fix(importer): skip transparency check on animated images (operator-flagged 2026-05-26: animated WebP triggered 5+ min PIL multi-frame decode → Celery hard-timeout SIGKILL); compute_phash seeks frame 0 defensively — Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/services/importer.py

@@ -860,8 +860,26 @@ class Importer:
                 pass
 
     def _transparency_pct(self, source: Path) -> float:
-        """Fraction of fully-transparent pixels in the image. 0.0 if no alpha."""
+        """Fraction of fully-transparent pixels in the image. 0.0 if no alpha.
+
+        For animated formats (multi-frame WebP / GIF / APNG), short-circuit
+        to 0.0 instead of decoding every frame. PIL's `getchannel("A")`
+        forces a full decode of all frames in an animated image, which for
+        a large animated WebP takes 5+ minutes and blows past the Celery
+        soft+hard time limits (300s/360s → SIGKILL). Operator-flagged
+        2026-05-26. Transparency analysis on a multi-frame image isn't
+        meaningful for art-curation purposes anyway — different frames
+        have different alpha — so the existing too_transparent skip rule
+        is bypassed entirely for animated content.
+        """
         with Image.open(source) as im:
+            if getattr(im, "is_animated", False):
+                log.info(
+                    "skipping transparency check for animated image %s "
+                    "(n_frames=%d) — avoids multi-frame decode timeout",
+                    source, getattr(im, "n_frames", 0),
+                )
+                return 0.0
             if im.mode not in ("RGBA", "LA") and not (
                 im.mode == "P" and "transparency" in im.info
             ):