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.
This commit is contained in:
Xinmin Zeng
@@ -7,7 +7,7 @@ from deerflow.config.app_config import AppConfig
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from deerflow.reflection import resolve_variable
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from deerflow.sandbox.security import is_host_bash_allowed
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from deerflow.tools.builtins import ask_clarification_tool, present_file_tool, task_tool, view_image_tool
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from deerflow.tools.builtins.tool_search import reset_deferred_registry
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from deerflow.tools.builtins.tool_search import get_deferred_registry
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from deerflow.tools.sync import make_sync_tool_wrapper
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logger = logging.getLogger(__name__)
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@@ -116,8 +116,6 @@ def get_available_tools(
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# made through the Gateway API (which runs in a separate process) are immediately
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# reflected when loading MCP tools.
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mcp_tools = []
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# Reset deferred registry upfront to prevent stale state from previous calls
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reset_deferred_registry()
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if include_mcp:
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try:
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from deerflow.config.extensions_config import ExtensionsConfig
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@@ -135,12 +133,51 @@ def get_available_tools(
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from deerflow.tools.builtins.tool_search import DeferredToolRegistry, set_deferred_registry
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from deerflow.tools.builtins.tool_search import tool_search as tool_search_tool
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registry = DeferredToolRegistry()
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for t in mcp_tools:
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registry.register(t)
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set_deferred_registry(registry)
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# Reuse the existing registry if one is already set for
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# this async context. ``get_available_tools`` is
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# re-entered whenever a subagent is spawned
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# (``task_tool`` calls it to build the child agent's
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# toolset), and previously we used to unconditionally
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# rebuild the registry — wiping out the parent agent's
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# tool_search promotions. The
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# ``DeferredToolFilterMiddleware`` then re-hid those
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# tools from subsequent model calls, leaving the agent
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# able to see a tool's name but unable to invoke it
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# (issue #2884). ``contextvars`` already gives us the
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# lifetime semantics we want: a fresh request / graph
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# run starts in a new asyncio task with the
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# ContextVar at its default of ``None``, so reuse is
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# only triggered for re-entrant calls inside one run.
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#
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# Intentionally NOT reconciling against the current
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# ``mcp_tools`` snapshot. The MCP cache only refreshes
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# on ``extensions_config.json`` mtime changes, which
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# in practice happens between graph runs — not inside
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# one. And even if a refresh did happen mid-run, the
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# already-built lead agent's ``ToolNode`` still holds
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# the *previous* tool set (LangGraph binds tools at
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# graph construction time), so a brand-new MCP tool
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# couldn't actually be invoked anyway. The
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# ``DeferredToolRegistry`` doesn't retain the names
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# of previously-promoted tools (``promote()`` drops
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# the entry entirely), so re-syncing the registry
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# against a fresh ``mcp_tools`` list would
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# mis-classify those promotions as new tools and
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# re-register them as deferred — exactly the bug
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# this fix exists to prevent.
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existing_registry = get_deferred_registry()
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if existing_registry is None:
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registry = DeferredToolRegistry()
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for t in mcp_tools:
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registry.register(t)
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set_deferred_registry(registry)
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logger.info(f"Tool search active: {len(mcp_tools)} tools deferred")
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else:
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mcp_tool_names = {t.name for t in mcp_tools}
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still_deferred = len(existing_registry)
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promoted_count = max(0, len(mcp_tool_names) - still_deferred)
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logger.info(f"Tool search active (preserved promotions): {still_deferred} tools deferred, {promoted_count} already promoted")
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builtin_tools.append(tool_search_tool)
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logger.info(f"Tool search active: {len(mcp_tools)} tools deferred")
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except ImportError:
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logger.warning("MCP module not available. Install 'langchain-mcp-adapters' package to enable MCP tools.")
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except Exception as e:
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