Add canonical source unit provenance

internal/modules/seriatim/input/transcript/adapter.go

@@ -65,18 +65,21 @@ func (a *Adapter) Parse(ctx context.Context, req contracts.ParseRequest) (*sourc
 		ID:       documentID(req.SourceID, parsed.Metadata, rawDigest),
 		Kind:     DocumentKind,
 		Format:   Format,
-		Digest:   rawDigest,
 		Metadata: copyMetadata(parsed.Metadata),
 	}
 
 	seenSegmentIDs := make(map[int]struct{}, len(parsed.Segments))
 	for i, segment := range parsed.Segments {
-		unit, err := sourceUnit(segment, i, seenSegmentIDs)
+		unit, err := sourceUnit(doc.ID, segment, i, seenSegmentIDs)
 		if err != nil {
 			return nil, err
 		}
 		doc.Units = append(doc.Units, unit)
 	}
+	doc.Digest, err = source.DigestDocument(doc)
+	if err != nil {
+		return nil, inputErrorf("digest source document: %w", err)
+	}
 
 	if err := source.ValidateDocument(doc); err != nil {
 		return nil, inputErrorf("validate source document: %w", err)
@@ -98,7 +101,7 @@ func Register(registry *pipeline.InputAdapterRegistry) error {
 	})
 }
 
-func sourceUnit(segment segment, index int, seen map[int]struct{}) (source.SourceUnit, error) {
+func sourceUnit(sourceID string, segment segment, index int, seen map[int]struct{}) (source.SourceUnit, error) {
 	segmentLabel := fmt.Sprintf("segment[%d]", index)
 	if segment.ID <= 0 {
 		return source.SourceUnit{}, inputErrorf("%s id must be positive", segmentLabel)
@@ -133,6 +136,11 @@ func sourceUnit(segment segment, index int, seen map[int]struct{}) (source.Sourc
 		ID:   segment.ID,
 		Kind: UnitKind,
 		Text: segment.Text,
+		Ref: source.SourceRef{
+			SourceID:    sourceID,
+			StartUnitID: segment.ID,
+			EndUnitID:   segment.ID,
+		},
 		Metadata: map[string]any{
 			MetadataSpeaker: segment.Speaker,
 			MetadataStart:   segment.Start,