fix(chunk-context): address PR #767 review — doc_type filter parity + tests

- Add `doc_type` FieldCondition to the chunk_index-path highlighted-image
  Qdrant filter in both `api/visualization.py` and `auth/viz_routes.py`,
  matching the shape of `_get_chunk_by_index_from_qdrant`. Safe today (the
  block is guarded by `doc_type == "file"` and Nextcloud file IDs are
  globally unique) but prevents a latent bug if other doc types start
  storing highlighted images.
- Demote `viz_routes.py` `ValueError` log from `error` to `warning` (lazy
  %-style) — `_parse_int_param` raises on user-supplied bad input, which
  is a 400 not a server error and shouldn't pollute error logs.
- Hoist `effective_chunk_index` to compute once at the top of
  `get_chunk_with_context`, removing two duplicate assignments.
- Add `test_file_doc_type_qdrant_miss_yields_fast_404` to the management
  endpoint tests, locking in the proxy-timeout fix contract.
- Add `tests/unit/test_viz_routes_chunk_context.py` mirroring management
  coverage for the OAuth-session route: param forwarding (chunk_index /
  total_chunks), `doc_type=file` fast 404, and 400 on invalid int params.

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

tests/unit/test_management_chunk_context_endpoint.py

@@ -258,6 +258,49 @@ class TestChunkContextCredentialPath:
             assert data["success"] is False
             assert "failed to fetch chunk context" in data["error"].lower()
 
+    def test_file_doc_type_qdrant_miss_yields_fast_404(self):
+        """For doc_type=file, a Qdrant miss must surface as 404 immediately
+        (no slow PDF re-parse fallback). Locks the proxy-timeout fix in.
+
+        At the unit level we only assert the response shape; the
+        no-fallback contract itself lives in `search/context.py` and is
+        exercised by chunk-context tests there.
+        """
+        mock_nc_client = _make_mock_nc_client()
+
+        with (
+            patch(
+                "nextcloud_mcp_server.api.visualization.validate_token_and_get_user",
+                new_callable=AsyncMock,
+                return_value=("testuser", True),
+            ),
+            patch(
+                "nextcloud_mcp_server.api.visualization.get_user_client_basic_auth",
+                new_callable=AsyncMock,
+                return_value=mock_nc_client,
+            ),
+            patch(
+                "nextcloud_mcp_server.api.visualization.get_chunk_with_context",
+                new_callable=AsyncMock,
+                return_value=None,
+            ) as mock_get_chunk,
+        ):
+            app = create_test_app()
+            client = TestClient(app)
+            response = client.get(
+                "/api/v1/chunk-context?doc_type=file&doc_id=12345"
+                "&start=0&end=10&chunk_index=3&total_chunks=20",
+                headers={"Authorization": "Bearer test-token"},
+            )
+            assert response.status_code == 404
+            data = response.json()
+            assert data["success"] is False
+            # Confirm the handler called the resolver with doc_type=file
+            # (not a coerced/normalized value) so the fast-fail path engages.
+            kwargs = mock_get_chunk.await_args.kwargs
+            assert kwargs["doc_type"] == "file"
+            assert kwargs["chunk_index"] == 3
+
 
 class TestChunkContextParameterForwarding:
     """Verify new chunk_index / total_chunks query params reach the lookup.