diff --git a/docs/consumers/pkg-promptkit.md b/docs/consumers/pkg-promptkit.md
index 61b13a7..23cf1e1 100644
--- a/docs/consumers/pkg-promptkit.md
+++ b/docs/consumers/pkg-promptkit.md
@@ -719,18 +719,19 @@ if err != nil {
 }
 
 target := inspection.EffectiveModelParams
+if inspection.APIKeyRequired {
+	// Arrange a usable direct or configured environment credential.
+}
 if target.APIKeyEnv != "" {
-	// This is a configured optional environment lookup source.
-} else if inspection.APIKeyRequired {
-	// Arrange a direct credential before later execution.
+	// This is the configured environment lookup source, not its value.
 }
 ```
 
 Use this configuration-time boundary when only the profile and its target need
 checking. Use `Prepare` when the application also needs prompt, input, schema,
 or rendering work; use prepared execution when that work must remain tied to a
-later execution. A reported `APIKeyEnv` is a configured optional source, while
-`APIKeyRequired` is the explicit local requirement. The
+later execution. A reported `APIKeyEnv` identifies a configured source, while
+`APIKeyRequired` is the explicit requirement; both may be present. The
 [credential format reference](../formats.md#credentials) and the method's
 [GoDoc](../../engine.go) own the exact precedence, timing, result, and error
 contracts.
diff --git a/docs/integrations/openai-compatible-chat.md b/docs/integrations/openai-compatible-chat.md
index 482ce95..79c01c0 100644
--- a/docs/integrations/openai-compatible-chat.md
+++ b/docs/integrations/openai-compatible-chat.md
@@ -115,9 +115,10 @@ The client conditionally includes:
   strict flag, and schema document. Plain JSON validation does not add an
   object-only response constraint.
 
-The engine resolves backend, profile, and request extra-parameter maps by
-whole-map replacement rather than key merging. The resulting effective map is
-merged into the top-level body. Empty keys, values that cannot be encoded, and
+Configured profile maps recursively overlay backend defaults, while a nonempty
+runtime override replaces the complete configured map. The [format reference](../formats.md#defaults-and-overrides)
+owns these resolution rules. The resulting effective map is merged into the
+top-level body. Empty keys, values that cannot be encoded, and
 collisions with these reserved fields are rejected before any provider call:
 
 - `model`
diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index d4594a0..b56cf9c 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -715,6 +715,11 @@ Go 1.27.3; an injected-observer test verifies permit release before callbacks.
 boundary, and changed documentation links and semantics agree with canonical
 GoDoc/formats. Do not snapshot whole diagnostic strings or unrelated JSON fields.
 
+Completion: marker-based request formatting and JSON checks cover value and
+pointer forms. Profile credential inspection, exact IDs, prompt listing, and
+provider-map precedence prose now match the implemented contracts. Focused
+privacy, profile, inheritance, and provider tests pass on Go 1.27.3.
+
 ## Stage 28: Give Bundled Catalog Expectations One Test Owner
 
 **Catalog:** 28. **Scope:** catalog tests, not bundled asset changes.
diff --git a/engine.go b/engine.go
index 4f57a74..9f8874a 100644
--- a/engine.go
+++ b/engine.go
@@ -312,8 +312,8 @@ func (e *Engine) InspectPrompt(
 // override. BackendID is empty for an endpoint-only profile.
 //
 // APIKeyEnv in the returned target is an environment-variable name, never its
-// value. APIKeyRequired instead reports a direct credential requirement and is
-// mutually exclusive with a nonblank APIKeyEnv. InspectProfile neither derives
+// value. APIKeyRequired reports that a credential is required; an explicit
+// profile environment source can also be present. InspectProfile neither derives
 // an ID from a prompt default_profile nor checks credential availability, so an
 // absent or blank named environment variable is not an error.
 //
diff --git a/listing.go b/listing.go
index 96733f3..ad925a6 100644
--- a/listing.go
+++ b/listing.go
@@ -93,8 +93,8 @@ func (e *Engine) ListProfiles(ctx context.Context, filters ...NamespaceFilter) (
 // behavior as [Engine.ListProfiles], using the prompt namespace by default.
 // At most one filter is accepted.
 //
-// The returned slice and each Version pointer are caller-owned and safe to
-// mutate while the engine is used concurrently. Empty inventories succeed.
+// The returned slice is caller-owned and safe to mutate while the engine is
+// used concurrently. Empty inventories succeed.
 //
 // Listing reports membership, not execution readiness. It does not reload
 // configuration or perform resource, credential, provider, or execution work.
diff --git a/request_privacy_contract_test.go b/request_privacy_contract_test.go
new file mode 100644
index 0000000..6184e85
--- /dev/null
+++ b/request_privacy_contract_test.go
@@ -0,0 +1,46 @@
+package promptkit_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+
+	"go.maximumdirect.net/promptkit"
+)
+
+func TestRunRequestFormattingAndJSONProtectDirectCredential(t *testing.T) {
+	markers := []string{"secret-key-marker", "variable-marker", "artifact-body-marker", "message-body-marker", "setting-marker", "schema-path-marker"}
+	request := promptkit.RunRequest{
+		PromptID: "prompt", ProfileID: "profile", APIKey: markers[0],
+		Vars:             map[string]string{"name": markers[1]},
+		Inputs:           map[string]promptkit.ArtifactRef{"input": {Type: promptkit.ArtifactRefInline, Body: markers[2]}},
+		AppendedMessages: []promptkit.RenderedMessage{{Role: promptkit.RoleUser, Content: markers[3]}},
+		Execution:        &promptkit.ExecutionTargetOverride{Model: markers[4]},
+		Validation:       &promptkit.OutputContract{SchemaPath: markers[5]},
+	}
+	for _, rendered := range []string{
+		fmt.Sprintf("%v", request), fmt.Sprintf("%+v", request), fmt.Sprintf("%#v", request),
+		fmt.Sprintf("%v", &request), fmt.Sprintf("%+v", &request), fmt.Sprintf("%#v", &request),
+		request.String(), request.GoString(), (&request).String(), (&request).GoString(),
+	} {
+		for _, marker := range markers {
+			if strings.Contains(rendered, marker) {
+				t.Fatalf("request formatting exposes %q: %s", marker, rendered)
+			}
+		}
+	}
+	for _, value := range []any{request, &request} {
+		encoded, err := json.Marshal(value)
+		if err != nil {
+			t.Fatal(err)
+		}
+		var object map[string]any
+		if err := json.Unmarshal(encoded, &object); err != nil {
+			t.Fatal(err)
+		}
+		if _, found := object["APIKey"]; found || strings.Contains(string(encoded), markers[0]) {
+			t.Fatal("request JSON exposed the direct credential")
+		}
+	}
+}
diff --git a/types.go b/types.go
index 533df8c..0ad4fa2 100644
--- a/types.go
+++ b/types.go
@@ -363,7 +363,7 @@ type ExecutionTarget struct {
 // separate from that target to preserve ExecutionTarget's general execution
 // and stable JSON contracts.
 type ProfileInspection struct {
-	// ProfileID is the trimmed, exact profile ID inspected by the engine.
+	// ProfileID is the exact profile ID inspected by the engine.
 	ProfileID string
 	// EffectiveModelParams contains settings resolved from the framework timeout
 	// baseline, selected backend, and then profile, without a request override.
@@ -371,9 +371,9 @@ type ProfileInspection struct {
 	// provider default. APIKeyEnv is an environment-variable name, never its
 	// credential value.
 	EffectiveModelParams ExecutionTarget
-	// APIKeyRequired reports that a later execution must supply a direct API
-	// key or an explicit request environment override. It is mutually exclusive
-	// with a nonblank EffectiveModelParams.APIKeyEnv.
+	// APIKeyRequired reports that a later execution must supply a usable direct
+	// key or environment credential. An explicit profile environment source can
+	// coexist with this requirement.
 	APIKeyRequired bool
 }