Xinmin Zeng f1a0ab699a
fix(tools): preserve tool_search promotions across re-entrant get_available_tools (#2885)
* fix(tools): preserve tool_search promotions across re-entrant get_available_tools

Closes #2884.

``get_available_tools`` used to unconditionally call
``reset_deferred_registry()`` and rebuild a fresh ``DeferredToolRegistry``
on every invocation. That works for the first call of a request (the
ContextVar starts at its default of ``None``), but any RE-ENTRANT call
during the same async context — e.g. ``task_tool`` building a subagent's
toolset, or a custom middleware that rebuilds tools mid-run — wiped any
``tool_search`` promotions the parent agent had already made. The
``DeferredToolFilterMiddleware`` would then re-hide those tools from the
next model call, leaving the agent able to see a tool's name (via the
prior ``tool_search`` result that's still in conversation history) but
unable to invoke it.

Fix: when the ContextVar already holds a registry, reuse it instead of
rebuilding. Fresh requests still get a fresh registry because each new
graph run starts in a new asyncio task with the ContextVar at ``None``.

## Verification

- Unit-level reproduction (``test_get_available_tools_resets_registry_wiping_promotion``):
  promote a tool in the registry, call ``get_available_tools`` again, assert
  the promotion is preserved. Fails on main, passes on this branch.

- Graph-execution reproduction (two tests): drive a real
  ``langchain.agents.create_agent`` graph with the real
  ``DeferredToolFilterMiddleware`` through two model turns, including one
  that issues a re-entrant ``get_available_tools`` call to simulate the
  task_tool subagent path.

- Real-LLM end-to-end (``test_deferred_tool_promotion_real_llm.py``,
  opt-in via ``ONEAPI_E2E=1``): drives the same flow against a real
  OpenAI-compatible model (verified on GPT-5.4-mini through the one-api
  gateway), watches the model call the promoted ``fake_calculator``
  through the deferred-filter middleware, and asserts the right arithmetic
  result. Passes against the fixed branch.

- Companion update to ``test_tool_deduplication.py``: dropped the
  ``@patch("deerflow.tools.tools.reset_deferred_registry")`` decorators
  because the symbol is no longer imported there.

- Test fixtures in the new files patch ``deerflow.tools.tools.get_app_config``
  with a minimal ``model_construct``-ed ``AppConfig`` instead of calling
  the real loader, so they never trigger ``_apply_singleton_configs`` and
  never leak ``_memory_config``/``_title_config``/… mutations into the
  rest of the suite.

Full backend suite: 3208 passed / 14 skipped / 0 failed. ruff check + format clean.

* fix(tools): address Copilot review on #2885

- tools.py: rewrite the reuse-path comment to spell out (a) why we don't
  reconcile the registry against the current ``mcp_tools`` snapshot — the
  MCP cache doesn't refresh mid-graph-run, the lead agent's ``ToolNode``
  is already bound to the previous tool set anyway, and ``promote()``
  drops the entry so a naive re-sync misclassifies promotions as new
  tools — and (b) why the log uses ``max(0, …)`` to avoid negative
  counts when the cache shrinks between snapshots.
- Replace direct ``ts_mod._registry_var.set(None)`` in test fixtures with
  the public ``reset_deferred_registry()`` helper so tests don't couple
  to module internals.
- Correct the docstring path in ``test_deferred_tool_registry_promotion.py``
  to match the actual monkeypatch target (``deerflow.mcp.cache.get_cached_mcp_tools``).
- Rename
  ``test_get_available_tools_resets_registry_wiping_promotion`` to
  ``test_get_available_tools_preserves_promotions_across_reentrant_calls``
  so the test name describes the contract being asserted, not the bug it
  originally reproduced.

Full backend suite: 3208 passed / 14 skipped. Real-LLM e2e: 1 passed.
2026-05-13 23:45:47 +08:00
..