fix(fc3c): distinct test JPEG colors so both attach (sha256 dedup was kicking in)

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

tests/test_download_service.py

@@ -34,10 +34,10 @@ async def seed_artist_and_source(db, db_sync):
     return artist, source
 
 
-def _make_jpg(path: Path):
+def _make_jpg(path: Path, color=(100, 100, 100)):
     from PIL import Image
     path.parent.mkdir(parents=True, exist_ok=True)
-    Image.new("RGB", (32, 32), (100, 100, 100)).save(path, "JPEG")
+    Image.new("RGB", (32, 32), color).save(path, "JPEG")
 
 
 def _make_fake_dl_result(
@@ -90,8 +90,9 @@ async def test_download_source_attaches_written_files(
     images_root = tmp_path / "images"
     f1 = images_root / "alice" / "patreon" / "post" / "a.jpg"
     f2 = images_root / "alice" / "patreon" / "post" / "b.jpg"
-    _make_jpg(f1)
-    _make_jpg(f2)
+    # Distinct colors → distinct sha256 → both attach (not deduped).
+    _make_jpg(f1, color=(200, 50, 50))
+    _make_jpg(f2, color=(50, 50, 200))
 
     fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
         success=True,