feat(bookmarks): location identity, origin provenance, KOReader-style labels

- Drop UNIQUE(media_item_id,user_id,title): titles are display labels
  shared verbatim across clients; same-title bookmarks on different pages
  now coexist instead of 500ing (deleting over a tombstone no longer
  blocks future creates with that title)
- Add origin_source column recording the creating client (android/web/
  koreader), set once at insert, exposed in API responses
- Web reader auto-title mirrors KOReader's 'in <chapter>' convention,
  falling back to 'Bookmark'; adds bookmark rename in the drawer

internal/database/models.go

@@ -185,6 +185,7 @@ type MediaBookmarks struct {
 	ChapterReference   pgtype.Int4        `db:"chapter_reference" json:"chapter_reference"`
 	Deleted            pgtype.Bool        `db:"deleted" json:"deleted"`
 	DeletedAt          pgtype.Timestamptz `db:"deleted_at" json:"deleted_at"`
+	OriginSource       pgtype.Text        `db:"origin_source" json:"origin_source"`
 }
 
 type MediaHighlights struct {

internal/database/queries.sql.go

@@ -624,7 +624,7 @@ func (q *Queries) CreateLibrary(ctx context.Context, arg CreateLibraryParams) (L
 const CreateMediaBookmark = `-- name: CreateMediaBookmark :one
 INSERT INTO media_bookmarks (media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes)
 VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
-RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at
+RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source
 `
 
 type CreateMediaBookmarkParams struct {
@@ -670,6 +670,7 @@ func (q *Queries) CreateMediaBookmark(ctx context.Context, arg CreateMediaBookma
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }
@@ -680,10 +681,10 @@ INSERT INTO media_bookmarks (
     cfi_position, title, position, notes,
     percentage_location, epubcfi_location, chapter_reference,
     dedup_key, last_modified_at, last_modified_source,
-    device_sync_data
+    device_sync_data, origin_source
 ) VALUES (
-    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15
-) RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at
+    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16
+) RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source
 `
 
 type CreateMediaBookmarkFullParams struct {
@@ -702,6 +703,7 @@ type CreateMediaBookmarkFullParams struct {
 	LastModifiedAt     pgtype.Timestamptz `db:"last_modified_at" json:"last_modified_at"`
 	LastModifiedSource pgtype.Text        `db:"last_modified_source" json:"last_modified_source"`
 	DeviceSyncData     []byte             `db:"device_sync_data" json:"device_sync_data"`
+	OriginSource       pgtype.Text        `db:"origin_source" json:"origin_source"`
 }
 
 func (q *Queries) CreateMediaBookmarkFull(ctx context.Context, arg CreateMediaBookmarkFullParams) (MediaBookmarks, error) {
@@ -721,6 +723,7 @@ func (q *Queries) CreateMediaBookmarkFull(ctx context.Context, arg CreateMediaBo
 		arg.LastModifiedAt,
 		arg.LastModifiedSource,
 		arg.DeviceSyncData,
+		arg.OriginSource,
 	)
 	var i MediaBookmarks
 	err := row.Scan(
@@ -743,6 +746,7 @@ func (q *Queries) CreateMediaBookmarkFull(ctx context.Context, arg CreateMediaBo
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }
@@ -4524,7 +4528,7 @@ func (q *Queries) GetLibraryWithType(ctx context.Context, id pgtype.UUID) (GetLi
 }
 
 const GetMediaBookmark = `-- name: GetMediaBookmark :one
-SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at FROM media_bookmarks WHERE id = $1
+SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source FROM media_bookmarks WHERE id = $1
 `
 
 func (q *Queries) GetMediaBookmark(ctx context.Context, id pgtype.UUID) (MediaBookmarks, error) {
@@ -4550,13 +4554,14 @@ func (q *Queries) GetMediaBookmark(ctx context.Context, id pgtype.UUID) (MediaBo
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }
 
 const GetMediaBookmarkByDedupKey = `-- name: GetMediaBookmarkByDedupKey :one
 
-SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at FROM media_bookmarks
+SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source FROM media_bookmarks
 WHERE user_id = $1 AND media_item_id = $2 AND dedup_key = $3
 ORDER BY deleted ASC, deleted_at DESC NULLS LAST
 LIMIT 1
@@ -4594,12 +4599,13 @@ func (q *Queries) GetMediaBookmarkByDedupKey(ctx context.Context, arg GetMediaBo
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }
 
 const GetMediaBookmarks = `-- name: GetMediaBookmarks :many
-SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at FROM media_bookmarks
+SELECT id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source FROM media_bookmarks
 WHERE media_item_id = $1 AND user_id = $2 AND COALESCE(deleted, FALSE) = FALSE
 ORDER BY created_at DESC
 `
@@ -4638,6 +4644,7 @@ func (q *Queries) GetMediaBookmarks(ctx context.Context, arg GetMediaBookmarksPa
 			&i.ChapterReference,
 			&i.Deleted,
 			&i.DeletedAt,
+			&i.OriginSource,
 		); err != nil {
 			return nil, err
 		}
@@ -11513,7 +11520,7 @@ SET
     position = $4,
     last_modified_at = NOW()
 WHERE id = $1 AND user_id = $5
-RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at
+RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source
 `
 
 type UpdateMediaBookmarkParams struct {
@@ -11553,6 +11560,7 @@ func (q *Queries) UpdateMediaBookmark(ctx context.Context, arg UpdateMediaBookma
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }
@@ -11575,7 +11583,7 @@ UPDATE media_bookmarks SET
     deleted = FALSE,
     deleted_at = NULL
 WHERE id = $1
-RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at
+RETURNING id, media_item_id, user_id, page_number, chapter_number, cfi_position, title, position, notes, created_at, dedup_key, last_modified_at, last_modified_source, device_sync_data, percentage_location, epubcfi_location, chapter_reference, deleted, deleted_at, origin_source
 `
 
 type UpdateMediaBookmarkForSyncParams struct {
@@ -11631,6 +11639,7 @@ func (q *Queries) UpdateMediaBookmarkForSync(ctx context.Context, arg UpdateMedi
 		&i.ChapterReference,
 		&i.Deleted,
 		&i.DeletedAt,
+		&i.OriginSource,
 	)
 	return i, err
 }

internal/database/queries/queries.sql

@@ -898,9 +898,9 @@ INSERT INTO media_bookmarks (
     cfi_position, title, position, notes,
     percentage_location, epubcfi_location, chapter_reference,
     dedup_key, last_modified_at, last_modified_source,
-    device_sync_data
+    device_sync_data, origin_source
 ) VALUES (
-    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15
+    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16
 ) RETURNING *;
 
 -- name: UpdateMediaBookmarkForSync :one

internal/handlers/koreader.go

@@ -741,6 +741,7 @@ func (h *KOReaderHandler) processBookAnnotations(ctx context.Context, deviceID,
 			Position:       position,
 			ChapterNumber:  int32(bookmark.Chapter),
 			Source:         "koreader",
+			OriginSource:   "koreader",
 			DeviceSyncData: deviceData,
 			DedupKey:       dedupKey,
 		})

internal/handlers/media.go

@@ -152,6 +152,9 @@ type CreateMediaBookmarkRequest struct {
 	ChapterNumber    int32   `json:"chapter_number"`
 	Percentage       float64 `json:"percentage"`
 	ChapterReference int32   `json:"chapter_reference"`
+	// Origin labels the creating client for display ("android", "web").
+	// Optional: defaults to "web" for browser callers.
+	Origin string `json:"origin" validate:"omitempty,max=30"`
 }
 
 // UpdateMediaBookmarkRequest represents the request for updating a media bookmark
@@ -1750,6 +1753,10 @@ func (mh *MediaHandler) CreateMediaBookmark(c *echo.Context) error {
 	// The sync-aware path (dedup + LWW + tombstones) is preferred; fall back
 	// to the plain query when the service isn't wired (e.g. some tests).
 	if mh.annotationSvc != nil {
+		origin := req.Origin
+		if origin == "" {
+			origin = "web"
+		}
 		result, err := mh.annotationSvc.SaveBookmark(c.Request().Context(), wsync.SaveBookmarkRequest{
 			MediaItemID:      pgtype.UUID{Bytes: mediaUUID, Valid: true},
 			UserID:           pgtype.UUID{Bytes: userUUID, Valid: true},
@@ -1762,6 +1769,7 @@ func (mh *MediaHandler) CreateMediaBookmark(c *echo.Context) error {
 			PercentageLoc:    req.Percentage,
 			ChapterReference: req.ChapterReference,
 			Source:           "web",
+			OriginSource:     origin,
 			ModifiedAt:       time.Now(),
 		})
 		if err != nil {

internal/sync/annotations.go

@@ -590,6 +590,9 @@ type SaveBookmarkRequest struct {
 	Source           string
 	ModifiedAt       time.Time
 	DeviceSyncData   json.RawMessage
+	// OriginSource records the client that created the bookmark (set once
+	// at insert; unlike Source it is not updated by later writers).
+	OriginSource string
 	// DedupKey overrides the computed key for device echoes (see
 	// SaveHighlightRequest).
 	DedupKey string
@@ -624,9 +627,9 @@ func (s *AnnotationService) SaveBookmark(ctx context.Context, req SaveBookmarkRe
 		if !incomingNewerThanTombstone(req.ModifiedAt, existing.DeletedAt, existing.LastModifiedAt) {
 			return &SaveBookmarkResult{Bookmark: existing, Outcome: SaveOutcomeDeleted}, nil
 		}
-		// Newer than the tombstone: a deliberate re-create. Resurrect via the
-		// LWW update instead of INSERT (the tombstoned row still holds the
-		// UNIQUE(media_item_id, user_id, title) slot).
+		// Newer than the tombstone: a deliberate re-create at the same
+		// location. Resurrect via the LWW update so the row keeps its id
+		// and origin.
 		return s.applyBookmarkLWW(ctx, req, existing, dedupKey)
 	}
 
@@ -656,6 +659,7 @@ func (s *AnnotationService) createBookmark(ctx context.Context, req SaveBookmark
 		LastModifiedAt:     pgtype.Timestamptz{Time: modifiedAt, Valid: true},
 		LastModifiedSource: pgtype.Text{String: req.Source, Valid: req.Source != ""},
 		DeviceSyncData:     deviceData,
+		OriginSource:       pgText(req.OriginSource),
 	})
 	if err != nil {
 		return nil, fmt.Errorf("create bookmark: %w", err)