* Restore task snapshot via a worker-level dependency
`get_access_token()` returned `None` inside background tasks whenever
`FASTMCP_DOCKET_URL` pointed at a `redis+cluster://` URL. The write side
was fine — it went through `docket.redis()`, which is cluster-aware —
but fastmcp kept a parallel sync Redis client just to read the snapshot
back, and `Redis.from_url()` rejects the cluster scheme.
Docket 0.19.1 ships worker-level dependencies that resolve per task in
the same asyncio.Task as user code, so ContextVars propagate cleanly.
That lets us load the snapshot once via `restore_task_snapshot` and
drop the sync Redis path entirely. Sync helpers like
`get_access_token()` and `get_http_request()` now just read a
ContextVar; Docket is the sole Redis consumer.
Closes#3897
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Revert TaskKey stub to a plain return
NotImplementedError would fire at module import if anything evaluated
the default; a no-op stub keeps the module usable without the
fastmcp[tasks] extra, which is what we want.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
* OTEL: Fix attribute compliance and improve telemetry helpers
Attribute compliance:
- Remove rpc.system/service/method (MCP is not traditional RPC)
- Add gen_ai.tool.name on tools/call spans
- Add gen_ai.prompt.name on prompts/get spans
- Fix session_id check (truthy -> is not None)
Telemetry helper improvements:
- Add is_recording() guards to skip work on non-recording spans
- Add error.type attribute with __qualname__ on error spans
- Use isinstance check for ToolError to set "tool_error" error type
- Include exception message in span status description
- Add tool_name/prompt_name params to server_span and client_span
Client call_tool enrichment:
- Reflect tool-level errors (result.isError) on client span status
so callers see ERROR even though the MCP protocol call succeeded
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: remove resource URI from span names to avoid high-cardinality
Per MCP semantic conventions, resource URIs SHOULD NOT be included in
span names by default since they can be unbounded (especially with
templates like users://{id}/profile). The URI remains available via
the mcp.resource.uri attribute.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: add missing gen_ai/mcp attributes to proxy and delegate spans
- Proxy tool spans: add gen_ai.tool.name
- Proxy prompt spans: add gen_ai.prompt.name
- All delegate spans: add mcp.method.name
- Docs: remove rpc.* references, update span names and attributes table
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Hoist ToolError imports to module level, add rpc.* migration note
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: handle non-TextContent error responses in ProxyTool
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Avoid serializing binary content into ToolError messages
Use type name instead of str(content) to prevent dumping
large base64 payloads into error messages.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* ruff format fix
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: server safety guards for self-mount, duplicate middleware, mount arg order
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Remove duplicate middleware and mount arg order checks
These are runtime type checking, not bugs — a type checker catches them.
Keep only the self-mount guard which is a semantic check.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Scope tasks to authorization context, not session
Tasks were keyed by the transport-layer Mcp-Session-Id, which is
server-assigned and changes on reconnect — so clients lost access to
their running tasks after any connection interruption.
The MCP spec says tasks should be bound to authorization context, not
session. This replaces session_id with task_scope (derived from
AccessToken.client_id, URL-encoded) in all task data Redis keys and
Docket task keys. When no auth is configured, a "_" sentinel is used
and security comes from UUID task ID entropy per the spec.
Session ID is still used for transport-level concerns (notification
queues, subscriber registration) and is now stored in the
TaskContextSnapshot payload so background workers can still deliver
notifications.
Also extracts all the task context infrastructure (TaskContextInfo,
TaskContextSnapshot, snapshot loading, session/server registries) from
server/dependencies.py into a new server/tasks/context.py to keep the
DI module from sprawling further.
Closes#3758🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Rename _redis_key to _snapshot_redis_key
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Document in-process session registry as an optimization
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Tidy imports and docstrings
Hoist imports where safe, keep subscriptions/notifications deferred in
handlers.py since they pull in docket at module level. Sharpen docstrings
on keys.py and context.py so each module owns its lane. Clean up the
re-export block in dependencies.py.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix misleading comment on re-export block
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Tighten task scope: include sub claim, partition keyspaces
Addresses review feedback on #3800:
- Compose task scope from client_id and the JWT sub claim (when present)
so fixed-OAuth deployments isolate per user, not just per client.
- Replace the "_" anonymous sentinel with a tagged keyspace partition.
Docket keys are now auth:{enc_scope}:... or anon:..., and Redis keys
use fastmcp:task:auth:{enc_scope}:... or fastmcp:task:anon:...,
routed through a single task_redis_prefix() helper.
- get_task_scope() returns the raw scope (or None); encoding happens
once at the keys.py boundary, collapsing the previous double-quote
invariant.
- Drop the dormant fallback in notifications.py that routed
input_required relays into the anon keyspace when task_scope was
missing -- log and skip instead.
- Add comprehensive parser/encoder tests in test_task_keys.py covering
round-trips, malformed keys, and adversarial scopes ("anon", "_", and
scopes containing : / | %).
- Add cross-scope rejection tests: distinct client_ids, distinct sub
claims under a shared client_id, and authenticated vs anonymous.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Delete entirely commented-out test_run_server.py (99 lines dead code)
- Fix test_pydantic_model_with_stringified_json_no_strict: replace
try/except-both-branches-pass with clear pytest.raises assertion
- Fix test_path_traversal_blocked: remove dead assertions after
pytest.raises (lines after raise never execute)
Error handling middleware test fixes are in a separate PR (#3858)
which also fixes the underlying RetryMiddleware bug.
🤖 Generated with Claude Code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Retry when LLM returns text instead of calling final_response tool
Instead of raising RuntimeError immediately when the LLM returns a text
response instead of calling the `final_response` tool for structured
output, retry up to 3 times with an explicit nudge message asking the
model to use the tool. This mirrors the existing retry behavior for
validation errors but with a separate, smaller cap.
Fixes#3847
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Add tests for text response retry logic
Tests cover:
- Text response followed by successful final_response (retry works)
- Text response exceeding max retries (raises RuntimeError)
- Nudge message appended to history on retry
- No retry when result_type is None (text is valid)
Addresses review feedback from PR review tool (v1 flagged missing tests as high severity).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Slim down text response retry tests
Remove test_nudge_message_in_history (implementation detail).
Reduce boilerplate in remaining 3 tests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix ruff format
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Replaces the ___ separator for FastMCPApp backend tool routing with a
deterministic hash(app_name, tool_name) prefix, and replaces the shared
singleton prefab renderer resource with per-tool resources synthesized
on demand.
Backend tools are now callable via <hash>_<local_name> instead of
<app_name>___<local_name>. The dispatcher walks the provider tree
recursively via get_tool_by_hash (same pattern as get_app_tool).
Each prefab tool gets its own renderer resource at
ui://prefab/tool/<hash>/renderer.html with per-tool CSP — fixing the
bug where PrefabAppConfig(csp=...) never actually applied.
Closes#3735, closes#3805
- AggregateProvider._collect_list_results detects duplicate component
names across providers, respecting the server's on_duplicate setting
- Provider errors logged at WARNING instead of DEBUG
- Parent server re-masks ToolErrors from mounted children at the
FastMCPError catch boundary instead of mutating the child server
Fixes#3825
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Enables stricter type checking by promoting rules that default to
ignore: division-by-zero, possibly-missing-attribute,
possibly-missing-import, possibly-unresolved-reference,
unsupported-dynamic-base, unsupported-operator, unused-ignore-comment.
6 of the 7 rules had zero violations. possibly-unresolved-reference
had 9 (5 in src/, 3 in tests/, 1 walrus-operator false positive
suppressed with ty: ignore).
🤖 Generated with Claude Code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Detect async/sync generators after tool execution and materialize
into lists before the result conversion pipeline processes them
- Generator materialization runs inside timeout scope so slow generators
respect the configured timeout
- Handle bytes return types: UTF-8 bytes as text, non-UTF-8 as base64
- Suppress output_schema for bytes return types (can't be structured JSON)
- Catch UnicodeDecodeError alongside PydanticSerializationError in
convert_result for robustness
Fixes#3829
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
pydocket 0.19.0 fixes the fakeredis 2.35.0 FakeConnection rename
internally, so we no longer need to carry the fakeredis ceiling
ourselves. Removes the direct fakeredis[lua]<2.35.0 dependency from the
tasks extra entirely — it's just a transitive of pydocket now.
🤖 Generated with Claude Code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: resolve OpenAPI 3.x server variables in _create_default_client
When an OpenAPI spec defines server variables (e.g. `https://{region}.api.example.com/v1`),
the default values are now substituted before constructing the httpx client base URL.
Previously, the URL was used as-is, causing all requests to fail for specs that use
server variable templating.
Fixes#1681
* fix: use str.replace instead of format_map for server variable substitution
format_map applies Python string formatting rules, so variable names
like {api.version} would be treated as attribute access and raise errors.
Literal token replacement handles all valid OpenAPI variable names safely.
* Unify background task context forwarding and fix concurrent dependency bugs
We've been getting a steady trickle of edge-case reports around background tasks
and contextual dependencies over the last few months (#3654, #3656, #3569). Each
one pointed at a different symptom, but they all traced back to the same area:
the way context is negotiated between the "frontend" server and Docket workers
was grown piecemeal, with each new piece of context (access tokens, HTTP headers,
origin request IDs) getting its own Redis key, its own restore function, and its
own ContextVar. This made it hard to reason about what state was available where,
and the shared-instance Dependency pattern made concurrent tasks stomp on each
other's cleanup state.
This takes a step back and reworks the whole thing as a single unified system:
- Dependency subclasses (_CurrentContext, Progress, _CurrentAccessToken, etc.)
are now stateless factories — __aenter__ returns a fresh per-invocation
object, so concurrent tasks never share mutable state. Fixes#3654, #3656.
- The three individual context-snapshot Redis keys (access_token, http_headers,
origin_request_id) are collapsed into a single TaskContextSnapshot stored as
one JSON key per task. The three _restore_task_* functions and two ContextVars
they populated are gone.
- Sync functions like get_http_request() and get_access_token() now find the
snapshot transparently in background tasks via a 3-tier sync fallback:
ContextVar (set by _CurrentContext for functions with deps) → in-memory dict
(same-process workers) → sync Redis GET (out-of-process workers). No function
wrapping needed.
- The _wrap_for_task_http_headers hack is deleted. FunctionTool registers its
raw function with Docket so Docket sees and resolves ALL dependencies,
including Docket-native ones like Retry and Timeout.
- ProxyTool.from_mcp_tool() now propagates execution.taskSupport metadata from
remote tools. Fixes#3569.
- Removed redundant _current_docket/_current_worker ContextVar management from
Context.__aenter__/__aexit__ (they're only set in the lifespan now).
Closes#3654Closes#3656Closes#3569🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Address code review feedback
- _OptionalCurrentContext: guard __aexit__ against cleaning up contexts it
didn't create (check is_background_task before delegating)
- Narrow except clauses in snapshot loading (OSError, JSONDecodeError, etc.
instead of bare Exception)
- Fix docstrings on register_with_docket for resources/prompts/templates
- Simplify Progress: read ExecutionProgress directly from current_execution
instead of creating and manually entering a DocketProgress wrapper
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Use pop-on-access transfer buffer instead of bounded LRU cache for snapshots
The in-memory snapshot dict is a transfer mechanism, not a cache. Entries go
in at submission and come out at the worker's first access. Using pop instead
of get means the dict only holds entries during the brief submission-to-execution
window, bounded by task concurrency (~10) rather than a 10,000-entry LRU limit.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Drop in-memory transfer buffer, use sync Redis for all backends
Instead of maintaining an in-memory dict to bridge the async/sync gap, use
a sync Redis client directly. For memory:// backends (fakeredis), shares the
same FakeServer instance via docket._redis.get_memory_server() so data written
by the async Docket client is visible to sync reads. For real Redis, creates a
standard sync connection. No in-process state to manage at all.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Move snapshot operations to TaskContextSnapshot methods
capture(), from_json(), to_json(), save() are now classmethod/instance methods
on the dataclass instead of free functions. Deduplicates JSON parsing that was
copy-pasted between the async and sync load paths.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Trim implementation details from register_with_docket docstrings
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Clarify docket lookup comment in submit_to_docket
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Restore docket/worker ContextVar bridge in Context.__aenter__
Servers that own the Docket (the parent) re-set _current_docket/_current_worker
from their instance attributes when entering a Context. Mounted children skip
this (their _docket is None), so they inherit the parent's value. This is needed
for ASGI deployments where ContextVars set during the lifespan don't propagate
to request handlers.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Key snapshot cache by task_id to prevent cross-task context leakage
Docket workers may reuse the same asyncio context for sequential tasks.
The ContextVar cache now stores (task_id, snapshot) tuples so stale entries
from previous tasks are automatically ignored.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
