feat(PROJ-44): ocr_chars-Spalte + SetOCRResult-Helper

DB-Schema bekommt eine idempotente ocr_chars BIGINT-Spalte (Default 0).
SetOCRResult schreibt status und chars atomar; GetOCRMeta liest beide
mit COALESCE-Defaults. Der OCR-Worker ersetzt jeden SetOCRStatus-Call
durch SetOCRResult und uebergibt die extrahierte Zeichenzahl bei 'done'.

internal/ocr/worker.go

@@ -137,26 +137,26 @@ func (w *Worker) process(ctx context.Context, job Job) {
 	logger := w.logger.With("mail_id", job.MailID, "tenant_id", job.TenantID)
 
 	if w.store.OCREnabled(ctx, job.TenantID) == false {
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "disabled")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "disabled", 0)
 		return
 	}
 
 	raw, err := w.store.Load(job.MailID)
 	if err != nil {
 		logger.Warn("ocr worker: load failed", "err", err)
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "failed")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "failed", 0)
 		return
 	}
 
 	pm, err := mailparser.Parse(raw)
 	if err != nil {
 		logger.Warn("ocr worker: parse failed", "err", err)
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "failed")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "failed", 0)
 		return
 	}
 
 	if len(pm.Attachments) == 0 {
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "skipped")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "skipped", 0)
 		return
 	}
 
@@ -183,7 +183,7 @@ func (w *Worker) process(ctx context.Context, job Job) {
 	}
 
 	if processed == 0 {
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "skipped")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "skipped", 0)
 		return
 	}
 
@@ -191,15 +191,16 @@ func (w *Worker) process(ctx context.Context, job Job) {
 	updater, ok := idx.(index.AttachmentTextUpdater)
 	if !ok {
 		logger.Warn("ocr worker: indexer does not support AttachmentTextUpdater — text dropped")
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "failed")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "failed", 0)
 		return
 	}
 	if err := updater.UpdateAttachmentText(job.MailID, combined.String()); err != nil {
 		logger.Warn("ocr worker: index update failed", "err", err)
-		_ = w.store.SetOCRStatus(ctx, job.MailID, "failed")
+		_ = w.store.SetOCRResult(ctx, job.MailID, "failed", 0)
 		return
 	}
 
-	_ = w.store.SetOCRStatus(ctx, job.MailID, "done")
-	logger.Info("ocr worker: indexed", "attachments", processed, "chars", combined.Len())
+	chars := int64(combined.Len())
+	_ = w.store.SetOCRResult(ctx, job.MailID, "done", chars)
+	logger.Info("ocr worker: indexed", "attachments", processed, "chars", chars)
 }

internal/storage/ocr.go

@@ -40,6 +40,57 @@ func (s *Store) SetOCRStatus(ctx context.Context, id, status string) error {
 	return nil
 }
 
+// SetOCRResult atomically writes both ocr_status and ocr_chars in one UPDATE.
+// Used by the OCR worker after a job completes (PROJ-44).
+// chars must be >= 0; for status='failed'/'skipped'/'disabled' callers pass 0.
+// Silently no-ops when no DB is configured.
+func (s *Store) SetOCRResult(ctx context.Context, id, status string, chars int64) error {
+	if s.db == nil {
+		return nil
+	}
+	if id == "" {
+		return errors.New("storage: SetOCRResult: empty id")
+	}
+	switch status {
+	case "pending", "done", "failed", "skipped", "disabled":
+	default:
+		return fmt.Errorf("storage: SetOCRResult: invalid status %q", status)
+	}
+	if chars < 0 {
+		chars = 0
+	}
+	_, err := s.db.Exec(ctx,
+		`UPDATE emails SET ocr_status = $1, ocr_chars = $2 WHERE id = $3`,
+		status, chars, id,
+	)
+	if err != nil {
+		return fmt.Errorf("storage: set ocr result: %w", err)
+	}
+	return nil
+}
+
+// GetOCRMeta returns ocr_status (defaulting to "pending" if NULL) and
+// ocr_chars (defaulting to 0) for a single mail. Returns "", 0, nil when no
+// DB is configured or the mail is not found.
+func (s *Store) GetOCRMeta(ctx context.Context, id string) (status string, chars int64, err error) {
+	if s.db == nil {
+		return "", 0, nil
+	}
+	if id == "" {
+		return "", 0, errors.New("storage: GetOCRMeta: empty id")
+	}
+	row := s.db.QueryRow(ctx,
+		`SELECT COALESCE(ocr_status, 'pending'), COALESCE(ocr_chars, 0)
+		   FROM emails WHERE id = $1`, id)
+	if scanErr := row.Scan(&status, &chars); scanErr != nil {
+		if errors.Is(scanErr, pgx.ErrNoRows) {
+			return "", 0, nil
+		}
+		return "", 0, fmt.Errorf("storage: get ocr meta: %w", scanErr)
+	}
+	return status, chars, nil
+}
+
 // OCREnabled reports whether OCR processing should run for the given tenant.
 // Defaults to true when:
 //   - no DB is configured (DB-less mode)

internal/storage/storage.go

@@ -317,6 +317,15 @@ func (s *Store) initSchema(ctx context.Context) error {
 		ALTER TABLE emails ADD COLUMN IF NOT EXISTS ocr_status TEXT DEFAULT 'pending';
 		CREATE INDEX IF NOT EXISTS idx_emails_ocr_status ON emails (ocr_status) WHERE ocr_status = 'pending';
 	`)
+	if err != nil {
+		return err
+	}
+
+	// PROJ-44: gecachte Anzahl der extrahierten OCR-Zeichen — vermeidet einen
+	// Manticore-Roundtrip auf der Mail-Detail-Seite. Idempotent wie ocr_status.
+	_, err = s.db.Exec(ctx, `
+		ALTER TABLE emails ADD COLUMN IF NOT EXISTS ocr_chars BIGINT DEFAULT 0;
+	`)
 	return err
 }