("public inspection leaked %q: %s", canary, output)
+			}
+		}
+	}
+
+	// Mutating published records and query copies must not alter the retained result.
+	returnedSources := first.Sources()
+	returnedSources[0].Destination = configkit.Keys("mutated")
+	if got := first.Sources()[0].Destination.String(); got != destination.String() {
+		t.Fatalf("source destination changed after caller mutation: %q", got)
+	}
+	info, ok := first.Metadata().Lookup(titlePath)
+	if !ok {
+		t.Fatal("mounted metadata lookup failed")
+	}
+	info.Origin.Locations[0].SourceID = "mutated"
+	if fresh, ok := first.Metadata().Lookup(titlePath); !ok || fresh.Origin.Locations[0].SourceID == "mutated" {
+		t.Fatalf("metadata copy mutation escaped: %#v, %v", fresh, ok)
+	}
+	history := first.Metadata().History(titlePath)
+	if len(history) == 0 {
+		t.Fatal("mounted history is empty")
+	}
+	history[0].Path = configkit.Keys("mutated")
+	if fresh := first.Metadata().History(titlePath); len(fresh) == 0 || fresh[0].Path.String() != titlePath.String() {
+		t.Fatalf("history copy mutation escaped: %#v", fresh)
+	}
+
+	differences, err := configkit.Diff(first, second)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(differences) != 1 || differences[0].Path.String() != tokenPath.String() ||
+		!differences[0].Left.Redacted || !differences[0].Right.Redacted ||
+		strings.Contains(differences[0].Left.YAML+differences[0].Right.YAML, "TOKEN-CANARY") {
+		t.Fatalf("public mounted secret diff = %#v", differences)
+	}
+	if callbacks.resolve != 2 || callbacks.validate != 2 {
+		t.Fatalf("inspection reran lifecycle callbacks: %#v", callbacks)
+	}
+}
+
+func TestFacadeFailedLoadExposesDetachedSourceDestination(t *testing.T) {
+	type configuration struct {
+		Tenant struct {
+			Count int `yaml:"count"`
+		} `yaml:"tenant"`
+	}
+	destination := configkit.Keys("tenant")
+	_, err := configkit.LoadLayered[configuration](configkit.Input{
+		Source: configkit.Bytes("invalid", []byte("count: not-an-integer\n")), Destination: destination,
+	})
+	loadError, ok := err.(*configkit.LoadError)
+	if !ok {
+		t.Fatalf("failed load error = %T %v", err, err)
+	}
+	sources := loadError.Sources()
+	if len(sources) != 1 || sources[0].Destination.String() != destination.String() {
+		t.Fatalf("failed source destinations = %#v", sources)
+	}
+	sources[0].Destination = configkit.Keys("caller-change")
+	if fresh := loadError.Sources(); len(fresh) != 1 || fresh[0].Destination.String() != destination.String() {
+		t.Fatalf("failed source destination was not detached: %#v", fresh)
+	}
+}
+
+func TestFacadeRelativeImportFailuresRetainSourceRecordsAndCoordinates(t *testing.T) {
+	directory := t.TempDir()
+	write := func(name, contents string) string {
+		t.Helper()
+		filename := filepath.Join(directory, name)
+		if err := os.MkdirAll(filepath.Dir(filename), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(filename, []byte(contents), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		return filename
+	}
+
+	t.Run("imported parse failure retains effective source destination", func(t *testing.T) {
+		mainPath := write("parse/main.yml", "configkit:\n  imports:\n    - path: child.yml\n      destination: [tenant]\n")
+		childPath := write("parse/child.yml", "count: [unterminated\n")
+		_, err := configkit.LoadLayered[map[string]any](configkit.Input{
+			Source: configkit.File(mainPath), Imports: true, Destination: configkit.Keys("mount"),
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) {
+			t.Fatalf("load error = %T %v", err, err)
+		}
+		diagnostics := loadError.Diagnostics()
+		if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeYAMLInvalid || diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "source-2" {
+			t.Fatalf("imported parse diagnostic = %#v", diagnostics)
+		}
+		sources := loadError.Sources()
+		if len(sources) != 2 || sources[0].Destination.String() != "/mount" || sources[1].Destination.String() != "/mount/tenant" || sources[1].Path != childPath {
+			t.Fatalf("imported parse failure sources = %#v", sources)
+		}
+	})
+
+	t.Run("directive failure stays source local", func(t *testing.T) {
+		mainPath := write("directive/main.yml", "configkit:\n  imports:\n    - path: parent.yml\n      destination: [tenant]\n")
+		parentPath := write("directive/parent.yml", "configkit:\n  imports:\n    - path: details.yml\n      destination: [3]\n")
+		_, err := configkit.LoadLayered[map[string]any](configkit.Input{
+			Source: configkit.File(mainPath), Imports: true, Destination: configkit.Keys("mount"),
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) {
+			t.Fatalf("load error = %T %v", err, err)
+		}
+		diagnostics := loadError.Diagnostics()
+		wantPath := configkit.Keys("configkit", "imports").Index(0).Key("destination").Index(0)
+		if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeImportInvalid || !reflect.DeepEqual(diagnostics[0].Path, wantPath) || diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "source-2" {
+			t.Fatalf("import directive diagnostic = %#v", diagnostics)
+		}
+		sources := loadError.Sources()
+		if len(sources) != 2 || sources[0].Destination.String() != "/mount" || sources[1].Destination.String() != "/mount/tenant" || sources[1].Path != parentPath {
+			t.Fatalf("directive failure sources = %#v", sources)
+		}
+	})
+
+	t.Run("composition failure reports effective path and all sources", func(t *testing.T) {
+		mainPath := write("compose/main.yml", "configkit:\n  imports:\n    - path: left.yml\n      destination: [tenant]\n    - path: right.yml\n      destination: [tenant]\n")
+		write("compose/left.yml", "value: same\n")
+		write("compose/right.yml", "value: same\n")
+		_, err := configkit.LoadLayered[map[string]any](configkit.Input{
+			Source: configkit.File(mainPath), Imports: true, Destination: configkit.Keys("mount"),
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) {
+			t.Fatalf("load error = %T %v", err, err)
+		}
+		diagnostics := loadError.Diagnostics()
+		if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeComposeConflict || diagnostics[0].Path.String() != "/mount/tenant/value" {
+			t.Fatalf("composition diagnostic = %#v", diagnostics)
+		}
+		sources := loadError.Sources()
+		if len(sources) != 3 || sources[0].Destination.String() != "/mount" || sources[1].Destination.String() != "/mount/tenant" || sources[2].Destination.String() != "/mount/tenant" {
+			t.Fatalf("composition failure sources = %#v", sources)
+		}
+	})
+
+	t.Run("version failure reports effective path and imported source", func(t *testing.T) {
+		mainPath := write("version/main.yml", "configkit:\n  imports:\n    - path: child.yml\n      destination: [tenant]\n")
+		childPath := write("version/child.yml", "version: forbidden\n")
+		_, err := configkit.LoadLayered[map[string]any](configkit.Input{
+			Source: configkit.File(mainPath), Imports: true, Destination: configkit.Keys("mount"),
+		}, configkit.LayeredOptions[map[string]any]{
+			Definition: configkit.Definition[map[string]any]{Version: &configkit.VersionRule{
+				Path:  configkit.Keys("mount", "tenant", "version"),
+				Check: func(configkit.Version, *configkit.Validation) error { return nil },
+			}},
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) {
+			t.Fatalf("load error = %T %v", err, err)
+		}
+		diagnostics := loadError.Diagnostics()
+		if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeImportVersion || diagnostics[0].Path.String() != "/mount/tenant/version" || diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "source-2" {
+			t.Fatalf("version diagnostic = %#v", diagnostics)
+		}
+		sources := loadError.Sources()
+		if len(sources) != 2 || sources[0].Destination.String() != "/mount" || sources[1].Destination.String() != "/mount/tenant" || sources[1].Path != childPath {
+			t.Fatalf("version failure sources = %#v", sources)
+		}
+	})
+
+	t.Run("typed validation reports effective path and authored location", func(t *testing.T) {
+		type configuration struct {
+			Mount struct {
+				Tenant struct {
+					Count int `yaml:"count"`
+				} `yaml:"tenant"`
+			} `yaml:"mount"`
+		}
+		mainPath := write("typed/main.yml", "configkit:\n  imports:\n    - path: child.yml\n      destination: [tenant]\n")
+		childPath := write("typed/child.yml", "count: invalid\n")
+		_, err := configkit.LoadLayered[configuration](configkit.Input{
+			Source: configkit.File(mainPath), Imports: true, Destination: configkit.Keys("mount"),
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) {
+			t.Fatalf("load error = %T %v", err, err)
+		}
+		diagnostics := loadError.Diagnostics()
+		if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeDecodeType || diagnostics[0].Path.String() != "/mount/tenant/count" || diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "source-2" || diagnostics[0].Primary.Line != 1 {
+			t.Fatalf("typed validation diagnostic = %#v", diagnostics)
+		}
+		sources := loadError.Sources()
+		if len(sources) != 2 || sources[0].Destination.String() != "/mount" || sources[1].Destination.String() != "/mount/tenant" || sources[1].Path != childPath {
+			t.Fatalf("typed validation sources = %#v", sources)
+		}
+	})
+}
+
+func TestFacadeDestinationMappingFailurePaths(t *testing.T) {
+	t.Parallel()
+
+	cycle := map[string]any{}
+	cycle["self"] = cycle
+	for _, fixture := range []struct {
+		name   string
+		values map[string]any
+		path   func(configkit.Path) configkit.Path
+	}{
+		{
+			name:   "unsupported nested sequence value",
+			values: map[string]any{"a/b": []any{map[string]any{"~": func() {}}}},
+			path:   func(base configkit.Path) configkit.Path { return base.Key("a/b").Index(0).Key("~") },
+		},
+		{
+			name:   "cyclic value",
+			values: map[string]any{"item": cycle},
+			path:   func(base configkit.Path) configkit.Path { return base.Key("item").Key("self") },
+		},
+		{
+			name: "constructor failure keeps source coordinates",
+			path: func(configkit.Path) configkit.Path { return configkit.Path{} },
+		},
+	} {
+		t.Run(fixture.name, func(t *testing.T) {
+			for _, role := range []string{"root", "mounted main", "mounted underlay"} {
+				t.Run(role, func(t *testing.T) {
+					var destination configkit.Path
+					if role != "root" {
+						destination = configkit.Keys("catalog", "entries")
+					}
+					wantPath := fixture.path(destination)
+					input := configkit.Input{Source: configkit.Mapping("invalid mapping", fixture.values), Destination: destination}
+					var result *configkit.Result[map[string]any]
+					var err error
+					if role == "mounted underlay" {
+						result, err = configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{
+							Underlays: []configkit.Underlay{{Inputs: []configkit.Input{input}}},
+						})
+					} else {
+						result, err = configkit.LoadLayered[map[string]any](input)
+					}
+					var loadError *configkit.LoadError
+					if result != nil || !errors.As(err, &loadError) {
+						t.Fatalf("failed load = %#v, %v", result, err)
+					}
+					diagnostics := loadError.Diagnostics()
+					if len(diagnostics) != 1 {
+						t.Fatalf("diagnostics = %#v", diagnostics)
+					}
+					diagnostic := diagnostics[0]
+					if diagnostic.Code != configkit.CodeSourceInvalid || !reflect.DeepEqual(diagnostic.Path, wantPath) {
+						t.Fatalf("diagnostic = %#v; want source.invalid at %q", diagnostic, wantPath.String())
+					}
+					if diagnostic.Primary == nil || *diagnostic.Primary != (configkit.Location{SourceID: "source-1"}) || len(diagnostic.Related) != 0 {
+						t.Fatalf("mapping source locations = %#v, %#v", diagnostic.Primary, diagnostic.Related)
+					}
+					sources := loadError.Sources()
+					if len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Destination.String() != destination.String() {
+						t.Fatalf("error sources = %#v", sources)
+					}
+				})
+			}
+		})
+	}
+}
+
+func facadeDestinationMap(t *testing.T, value map[string]any, keys ...string) map[string]any {
+	t.Helper()
+	for _, key := range keys {
+		child, ok := value[key].(map[string]any)
+		if !ok {
+			t.Fatalf("%q = %#v, want mapping", key, value[key])
+		}
+		value = child
+	}
+	return value
+}
+
+func facadeDestinationValue(t *testing.T, value map[string]any, keys ...string) any {
+	t.Helper()
+	return facadeDestinationMap(t, value, keys[:len(keys)-1]...)[keys[len(keys)-1]]
+}

facade_diagnostic_order_test.go

@@ -0,0 +1,95 @@
+package configkit_test
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeCompositionConflictKeepsClaimantOrder(t *testing.T) {
+	filesystem := configkit.NewFilesystem("bundle", fstest.MapFS{
+		"a.yml": &fstest.MapFile{Data: []byte(`configkit:
+  imports:
+    - path: z.yml
+`)},
+		"b.yml": &fstest.MapFile{Data: []byte("x: b\n")},
+		"c.yml": &fstest.MapFile{Data: []byte("x: c\n")},
+		"z.yml": &fstest.MapFile{Data: []byte("x: z\n")},
+	})
+	main := configkit.Mapping("main", map[string]any{
+		"configkit": map[string]any{"imports": []any{
+			map[string]any{"path": "a.yml"},
+			map[string]any{"path": "b.yml"},
+			map[string]any{"path": "c.yml"},
+		}},
+	})
+	_, err := configkit.Load[map[string]any](main, configkit.Options[map[string]any]{
+		Imports: true,
+		Filesystem: &configkit.FilesystemContext{
+			FS: &filesystem, Root: ".", BaseDir: ".",
+		},
+	})
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) {
+		t.Fatalf("Load error = %v, want composition LoadError", err)
+	}
+	diagnostics := loadError.Diagnostics()
+	if len(diagnostics) != 1 {
+		t.Fatalf("diagnostics = %#v, want one composition conflict", diagnostics)
+	}
+	diagnostic := diagnostics[0]
+	if diagnostic.Code != configkit.CodeComposeConflict || diagnostic.Path.String() != "/x" || diagnostic.Primary == nil {
+		t.Fatalf("composition diagnostic = %#v", diagnostic)
+	}
+
+	pathsByID := make(map[string]string)
+	var acquisitionOrder []string
+	for _, source := range loadError.Sources() {
+		pathsByID[source.ID] = source.Path
+		for _, name := range []string{"z.yml", "b.yml", "c.yml"} {
+			if source.Path == name || strings.HasSuffix(source.Path, "/"+name) {
+				acquisitionOrder = append(acquisitionOrder, strings.TrimSuffix(name, ".yml"))
+				break
+			}
+		}
+	}
+	if strings.Join(acquisitionOrder, ",") != "z,b,c" {
+		t.Fatalf("claimant acquisition order = %v, want z,b,c", acquisitionOrder)
+	}
+	claimant := func(location configkit.Location) string {
+		for _, name := range []string{"b.yml", "c.yml", "z.yml"} {
+			if pathsByID[location.SourceID] == name || strings.HasSuffix(pathsByID[location.SourceID], "/"+name) {
+				return strings.TrimSuffix(name, ".yml")
+			}
+		}
+		return ""
+	}
+	if got := claimant(*diagnostic.Primary); got != "b" {
+		t.Fatalf("primary claimant = %q, want b (sources: %#v)", got, pathsByID)
+	}
+	if len(diagnostic.Related) != 2 || claimant(diagnostic.Related[0]) != "c" || claimant(diagnostic.Related[1]) != "z" {
+		t.Fatalf("related claimants = %#v, want c then z", diagnostic.Related)
+	}
+
+	var output bytes.Buffer
+	if err := configkit.WriteDiagnostics(&output, diagnostics); err != nil {
+		t.Fatal(err)
+	}
+	positions := []int{
+		strings.Index(output.String(), diagnostic.Primary.SourceID),
+		strings.Index(output.String(), diagnostic.Related[0].SourceID),
+		strings.Index(output.String(), diagnostic.Related[1].SourceID),
+	}
+	if positions[0] < 0 || positions[1] <= positions[0] || positions[2] <= positions[1] {
+		t.Fatalf("rendered claimant order = %v in %q", positions, output.String())
+	}
+
+	diagnostics[0].Related[0].SourceID = "mutated"
+	if got := claimant(loadError.Diagnostics()[0].Related[0]); got != "c" {
+		t.Fatalf("LoadError.Diagnostics retained caller mutation; first claimant = %q", got)
+	}
+}

facade_diff_test.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type facadeDiffConfig struct {
@@ -29,10 +29,10 @@ func TestFacadeDiffKeepsPublicSequenceChangesWithHistoricalDescendants(t *testin
 		t.Helper()
 		result, err := configkit.Load(configkit.Bytes("historical-sequence.yml", []byte("items: [{secret: disposable-canary}, "+public+"]\n")),
 			configkit.Options[configuration]{Definition: configkit.Definition[configuration]{
-				Secret: func(path configkit.Path) bool { return path.String() == "/items/0/secret" },
+				Sensitive: func(path configkit.Path) bool { return path.String() == "/items/0/secret" },
 				Resolve: func(current *configuration, resolution *configkit.Resolution) error {
 					current.Items[0] = "public scalar"
-					resolution.Record(configkit.Keys("items"), configkit.ChangeNormalization, "normalize first item")
+					resolution.RecordNormalization(configkit.Keys("items"), "normalize first item")
 					return nil
 				},
 			}})
@@ -71,10 +71,10 @@ func TestFacadeDiffKeepsPublicScalarAcrossHistoricalAbsence(t *testing.T) {
 		Dynamic map[string]any `yaml:"dynamic"`
 	}
 	options := configkit.Options[configuration]{Definition: configkit.Definition[configuration]{
-		Secret: func(path configkit.Path) bool { return path.String() == "/dynamic/entry/token" },
+		Sensitive: func(path configkit.Path) bool { return path.String() == "/dynamic/entry/token" },
 		Resolve: func(current *configuration, resolution *configkit.Resolution) error {
 			delete(current.Dynamic, "entry")
-			resolution.Record(configkit.Keys("dynamic", "entry"), configkit.ChangeNormalization, "remove entry")
+			resolution.RecordNormalization(configkit.Keys("dynamic", "entry"), "remove entry")
 			return nil
 		},
 	}}
@@ -221,7 +221,7 @@ func TestFacadeDiffIgnoresSourceAndResolutionHistory(t *testing.T) {
 	resolve := func(value string) configkit.Options[config] {
 		return configkit.Options[config]{Definition: configkit.Definition[config]{Resolve: func(current *config, resolution *configkit.Resolution) error {
 			current.Count = len(value) + 8
-			resolution.Record(configkit.Keys("count"), configkit.ChangeNormalization, "set effective count")
+			resolution.RecordNormalization(configkit.Keys("count"), "set effective count")
 			return nil
 		}}}
 	}
@@ -281,7 +281,7 @@ func TestFacadeDiffUsesFrozenFilesAndRunsCallbacksOnlyDuringLoad(t *testing.T) {
 
 func TestFacadeDiffCombinesSecretSensitivityAndLoadErrors(t *testing.T) {
 	t.Setenv("FACADE_DIFF_SECRET", "credential-one")
-	secretOptions := configkit.Options[facadeDiffSecretConfig]{Definition: configkit.Definition[facadeDiffSecretConfig]{Secret: func(path configkit.Path) bool {
+	secretOptions := configkit.Options[facadeDiffSecretConfig]{Definition: configkit.Definition[facadeDiffSecretConfig]{Sensitive: func(path configkit.Path) bool {
 		return path.String() == "/secret"
 	}}}
 	left, err := configkit.Load[facadeDiffSecretConfig](configkit.Bytes("left.yml", []byte("secret: FACADE_DIFF_SECRET\n")), secretOptions)

facade_discovery_test.go

@@ -0,0 +1,316 @@
+package configkit
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"testing/fstest"
+)
+
+type facadeDiscoveryConfig struct {
+	Value    string            `yaml:"value"`
+	Settings map[string]string `yaml:"settings"`
+}
+
+type facadeDiscoveryLifecycleConfig struct {
+	Value    string `yaml:"value"`
+	Resolved string `yaml:"resolved"`
+}
+
+type facadeDiscoveryPlacementConfig struct {
+	Items []facadeDiscoveryPlacementItem `yaml:"items"`
+}
+
+type facadeDiscoveryPlacementItem struct {
+	Name string `yaml:"name"`
+}
+
+func TestFacadeSearchPresetUsesCurrentWorkingDirectory(t *testing.T) {
+	original, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	root := t.TempDir()
+	if err := os.Chdir(root); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if err := os.Chdir(original); err != nil {
+			t.Errorf("restore working directory: %v", err)
+		}
+	})
+	writeFacadeImportFile(t, root, "myapp.yml", "value: working\n")
+
+	result, err := Load[facadeDiscoveryConfig](SearchConfig("myapp", WorkingDirectory()))
+	if err != nil || result.Config.Value != "working" {
+		t.Fatalf("working-directory search = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, filepath.Join(root, "myapp.yml")) {
+		t.Fatalf("working-directory sources = %#v", sources)
+	}
+}
+
+func TestFacadeSearchCustomGenericNamesAndEmptyFilenameSelection(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	filename := writeFacadeImportFile(t, root, "config.yml", "value: found\n")
+	custom := SearchDirectory(root, DirectorySearchOptions{
+		Filenames: []FilenameGroup{CustomFilenames("config.yml")},
+	})
+	result, err := Load[facadeDiscoveryConfig](SearchConfig("", custom))
+	if err != nil || result.Config.Value != "found" {
+		t.Fatalf("custom generic-only search with empty slug = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, filename) {
+		t.Fatalf("custom generic-only sources = %#v", sources)
+	}
+
+	defaults := func() facadeDiscoveryConfig { return facadeDiscoveryConfig{Value: "default"} }
+	empty := SearchDirectory(root, DirectorySearchOptions{Filenames: []FilenameGroup{}})
+	absent, err := Load(SearchConfig("myapp", empty), Options[facadeDiscoveryConfig]{
+		Definition: Definition[facadeDiscoveryConfig]{Defaults: defaults},
+	})
+	if err != nil || absent.Config.Value != "default" || len(absent.Sources()) != 0 {
+		t.Fatalf("explicit empty filename selection = %#v, %v", absent, err)
+	}
+	omitted, err := Load[facadeDiscoveryConfig](SearchConfig("myapp", SearchDirectory(root)))
+	if err != nil || omitted.Config.Value != "found" {
+		t.Fatalf("omitted filename selection did not use defaults = %#v, %v", omitted, err)
+	}
+}
+
+func TestFacadeSearchOrderingRequirednessAndSnapshots(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "config.yml", "value: selected\n")
+	laterPath := writeFacadeImportFile(t, root, "later.yml", "value: later\n")
+	paths := []string{filepath.Join(root, "missing.yml")}
+	names := []string{"config.yml"}
+	groups := []FilenameGroup{CustomFilenames(names...)}
+	directoryOptions := []DirectorySearchOptions{{Filenames: groups}}
+	search := Searches(SearchPaths(paths...), SearchDirectory(root, directoryOptions...), SearchPaths(laterPath))
+	source := SearchConfig("", search, SearchOptions{Required: true})
+
+	paths[0] = laterPath
+	names[0] = "later.yml"
+	groups[0] = CustomFilenames("later.yml")
+	directoryOptions[0].Filenames[0] = CustomFilenames("later.yml")
+	search = SearchPaths(laterPath)
+
+	result, err := Load[facadeDiscoveryConfig](source)
+	if err != nil || result.Config.Value != "selected" {
+		t.Fatalf("ordered required search after caller mutation = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, selectedPath) {
+		t.Fatalf("ordered search sources = %#v", sources)
+	}
+
+	_, err = Load[facadeDiscoveryConfig](SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml")), SearchOptions{Required: true}))
+	var loadErr *LoadError
+	if !errors.As(err, &loadErr) {
+		t.Fatalf("required exhausted search error = %v, want *LoadError", err)
+	}
+	foundMissing := false
+	for _, diagnostic := range loadErr.Diagnostics() {
+		foundMissing = foundMissing || diagnostic.Code == CodeSourceMissing
+	}
+	if !foundMissing {
+		t.Fatalf("required exhausted search diagnostics = %#v", loadErr.Diagnostics())
+	}
+}
+
+func TestFacadeSearchWorksForLayeredMainAndUnderlay(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	mainPath := writeFacadeImportFile(t, root, "main.yml", "settings: {main: value}\n")
+	underlayPath := writeFacadeImportFile(t, root, "underlay/base.yml", "settings: {underlay: value}\n")
+	result, err := LoadLayered(
+		Input{Source: SearchConfig("", SearchPaths(mainPath))},
+		LayeredOptions[facadeDiscoveryConfig]{Underlays: []Underlay{{Inputs: []Input{{
+			Source: SearchConfig("", SearchDirectory(filepath.Dir(underlayPath), DirectorySearchOptions{
+				Filenames: []FilenameGroup{CustomFilenames("base.yml")},
+			})),
+		}}}}},
+	)
+	if err != nil || !reflect.DeepEqual(result.Config.Settings, map[string]string{"main": "value", "underlay": "value"}) {
+		t.Fatalf("layered search = %#v, %v", result, err)
+	}
+	sources := result.Sources()
+	if len(sources) != 2 || sources[0].Path != canonicalFacadePath(t, mainPath) || sources[0].Layer != LayerMain ||
+		sources[1].Path != canonicalFacadePath(t, underlayPath) || sources[1].Layer != LayerUnderlay {
+		t.Fatalf("layered search sources = %#v", sources)
+	}
+}
+
+func TestFacadeSearchSelectedAndAbsentUseRootOnlyContext(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	mainPath := writeFacadeImportFile(t, root, "main.yml", "value: main\n")
+	writeFacadeImportFile(t, root, "overlays/testing.yml", "value: overlay\n")
+	filesystem := &FilesystemContext{Root: root}
+	options := Options[facadeDiscoveryConfig]{Overlay: "testing", Filesystem: filesystem}
+
+	selected, err := Load(SearchConfig("", SearchPaths(mainPath)), options)
+	if err != nil || selected.Config.Value != "overlay" {
+		t.Fatalf("selected search with root-only context = %#v, %v", selected, err)
+	}
+	sources := selected.Sources()
+	if len(sources) != 2 || sources[0].Path != canonicalFacadePath(t, mainPath) || sources[0].ID != "source-1" ||
+		sources[1].ID != "source-2" || sources[1].Layer != LayerOverlay {
+		t.Fatalf("selected search source evidence = %#v", sources)
+	}
+	mainContext, ok := selected.SourceContext("source-1")
+	if !ok || mainContext.BaseDir != "." {
+		t.Fatalf("selected file base context = %#v, %v", mainContext, ok)
+	}
+
+	missing := SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml")))
+	searchedAbsent, err := Load(missing, options)
+	if err != nil {
+		t.Fatalf("exhausted search with root-only overlay context: %v", err)
+	}
+	explicitAbsent, err := Load(NoSource(), options)
+	if err != nil {
+		t.Fatalf("NoSource with root-only overlay context: %v", err)
+	}
+	if !reflect.DeepEqual(searchedAbsent.Config, explicitAbsent.Config) ||
+		!reflect.DeepEqual(searchedAbsent.Sources(), explicitAbsent.Sources()) {
+		t.Fatalf("searched absence differs from NoSource: %#v / %#v", searchedAbsent, explicitAbsent)
+	}
+	left, leftOK := searchedAbsent.Metadata().Lookup(Keys("value"))
+	right, rightOK := explicitAbsent.Metadata().Lookup(Keys("value"))
+	if leftOK != rightOK || !reflect.DeepEqual(left, right) || !leftOK {
+		t.Fatalf("searched absence metadata = %#v, %v; NoSource metadata = %#v, %v", left, leftOK, right, rightOK)
+	}
+	if sources := searchedAbsent.Sources(); len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Layer != LayerOverlay {
+		t.Fatalf("absent search created unexpected source evidence = %#v", sources)
+	}
+}
+
+func TestFacadeSearchRejectsSelectedContextWithoutFallback(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	inside := writeFacadeImportFile(t, root, "inside.yml", "value: fallback\n")
+	outsideRoot := t.TempDir()
+	outside := writeFacadeImportFile(t, outsideRoot, "outside.yml", "value: selected\n")
+	search := SearchConfig("", SearchPaths(outside, inside))
+
+	_, err := Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{Root: root}})
+	var loadErr *LoadError
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeImportOutsideRoot) {
+		t.Fatalf("selected outside-root file error = %v, want containment failure", err)
+	}
+
+	_, err = Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{BaseDir: root, Root: root}})
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeOptionsInvalid) {
+		t.Fatalf("selected file with explicit base error = %v, want option failure", err)
+	}
+
+	native := NewFilesystem("native", fstest.MapFS{})
+	_, err = Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{FS: &native, BaseDir: ".", Root: "."}})
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeOptionsInvalid) {
+		t.Fatalf("selected file with native context error = %v, want option failure", err)
+	}
+}
+
+func TestFacadeSearchRunsCallbacksOnceAndKeepsInspectionWithSelectedFile(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "selected.yml", "value: selected\n")
+	writeFacadeImportFile(t, root, "later.yml", "value: later\n")
+	defaultsCalls, resolveCalls, validateCalls := 0, 0, 0
+	result, err := Load(SearchConfig("", SearchPaths(selectedPath, filepath.Join(root, "later.yml"))), Options[facadeDiscoveryLifecycleConfig]{
+		Definition: Definition[facadeDiscoveryLifecycleConfig]{
+			Defaults: func() facadeDiscoveryLifecycleConfig {
+				defaultsCalls++
+				return facadeDiscoveryLifecycleConfig{}
+			},
+			Resolve: func(configuration *facadeDiscoveryLifecycleConfig, resolution *Resolution) error {
+				resolveCalls++
+				configuration.Resolved = "from:" + configuration.Value
+				resolution.RecordNormalization(Keys("resolved"), "derive from selected value", Keys("value"))
+				return nil
+			},
+			Validate: func(_ *facadeDiscoveryLifecycleConfig, _ *Validation) { validateCalls++ },
+		},
+	})
+	if err != nil || result.Config.Value != "selected" || result.Config.Resolved != "from:selected" {
+		t.Fatalf("search lifecycle result = %#v, %v", result, err)
+	}
+	if defaultsCalls != 1 || resolveCalls != 1 || validateCalls != 1 {
+		t.Fatalf("search callbacks ran defaults=%d resolve=%d validate=%d times", defaultsCalls, resolveCalls, validateCalls)
+	}
+	sources := result.Sources()
+	if len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, selectedPath) || sources[0].ID != "source-1" {
+		t.Fatalf("selected source evidence = %#v", sources)
+	}
+	valueInfo, found := result.Metadata().Lookup(Keys("value"))
+	if !found || len(valueInfo.Origin.Locations) != 1 || valueInfo.Origin.Locations[0].SourceID != sources[0].ID {
+		t.Fatalf("selected value metadata = %#v, %v", valueInfo, found)
+	}
+	var rendered strings.Builder
+	if err := result.WriteEffective(&rendered); err != nil || !strings.Contains(rendered.String(), "value: selected") || strings.Contains(rendered.String(), "later") {
+		t.Fatalf("effective output = %q, %v", rendered.String(), err)
+	}
+}
+
+func TestFacadeSearchSequenceItemAndAbsentInputPlacement(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "item.yml", "name: selected\n")
+	options := Options[facadeDiscoveryPlacementConfig]{
+		Destination:   Keys("items"),
+		PlacementMode: PlacementModeSequenceItem,
+	}
+	selected, err := Load(SearchConfig("", SearchPaths(selectedPath)), options)
+	if err != nil || len(selected.Config.Items) != 1 || selected.Config.Items[0].Name != "selected" {
+		t.Fatalf("selected sequence item = %#v, %v", selected, err)
+	}
+	if sources := selected.Sources(); len(sources) != 1 || sources[0].Destination.String() != "/items" || sources[0].PlacementMode != PlacementModeSequenceItem {
+		t.Fatalf("selected sequence-item source = %#v", sources)
+	}
+
+	defaults := func() facadeDiscoveryPlacementConfig {
+		return facadeDiscoveryPlacementConfig{Items: []facadeDiscoveryPlacementItem{}}
+	}
+	absent, err := Load(SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml"))), Options[facadeDiscoveryPlacementConfig]{
+		Definition:    Definition[facadeDiscoveryPlacementConfig]{Defaults: defaults},
+		Destination:   options.Destination,
+		PlacementMode: options.PlacementMode,
+	})
+	if err != nil || len(absent.Config.Items) != 0 || len(absent.Sources()) != 0 {
+		t.Fatalf("absent search created a sequence item: %#v, %v", absent, err)
+	}
+}
+
+func hasFacadeDiagnostic(err *LoadError, code Code) bool {
+	for _, diagnostic := range err.Diagnostics() {
+		if diagnostic.Code == code {
+			return true
+		}
+	}
+	return false
+}
+
+func canonicalFacadePath(t *testing.T, path string) string {
+	t.Helper()
+	absolute, err := filepath.Abs(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	canonical, err := filepath.EvalSymlinks(absolute)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return canonical
+}

facade_dynamic_redaction_test.go

@@ -0,0 +1,53 @@
+package configkit_test
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFinalDynamicTagRedactsEqualValuedResolution(t *testing.T) {
+	t.Parallel()
+	type classified struct {
+		Token string `yaml:"token" configkit:"secret"`
+	}
+	type configuration struct {
+		Value any `yaml:"value"`
+	}
+	const canary = "DYNAMIC-TAG-CANARY"
+	result, err := configkit.Load(configkit.Bytes("input", []byte("value: {token: "+canary+"}\n")), configkit.Options[configuration]{
+		Definition: configkit.Definition[configuration]{
+			Resolve: func(c *configuration, _ *configkit.Resolution) error {
+				// No canonical value changes, so no normalization record is needed.
+				c.Value = classified{Token: canary}
+				return nil
+			},
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var effective bytes.Buffer
+	if err := result.WriteEffective(&effective); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(effective.String(), canary) || !strings.Contains(effective.String(), "[REDACTED]") {
+		t.Fatal("effective rendering did not preserve the final dynamic tag")
+	}
+	explanation, found := result.Explain(configkit.Keys("value", "token"))
+	if !found || !explanation.Effective.Redacted || strings.Contains(explanation.Effective.YAML, canary) {
+		t.Fatal("effective explanation did not preserve the final dynamic tag")
+	}
+	if len(explanation.History) == 0 {
+		t.Fatal("source history is absent")
+	}
+	for _, change := range explanation.History {
+		for _, value := range []configkit.ValueSnapshot{change.Before, change.After} {
+			if value.Present && (!value.Redacted || strings.Contains(value.YAML, canary)) {
+				t.Fatal("historical explanation did not preserve the final dynamic tag")
+			}
+		}
+	}
+}

facade_equivalence_test.go

@@ -9,7 +9,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type equivalentConfig struct {
@@ -23,6 +23,9 @@ type equivalentConfig struct {
 
 func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 	const yaml = "version: 1\nname: retained\nenabled: false\ncount: 0\nitems: []\noptional: null\n"
+	bytesData := []byte(yaml)
+	bytesSource := configkit.Bytes("memory", bytesData)
+	bytesData[0] = 'X'
 	hostPath := filepath.Join(t.TempDir(), "main.yml")
 	if err := os.WriteFile(hostPath, []byte(yaml), 0o600); err != nil {
 		t.Fatal(err)
@@ -37,7 +40,7 @@ func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 	}{
 		{"host", configkit.File(hostPath), nil, configkit.SourceKindFile},
 		{"native", namespace.File("main.yml"), nil, configkit.SourceKindFilesystem},
-		{"bytes", configkit.Bytes("memory", []byte(yaml)), context, configkit.SourceKindBytes},
+		{"bytes", bytesSource, context, configkit.SourceKindBytes},
 		{"reader", configkit.Reader("stream", strings.NewReader(yaml)), context, configkit.SourceKindReader},
 		{"mapping", configkit.Mapping("programmatic", map[string]any{
 			"version": uint64(1), "name": "retained", "enabled": false, "count": 0,
@@ -66,7 +69,7 @@ func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 			}
 			for _, field := range []string{"version", "name", "enabled", "count", "items", "optional"} {
 				info, ok := result.Metadata().Lookup(configkit.Keys(field))
-				if !ok || !info.Explicit || info.Origin.Layer != configkit.LayerBase || info.Null != (field == "optional") {
+				if !ok || !info.Explicit || info.Origin.Layer != configkit.LayerMain || info.Null != (field == "optional") {
 					t.Errorf("%s input info = %#v, %v", field, info, ok)
 				}
 			}
@@ -112,6 +115,15 @@ func TestRepeatedImportsAcrossTiersAndReaderConsumption(t *testing.T) {
 	if got := layeredErrorCode(t, err); got != configkit.CodeSourceReaderUsed {
 		t.Fatalf("reader re-consumption = %s", got)
 	}
+	copiedReader := configkit.Reader("copied-single-use", strings.NewReader("name: retained\n"))
+	readerCopy := copiedReader
+	if _, err := configkit.Load[config](readerCopy, configkit.Options[config]{}); err != nil {
+		t.Fatal(err)
+	}
+	_, err = configkit.Load[config](copiedReader, configkit.Options[config]{})
+	if got := layeredErrorCode(t, err); got != configkit.CodeSourceReaderUsed {
+		t.Fatalf("copied reader re-consumption = %s", got)
+	}
 }
 
 func TestReplacedSecretRemainsAbsentFromSafeOutput(t *testing.T) {
@@ -120,7 +132,7 @@ func TestReplacedSecretRemainsAbsentFromSafeOutput(t *testing.T) {
 	}
 	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main", []byte("secret: new-secret-canary\n"))}, configkit.LayeredOptions[config]{
 		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"secret": "old-secret-canary"})}}}},
-		Definition: configkit.Definition[config]{Secret: func(path configkit.Path) bool { return path.String() == "/secret" }},
+		Definition: configkit.Definition[config]{Sensitive: func(path configkit.Path) bool { return path.String() == "/secret" }},
 	})
 	if err != nil || result.Config.Secret != "new-secret-canary" {
 		t.Fatalf("secret load = %#v, %v", result, err)

facade_filesystem_test.go

@@ -9,7 +9,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 //go:embed testdata/filesystem

facade_final_sequence_identity_test.go

@@ -0,0 +1,249 @@
+package configkit_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"go.maximumdirect.net/configkit"
+)
+
+func TestFinalSequenceIdentityTreatsLateExtendsFieldsAsPayload(t *testing.T) {
+	for _, phase := range []string{"defaults", "resolution"} {
+		for _, component := range []any{"application-data", nil} {
+			for _, duplicate := range []bool{false, true} {
+				t.Run(fmt.Sprintf("%s/%v/duplicate=%t", phase, component, duplicate), func(t *testing.T) {
+					items := []any{map[string]any{"extends": component}}
+					if duplicate {
+						items = append(items, map[string]any{"extends": component})
+					}
+					definition := configkit.Definition[map[string]any]{
+						SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "extends")},
+						Defaults: func() map[string]any {
+							if phase == "defaults" {
+								return map[string]any{"items": items}
+							}
+							return map[string]any{}
+						},
+					}
+					if phase == "resolution" {
+						definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+							(*value)["items"] = items
+							resolution.RecordNormalization(configkit.Keys("items"), "supply application payload")
+							return nil
+						}
+					}
+					loaded, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{Definition: definition})
+					if duplicate {
+						loadErr := requireFacadeLoadError(t, err)
+						diagnostics := loadErr.Diagnostics()
+						if loaded != nil || len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict || diagnostics[0].Path.String() != "/items" {
+							t.Fatalf("duplicate effective payload diagnostics = %#v", diagnostics)
+						}
+						return
+					}
+					if err != nil || loaded == nil {
+						t.Fatalf("ordinary effective identity was interpreted as a directive: %v", err)
+					}
+					value := loaded.Config["items"].([]any)[0].(map[string]any)
+					if actual, present := value["extends"]; !present || actual != component {
+						t.Fatalf("effective payload = %#v", value)
+					}
+				})
+			}
+		}
+	}
+}
+
+func TestFinalSequenceIdentityValidatesLateValues(t *testing.T) {
+	identity := configkit.SequenceIdentityAt(configkit.Keys("items"), "id")
+	for _, source := range []string{"defaults", "CLI", "resolution"} {
+		for _, shape := range []string{"duplicate", "missing", "non-scalar"} {
+			t.Run(source+"/"+shape, func(t *testing.T) {
+				items := finalIdentityRecords(shape)
+				definition := configkit.Definition[map[string]any]{
+					SequenceIdentities: []configkit.SequenceIdentity{identity},
+					Defaults: func() map[string]any {
+						if source == "defaults" {
+							return map[string]any{"items": items}
+						}
+						return map[string]any{}
+					},
+				}
+				options := configkit.Options[map[string]any]{Definition: definition}
+				switch source {
+				case "CLI":
+					options.Overrides = []configkit.Override{{Path: configkit.Keys("items"), Value: items, Flag: "--items"}}
+				case "resolution":
+					options.Definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+						(*value)["items"] = items
+						resolution.RecordNormalization(configkit.Keys("items"), "create effective records")
+						return nil
+					}
+				}
+				result, err := configkit.Load(configkit.NoSource(), options)
+				if result != nil {
+					t.Fatalf("invalid final identities returned a result: %#v", result.Config)
+				}
+				loadErr := requireFacadeLoadError(t, err)
+				if len(loadErr.Diagnostics()) != 1 {
+					t.Fatalf("diagnostics = %#v", loadErr.Diagnostics())
+				}
+				diagnostic := loadErr.Diagnostics()[0]
+				wantCode, wantPath := configkit.CodeSequenceInvalid, "/items/0/id"
+				if shape == "duplicate" {
+					wantCode, wantPath = configkit.CodeSequenceConflict, "/items"
+				}
+				if diagnostic.Code != wantCode || diagnostic.Path.String() != wantPath {
+					t.Fatalf("diagnostic = %#v, want %s at %s", diagnostic, wantCode, wantPath)
+				}
+				if source == "CLI" && (diagnostic.Primary == nil || diagnostic.Primary.SourceID != "source-1") {
+					t.Fatalf("CLI identity diagnostic lost its source: %#v", diagnostic)
+				}
+			})
+		}
+	}
+}
+
+func TestFinalSequenceIdentityMatchesLateDynamicNamespaces(t *testing.T) {
+	selector := configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("items"),
+	}
+	for _, source := range []string{"defaults", "CLI", "resolution"} {
+		t.Run(source, func(t *testing.T) {
+			name := map[string]string{"defaults": "team", "CLI": "cloud", "resolution": "orbit"}[source]
+			path := configkit.Keys("collections", name, "items")
+			items := finalIdentityRecords("duplicate")
+			definition := configkit.Definition[map[string]any]{
+				SequenceIdentities: []configkit.SequenceIdentity{
+					configkit.SequenceIdentityMatching(selector, "id"),
+				},
+				Defaults: func() map[string]any {
+					if source == "defaults" {
+						return map[string]any{"collections": map[string]any{name: map[string]any{"items": items}}}
+					}
+					return map[string]any{}
+				},
+			}
+			options := configkit.Options[map[string]any]{Definition: definition}
+			switch source {
+			case "CLI":
+				options.Overrides = []configkit.Override{{Path: path, Value: items, Flag: "--items"}}
+			case "resolution":
+				options.Definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+					(*value)["collections"] = map[string]any{name: map[string]any{"items": items}}
+					resolution.RecordNormalization(configkit.Keys("collections"), "create namespaced records")
+					return nil
+				}
+			}
+			result, err := configkit.Load(configkit.NoSource(), options)
+			if result != nil {
+				t.Fatalf("invalid dynamic identity returned a result: %#v", result.Config)
+			}
+			loadErr := requireFacadeLoadError(t, err)
+			if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict || diagnostics[0].Path.String() != path.String() {
+				t.Fatalf("dynamic identity diagnostics = %#v", diagnostics)
+			}
+		})
+	}
+}
+
+func TestFinalSequenceIdentityAppliesToLayeredLoads(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+		Defaults: func() map[string]any {
+			return map[string]any{"items": finalIdentityRecords("duplicate")}
+		},
+	}
+	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{Definition: definition})
+	if result != nil {
+		t.Fatalf("invalid layered final identities returned a result: %#v", result.Config)
+	}
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("layered identity diagnostics = %#v", diagnostics)
+	}
+}
+
+func TestFinalSequenceIdentityUsesTypedNumbersAndIgnoresUnmatchedShapes(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("items"), "id"),
+			configkit.SequenceIdentityAt(configkit.Keys("unmatched"), "id"),
+		},
+	}
+	_, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{
+		Definition: configkit.Definition[map[string]any]{
+			SequenceIdentities: definition.SequenceIdentities,
+			Defaults: func() map[string]any {
+				return map[string]any{"items": []any{
+					map[string]any{"id": int64(1)}, map[string]any{"id": float64(1)},
+				}}
+			},
+		},
+	})
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("typed numeric identity diagnostics = %#v", diagnostics)
+	}
+
+	valid, err := configkit.Load(configkit.Mapping("valid", map[string]any{
+		"items": []any{
+			map[string]any{"id": nil}, map[string]any{"id": true},
+			map[string]any{"id": int64(1)}, map[string]any{"id": "one"},
+		},
+		"other": []any{map[string]any{"id": "same"}, map[string]any{"id": "same"}},
+	}), configkit.Options[map[string]any]{Definition: definition})
+	if err != nil || valid == nil {
+		t.Fatalf("valid scalar identities and unmatched duplicate sequence = %#v, %v", valid, err)
+	}
+	if _, err := configkit.Load(configkit.Mapping("other-shapes", map[string]any{"items": nil}), configkit.Options[map[string]any]{Definition: definition}); err != nil {
+		t.Fatalf("null at a registered path was validated as an identity sequence: %v", err)
+	}
+}
+
+func TestFinalSequenceIdentityDiagnosticDoesNotRevealResolvedSecrets(t *testing.T) {
+	const canary = "FINAL-IDENTITY-CREDENTIAL-CANARY"
+	const secretName = "CONFIGKIT_FINAL_IDENTITY_SECRET"
+	t.Setenv(secretName, canary)
+	type item struct {
+		ID    string           `yaml:"id"`
+		Token configkit.Secret `yaml:"token"`
+	}
+	type config struct {
+		Items []item `yaml:"items"`
+	}
+	definition := configkit.Definition[config]{
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+		Defaults: func() config {
+			return config{Items: []item{
+				{ID: "duplicate", Token: configkit.SecretEnv(secretName)},
+				{ID: "duplicate", Token: configkit.SecretEnv(secretName)},
+			}}
+		},
+	}
+	result, err := configkit.Load(configkit.NoSource(), configkit.Options[config]{Definition: definition})
+	if result != nil {
+		t.Fatalf("duplicate identity returned a result: %#v", result.Config)
+	}
+	if err == nil || strings.Contains(err.Error(), canary) {
+		t.Fatalf("identity diagnostic leaked a resolved secret: %v", err)
+	}
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("secret-bearing identity diagnostics = %#v", diagnostics)
+	}
+}
+
+func finalIdentityRecords(shape string) []any {
+	switch shape {
+	case "duplicate":
+		return []any{map[string]any{"id": "same"}, map[string]any{"id": "same"}}
+	case "missing":
+		return []any{map[string]any{"other": "value"}}
+	default:
+		return []any{map[string]any{"id": map[string]any{"nested": "value"}}}
+	}
+}

facade_historical_paths_test.go

@@ -0,0 +1,120 @@
+package configkit_test
+
+import (
+	"reflect"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestPublicHistoricalPathsEnumerateContextualShapes(t *testing.T) {
+	loaded, err := configkit.Load[map[string]any](configkit.Bytes("main", []byte(
+		"retired: {child: 1}\nshape: {'0': base}\n'a/b~': {'': 2}\n",
+	)), configkit.Options[map[string]any]{Overrides: []configkit.Override{
+		{Path: configkit.Keys("retired"), Value: nil, Flag: "--retired"},
+		{Path: configkit.Keys("shape"), Value: []any{"replacement"}, Flag: "--shape"},
+	}})
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+
+	metadata := loaded.Metadata()
+	paths := metadata.HistoricalPaths()
+	got := make([]string, len(paths))
+	for index, path := range paths {
+		got[index] = path.String()
+		if len(metadata.History(path)) == 0 {
+			t.Errorf("enumerated path %s has no history", path)
+		}
+	}
+	want := []string{"", "/a~1b~0", "/a~1b~0/", "/retired", "/retired/child", "/shape", "/shape/0"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("historical paths = %v, want sorted unique pointers %v", got, want)
+	}
+	if _, ok := metadata.Lookup(paths[4]); ok {
+		t.Fatal("removed descendant remains effective")
+	}
+	if _, ok := metadata.Lookup(paths[6]); !ok {
+		t.Fatal("enumerated numeric path did not follow the effective sequence shape")
+	}
+	if len(metadata.History(paths[6])) == 0 {
+		t.Fatal("enumerated numeric path lost history")
+	}
+	assertPublicShapeHistory(t, metadata, configkit.LayerCLI)
+	if _, ok := metadata.Lookup(configkit.Keys("shape", "0")); ok {
+		t.Fatal("mapping-key path resolved against the effective sequence")
+	}
+	if len((configkit.Metadata{}).HistoricalPaths()) != 0 {
+		t.Fatal("zero metadata contains historical paths")
+	}
+	if (configkit.Metadata{}).History(configkit.Keys("shape")) != nil {
+		t.Fatal("zero metadata contains history")
+	}
+
+	paths[1] = configkit.Keys("mutated")
+	if again := metadata.HistoricalPaths(); !reflect.DeepEqual(pathStrings(again), want) {
+		t.Fatalf("returned path slice mutated retained metadata: %v", pathStrings(again))
+	}
+}
+
+func TestPublicHistoryUsesResolutionShapeAttribution(t *testing.T) {
+	loaded, err := configkit.Load[map[string]any](configkit.Bytes("main", []byte("shape: {'0': base}\n")), configkit.Options[map[string]any]{
+		Definition: configkit.Definition[map[string]any]{
+			Resolve: func(configuration *map[string]any, resolution *configkit.Resolution) error {
+				(*configuration)["shape"] = []any{"replacement"}
+				resolution.RecordNormalization(configkit.Keys("shape"), "replace numeric mapping key")
+				return nil
+			},
+		},
+	})
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	assertPublicShapeHistory(t, loaded.Metadata(), configkit.LayerResolution)
+}
+
+func assertPublicShapeHistory(t *testing.T, metadata configkit.Metadata, operationLayer configkit.Layer) {
+	t.Helper()
+
+	keyPath := configkit.Keys("shape", "0")
+	indexPath := configkit.Keys("shape").Index(0)
+	keyHistory := metadata.History(keyPath)
+	indexHistory := metadata.History(indexPath)
+	if len(keyHistory) == 0 || len(indexHistory) == 0 {
+		t.Fatalf("explicit shape histories = key %#v, index %#v", keyHistory, indexHistory)
+	}
+	var keyDefinition, keyReplacement, indexReplacement bool
+	for _, change := range keyHistory {
+		keyDefinition = keyDefinition || change.Origin.Layer == configkit.LayerMain
+		keyReplacement = keyReplacement || change.Origin.Layer == operationLayer && change.Path.String() == "/shape"
+	}
+	for _, change := range indexHistory {
+		if change.Origin.Layer == configkit.LayerMain {
+			t.Fatalf("introduced index inherited mapping-key history: %#v", indexHistory)
+		}
+		indexReplacement = indexReplacement || change.Origin.Layer == operationLayer && change.Path.String() == "/shape"
+		for _, previous := range change.Previous {
+			if previous.Layer == configkit.LayerMain {
+				t.Fatalf("introduced index inherited mapping-key previous origin: %#v", change)
+			}
+		}
+	}
+	if !keyDefinition || !keyReplacement || !indexReplacement {
+		t.Fatalf("shape histories missed applicable definitions or replacement: key %#v, index %#v", keyHistory, indexHistory)
+	}
+	parsed, err := configkit.ParsePath("/shape/0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if parsedHistory := metadata.History(parsed); len(parsedHistory) == 0 {
+		t.Fatal("parsed numeric query lost contextual history")
+	}
+}
+
+func pathStrings(paths []configkit.Path) []string {
+	result := make([]string, len(paths))
+	for index, path := range paths {
+		result[index] = path.String()
+	}
+	return result
+}