feat: add OCR text extraction and Postgres full-text search

- Create ocr_text table for storing per-region OCR results
- Add tsvector search_vector column to photos with GIN index and
  auto-update trigger on filename/user_title/user_notes
- Implement ocr_photo Celery task using rapidocr-onnxruntime
- Add FTS leg to hybrid search: queries photos.search_vector and
  ocr_text via UNION, fused with semantic results via RRF (k=60)

Migration 0004 backfills search_vector for existing rows.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/alembic/versions/0004_ocr_text_and_fts.py

@@ -0,0 +1,82 @@
+"""ocr_text table and Postgres FTS
+
+Revision ID: 0004_ocr_fts
+Revises: 0003_pgvector_embeddings
+Create Date: 2026-04-10
+
+Create ocr_text table for storing OCR results. Add a tsvector column
+to photos for unified full-text search (filename + user_title +
+user_notes) with a GIN index. OCR text is rolled up into a materialized
+view or joined at query time.
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+revision: str = "0004_ocr_fts"
+down_revision: Union[str, None] = "0003_pgvector_embeddings"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ── ocr_text table ────────────────────────────────────────────────
+    op.execute("""
+        CREATE TABLE IF NOT EXISTS ocr_text (
+            id VARCHAR PRIMARY KEY,
+            photo_id VARCHAR NOT NULL REFERENCES photos(id) ON DELETE CASCADE,
+            text TEXT NOT NULL,
+            language VARCHAR(8) DEFAULT '',
+            confidence FLOAT,
+            bbox JSONB,
+            created_at TIMESTAMPTZ DEFAULT now()
+        )
+    """)
+    op.execute("CREATE INDEX IF NOT EXISTS ix_ocr_text_photo_id ON ocr_text(photo_id)")
+
+    # ── tsvector column on photos ─────────────────────────────────────
+    op.execute("ALTER TABLE photos ADD COLUMN IF NOT EXISTS search_vector tsvector")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_photos_search_vector ON photos USING GIN (search_vector)")
+
+    # Trigger to auto-update search_vector on INSERT/UPDATE
+    op.execute("""
+        CREATE OR REPLACE FUNCTION photos_search_vector_update() RETURNS trigger AS $$
+        BEGIN
+            NEW.search_vector :=
+                setweight(to_tsvector('english', coalesce(NEW.filename, '')), 'A') ||
+                setweight(to_tsvector('english', coalesce(NEW.user_title, '')), 'A') ||
+                setweight(to_tsvector('english', coalesce(NEW.user_notes, '')), 'B');
+            RETURN NEW;
+        END
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("""
+        DO $$
+        BEGIN
+            IF NOT EXISTS (
+                SELECT 1 FROM pg_trigger WHERE tgname = 'photos_search_vector_trigger'
+            ) THEN
+                CREATE TRIGGER photos_search_vector_trigger
+                BEFORE INSERT OR UPDATE OF filename, user_title, user_notes
+                ON photos
+                FOR EACH ROW
+                EXECUTE FUNCTION photos_search_vector_update();
+            END IF;
+        END $$;
+    """)
+
+    # Backfill existing rows
+    op.execute("""
+        UPDATE photos SET search_vector =
+            setweight(to_tsvector('english', coalesce(filename, '')), 'A') ||
+            setweight(to_tsvector('english', coalesce(user_title, '')), 'A') ||
+            setweight(to_tsvector('english', coalesce(user_notes, '')), 'B')
+    """)
+
+
+def downgrade() -> None:
+    op.execute("DROP TRIGGER IF EXISTS photos_search_vector_trigger ON photos")
+    op.execute("DROP FUNCTION IF EXISTS photos_search_vector_update()")
+    op.execute("DROP INDEX IF EXISTS ix_photos_search_vector")
+    op.execute("ALTER TABLE photos DROP COLUMN IF EXISTS search_vector")
+    op.execute("DROP TABLE IF EXISTS ocr_text")

backend/app/models/__init__.py

@@ -6,6 +6,7 @@ from app.models.folders import Folder, SourceRoot
 from app.models.tags import Tag, PhotoTag
 from app.models.heaps import Heap, HeapPhoto
 from app.models.embeddings import Embedding
+from app.models.ocr_text import OCRText
 
 __all__ = [
     'Photo',
@@ -15,5 +16,6 @@ __all__ = [
     'PhotoTag',
     'Heap',
     'HeapPhoto',
-    'Embedding'
+    'Embedding',
+    'OCRText',
 ]

backend/app/models/ocr_text.py

@@ -0,0 +1,20 @@
+"""
+OCR text model — stores text regions extracted from photos via rapidocr.
+"""
+from sqlalchemy import Column, String, Float, ForeignKey, Text, DateTime, func
+from sqlalchemy.dialects.postgresql import JSONB
+import uuid
+
+from app.database import Base
+
+
+class OCRText(Base):
+    __tablename__ = 'ocr_text'
+
+    id = Column(String, primary_key=True, default=lambda: str(uuid.uuid4()))
+    photo_id = Column(String, ForeignKey('photos.id', ondelete='CASCADE'), nullable=False, index=True)
+    text = Column(Text, nullable=False)
+    language = Column(String(8), default='')
+    confidence = Column(Float)
+    bbox = Column(JSONB)  # [x1, y1, x2, y2] normalized 0-1
+    created_at = Column(DateTime(timezone=True), server_default=func.now())

backend/app/services/search.py

@@ -62,9 +62,30 @@ async def hybrid_search(
         except Exception as e:
             logger.warning("Semantic search failed (models may not be loaded): %s", e)
 
-    # ── FTS search (placeholder for PR5) ──────────────────────────────
-    # Will be: tsvector @@ plainto_tsquery(q), ranked by ts_rank.
-    # For now, skip.
+    # ── FTS search (photos.search_vector + ocr_text) ────────────────
+    if q:
+        try:
+            fts_stmt = text("""
+                SELECT id, ts_rank(search_vector, plainto_tsquery('english', :q)) AS rank
+                FROM photos
+                WHERE search_vector @@ plainto_tsquery('english', :q)
+                UNION
+                SELECT o.photo_id AS id,
+                       MAX(o.confidence) AS rank
+                FROM ocr_text o
+                WHERE to_tsvector('english', o.text) @@ plainto_tsquery('english', :q)
+                GROUP BY o.photo_id
+                ORDER BY rank DESC
+                LIMIT 200
+            """)
+            fts_rows = (await db.execute(fts_stmt, {"q": q})).fetchall()
+            for rank, (photo_id, score) in enumerate(fts_rows):
+                if photo_id not in results:
+                    results[photo_id] = {"semantic_rank": None, "fts_rank": rank}
+                else:
+                    results[photo_id]["fts_rank"] = rank
+        except Exception as e:
+            logger.warning("FTS search failed: %s", e)
 
     # ── RRF fusion ────────────────────────────────────────────────────
     k = 60

backend/app/tasks/vision.py

@@ -92,8 +92,44 @@ def vision_fanout(photo_id: str):
 
 @shared_task(name='ocr_photo', queue='vision')
 def ocr_photo(photo_id: str):
-    """OCR a photo — implemented in PR5."""
-    return {'status': 'not_implemented'}
+    """Run OCR on a photo and store text regions."""
+    if not settings.vision.enabled or not settings.vision.ocr.enabled:
+        return {'status': 'skipped', 'reason': 'OCR disabled'}
+    return asyncio.run(_ocr_photo_async(photo_id))
+
+
+async def _ocr_photo_async(photo_id: str):
+    image = _load_thumb(photo_id, "large")  # 1280px for better OCR accuracy
+    if image is None:
+        return {'status': 'error', 'message': 'thumbnail not found'}
+
+    from app.services.vision.registry import registry
+    ocr_engine = registry.get_ocr()
+    results = ocr_engine.run(image)
+
+    if not results:
+        logger.info("No OCR text found for photo %s", photo_id)
+        return {'status': 'success', 'photo_id': photo_id, 'regions': 0}
+
+    from app.models.ocr_text import OCRText
+
+    async with AsyncSessionLocal() as session:
+        # Delete existing OCR results for this photo (re-run safe)
+        await session.execute(
+            delete(OCRText).where(OCRText.photo_id == photo_id)
+        )
+        for r in results:
+            session.add(OCRText(
+                photo_id=photo_id,
+                text=r.text,
+                language=r.language,
+                confidence=r.confidence,
+                bbox=r.bbox,
+            ))
+        await session.commit()
+
+    logger.info("OCR: %d text regions for photo %s", len(results), photo_id)
+    return {'status': 'success', 'photo_id': photo_id, 'regions': len(results)}
 
 
 @shared_task(name='detect_objects', queue='vision')