fix(importer): catch PIL OSError during transparency + phash blocks, skip as invalid_image instead of letting Celery autoretry loop forever

Operator hit a corrupt JPEG in the IR set 2026-05-25: PIL.verify() only
validates header structure but doesn't catch truncated/broken pixel
data. The error surfaces later in _transparency_pct (via getchannel
'A' -> load) or compute_phash (load) — both blow up with OSError
'broken data stream when reading image file'. Celery's autoretry_for
then bounces the same file forever instead of marking it skipped.

Wrap both PIL.load-triggering call sites with try/except OSError ->
ImportResult(status=skipped, skip_reason=invalid_image).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/services/importer.py

@@ -280,7 +280,18 @@ class Importer:
                 )
 
             if self.settings.skip_transparent and has_alpha:
-                pct = self._transparency_pct(source)
+                try:
+                    pct = self._transparency_pct(source)
+                except OSError as exc:
+                    # PIL.verify() at line 263 only validates header structure;
+                    # truncated/corrupt pixel data only surfaces when load()
+                    # actually decodes (here via getchannel('A')). Convert to
+                    # invalid_image skip so the Celery autoretry loop doesn't
+                    # bounce the same broken file forever.
+                    return ImportResult(
+                        status="skipped", skip_reason=SkipReason.invalid_image,
+                        error=f"PIL load failed during transparency check: {exc}",
+                    )
                 if pct >= self.settings.transparency_threshold:
                     return ImportResult(
                         status="skipped", skip_reason=SkipReason.too_transparent,
@@ -302,8 +313,16 @@ class Importer:
         # Perceptual near-dup (images only; videos keep phash NULL).
         phash = None
         if not is_video(source):
-            with Image.open(source) as im:
-                phash = compute_phash(im)
+            try:
+                with Image.open(source) as im:
+                    phash = compute_phash(im)
+            except OSError as exc:
+                # Same rationale as the transparency-check guard above:
+                # broken-pixel-data files pass verify() but blow up here.
+                return ImportResult(
+                    status="skipped", skip_reason=SkipReason.invalid_image,
+                    error=f"PIL load failed during phash compute: {exc}",
+                )
             if phash is not None:
                 cand_rows = self.session.execute(
                     select(

tests/test_importer.py

@@ -134,3 +134,58 @@ def test_root_level_file_has_no_artist(importer, import_layout):
     importer.import_one(src)
     artists = importer.session.execute(select(Artist)).scalars().all()
     assert artists == []
+
+
+def test_pil_load_oserror_in_transparency_check_skips_not_raises(
+    importer, import_layout, monkeypatch,
+):
+    """PIL.verify() only validates header structure — broken pixel data
+    only surfaces when load() actually decodes. The importer must catch
+    the OSError and return a skipped: invalid_image result so the Celery
+    autoretry loop doesn't bounce the same broken file forever.
+    Operator hit this 2026-05-25 with a corrupt JPEG in the IR set."""
+    import_root, _ = import_layout
+    src = import_root / "Bob" / "corrupt.png"
+    # Make a real RGBA PNG so the has_alpha path engages.
+    _make_png_rgba(src, (100, 100), alpha=128)
+
+    importer.settings.skip_transparent = True
+    importer.settings.transparency_threshold = 0.5
+
+    # Force the next _transparency_pct call to raise as if PIL's load()
+    # blew up on truncated pixel data.
+    def _boom(_self, _src):
+        raise OSError("broken data stream when reading image file")
+    monkeypatch.setattr(
+        type(importer), "_transparency_pct", _boom,
+    )
+
+    result = importer.import_one(src)
+    assert result.status == "skipped"
+    assert result.skip_reason == SkipReason.invalid_image
+    assert "transparency check" in (result.error or "")
+
+
+def test_pil_load_oserror_in_phash_compute_skips_not_raises(
+    importer, import_layout, monkeypatch,
+):
+    """Same shape as the transparency-check guard, but for the phash
+    compute block — the OTHER place PIL.load() runs implicitly during
+    the dedup pipeline."""
+    import_root, _ = import_layout
+    src = import_root / "Carol" / "corrupt.jpg"
+    _make_jpeg(src)
+
+    # Disable transparency check so we reach the phash compute block.
+    importer.settings.skip_transparent = False
+
+    from backend.app.services import importer as importer_module
+
+    def _boom(_im):
+        raise OSError("broken data stream when reading image file")
+    monkeypatch.setattr(importer_module, "compute_phash", _boom)
+
+    result = importer.import_one(src)
+    assert result.status == "skipped"
+    assert result.skip_reason == SkipReason.invalid_image
+    assert "phash compute" in (result.error or "")