Add captured flag value application

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Implement the optional integration modules and captured registration API
 
-Status: implementation in progress. Stages 1 through 3 are complete; subsequent work follows the ordered roadmap.
+Status: implementation in progress. Stages 1 through 4 are complete; subsequent work follows the ordered roadmap.
 Execute the stages in order. Each stage is sized as a separate Luna coding-agent
 assignment. This document authorizes no publication or changes to sibling
 repositories.
@@ -254,10 +254,14 @@ checks. No new grammar restriction was added.
    materialize or apply the target's input. Scope inapplicability never skips
    supplied-value conversion.
 
-**Completion evidence:** original/copied/lookalike identity, defaults and presence,
+**Completion evidence — complete:** `CaptureFlags` stores invocation-local
-selected required flags, wrapped errors, nil destination, empty selection,
+prepared values by original binding identity, and `ApplyTo` accepts copied handles
-repeatable independence, and no second conversion. Check both ordinary and
+while rejecting lookalikes, uncaptured handles, and nil destinations with
-captured bindings through the same preparation path.
+`ErrFlagWiring`. Required checks apply only to selected bindings and match
+`ErrFlagInput`; defaults and explicit presence are retained. Nil accessors and
+invalid inner bindings are rejected at installation. Repeat applications copy
+core-owned slices without reconversion. Wrapped wiring/input errors route to
+operational/usage outcomes respectively. Root tests pass.
 
 ## Stage 5: Compile typed runners and real built-in declarations
 

execute.go

@@ -39,7 +39,7 @@ func (a *App) Execute(ctx context.Context, args []string, streams Streams) Outco
 	}
 	input := buildInput()
 	if err := command.record.payload.checkInput(input); err != nil {
-		return current.present(Usage(err), parsed.Path)
+		return current.present(classifyInputError(err), parsed.Path)
 	}
 	if len(parsed.Path) == 1 && parsed.Path[0] == "help" {
 		help, ok := input.(*helpInput)

flag_values.go

@@ -0,0 +1,89 @@
+package commandkit
+
+import (
+	"errors"
+	"fmt"
+)
+
+// ErrFlagInput identifies a missing required captured flag selected for an input.
+var ErrFlagInput = errors.New("required flag input is missing")
+
+// ErrFlagWiring identifies an invalid captured binding or destination.
+var ErrFlagWiring = errors.New("flag wiring is invalid")
+
+// FlagValues stores invocation-local values prepared for captured flags.
+type FlagValues[I any] struct {
+	values map[*bindingIdentity]preparedValue[I]
+}
+
+// CaptureFlags adapts flags declared for I into flags on Outer. The returned
+// flags preserve the original identities and store prepared values in target.
+func CaptureFlags[Outer, I any](flags []Flag[I], target func(*Outer) *FlagValues[I]) []Flag[Outer] {
+	captured := make([]Flag[Outer], len(flags))
+	for index, original := range flags {
+		inner := original
+		identity := newBindingIdentity()
+		binding := flagBinding[Outer]{
+			identity:    identity,
+			meta:        inner.binding.meta,
+			defaultText: inner.binding.defaultText,
+			repeated:    inner.binding.repeated,
+			boolean:     inner.binding.boolean,
+		}
+		if target != nil && inner.binding.identity != nil && inner.binding.valid && inner.binding.prepare != nil {
+			binding.valid = true
+			binding.prepare = func(raw []string) (preparedValue[Outer], error) {
+				prepared, err := inner.binding.prepare(raw)
+				if err != nil {
+					return preparedValue[Outer]{}, err
+				}
+				return preparedValue[Outer]{
+					identity: identity,
+					supplied: prepared.supplied,
+					apply: func(outer *Outer) {
+						store := target(outer)
+						if store == nil {
+							return
+						}
+						if store.values == nil {
+							store.values = make(map[*bindingIdentity]preparedValue[I])
+						}
+						store.values[inner.binding.identity] = prepared
+					},
+				}, nil
+			}
+		}
+		captured[index] = Flag[Outer]{binding: binding}
+	}
+	return captured
+}
+
+// ApplyTo applies selected captured flags to an initialized destination.
+// Repeated core-owned values are copied for each application.
+func (values FlagValues[I]) ApplyTo(target *I, selected ...Flag[I]) error {
+	if target == nil {
+		return fmt.Errorf("%w: destination is nil", ErrFlagWiring)
+	}
+	for _, flag := range selected {
+		binding := flag.binding
+		if binding.identity == nil {
+			return fmt.Errorf("%w: selected flag has no identity", ErrFlagWiring)
+		}
+		prepared, exists := values.values[binding.identity]
+		if !exists {
+			return fmt.Errorf("%w: flag --%s was not captured", ErrFlagWiring, binding.meta.Name)
+		}
+		if binding.meta.Required && !prepared.supplied {
+			return fmt.Errorf("flag --%s: %w", binding.meta.Name, ErrFlagInput)
+		}
+		prepared.apply(target)
+	}
+	return nil
+}
+
+func classifyInputError(err error) Outcome {
+	if errors.Is(err, ErrFlagWiring) {
+		return Failure(err)
+	}
+	return Usage(err)
+}

flag_values_test.go

@@ -0,0 +1,144 @@
+package commandkit
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+type capturedInput struct {
+	name Supplied[string]
+	tags Supplied[[]string]
+}
+
+type capturedOuter struct {
+	flags FlagValues[capturedInput]
+}
+
+func TestCaptureFlagsAppliesOnlyOriginalBindingWithoutReconversion(t *testing.T) {
+	parseCalls := 0
+	original := ValueFlag(FlagMeta{Name: "name"}, nil, func(value string) (string, error) {
+		parseCalls++
+		return value, nil
+	}, func(input *capturedInput, value Supplied[string]) { input.name = value })
+	copied := original
+	captured := CaptureFlags([]Flag[capturedInput]{original}, func(input *capturedOuter) *FlagValues[capturedInput] { return &input.flags })
+	prepared, err := captured[0].binding.prepare([]string{"chosen"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	outer := capturedOuter{}
+	prepared.apply(&outer)
+	var target capturedInput
+	if err := outer.flags.ApplyTo(&target, copied); err != nil {
+		t.Fatal(err)
+	}
+	if target.name.Value != "chosen" || !target.name.Set || parseCalls != 1 {
+		t.Fatalf("target=%#v parse calls=%d", target, parseCalls)
+	}
+	lookalike := ValueFlag(FlagMeta{Name: "name"}, nil, func(value string) (string, error) { return value, nil }, func(*capturedInput, Supplied[string]) {})
+	if err := outer.flags.ApplyTo(&target, lookalike); !errors.Is(err, ErrFlagWiring) {
+		t.Fatalf("lookalike binding error = %v", err)
+	}
+	if err := outer.flags.ApplyTo(nil, copied); !errors.Is(err, ErrFlagWiring) {
+		t.Fatalf("nil target error = %v", err)
+	}
+	if err := (FlagValues[capturedInput]{}).ApplyTo(&target); err != nil {
+		t.Fatalf("empty selection from zero store: %v", err)
+	}
+}
+
+func TestCaptureFlagsDefersRequiredCheckToSelectedBindings(t *testing.T) {
+	required := ValueFlag(FlagMeta{Name: "name", Required: true}, strptr("default"), func(value string) (string, error) { return value, nil }, func(input *capturedInput, value Supplied[string]) { input.name = value })
+	captured := CaptureFlags([]Flag[capturedInput]{required}, func(input *capturedOuter) *FlagValues[capturedInput] { return &input.flags })
+	prepared, err := captured[0].binding.prepare(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	outer := capturedOuter{}
+	prepared.apply(&outer)
+	var target capturedInput
+	if err := outer.flags.ApplyTo(&target); err != nil {
+		t.Fatalf("unselected required flag failed: %v", err)
+	}
+	if err := outer.flags.ApplyTo(&target, required); !errors.Is(err, ErrFlagInput) {
+		t.Fatalf("selected missing required flag error = %v", err)
+	}
+	optional := ValueFlag(FlagMeta{Name: "name"}, strptr("default"), func(value string) (string, error) { return value, nil }, func(input *capturedInput, value Supplied[string]) { input.name = value })
+	optionalCapture := CaptureFlags([]Flag[capturedInput]{optional}, func(input *capturedOuter) *FlagValues[capturedInput] { return &input.flags })
+	optionalPrepared, err := optionalCapture[0].binding.prepare(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	outer = capturedOuter{}
+	optionalPrepared.apply(&outer)
+	target = capturedInput{}
+	if err := outer.flags.ApplyTo(&target, optional); err != nil {
+		t.Fatal(err)
+	}
+	if target.name.Value != "default" || target.name.Set {
+		t.Fatalf("captured default value = %#v", target.name)
+	}
+
+	badCapture := CaptureFlags[capturedOuter]([]Flag[capturedInput]{required}, nil)
+	command := NewCommand(CommandSpec[capturedOuter]{Name: "broken", Flags: badCapture})
+	if _, err := New(Identity{Name: "example"}, command); err == nil {
+		t.Fatal("installation accepted a nil captured-flag accessor")
+	}
+}
+
+func TestCaptureFlagsCopiesRepeatedValuesOnEachApplication(t *testing.T) {
+	original := RepeatFlag(FlagMeta{Name: "tag"}, nil, func(value string) (string, error) { return value, nil }, func(input *capturedInput, value Supplied[[]string]) { input.tags = value })
+	captured := CaptureFlags([]Flag[capturedInput]{original}, func(input *capturedOuter) *FlagValues[capturedInput] { return &input.flags })
+	prepared, err := captured[0].binding.prepare([]string{"a,b", "c"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	outer := capturedOuter{}
+	prepared.apply(&outer)
+	var first, second capturedInput
+	if err := outer.flags.ApplyTo(&first, original); err != nil {
+		t.Fatal(err)
+	}
+	if err := outer.flags.ApplyTo(&second, original); err != nil {
+		t.Fatal(err)
+	}
+	first.tags.Value[0] = "changed"
+	if second.tags.Value[0] != "a,b" || second.tags.Value[1] != "c" || !second.tags.Set {
+		t.Fatalf("second application shares repeat storage: %#v", second.tags)
+	}
+}
+
+func TestCapturedFlagErrorClassificationPreservesWrappedCategories(t *testing.T) {
+	if got := classifyInputError(fmt.Errorf("scope input: %w", ErrFlagWiring)); got.Kind != OutcomeOperational {
+		t.Fatalf("wiring outcome = %#v", got)
+	}
+	if got := classifyInputError(fmt.Errorf("scope input: %w", ErrFlagInput)); got.Kind != OutcomeUsage {
+		t.Fatalf("input outcome = %#v", got)
+	}
+}
+
+func TestCheckInputClassifiesWrappedFlagWiringAsOperational(t *testing.T) {
+	command := NewCommand(CommandSpec[struct{}]{
+		Name:       "run",
+		CheckInput: func(struct{}) error { return fmt.Errorf("scope selector: %w", ErrFlagWiring) },
+		Run:        func(Invocation, struct{}) Outcome { t.Fatal("run called after wiring error"); return Success() },
+	})
+	app, err := New(Identity{Name: "example"}, command)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if outcome := app.Execute(t.Context(), []string{"run"}, Streams{}); outcome.Kind != OutcomeOperational || !errors.Is(outcome.Cause, ErrFlagWiring) {
+		t.Fatalf("wrapped wiring outcome = %#v", outcome)
+	}
+	usage := NewCommand(CommandSpec[struct{}]{Name: "usage", CheckInput: func(struct{}) error { return fmt.Errorf("selected value: %w", ErrFlagInput) }, Run: func(Invocation, struct{}) Outcome { return Success() }})
+	app, err = New(Identity{Name: "example"}, usage)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if outcome := app.Execute(t.Context(), []string{"usage"}, Streams{}); outcome.Kind != OutcomeUsage || !errors.Is(outcome.Cause, ErrFlagInput) {
+		t.Fatalf("wrapped input outcome = %#v", outcome)
+	}
+}
+
+func strptr(value string) *string { return &value }