Bind extraction reuse to transcript identity

internal/artifacts/extraction_input.go

@@ -0,0 +1,76 @@
+package artifacts
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/fileops"
+	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
+)
+
+const extractionMetadataInput = "direct_input"
+
+// ExtractionInputIdentity identifies the exact trimmed transcript used for extraction.
+type ExtractionInputIdentity struct {
+	Path          string `json:"-"`
+	Checksum      string `json:"checksum"`
+	SourceID      string `json:"source_id"`
+	ProducerStage string `json:"producer_stage"`
+	OutputKind    string `json:"output_kind"`
+	ProducerRunID string `json:"producer_run_id"`
+	Provenance    string `json:"provenance"`
+}
+
+// ResolveExtractionInputIdentity resolves and hashes the direct transcript input.
+func ResolveExtractionInputIdentity(paths SessionPaths, m *manifest.Manifest) (ExtractionInputIdentity, error) {
+	resolved, err := ResolveSessionArtifact(paths, m, ArtifactTranscriptFinalTrimmed)
+	if err != nil {
+		return ExtractionInputIdentity{}, err
+	}
+	path, err := filepath.Abs(resolved.Path)
+	if err != nil {
+		return ExtractionInputIdentity{}, fmt.Errorf("resolve trimmed transcript path: %w", err)
+	}
+	bytes, err := fileops.ReadRegularFile(path, MaxResolvedArtifactBytes)
+	if err != nil {
+		return ExtractionInputIdentity{}, fmt.Errorf("read trimmed transcript: %w", err)
+	}
+	digest := sha256.Sum256(bytes)
+	return ExtractionInputIdentity{
+		Path:          filepath.Clean(path),
+		Checksum:      hex.EncodeToString(digest[:]),
+		SourceID:      resolved.ID,
+		ProducerStage: resolved.ProducerStage,
+		OutputKind:    resolved.OutputKind,
+		ProducerRunID: resolved.ProducerRunID,
+		Provenance:    resolved.Provenance,
+	}, nil
+}
+
+// Metadata returns the durable fields needed to compare this identity on reuse.
+func (identity ExtractionInputIdentity) Metadata() map[string]any {
+	return map[string]any{
+		"checksum":        identity.Checksum,
+		"source_id":       identity.SourceID,
+		"producer_stage":  identity.ProducerStage,
+		"output_kind":     identity.OutputKind,
+		"producer_run_id": identity.ProducerRunID,
+		"provenance":      identity.Provenance,
+	}
+}
+
+func extractionInputMatchesMetadata(metadata map[string]any, current ExtractionInputIdentity) bool {
+	stored, ok := metadata[extractionMetadataInput].(map[string]any)
+	if !ok || strings.TrimSpace(current.Checksum) == "" || strings.TrimSpace(current.SourceID) == "" {
+		return false
+	}
+	for key, want := range current.Metadata() {
+		if extractionMetadataString(stored, key) != want {
+			return false
+		}
+	}
+	return true
+}