feat(post-api): get_post returns uncapped thumbnails — PostModal masonry needs full image list; feed query unchanged (still capped at 6 for previews). _thumbnails_for gains a limit kwarg; get_post passes limit=None.

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

tests/test_api_posts.py

@@ -117,3 +117,50 @@ async def test_detail_404_for_unknown(client):
     assert resp.status_code == 404
     body = await resp.get_json()
     assert body["error"] == "not_found"
+
+
+@pytest.mark.asyncio
+async def test_detail_returns_uncapped_thumbnails(client, db):
+    """Feed query caps thumbnails at 6 for previews; detail endpoint
+    returns the full list so PostModal can render the masonry grid."""
+    from backend.app.models import ImageRecord
+
+    a = Artist(name="yuki-api", slug="yuki-api")
+    db.add(a)
+    await db.flush()
+    s = Source(
+        artist_id=a.id, platform="patreon",
+        url="https://patreon.com/cw/yuki-api", enabled=True,
+    )
+    db.add(s)
+    await db.flush()
+    p = Post(
+        source_id=s.id, external_post_id="DETAIL10",
+        post_title="big post", description="<p>body</p>",
+    )
+    db.add(p)
+    await db.flush()
+    # Seed 10 ImageRecord rows linked to this post via primary_post_id.
+    for i in range(10):
+        sha = f"y{i:x}".ljust(64, "0")[:64]
+        rec = ImageRecord(
+            path=f"/images/test-yuki-{i}.jpg",
+            sha256=sha,
+            size_bytes=1,
+            mime="image/jpeg",
+            width=64,
+            height=64,
+            origin="downloaded",
+            integrity_status="unknown",
+            primary_post_id=p.id,
+            artist_id=a.id,
+        )
+        db.add(rec)
+    await db.commit()
+
+    resp = await client.get(f"/api/posts/{p.id}")
+    assert resp.status_code == 200
+    body = await resp.get_json()
+    # Detail returns ALL 10 thumbnails (feed would return 6 + thumbnails_more).
+    assert len(body["thumbnails"]) == 10
+    assert body["description_full"] == "body"