11 Commits

Author SHA1 Message Date
spud
eadc1e230e
feat(mcp): reuse unchanged per-server tool discovery results (#6795)
* feat(mcp): add per-server discovery cache scaffolding

Introduce the per-server tool cache entry, canonical parsed-config snapshots on the applied revision, and the shared _binding_matches reuse predicate. Identity reuse is object-identity based on the pool's current binding (no value equality); snapshots and ownership handles stay out of repr. No selection, eviction or publication is wired yet.

* feat(mcp): selectively evict stale per-server tool cache entries

Evict per-server discovery results during selective reconciliation, after the new binding epoch is installed, so unchanged servers keep their exact entry objects while changed, removed or re-bound servers (including lifecycle-token rotations) are dropped. Delegate the binding verdict to _binding_matches so reuse and eviction cannot diverge.

Clear _server_tool_cache on every full reset, and count retained entries in the reconciliation state predicates so a lingering entry can never let a later config change be silently skipped.

* feat(mcp): reuse unchanged per-server results during initialization

Initialize MCP tools from per-server discovery instead of a single full pass: select reusable entries under the claim lock, discover only the missing servers with get_mcp_tools_by_server, then publish atomically after re-validating every candidate binding against the pool's current binding via _binding_matches. Failed servers stay absent (never cached as empty), and superseded or partially bound candidates are discarded whole. Test fixtures now drive the grouped entry point.

* fix(mcp): close T4 review gaps in per-server cache publication

Address four findings from the adversarial review: treat retained entries as unverifiable when the applied baseline is None so an interceptor change still forces a full reset; count retained entries in the claim-time shared-reset predicate; refuse to publish a false-success empty cache when every enabled server failed discovery; and hoist the lazy imports inside the initializer's try/finally so an import failure releases the initialization claim.

* fix(mcp): sanitize cache failure logging and document per-server cache

The outer lazy-initialization handler now logs only the exception type, never the raw message or traceback, so a discovery error cannot print a resolved $VAR credential. The committed-writer planner mirrors the reader's no-baseline guard so retained entries are never reused under an unknown interceptor chain. Document the per-server tool cache (reuse, invalidation, failure handling, remote tool changes) in MCP_SERVER.md and mcp/AGENTS.md, and drop phase-staging wording from the new code and tests.

* docs(mcp): keep the agent-guidance chain under its hard limit

F2's cache notes pushed the effective AGENTS.md instruction chain 905 bytes past its 98304-byte hard limit, failing the agent-guidance CI job. Compress the selective-reconciliation bullet to its invariants (the full cache behaviour lives in docs/MCP_SERVER.md), and reword the total-failure comment so it no longer implies that build-invalid connections were attempted.

* fix(mcp): fence cached tools by interceptor chain

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-10-14 08:44:21 +08:00
spud
75ce6f4920
fix(mcp): preserve server binding history across gateway workers (#6617)
* fix(mcp): preserve server binding history across gateway workers

A peer Gateway worker could keep a stale pooled session after another worker deleted and identically re-added a stdio server, because the final effective MCP slice matched the revision it had already applied.

Record a per-server lifecycle generation in the shared extensions config and consume it in the reader, discovery claim, and committed handoff so an observed generation change force-rebinds only the affected server. Legacy configs derive a stable in-memory token; deletions leave permanent tombstones.

* fix(mcp): fail closed on an invalid mcpLifecycle instead of retrying

An unverifiable mcpLifecycle made initialize_mcp_tools() unpublishable, so get_cached_mcp_tools() retried discovery forever and could keep respawning stdio servers. Abort discovery on an invalid ledger after conservatively retiring local MCP state; a fixed config recovers on the next call.

Also documents the rolling-upgrade prerequisite: cross-worker ABA detection requires configuration writes to go through a lifecycle-aware writer.

* refactor(mcp): share stdio fingerprinting across lifecycle paths

Reuse lifecycle._stdio_fingerprints from the applied-revision builder so the connection-identity rule has a single implementation, and move the unusable-server diagnostic into the shared helper.

Add a regression proving the Gateway Skills writer preserves mcpLifecycle byte-for-value, and document that DeerFlowClient.update_mcp_config can raise RuntimeError after the config was committed.

* docs(mcp): condense lifecycle guidance under the AGENTS chain limit

The effective mcp/AGENTS.md chain was 15 bytes under the 98,304-byte CI hard limit, so the standalone cross-worker lifecycle bullet pushed it over. Fold the mcpLifecycle and rolling-upgrade facts into the existing selective-reconciliation bullet and condense it, keeping the chain under the limit while preserving the contract.

* docs: trim inherited agent guidance below CI size limit

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-10-11 11:45:28 +08:00
spud
db1e0e10b4
fix(mcp): selectively reconcile changed deployment servers (#6487)
* fix(mcp): selectively reconcile changed deployment servers

* fix(mcp): validate the frozen task snapshot before installing epochs

Durable background calls resolve their connection from the configuration frozen
at Gateway startup, so installing a newer revision's binding epoch fenced every
status/cancel call with `StaleMCPBindingError` — even though hot reload of that
server is correctly rejected. The rejection only landed in `get_mcp_tools()`,
which runs after the cache had already installed the epoch.

Both decisions that install an epoch now consult the frozen snapshot first. The
reconciliation planner falls back to the conservative full reset, where callers
that still run against the startup configuration rebind in the replacement pool,
and never installs the rejected epoch. A discovery claim raises the same
`McpTaskConfigurationError` that `get_mcp_tools()` would, before touching the
pool and without recording the revision as applied. Unrelated non-task servers
still reconcile selectively.

Adds the three requested regressions — a rejected hot change keeps background
task callers working, a rejected revision installs neither epoch nor tombstone
(changed connection and disabled server), and an unrelated server change stays
selective — plus mutation proofs for both new gates.

* fix(mcp): always tear down a pool the claim path retired

`reset_session_pool()` only fences and unlinks the singleton; the owners are
signalled by `close_all_sync()`. The claim ran that teardown *after* its critical
section, so a claim that retired the pool for a new shared-reset generation and
then raised — a revision the frozen durable-task snapshot rejects is the
reachable case — left the retired pool's sessions running without ever receiving
a close signal.

Wrap the claim in `try`/`finally` so the retired pool is torn down on every path,
still outside every lock and after the lock is released. Adds a regression
covering the shared-reset-then-rejected-revision sequence: the error propagates,
the retired pool's owner observes exactly one `__aexit__`, the replacement pool
holds no rejected epoch, and restoring the startup configuration initializes
normally again.

* fix(mcp): deliver retired-pool cleanup before the cache reader waits

A synchronous `get_cached_mcp_tools()` reader can apply a full reconciliation
while a discovery is in flight — an interceptor change and a new shared-reset
generation both qualify, because the applied baseline exists before any cache is
published. `reset_session_pool()` only fences and unlinks the pool, and the
reader then entered its wait/retry branch from inside the condition, skipping the
`close_all_sync()` that signals the retired pool's owners. The replacement cache
published normally while the discarded pool kept a live owner and stdio
subprocess that no later reset could reach.

Hoist the observed waiting generation out of the critical section and deliver the
retirement before every wait/retry path, then re-acquire the condition and wait
on that exact generation so the predicate cannot miss a wakeup. Cleanup stays
outside `_init_condition`, and the early `return _mcp_tools_cache` cannot skip a
retirement because applying a plan always clears the published cache.

Adds both triggers as a parametrised regression asserting the retired pool's
owner observes exactly one `__aexit__` and the registry drains — not merely that
the pool is fenced — plus a mutation proof for the wait-path cleanup.

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-10-09 16:41:29 +08:00
Hyeonsang Cho
89c9f08714
fix(mcp): skip task servers whose discovery failed instead of dropping all tools (#6481)
* fix(mcp): skip task servers whose discovery failed instead of dropping all tools

Per-server discovery replaced a failed or timed-out server with an empty
tool list. For a server with task_toolsets, _configure_task_tools_for_server
then reported submit/status/cancel as missing and raised
McpTaskConfigurationError, which get_mcp_tools re-raises, so the tools of
every healthy server were discarded and the cache was never published:
each agent build rediscovered every server.

load_server_tools now returns None for a failed discovery, distinct from a
server that answered with zero tools, and the wrapping loop skips such
servers before task-toolset validation. A server that answers without its
configured raw tools still raises as a configuration error.

* docs(changelog): reference #6481

* docs(mcp): name the cache-reset endpoint as a task-server recovery path

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-10-08 14:24:51 +08:00
spud
b58aea3101
fix(mcp): fence superseded stdio server bindings (#6435)
* test(mcp): pin stdio binding fencing

* fix(mcp): fence superseded stdio server bindings

* docs(mcp): document stdio binding fence

* fix(mcp): address binding fencing review

* fix(mcp): bind discovery to cache-owned pool
2026-10-08 09:02:47 +08:00
PeaceMaker-best
90d466c917
feat(mcp): propagate cache resets across workers (#6126)
* feat(mcp): propagate cache resets across workers

Signed-off-by: PeaceMaker-best <221849497+PeaceMaker-best@users.noreply.github.com>

* docs: keep MCP reset guidance within instruction budgets

---------

Signed-off-by: PeaceMaker-best <221849497+PeaceMaker-best@users.noreply.github.com>
Co-authored-by: PeaceMaker-best <221849497+PeaceMaker-best@users.noreply.github.com>
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-10-01 10:21:24 +08:00
Hyeonsang Cho
174c6f7fd3
fix(mcp): run lazy MCP discovery once when initialization itself raises (#5836)
* fix(mcp): run lazy MCP discovery once when initialization itself raises

get_cached_mcp_tools() wrapped the whole lazy-initialization call in the
`except RuntimeError` that was only meant to catch asyncio.get_event_loop()
raising when no loop is set. run_until_complete() and Future.result() re-raise
the coroutine's own exception, so a RuntimeError from discovery — e.g. the
deliberately re-raised McpTaskConfigurationError — took the same fallback and
ran asyncio.run(initialize_mcp_tools()) a second time, respawning every stdio
server and re-fetching OAuth tokens before giving up. Inside a running loop
that fallback fails with "asyncio.run() cannot be called from a running event
loop", so the logged traceback hid the real cause.

Resolve the loop first, in its own try/except, and drive initialization exactly
once: asyncio.run when no loop is set or the current loop is closed, a worker
thread when the loop is running, run_until_complete otherwise. Any failure is
logged once and returns [] as before.

Regression tests pin one discovery call and the real logged cause with and
without a running loop, and keep both fallbacks (no loop set, closed loop)
covered.

* test(mcp): surface worker-thread failures in the no-loop fallback test

Thread.join() does not propagate exceptions, so a regression of the
asyncio.run fallback failed this test with a bare KeyError: 'result' instead
of the real traceback. Capture sys.exc_info() in the worker and re-raise it
on the main thread before the assertions.
2026-09-25 10:28:28 +08:00
spud
8204dcbb20
fix(mcp): invalidate cache only for effective MCP config changes (#5750)
* fix(mcp): avoid cache resets for unrelated config changes

extensions_config.json carries MCP servers, skills and middleware settings, but the MCP cache treated any whole-file signature change as MCP state change, so toggling a skill retired every cached tool and closed all pooled sessions.

Record a snapshot of the effective MCP slice (enabled servers' parsed config plus mcpInterceptors) and retire MCP state only when that slice changes. Hand the exact config revision to tool discovery so a change during discovery cannot publish tools built from a superseded revision, and add a non-initializing refresh entry point so disabling the last enabled server still converges the cache and pool on the next tool assembly.

* docs(mcp): align cache guide and restore error diagnostics

Review feedback on #5750 flagged three non-blocking issues: the MCP module guide still described the pre-semantic-snapshot invalidation contract; the tools.py sanitization covered every exception in the MCP block, discarding diagnostics for failures that cannot carry resolved credentials; and _is_cache_stale()'s docstring presented it as a pure predicate despite adopting a new file signature.

Narrow the type-only logging to ExtensionsConfig.from_file() and restore logger.exception() for tool caching, pool cleanup and plugin filtering, with a regression test asserting the message and traceback survive. Document the effective-MCP-slice comparison, the stable config handoff to discovery, refresh_mcp_cache_if_active() and the _initialized_without_config handling in the module guide, and note the signature-adoption side effect in the docstring.

* fix(mcp): unify config normalization and verify signatures

Review follow-up on #5750.

- Normalize mcpInterceptors (bare string == single-element list; missing key == empty list) and the type/transport alias through one shared module used by the tools cache, the interceptor builder and the durable-task config snapshot, so equivalent spellings no longer retire tools/sessions or raise McpTaskConfigurationError.
- Treat a resolved-path switch as a signal to re-read the effective MCP slice instead of an invalidation reason: an identical slice adopts the new path and signature and keeps pooled sessions.
- Refuse to publish or adopt a signature whose sha256 digest is missing ((mtime, size, None) from a file that could not be read).
- Sync the English and Chinese MCP user docs with the effective-config comparison, and document that the Gateway admin reset stays unconditional.

* docs(mcp): note the unverifiable-signature fail-closed branch

A present config file whose content cannot be hashed is treated as stale, unlike a deleted file which keeps the last-known-good cache. Record that asymmetry in the module guide.

* docs(mcp): scope the no-hash rationale to never-initialized processes

The cost-free early return in refresh_mcp_cache_if_active() only covers a process that never published an MCP cache. A process that did publish one (including an empty cache from the zero-server or LangGraph Studio lazy-init path) still pays one stat+sha256 per tool assembly. Correct the rationale in the docstring and the matching comment in get_available_tools().
2026-09-24 17:19:01 +08:00
goloisme
683d146a30
fix(mcp): MCP cache re-initialization broken by cross-loop asyncio.Lock (#5062)
* Fixes #5060: P1 snapshot config before loading, P2 RLock for sync path

P1: Config changes during initialization can permanently cache stale tools.
    - Snapshot _config_path and _config_signature BEFORE await get_mcp_tools()
    - Compare AFTER get_mcp_tools() completes using _current_config_state()
    - If config changed during loading, discard stale result and retry
    - Prevents publishing old tools with new signature, which would make
      _is_cache_stale() permanently return False

P2: Module-level asyncio.Lock still fails across event loops after real contention.
    - _init_lock = threading.RLock() for sync path (reentrant, prevents races)
    - _async_init_lock = asyncio.Lock() for async init serialization
    - reset_mcp_tools_cache() now acquires _init_lock for serialization

Also fixes test P3: removed duplicated test bodies that leaked state between tests.

* fix(mcp): make cache initialization cross-loop safe

- Replace the module-level asyncio.Lock with thread-safe generation claiming
- Snapshot config state before/after MCP loading and discard stale results
- Keep reset state changes short and non-blocking for async endpoints
- Add regression coverage for contended cross-loop init, config rewrites during load, and reset while init is in flight

* fix: release MCP init claim on cancellation

Release the in-flight generation claim from a cancellation-safe finally block so cancelling the task that owns initialization does not strand future callers. Add regression coverage for cancelling the owner and then reinitializing successfully.

* fix(mcp): retire session pool before cache reset release

Prevent a concurrent MCP cache initializer from publishing tool wrappers
bound to the session-pool singleton that reset_mcp_tools_cache() is
already retiring. Add regression coverage for that interleaving.

* fix(mcp): retire session pool on stale cache invalidation

* fix(mcp): retire pool on init discard

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-09-04 11:30:36 +08:00
Daoyuan Li
3ed2e1f1d9
fix(config): close out #4124 review follow-ups (shared signature helper, resolve_config_path None contract) (#4275)
* fix(config): close out #4124 review follow-ups

Extracts the (mtime, size, sha256) content-signature helper that was
duplicated between config/app_config.py and mcp/cache.py into a new
config/file_signature.py, and fixes ExtensionsConfig.resolve_config_path()
to return None instead of raising FileNotFoundError when an explicit
config_path argument or DEER_FLOW_EXTENSIONS_CONFIG_PATH points at a file
that has since been deleted -- the exact resolution mode Docker dev/prod
uses per AGENTS.md, so the MCP tools-cache staleness check could raise
instead of degrading to "not stale". Both were flagged by willem-bd in
review on #4124 and explicitly deferred there ("flagging for visibility",
"leaving the extraction as the follow-up you suggested").

* fix(config): keep explicit extensions-config paths fail-loud

resolve_config_path() previously turned every missing-file case into a
clean None, including an explicit config_path argument or
DEER_FLOW_EXTENSIONS_CONFIG_PATH (the exact mode Docker dev/prod uses).
That silently downgrades a bad Docker mount, typo, or deleted
production config to "no extensions" instead of surfacing the
misconfiguration, per fancyboi999's review [P1] and willem-bd's
follow-up notes on this PR.

Restores FileNotFoundError for the two explicit modes (config_path
argument, DEER_FLOW_EXTENSIONS_CONFIG_PATH); only the fallback search
mode (no explicit path/env var, nothing found in the usual locations)
still returns None, since that is the legitimate "extensions were
never configured" case.

The one caller that needs the old fail-soft behavior -- the MCP
tools-cache staleness check, which re-resolves the path on every
get_cached_mcp_tools() call -- gets a narrow, local catch instead
(deerflow.mcp.cache._resolve_config_path) so a config file going
missing mid-run still degrades the cache to "not stale" rather than
crashing a hot per-request path. Also hoists the double os.getenv()
read in the env-var branch into a local, per willem-bd's nit.

Adds resolver-level tests for both explicit-path and env-var raises,
a dedicated search-mode None regression test, and updates the
existing MCP-cache docstrings to describe the corrected split.
2026-07-19 22:12:30 +08:00
Daoyuan Li
cdefd4a8aa
fix(mcp): invalidate tools cache on config content + path, not just newer mtime (#4124)
* fix(mcp): invalidate tools cache on config content + path, not just newer mtime

The MCP tools cache invalidated only on a strict extensions-config mtime `>`
comparison and tracked no resolved config path, so `_is_cache_stale()` missed:

- content changes with an unchanged mtime (same-second edits; object-store /
  network mounts that do not bump mtime);
- content changes with a backward mtime (git checkout, cp -p / backup restore,
  tar / rsync preserving timestamps);
- a resolved-path switch to a different config file with mtime <= the recorded
  value (structurally invisible — no path was tracked at all).

On multi-worker (uvicorn/gunicorn) or stale-mtime deployments this leaves the
LangGraph-embedded runtime and every non-writer worker serving stale MCP tools
after `PUT /api/mcp/config`, breaking the module's documented promise that
changes made through the Gateway API are reflected in the embedded runtime.

Record the resolved config path and a `(mtime, size, sha256)` content signature
at initialization and invalidate when the path OR the signature differs (`!=`),
mirroring `config/app_config.py::get_app_config()` so the two runtime-editable
config files share one content-based staleness signal. The per-call stat was
already paid, and the small-file sha256 matches the cost app_config pays per
request. The "config missing / not yet initialized" no-op behavior and the
cache reset endpoint are preserved.

Adds backend/tests/test_mcp_cache.py covering all three failure modes plus
unchanged-file and forward-edit sanity cases. Also folds in an incidental
backend/AGENTS.md doc-sync: the restart-required field list was missing
`scheduler` and `run_ownership`, both present in
reload_boundary.py::STARTUP_ONLY_FIELDS.

* test(mcp): pin cache staleness contracts raised in review

Two review observations on the content-signature cache fix, both raised as
non-blocking design questions rather than bugs:

- Whether relying on mtime+size alone (skipping the sha256) could ever be
  "optimized" back in, reopening the narrow same-second / identical-length
  swap gap the signature was built to close.
- Whether the extensions config being deleted entirely after a successful
  init leaves the cache in a defined state, since current_signature flips
  to None and _is_cache_stale() returns False.

Neither is a behavior change: both were already the intended contract,
preserved verbatim from the pre-fix mtime-only code (which also returned
False once the file could no longer be stat-ed). Record the reasoning
inline and add regression tests that pin each contract so a future change
cannot alter either silently:

- test_same_mtime_same_size_swap_is_stale: a same-length server-name swap
  that leaves mtime AND size unchanged (the precise scenario from review,
  sharper than the existing same-mtime test, which also changes size) is
  still caught only because the sha256 is computed unconditionally.
- test_config_deleted_after_init_is_not_stale: deleting the config file
  after init keeps the cache serving its last-known-good MCP tools instead
  of invalidating into an unconfigured state.

Both new tests were confirmed to fail against a deliberately reintroduced
version of the regression they guard (hash short-circuit / removed
None-guard), then confirmed to pass against the real code.
2026-07-14 22:40:51 +08:00