fix(tags): invalid 'copyright' kind 500 — KINDS uses real enum 'fandom'; directory 400s on bad kind

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

tests/test_api_tags_directory.py

@@ -28,3 +28,22 @@ async def test_directory_endpoint(client, db):
 async def test_directory_bad_limit(client):
     resp = await client.get("/api/tags/directory?limit=nan")
     assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_directory_invalid_kind_is_400_not_500(client):
+    # 'copyright' is not a TagKind member; the route must reject it
+    # cleanly (400) instead of letting the enum cast 500.
+    resp = await client.get("/api/tags/directory?kind=copyright")
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_directory_valid_kind_ok(client, db):
+    db.add(Tag(name="a_fandom", kind=TagKind.fandom))
+    await db.flush()
+    await db.commit()
+    resp = await client.get("/api/tags/directory?kind=fandom&limit=10")
+    assert resp.status_code == 200
+    body = await resp.get_json()
+    assert any(c["name"] == "a_fandom" for c in body["cards"])