Hydrate accepted producer checkpoints

2026-07-22 02:27:19 +00:00
parent 9de399432e
commit 7aadb088a6
11 changed files with 565 additions and 21 deletions
--- a/docs/internal/pipeline.md
+++ b/docs/internal/pipeline.md
@@ -313,12 +313,31 @@ bytes, and decode failures become explicit reuse misses and execute the lane
 normally. Dependency fingerprints and debug content digests use the same stable
 codec bytes that cross those boundaries.

+That progressive extract, merge, and normalize reuse is the ordinary resume
+path. A lane marked as a required predecessor for selective recomputation takes
+a separate accepted-output path before extract scheduling. The loader reads the
+existing successful normalize manifest and payload by step, lane, and
+normalizer, without consulting extract or merge dependencies. It requires the
+current non-empty checkpoint identity to match, so the invocation identity
+still binds the input, resolved topology and configuration, references, runtime
+overrides, profiles, and component fingerprints.
+
+The runner decodes that accepted normalized artifact with the prepared codec,
+re-encodes it, and requires exact kind, schema identity and digest, media type,
+canonical bytes, content digest, and producer provenance. A valid result becomes
+a runner-owned cloned normalized output, restores only normalize-checkpoint
+warnings, and records one `accepted_artifact_reused` normalize decision. It does
+not invoke or record extract, merge, normalize, or their validators. Invalid or
+unavailable accepted state records its decision and fails the producer step;
+the dependent step never starts and the producer is not implicitly rerun.
+
 Generated references add downstream dependencies containing the producer's
 artifact kind, complete schema identity, media type, canonical content digest,
-and size. Compatible producer checkpoints may therefore feed a later step
-without re-executing the producer. A missing, rejected, corrupt, incompatible,
-or changed producer invalidates every transitive dependent lane while leaving
-independent work eligible for reuse. The runner records bounded decision
+and size. Compatible accepted producer outputs may therefore feed a later step
+without re-executing the producer. Forced lanes bypass accepted-output
+hydration and execute normally. A missing, rejected, corrupt, incompatible, or
+changed producer blocks its dependent while leaving independent work eligible
+for reuse. The runner records bounded decision
 categories: `reused`, `executed`, `forced_recompute`, and
 `dependency_invalidated`.

--- a/docs/internal/state.md
+++ b/docs/internal/state.md
@@ -43,6 +43,17 @@ not permit stale downstream reuse. The CLI's selective recomputation policy
 records `forced_recompute` for the selected step and its dependents while
 requiring compatible predecessor checkpoints.

+Ordinary resume loads extract, merge, and normalize checkpoints progressively
+and may execute later lane stages after an earlier cache miss. Selective
+recomputation instead asks the loader for the required producer's accepted
+normalize artifact. That lookup reuses the existing normalize files, requires
+workspace schema v3 plus an exact non-empty invocation identity, and deliberately
+does not require extract or merge checkpoint files or dependency fingerprints.
+The runner performs canonical codec and producer-provenance validation before
+cloning the artifact into normal step output. Success restores only stored
+normalize warnings and emits one normalize decision; failure retains the files,
+records the decision, and stops without executing the producer or consumer.
+
 The loader assigns a typed category and reason code at each validation site;
 diagnostic prose is not classified after the fact. The runner then applies
 forced-execution policy, validates reusable artifact bytes through the prepared
--- a/docs/operations.md
+++ b/docs/operations.md
@@ -151,7 +151,8 @@ recomputation is acceptable.

 `--resume` loads compatible accepted work only when checkpoint recording is
 enabled. A normal resumed run may reuse source, extract, merge, and normalize
-checkpoints independently. Generated references add a dependency fingerprint
+checkpoints independently and may recompute a stage after a cache miss.
+Generated references add a dependency fingerprint
 for the producer's artifact kind, schema identity, media type, canonical
 content digest, and size. If that fingerprint changes or the producer is
 missing, dependent checkpoints are invalidated; unrelated work remains eligible
@@ -165,14 +166,22 @@ persistent identity of otherwise identical checkpoints. Decisions are bounded
 and categorized as `reused`, `executed`, `forced_recompute`, or
 `dependency_invalidated`.

-If a required predecessor cannot be reused during selective recomputation, the
-run fails before the dependent step starts. The failure manifest retains the
-completed upstream outcomes and dependency context but not generated reference
-content. For diagnosis, first check the failed step and lane in the manifest,
-then inspect checkpoint decision categories and reason codes. A
-`dependency_invalidated` decision means the stored producer, codec identity,
-schema, or canonical content no longer matches; a missing or rejected producer
-requires rerunning it rather than copying an artifact into the checkpoint root.
+For an unselected producer required by a recomputed step, Notarius loads the
+accepted normalized artifact directly. Valid normalize state is sufficient even
+when that producer's extract or merge checkpoint is missing or corrupt. The
+normalize manifest must be successful and match workspace schema v3, the exact
+current invocation identity, step, lane, and normalizer; its payload digest and
+canonical codec representation must also validate. A forced producer bypasses
+this lookup and executes.
+
+If a required predecessor's accepted normalized artifact is missing, rejected,
+corrupt, non-canonical, or incompatible, the run fails before the dependent
+step starts. It does not fall back to rerunning that predecessor. The failure
+manifest retains completed upstream outcomes and dependency context but not
+generated reference content. For diagnosis, first check the producer step and
+lane in the manifest, then inspect checkpoint decision categories and reason
+codes. Rerun the producer explicitly rather than copying an artifact into the
+checkpoint root.
 The decision that caused a required-predecessor failure is retained before the
 run returns, and the CLI error identifies its step, lane, and reason code.

@@ -195,6 +204,7 @@ Checkpoint reason codes are stable diagnostic identifiers:
 | `artifact_codec_incompatible` | Stored artifact identity is incomplete or incompatible with the codec contract. |
 | `artifact_not_canonical` | The codec can decode the artifact, but its bytes are not canonical. |
 | `checkpoint_reused` | The stored checkpoint passed validation and was reused. |
+| `accepted_artifact_reused` | A required producer's accepted normalized artifact was canonically validated and hydrated. |
 | `recompute_step` | Selective recomputation forced execution of this lane. |

 Decision detail is bounded explanatory text, not a data-recovery channel. It
--- a/internal/framework/checkpoint/filesystem_test.go
+++ b/internal/framework/checkpoint/filesystem_test.go
@@ -322,6 +322,107 @@ func TestFilesystemCheckpointDecisionFamiliesAreStableAndSafe(t *testing.T) {
 	}
 }

+func TestFilesystemLoaderReadsAcceptedNormalizeWithoutStageDependencies(t *testing.T) {
+	fixture := seedAcceptedNormalizeCheckpoint(t)
+	identityRoot := filepath.Join(fixture.root, mustRelativePath(t, fixture.identity))
+	for _, stage := range []string{"extract", "merge"} {
+		if _, err := os.Stat(filepath.Join(identityRoot, laneManifestPath(stage, "step-1", "lane-a"))); !os.IsNotExist(err) {
+			t.Fatalf("%s checkpoint stat error = %v, want absent prerequisite", stage, err)
+		}
+	}
+	checkpoint, decision := fixture.loader.AcceptedNormalize("step-1", "lane-a", "normalize-module")
+	if !decision.Reused || decision.Category != pipeline.CheckpointDecisionReused || decision.ReasonCode != pipeline.CheckpointReasonAcceptedArtifactReused {
+		t.Fatalf("accepted normalize decision = %#v", decision)
+	}
+	if checkpoint.Output.Artifact.Content == nil || string(checkpoint.Output.Artifact.Content) != string(fixture.normalize.Artifact.Content) {
+		t.Fatalf("accepted normalize output = %#v, want recorded artifact", checkpoint.Output)
+	}
+	if len(checkpoint.Warnings) != 1 || checkpoint.Warnings[0].ReasonCode != "normalized" {
+		t.Fatalf("accepted normalize warnings = %#v", checkpoint.Warnings)
+	}
+}
+
+func TestFilesystemLoaderRejectsInvalidAcceptedNormalize(t *testing.T) {
+	tests := []struct {
+		name   string
+		mutate func(*testing.T, *filesystemCheckpointFixture)
+		code   pipeline.CheckpointReasonCode
+	}{
+		{"missing", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			if err := os.Remove(acceptedNormalizeManifest(t, *fixture)); err != nil {
+				t.Fatal(err)
+			}
+		}, pipeline.CheckpointReasonMissing},
+		{"rejected status", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			editManifest(t, acceptedNormalizeManifest(t, *fixture), func(m map[string]any) { m["status"] = string(StatusSucceededWithRejections) })
+		}, pipeline.CheckpointReasonStatusNotReusable},
+		{"corrupt payload", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			if err := os.WriteFile(acceptedNormalizePayload(t, *fixture), []byte("{"), 0o600); err != nil {
+				t.Fatal(err)
+			}
+		}, pipeline.CheckpointReasonDecodeFailed},
+		{"wrong codec identity", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			editJSON(t, acceptedNormalizePayload(t, *fixture), func(m map[string]any) { m["output"].(map[string]any)["artifact_kind"] = "" })
+		}, pipeline.CheckpointReasonArtifactCodecIncompatible},
+		{"wrong content digest", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			editJSON(t, acceptedNormalizePayload(t, *fixture), func(m map[string]any) {
+				m["output"].(map[string]any)["content"].(map[string]any)["content_digest"] = "sha256:wrong"
+			})
+		}, pipeline.CheckpointReasonArtifactDigestMismatch},
+		{"unverifiable identity", func(t *testing.T, fixture *filesystemCheckpointFixture) {
+			loader := fixture.loader.(*FilesystemLoader)
+			fixture.loader = &FilesystemLoader{root: loader.root}
+		}, pipeline.CheckpointReasonIdentityMismatch},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fixture := seedAcceptedNormalizeCheckpoint(t)
+			test.mutate(t, &fixture)
+			_, decision := fixture.loader.AcceptedNormalize("step-1", "lane-a", "normalize-module")
+			if decision.Reused || decision.ReasonCode != test.code {
+				t.Fatalf("accepted normalize decision = %#v, want %q", decision, test.code)
+			}
+			if strings.Contains(decision.Detail, fixture.root) || strings.Contains(decision.Detail, string(fixture.normalize.Artifact.Content)) {
+				t.Fatalf("accepted normalize decision leaked path or content: %#v", decision)
+			}
+			if _, err := os.Stat(acceptedNormalizePayload(t, fixture)); err != nil {
+				t.Fatalf("accepted normalize payload was removed after rejection: %v", err)
+			}
+		})
+	}
+}
+
+func seedAcceptedNormalizeCheckpoint(t *testing.T) filesystemCheckpointFixture {
+	t.Helper()
+	root := t.TempDir()
+	identity := testIdentity(t)
+	artifact := checkpointArtifact("normalize-module", `{"accepted":true}`)
+	recorder, err := NewFilesystemRecorder(root, identity)
+	if err != nil {
+		t.Fatal(err)
+	}
+	stepRecorder := recorder.(pipeline.StepCheckpointRecorder)
+	warnings := []contracts.Warning{{Scope: "normalize", ReasonCode: "normalized", Message: "normalized warning"}}
+	if err := stepRecorder.NormalizeSucceededForStep("step-1", "lane-a", "normalize-module", []pipeline.CheckpointFingerprint{{Name: "merge", Value: "sha256:unavailable"}}, artifact, warnings); err != nil {
+		t.Fatal(err)
+	}
+	loader, err := NewFilesystemLoader(root, identity)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return filesystemCheckpointFixture{root: root, identity: identity, loader: loader, normalize: artifact}
+}
+
+func acceptedNormalizeManifest(t *testing.T, fixture filesystemCheckpointFixture) string {
+	t.Helper()
+	return filepath.Join(fixture.root, mustRelativePath(t, fixture.identity), laneManifestPath("normalize", "step-1", "lane-a"))
+}
+
+func acceptedNormalizePayload(t *testing.T, fixture filesystemCheckpointFixture) string {
+	t.Helper()
+	return filepath.Join(fixture.root, mustRelativePath(t, fixture.identity), lanePayloadPath("normalize", "step-1", "lane-a", "output.json"))
+}
+
 type checkpointStage struct {
 	name     string
 	manifest func(filesystemCheckpointFixture) string
--- a/internal/framework/checkpoint/loader.go
+++ b/internal/framework/checkpoint/loader.go
@@ -141,6 +141,57 @@ func (l *FilesystemLoader) NormalizeForStep(stepID, laneID, moduleKey string, de
 	return pipeline.NormalizeCheckpoint{Output: values[0], Warnings: cloneWarnings(payload.Warnings)}, reusedDecision()
 }

+func (l *FilesystemLoader) AcceptedNormalize(stepID, laneID, moduleKey string) (pipeline.NormalizeCheckpoint, pipeline.CheckpointDecision) {
+	var manifest NormalizeLaneManifest
+	if d := l.readJSON(laneManifestPath("normalize", stepID, laneID), &manifest); !d.Reused {
+		return pipeline.NormalizeCheckpoint{}, d
+	}
+	if d := l.validateAcceptedNormalizeManifest(manifest.StageManifest, stepID, laneID, moduleKey); !d.Reused {
+		return pipeline.NormalizeCheckpoint{}, d
+	}
+	var payload artifactSingleEnvelope
+	if d := l.readJSON(lanePayloadPath("normalize", stepID, laneID, "output.json"), &payload); !d.Reused {
+		return pipeline.NormalizeCheckpoint{}, d
+	}
+	values, err := artifactCheckpointOutputs([]artifactCheckpointEnvelope{payload.Output})
+	if err != nil {
+		return pipeline.NormalizeCheckpoint{}, artifactDecision(err, "accepted normalize checkpoint artifact is invalid")
+	}
+	if len(values) != 1 {
+		return pipeline.NormalizeCheckpoint{}, decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonArtifactPayloadInvalid, "accepted normalize checkpoint payload is invalid")
+	}
+	if !fingerprintsEqual(checkpointToPipelineFingerprints(manifest.OutputDigests), artifactOutputDigests(values)) {
+		return pipeline.NormalizeCheckpoint{}, decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonArtifactDigestMismatch, "accepted normalize checkpoint digest does not match its payload")
+	}
+	return pipeline.NormalizeCheckpoint{Output: values[0], Warnings: cloneWarnings(payload.Warnings)}, decision(pipeline.CheckpointDecisionReused, pipeline.CheckpointReasonAcceptedArtifactReused, "accepted normalized artifact is reusable")
+}
+
+func (l *FilesystemLoader) validateAcceptedNormalizeManifest(manifest StageManifest, stepID, laneID, moduleKey string) pipeline.CheckpointDecision {
+	if manifest.WorkspaceSchemaVersion != WorkspaceSchemaVersion {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonWorkspaceSchemaIncompatible, "checkpoint workspace schema is incompatible")
+	}
+	identity := strings.TrimSpace(l.identityDigest)
+	if identity == "" || strings.TrimSpace(manifest.Metadata["checkpoint_identity_digest"]) == "" || manifest.Metadata["checkpoint_identity_digest"] != identity {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonIdentityMismatch, "checkpoint identity is unavailable or does not match the current invocation")
+	}
+	if manifest.Stage != StageNormalize {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonStageMismatch, "checkpoint stage does not match normalize")
+	}
+	if strings.TrimSpace(stepID) == "" || manifest.StepID != stepID {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonStepMismatch, "checkpoint step does not match the requested step")
+	}
+	if strings.TrimSpace(laneID) == "" || manifest.LaneID != laneID {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonLaneMismatch, "checkpoint lane does not match the requested lane")
+	}
+	if strings.TrimSpace(moduleKey) == "" || manifest.ModuleKey != moduleKey {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonModuleMismatch, "checkpoint module does not match the requested normalizer")
+	}
+	if manifest.Status != StatusSucceeded {
+		return decision(pipeline.CheckpointDecisionExecuted, pipeline.CheckpointReasonStatusNotReusable, "checkpoint status cannot provide an accepted normalized artifact")
+	}
+	return reusedDecision()
+}
+
 func artifactCheckpointOutputs(values []artifactCheckpointEnvelope) ([]pipeline.CheckpointArtifact, error) {
 	if len(values) == 0 {
 		return nil, nil
--- a/internal/framework/pipeline/checkpoint.go
+++ b/internal/framework/pipeline/checkpoint.go
@@ -176,7 +176,7 @@ func forceCheckpointDecision(policy CheckpointExecutionPolicy, stepID, laneID st
 }

 func requireReusableCheckpoint(policy CheckpointExecutionPolicy, stepID, laneID string, decision CheckpointDecision) error {
-	if policy.requiresReusable(stepID, laneID) && !decision.Reused {
+	if policy.requiresReusable(stepID, laneID) && !policy.forced(stepID, laneID) && !decision.Reused {
 		return fmt.Errorf("required reusable checkpoint unavailable for step %q lane %q (%s)", strings.TrimSpace(stepID), strings.TrimSpace(laneID), decision.ReasonCode)
 	}
 	return nil
@@ -241,6 +241,7 @@ type CheckpointLoader interface {
 	Extract(laneID string, moduleKey string, dependencies []CheckpointFingerprint) (ExtractCheckpoint, CheckpointDecision)
 	Merge(laneID string, moduleKey string, dependencies []CheckpointFingerprint) (MergeCheckpoint, CheckpointDecision)
 	Normalize(laneID string, moduleKey string, dependencies []CheckpointFingerprint) (NormalizeCheckpoint, CheckpointDecision)
+	AcceptedNormalize(stepID, laneID, moduleKey string) (NormalizeCheckpoint, CheckpointDecision)
 }

 // StepCheckpointLoader is the step-aware counterpart used by the persistent
@@ -306,6 +307,9 @@ func (noopCheckpointLoader) Merge(string, string, []CheckpointFingerprint) (Merg
 func (noopCheckpointLoader) Normalize(string, string, []CheckpointFingerprint) (NormalizeCheckpoint, CheckpointDecision) {
 	return NormalizeCheckpoint{}, checkpointDecision(CheckpointDecisionExecuted, CheckpointReasonLoadingDisabled, "checkpoint loading disabled")
 }
+func (noopCheckpointLoader) AcceptedNormalize(string, string, string) (NormalizeCheckpoint, CheckpointDecision) {
+	return NormalizeCheckpoint{}, checkpointDecision(CheckpointDecisionExecuted, CheckpointReasonLoadingDisabled, "checkpoint loading disabled")
+}

 func checkpointExtractRunning(recorder CheckpointRecorder, stepID, laneID, moduleKey string, deps []CheckpointFingerprint) error {
 	if stepAware, ok := recorder.(StepCheckpointRecorder); ok {
--- a/internal/framework/pipeline/runner_accepted_checkpoint_test.go
+++ b/internal/framework/pipeline/runner_accepted_checkpoint_test.go
@@ -0,0 +1,290 @@
+package pipeline
+
+import (
+	"context"
+	"encoding/json"
+	"reflect"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+)
+
+type acceptedCheckpointLoader struct {
+	CheckpointLoader
+	accepted         map[string]NormalizeCheckpoint
+	acceptedDecision map[string]CheckpointDecision
+	acceptedCalls    map[string]int
+	extractDeps      [][]CheckpointFingerprint
+	mergeDeps        [][]CheckpointFingerprint
+	normalizeDeps    [][]CheckpointFingerprint
+}
+
+func newAcceptedCheckpointLoader() *acceptedCheckpointLoader {
+	return &acceptedCheckpointLoader{
+		CheckpointLoader: NoopCheckpointLoader(),
+		accepted:         make(map[string]NormalizeCheckpoint),
+		acceptedDecision: make(map[string]CheckpointDecision),
+		acceptedCalls:    make(map[string]int),
+	}
+}
+
+func (l *acceptedCheckpointLoader) Enabled() bool { return true }
+func (l *acceptedCheckpointLoader) AcceptedNormalize(stepID, laneID, _ string) (NormalizeCheckpoint, CheckpointDecision) {
+	key := CheckpointLaneKey(stepID, laneID)
+	l.acceptedCalls[key]++
+	return l.accepted[key], l.acceptedDecision[key]
+}
+func (l *acceptedCheckpointLoader) Extract(_ string, _ string, dependencies []CheckpointFingerprint) (ExtractCheckpoint, CheckpointDecision) {
+	l.extractDeps = append(l.extractDeps, append([]CheckpointFingerprint(nil), dependencies...))
+	return ExtractCheckpoint{}, NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonMissing, "checkpoint missing")
+}
+func (l *acceptedCheckpointLoader) Merge(_ string, _ string, dependencies []CheckpointFingerprint) (MergeCheckpoint, CheckpointDecision) {
+	l.mergeDeps = append(l.mergeDeps, append([]CheckpointFingerprint(nil), dependencies...))
+	return MergeCheckpoint{}, NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonMissing, "checkpoint missing")
+}
+func (l *acceptedCheckpointLoader) Normalize(_ string, _ string, dependencies []CheckpointFingerprint) (NormalizeCheckpoint, CheckpointDecision) {
+	l.normalizeDeps = append(l.normalizeDeps, append([]CheckpointFingerprint(nil), dependencies...))
+	return NormalizeCheckpoint{}, NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonMissing, "checkpoint missing")
+}
+
+func TestRunnerHydratesRequiredNormalizedArtifact(t *testing.T) {
+	value := codecNotes{Items: []string{"canonical producer value"}}
+	input, _, _ := handoffFixture(t, value)
+	prepared := input.Prepared
+	producer := &prepared.Steps[0].lanes[0]
+	consumer := &prepared.Steps[1].lanes[0]
+	doc := prepared.input.(*typedTestInput).doc
+	stored, err := checkpointArtifact(producer.typed.codec, producer.resolved.ID, producer.resolved.Normalize.Module, doc.ID, value)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	operationCalls := 0
+	producer.typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		operationCalls++
+		return erasedTypedResult{Value: value}, nil
+	}
+	producer.typed.merge = func(context.Context, any, contracts.TypedMergeRequest[any]) (erasedTypedResult, error) {
+		operationCalls++
+		return erasedTypedResult{Value: value}, nil
+	}
+	producer.typed.normalize = func(context.Context, any, contracts.TypedNormalizeRequest[any]) (erasedTypedResult, error) {
+		operationCalls++
+		return erasedTypedResult{Value: value}, nil
+	}
+	validatorCalls := 0
+	validator := preparedValidator{typedValidate: func(context.Context, any, typedValidationTarget) (contracts.ValidationResult, error) {
+		validatorCalls++
+		return contracts.ValidationResult{Approved: true}, nil
+	}}
+	producer.extractValidators.validators = []preparedValidator{validator}
+	producer.mergeValidators.validators = []preparedValidator{validator}
+	producer.normalizeValidators.validators = []preparedValidator{validator}
+
+	var received contracts.ReferenceSet
+	consumer.typed.extract = func(_ context.Context, _ any, request contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		received = CloneReferenceSet(request.References)
+		return erasedTypedResult{Value: codecScore{Value: 3}}, nil
+	}
+	loader := newAcceptedCheckpointLoader()
+	producerKey := CheckpointLaneKey(producer.resolved.StepID, producer.resolved.ID)
+	consumerKey := CheckpointLaneKey(consumer.resolved.StepID, consumer.resolved.ID)
+	loader.accepted[producerKey] = NormalizeCheckpoint{Output: stored, Warnings: []contracts.Warning{{Scope: "normalize", ReasonCode: "stored-warning", Message: "stored normalize warning"}}}
+	loader.acceptedDecision[producerKey] = NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable")
+	policy := CheckpointExecutionPolicy{
+		RequireReusableLanes: map[string]struct{}{producerKey: {}},
+		ForcedLanes:          map[string]struct{}{consumerKey: {}},
+	}
+	output, err := New().Run(context.Background(), RunInput{Prepared: prepared, RawInput: []byte("input"), Checkpoint: loader, CheckpointPolicy: policy})
+	if err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	if operationCalls != 0 || validatorCalls != 0 {
+		t.Fatalf("hydrated producer calls = operations %d validators %d, want zero", operationCalls, validatorCalls)
+	}
+	if loader.acceptedCalls[producerKey] != 1 || len(loader.extractDeps) != 1 {
+		t.Fatalf("loader calls = accepted %#v extract %d, want producer hydration and consumer execution only", loader.acceptedCalls, len(loader.extractDeps))
+	}
+	item := received.Slots["producer-output"].Items[0]
+	if string(item.Content) != string(stored.Artifact.Content) || item.Producer.StepID != producer.resolved.StepID || item.Producer.LaneID != producer.resolved.ID {
+		t.Fatalf("consumer generated reference = %#v, want exact hydrated producer bytes and identity", item)
+	}
+	if len(output.Warnings) != 1 || output.Warnings[0].ReasonCode != "stored-warning" {
+		t.Fatalf("hydrated warnings = %#v, want normalize checkpoint warnings only", output.Warnings)
+	}
+	assertAcceptedNormalizeEvent(t, output.CheckpointEvents, producer.resolved.StepID, producer.resolved.ID, CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused)
+	for _, event := range output.CheckpointEvents {
+		if event.StepID == producer.resolved.StepID && event.LaneID == producer.resolved.ID && event.Stage != string(StageNormalize) {
+			t.Fatalf("hydrated producer synthesized checkpoint event: %#v", event)
+		}
+	}
+
+	freshInput, _, _ := handoffFixture(t, value)
+	freshPrepared := freshInput.Prepared
+	freshPrepared.Steps[0].lanes[0].typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		return erasedTypedResult{Value: value}, nil
+	}
+	freshPrepared.Steps[0].lanes[0].typed.normalize = func(context.Context, any, contracts.TypedNormalizeRequest[any]) (erasedTypedResult, error) {
+		return erasedTypedResult{Value: value}, nil
+	}
+	freshPrepared.Steps[1].lanes[0].typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		return erasedTypedResult{Value: codecScore{Value: 3}}, nil
+	}
+	freshLoader := &handoffDependencyLoader{CheckpointLoader: NoopCheckpointLoader()}
+	freshOutput, err := New().Run(context.Background(), RunInput{Prepared: freshPrepared, RawInput: []byte("input"), Checkpoint: freshLoader})
+	if err != nil {
+		t.Fatalf("fresh Run() error = %v", err)
+	}
+	if len(freshLoader.extract) != 2 || len(loader.extractDeps) != 1 || !reflect.DeepEqual(freshLoader.extract[1], loader.extractDeps[0]) {
+		t.Fatalf("consumer dependencies differ: fresh %#v hydrated %#v", freshLoader.extract, loader.extractDeps)
+	}
+	if !reflect.DeepEqual(freshOutput.Manifest.References, output.Manifest.References) {
+		t.Fatalf("generated provenance differs: fresh %#v hydrated %#v", freshOutput.Manifest.References, output.Manifest.References)
+	}
+}
+
+func TestRunnerRejectsInvalidRequiredNormalizedArtifactBeforeConsumer(t *testing.T) {
+	const contentSentinel = "sensitive-campaign-payload-74291"
+	tests := []struct {
+		name     string
+		decision CheckpointDecision
+		mutate   func(*CheckpointArtifact)
+		wantCode CheckpointReasonCode
+	}{
+		{"missing", NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonMissing, "checkpoint missing"), nil, CheckpointReasonMissing},
+		{"rejected status", NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonStatusNotReusable, "status rejected"), nil, CheckpointReasonStatusNotReusable},
+		{"corrupt payload", NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable"), func(v *CheckpointArtifact) { v.Artifact.Content = []byte(`{"items":[`) }, CheckpointReasonArtifactPayloadInvalid},
+		{"non canonical", NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable"), func(v *CheckpointArtifact) { v.Artifact.Content = []byte(`{"items": ["stored"]}`) }, CheckpointReasonArtifactNotCanonical},
+		{"wrong codec identity", NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable"), func(v *CheckpointArtifact) { v.Artifact.Kind = "test/score" }, CheckpointReasonArtifactCodecIncompatible},
+		{"wrong content digest", NewCheckpointDecision(CheckpointDecisionExecuted, CheckpointReasonArtifactDigestMismatch, "content digest mismatch"), nil, CheckpointReasonArtifactDigestMismatch},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			input, _, _ := handoffFixture(t, codecNotes{Items: []string{contentSentinel}})
+			prepared := input.Prepared
+			producer := &prepared.Steps[0].lanes[0]
+			consumer := &prepared.Steps[1].lanes[0]
+			doc := prepared.input.(*typedTestInput).doc
+			stored, err := checkpointArtifact(producer.typed.codec, producer.resolved.ID, producer.resolved.Normalize.Module, doc.ID, codecNotes{Items: []string{contentSentinel}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if test.mutate != nil {
+				test.mutate(&stored)
+			}
+			consumerCalls := 0
+			consumer.typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+				consumerCalls++
+				return erasedTypedResult{Value: codecScore{Value: 1}}, nil
+			}
+			loader := newAcceptedCheckpointLoader()
+			producerKey := CheckpointLaneKey(producer.resolved.StepID, producer.resolved.ID)
+			loader.accepted[producerKey] = NormalizeCheckpoint{Output: stored}
+			loader.acceptedDecision[producerKey] = test.decision
+			policy := CheckpointExecutionPolicy{RequireReusableLanes: map[string]struct{}{producerKey: {}}}
+			output, runErr := New().Run(context.Background(), RunInput{Prepared: prepared, RawInput: []byte("input"), Checkpoint: loader, CheckpointPolicy: policy})
+			if runErr == nil || !strings.Contains(runErr.Error(), string(test.wantCode)) || consumerCalls != 0 {
+				t.Fatalf("Run() error = %v consumer calls = %d, want %q before consumer", runErr, consumerCalls, test.wantCode)
+			}
+			assertAcceptedNormalizeEvent(t, output.CheckpointEvents, producer.resolved.StepID, producer.resolved.ID, CheckpointDecisionExecuted, test.wantCode)
+			encoded, err := json.Marshal(struct {
+				Manifest any
+				Events   any
+				Error    string
+			}{output.Manifest, output.CheckpointEvents, runErr.Error()})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if strings.Contains(string(encoded), contentSentinel) || strings.Contains(string(encoded), string(stored.Artifact.Content)) {
+				t.Fatalf("failed hydration diagnostics leaked artifact content: %s", encoded)
+			}
+		})
+	}
+}
+
+func TestForcedRequiredLaneExecutesInsteadOfHydrating(t *testing.T) {
+	prepared := preparedOrderedPipeline(t, 1,
+		orderedLaneSpec{id: "unrelated", profile: "score"},
+		orderedLaneSpec{id: "producer", profile: "notes"},
+		orderedLaneSpec{id: "consumer", profile: "score"},
+	)
+	unrelated := &prepared.Steps[0].lanes[0]
+	producer := &prepared.Steps[1].lanes[0]
+	consumer := &prepared.Steps[2].lanes[0]
+	installGeneratedReferenceTarget(&consumer.resolved.ExtractReferences, StageExtract, consumer, "step-2", "producer")
+
+	doc := prepared.input.(*typedTestInput).doc
+	unrelatedArtifact, err := checkpointArtifact(unrelated.typed.codec, unrelated.resolved.ID, unrelated.resolved.Normalize.Module, doc.ID, codecScore{Value: 9})
+	if err != nil {
+		t.Fatal(err)
+	}
+	producerArtifact, err := checkpointArtifact(producer.typed.codec, producer.resolved.ID, producer.resolved.Normalize.Module, doc.ID, codecNotes{Items: []string{"stale"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	unrelatedCalls, producerCalls := 0, 0
+	unrelated.typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		unrelatedCalls++
+		return erasedTypedResult{Value: codecScore{Value: 9}}, nil
+	}
+	producer.typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		producerCalls++
+		return erasedTypedResult{Value: codecNotes{Items: []string{"fresh"}}}, nil
+	}
+	producer.typed.normalize = func(context.Context, any, contracts.TypedNormalizeRequest[any]) (erasedTypedResult, error) {
+		return erasedTypedResult{Value: codecNotes{Items: []string{"fresh"}}}, nil
+	}
+	consumer.typed.extract = func(context.Context, any, contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		return erasedTypedResult{Value: codecScore{Value: 1}}, nil
+	}
+	loader := newAcceptedCheckpointLoader()
+	unrelatedKey := CheckpointLaneKey(unrelated.resolved.StepID, unrelated.resolved.ID)
+	producerKey := CheckpointLaneKey(producer.resolved.StepID, producer.resolved.ID)
+	consumerKey := CheckpointLaneKey(consumer.resolved.StepID, consumer.resolved.ID)
+	loader.accepted[unrelatedKey] = NormalizeCheckpoint{Output: unrelatedArtifact}
+	loader.acceptedDecision[unrelatedKey] = NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable")
+	loader.accepted[producerKey] = NormalizeCheckpoint{Output: producerArtifact}
+	loader.acceptedDecision[producerKey] = NewCheckpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted artifact reusable")
+	policy := CheckpointExecutionPolicy{
+		ForcedLanes:          map[string]struct{}{producerKey: {}, consumerKey: {}},
+		RequireReusableLanes: map[string]struct{}{unrelatedKey: {}, producerKey: {}},
+	}
+	if _, err := New().Run(context.Background(), RunInput{Prepared: prepared, RawInput: []byte("input"), Checkpoint: loader, CheckpointPolicy: policy}); err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	if producerCalls == 0 || unrelatedCalls != 0 || loader.acceptedCalls[producerKey] != 0 || loader.acceptedCalls[unrelatedKey] != 1 {
+		t.Fatalf("calls producer=%d unrelated=%d accepted=%#v, want forced producer execution and unrelated hydration", producerCalls, unrelatedCalls, loader.acceptedCalls)
+	}
+}
+
+func installGeneratedReferenceTarget(target *ResolvedReferenceTarget, stage ModuleStage, consumer *preparedLaneExecutor, producerStep, producerLane string) {
+	*target = ResolvedReferenceTarget{
+		Stage:  stage,
+		StepID: consumer.resolved.StepID,
+		LaneID: consumer.resolved.ID,
+		Module: consumer.resolved.Extract.Module,
+		Bindings: []ReferenceBinding{{
+			Stage:    stage,
+			LaneID:   consumer.resolved.ID,
+			SlotName: "producer-output",
+			Artifact: &ArtifactReference{Step: producerStep, Lane: producerLane},
+		}},
+		ReferenceSet: contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{
+			"producer-output": {Slot: contracts.ReferenceSlot{Name: "producer-output", AcceptedArtifactKinds: []contracts.ArtifactKind{"test/notes"}, AcceptedMediaTypes: []string{"application/json"}}},
+		}},
+	}
+}
+
+func assertAcceptedNormalizeEvent(t *testing.T, events []CheckpointEvent, stepID, laneID string, category CheckpointDecisionCategory, code CheckpointReasonCode) {
+	t.Helper()
+	for _, event := range events {
+		if event.Stage == string(StageNormalize) && event.StepID == stepID && event.LaneID == laneID {
+			if event.Category != category || event.ReasonCode != code {
+				t.Fatalf("accepted normalize event = %#v, want %q/%q", event, category, code)
+			}
+			return
+		}
+	}
+	t.Fatalf("accepted normalize event missing from %#v", events)
+}
--- a/internal/framework/pipeline/runner_concurrent.go
+++ b/internal/framework/pipeline/runner_concurrent.go
@@ -26,6 +26,8 @@ type laneExtractState struct {
 	results    map[int]extractJobResult
 	remaining  int
 	failed     bool
+	terminal   bool
+	output     RunOutput
 }

 type finalizedExtractResults struct {
@@ -100,6 +102,14 @@ func initializeLaneStates(input RunInput, step PreparedPipelineStep, checkpoints
 		if err := setTypedLaneManifestMetadata(output, prepared.resolved.ID, prepared.typed.extractor, prepared.typed.merger, prepared.typed.normalizer); err != nil {
 			return nil, err
 		}
+		if input.CheckpointPolicy.requiresReusable(input.stepID, prepared.resolved.ID) && !input.CheckpointPolicy.forced(input.stepID, prepared.resolved.ID) {
+			state, err := hydrateRequiredLane(input, loader, doc, i, prepared, output)
+			if err != nil {
+				return nil, err
+			}
+			states[i] = state
+			continue
+		}
 		state, err := prepareLaneExtract(input, loader, doc, chunks, i, prepared, output)
 		if err != nil {
 			return nil, err
@@ -147,7 +157,7 @@ func (r *Runner) runLaneEngine(parent context.Context, input RunInput, checkpoin
 		for chunkIndex := range chunks {
 			for laneIndex := range states {
 				state := states[laneIndex]
-				if state.decision.Reused {
+				if state.terminal || state.decision.Reused {
 					continue
 				}
 				select {
@@ -187,7 +197,9 @@ func collectLaneResults(ctx context.Context, cancel context.CancelFunc, input Ru
 	var pendingContinuations []*laneExtractState
 	launched, completed := 0, 0
 	for _, state := range states {
-		if state.decision.Reused {
+		if state.terminal {
+			completedOutputs[state.index] = state.output
+		} else if state.decision.Reused {
 			pendingContinuations = append(pendingContinuations, state)
 		}
 	}
@@ -241,6 +253,38 @@ func collectLaneResults(ctx context.Context, cancel context.CancelFunc, input Ru
 	return completedOutputs, runErrors
 }

+func hydrateRequiredLane(input RunInput, loader CheckpointLoader, doc *source.SourceDocument, index int, prepared preparedLaneExecutor, output *RunOutput) (*laneExtractState, error) {
+	lane, typed := prepared.resolved, prepared.typed
+	local := RunOutput{Manifest: manifestFromPipeline(input)}
+	checkpoint, decision := loader.AcceptedNormalize(input.stepID, lane.ID, lane.Normalize.Module)
+	if decision.Reused {
+		decision = checkpointDecision(CheckpointDecisionReused, CheckpointReasonAcceptedArtifactReused, "accepted normalized artifact is reusable")
+		if checkpoint.Output.LaneID != lane.ID || checkpoint.Output.ModuleKey != lane.Normalize.Module || checkpoint.Output.SourceID != doc.ID {
+			decision = checkpointDecision(CheckpointDecisionExecuted, CheckpointReasonArtifactPayloadInvalid, "accepted normalized artifact provenance does not match the producer lane")
+		}
+	}
+	decision, err := resolveCheckpointDecision(&local, loader, input.CheckpointPolicy, StageNormalize, input.stepID, lane.ID, lane.Normalize.Module, decision, typed.codec, []CheckpointArtifact{checkpoint.Output})
+	if err != nil {
+		if mergeErr := mergeLaneOutput(output, local); mergeErr != nil {
+			return nil, mergeErr
+		}
+		return nil, err
+	}
+	_, hydrated, err := decodeCanonicalCheckpointArtifact(typed.codec, checkpoint.Output)
+	if err != nil {
+		return nil, fmt.Errorf("hydrate accepted normalized artifact for step %q lane %q: %w", input.stepID, lane.ID, err)
+	}
+	local.Warnings = append(local.Warnings, cloneWarnings(checkpoint.Warnings)...)
+	local.NormalizeOutputs = append(local.NormalizeOutputs, contracts.SerializedOutput{
+		StepID:        input.stepID,
+		LaneID:        lane.ID,
+		NormalizerKey: lane.Normalize.Module,
+		SourceID:      doc.ID,
+		Artifact:      contracts.CloneSerializedArtifact(hydrated.Artifact),
+	})
+	return &laneExtractState{index: index, prepared: prepared, decision: decision, terminal: true, output: local}, nil
+}
+
 func mergeCompletedLanes(output *RunOutput, completedOutputs []RunOutput) error {
 	for i := range completedOutputs {
 		if err := mergeLaneOutput(output, completedOutputs[i]); err != nil {
--- a/internal/framework/pipeline/runner_typed.go
+++ b/internal/framework/pipeline/runner_typed.go
@@ -1,6 +1,7 @@
 package pipeline

 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
@@ -125,7 +126,7 @@ func decodeCheckpointArtifact(codec artifactCodecEntry, artifact CheckpointArtif
 	if artifact.Artifact.Kind != codec.spec.Kind {
 		return nil, checkpointArtifactValidationFailure(CheckpointReasonArtifactCodecIncompatible, "artifact kind %q does not match codec %q", artifact.Artifact.Kind, codec.spec.Kind)
 	}
-	if artifact.Artifact.Schema.ID != codec.spec.Schema.ID || artifact.Artifact.Schema.Version != codec.spec.Schema.Version {
+	if artifact.Artifact.Schema.ID != codec.spec.Schema.ID || artifact.Artifact.Schema.Name != codec.spec.Schema.Name || artifact.Artifact.Schema.Version != codec.spec.Schema.Version {
 		return nil, checkpointArtifactValidationFailure(CheckpointReasonArtifactCodecIncompatible, "artifact schema %q version %q does not match codec schema %q version %q", artifact.Artifact.Schema.ID, artifact.Artifact.Schema.Version, codec.spec.Schema.ID, codec.spec.Schema.Version)
 	}
 	if artifact.SchemaDigest != expectedDigest {
@@ -150,7 +151,7 @@ func decodeCanonicalCheckpointArtifact(codec artifactCodecEntry, artifact Checkp
 	if err != nil {
 		return nil, CheckpointArtifact{}, checkpointArtifactValidationFailure(CheckpointReasonArtifactPayloadInvalid, "encode canonical artifact: %w", err)
 	}
-	if canonical.Kind != artifact.Artifact.Kind || canonical.MediaType != artifact.Artifact.MediaType || checkpointContentDigest(canonical.Content) != checkpointContentDigest(artifact.Artifact.Content) {
+	if canonical.Kind != artifact.Artifact.Kind || canonical.Schema.ID != artifact.Artifact.Schema.ID || canonical.Schema.Name != artifact.Artifact.Schema.Name || canonical.Schema.Version != artifact.Artifact.Schema.Version || canonical.MediaType != artifact.Artifact.MediaType || !bytes.Equal(canonical.Content, artifact.Artifact.Content) || checkpointContentDigest(canonical.Content) != checkpointContentDigest(artifact.Artifact.Content) {
 		return nil, CheckpointArtifact{}, checkpointArtifactValidationFailure(CheckpointReasonArtifactNotCanonical, "stored artifact is not canonical")
 	}
 	hydrated, err := hydrateCheckpointArtifact(codec, cloneCheckpointArtifact(artifact), value)
--- a/internal/framework/pipeline/runner_typed_checkpoint_test.go
+++ b/internal/framework/pipeline/runner_typed_checkpoint_test.go
@@ -19,6 +19,13 @@ func (l requiredCheckpointLoader) Enabled() bool { return true }
 func (l requiredCheckpointLoader) Extract(string, string, []CheckpointFingerprint) (ExtractCheckpoint, CheckpointDecision) {
 	return l.checkpoint, l.decision
 }
+func (l requiredCheckpointLoader) AcceptedNormalize(string, string, string) (NormalizeCheckpoint, CheckpointDecision) {
+	output := CheckpointArtifact{}
+	if len(l.checkpoint.Outputs) > 0 {
+		output = l.checkpoint.Outputs[0]
+	}
+	return NormalizeCheckpoint{Output: output}, l.decision
+}

 func TestRequiredCheckpointFailureRetainsDecision(t *testing.T) {
 	const unsafeDetail = "unsafe-loader-detail-/private/checkpoint/path"
@@ -39,9 +46,10 @@ func TestRequiredCheckpointFailureRetainsDecision(t *testing.T) {
 			prepared := preparedConcurrentPipeline(t, 1)
 			step := prepared.Steps[0]
 			lane := step.lanes[0]
+			doc := prepared.input.(*typedTestInput).doc
 			checkpoint := ExtractCheckpoint{}
 			if test.corrupt {
-				stored, err := checkpointArtifact(lane.typed.codec, lane.resolved.ID, lane.resolved.Extract.Module, "source", codecNotes{Items: []string{"stored"}})
+				stored, err := checkpointArtifact(lane.typed.codec, lane.resolved.ID, lane.resolved.Normalize.Module, doc.ID, codecNotes{Items: []string{"stored"}})
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -59,7 +67,7 @@ func TestRequiredCheckpointFailureRetainsDecision(t *testing.T) {
 			}
 			var found bool
 			for _, event := range output.CheckpointEvents {
-				if event.Stage == string(StageExtract) && event.StepID == step.ID && event.LaneID == lane.resolved.ID {
+				if event.Stage == string(StageNormalize) && event.StepID == step.ID && event.LaneID == lane.resolved.ID {
 					found = true
 					if event.Action != test.wantAction || event.ReasonCode != test.wantCode {
 						t.Fatalf("checkpoint event = %#v, want action %q and reason %q", event, test.wantAction, test.wantCode)
@@ -74,7 +82,7 @@ func TestRequiredCheckpointFailureRetainsDecision(t *testing.T) {
 			}
 			var manifestFound bool
 			for _, decision := range output.Manifest.CheckpointDecisions {
-				if decision.Stage == string(StageExtract) && decision.StepID == step.ID && decision.LaneID == lane.resolved.ID {
+				if decision.Stage == string(StageNormalize) && decision.StepID == step.ID && decision.LaneID == lane.resolved.ID {
 					manifestFound = decision.Category == string(test.wantAction) && decision.ReasonCode == string(test.wantCode)
 				}
 			}
--- a/internal/framework/pipeline/synchronized_collaborators.go
+++ b/internal/framework/pipeline/synchronized_collaborators.go
@@ -76,6 +76,11 @@ func (l *lockedCheckpointLoader) Normalize(lane, key string, deps []CheckpointFi
 	defer l.mu.Unlock()
 	return l.inner.Normalize(lane, key, deps)
 }
+func (l *lockedCheckpointLoader) AcceptedNormalize(step, lane, key string) (NormalizeCheckpoint, CheckpointDecision) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	return l.inner.AcceptedNormalize(step, lane, key)
+}
 func (l *lockedCheckpointLoader) ExtractForStep(step, lane, key string, deps []CheckpointFingerprint) (ExtractCheckpoint, CheckpointDecision) {
 	l.mu.Lock()
 	defer l.mu.Unlock()