fix(sidecar): strip gallery-dl 'NN_' numbering prefix when locating sidecars — fixes 'deep scan refresh count high but 0 Posts created' (operator-flagged 2026-05-26) — Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/utils/sidecar.py

@@ -4,6 +4,7 @@ No per-platform branching: a small common key set with fallbacks; the
 full JSON is kept in raw so anything unmapped is recoverable later.
 """
 
+import re
 from dataclasses import dataclass
 from datetime import UTC, datetime
 from pathlib import Path
@@ -21,10 +22,28 @@ class SidecarData:
     raw: dict
 
 
+# gallery-dl prefixes media filenames with `NN_` for in-post ordering
+# (`01_HOLLOW-ICHIGO.png`, `02_HOLOW ICHIGO.zip`) but writes the sidecar
+# under the attachment's stem WITHOUT that ordering prefix
+# (`HOLLOW-ICHIGO.json`). Strip the prefix when looking for sidecars.
+# Confirmed against real Patreon downloads 2026-05-26 — without this
+# strip, every gallery-dl post-level sidecar was invisible to FC since
+# FC-3 shipped (24 deep-refresh calls produced 0 Posts in operator's DB).
+_NUMBERING_PREFIX = re.compile(r"^\d+_(.+)$")
+
+
 def find_sidecar(media: Path) -> Path | None:
+    # Attachment-level sidecars (image.jpg.json, image.json).
     for cand in (media.with_suffix(".json"), Path(str(media) + ".json")):
         if cand.is_file():
             return cand
+    # gallery-dl post-numbered convention: strip the `NN_` prefix from
+    # the stem and look for that.json in the same directory.
+    m = _NUMBERING_PREFIX.match(media.stem)
+    if m:
+        cand = media.parent / f"{m.group(1)}.json"
+        if cand.is_file():
+            return cand
     return None