Deep-clone source metadata during chunk materialization

internal/framework/pipeline/runner_extract_handoff_test.go

@@ -16,6 +16,24 @@ type extractCaptureRecorder struct {
 	checkpoint ExtractCheckpoint
 }
 
+type pipelineTypedMetadata map[string]any
+
+type mutatingMetadataValidator struct {
+	seen string
+}
+
+func (*mutatingMetadataValidator) Name() string { return "test/mutating-metadata" }
+func (*mutatingMetadataValidator) ExecutionClass() contracts.ExecutionClass {
+	return contracts.ExecutionClassDeterministic
+}
+func (v *mutatingMetadataValidator) Validate(_ context.Context, request contracts.ChunkValidationRequest) (contracts.ValidationResult, error) {
+	nested := request.Chunks[0].Units[0].Metadata["typed"].(pipelineTypedMetadata)
+	v.seen = string(nested["raw"].(json.RawMessage))
+	nested["raw"].(json.RawMessage)[0] = '['
+	nested["changed"] = true
+	return contracts.ValidationResult{Approved: true}, nil
+}
+
 func (r *extractCaptureRecorder) ExtractSucceeded(_ string, _ string, _ []CheckpointFingerprint, outputs []CheckpointArtifact, rejected []contracts.RejectedOutput, warnings []contracts.Warning) error {
 	r.checkpoint = ExtractCheckpoint{
 		Outputs:  cloneCheckpointArtifacts(outputs),
@@ -77,6 +95,46 @@ func TestRunnerPassesIndependentAnnotationScopesToExtractors(t *testing.T) {
 	}
 }
 
+func TestRunnerPassesIndependentConcreteMetadataToValidatorsAndExtractors(t *testing.T) {
+	prepared := preparedAttemptDebugPipeline(t)
+	input := prepared.input.(*typedTestInput)
+	input.doc.Units[0].Metadata = map[string]any{
+		"typed": pipelineTypedMetadata{"raw": json.RawMessage(`{"value":true}`)},
+	}
+	var err error
+	input.doc.Digest, err = source.DigestDocument(input.doc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	chunker := prepared.chunker.(*typedTestChunker)
+	chunker.plan = typedTestPlan(input.doc)
+
+	validator := &mutatingMetadataValidator{}
+	prepared.chunkValidators.validators = []preparedValidator{{
+		resolved: ResolvedValidator{Binding: Binding(validator.Name()), Target: ValidatorTargetChunk},
+		chunk:    validator,
+	}}
+	var extractorSeen string
+	installExtractOperation(prepared, 0, func(_ context.Context, request contracts.TypedExtractionRequest) (erasedTypedResult, error) {
+		nested := request.Chunk.Units[0].Metadata["typed"].(pipelineTypedMetadata)
+		extractorSeen = string(nested["raw"].(json.RawMessage))
+		nested["raw"].(json.RawMessage)[0] = '['
+		nested["changed"] = true
+		return erasedTypedResult{Value: typedValueForLane(0, request.Chunk.Index)}, nil
+	})
+
+	if _, err := New().Run(context.Background(), RunInput{Prepared: prepared, RawInput: []byte("input")}); err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	if validator.seen != `{"value":true}` || extractorSeen != `{"value":true}` {
+		t.Fatalf("validator/extractor metadata = %q / %q", validator.seen, extractorSeen)
+	}
+	original := input.doc.Units[0].Metadata["typed"].(pipelineTypedMetadata)
+	if _, changed := original["changed"]; changed || string(original["raw"].(json.RawMessage)) != `{"value":true}` {
+		t.Fatalf("source metadata changed through runner handoff: %#v", original)
+	}
+}
+
 func TestRunnerContinuesFromFreshAndReusedExtractResults(t *testing.T) {
 	prepared := preparedAttemptDebugPipeline(t)
 	extractCalls := 0