* Comprehensive MCP Apps docs, string CallTool resolution, bump prefab-ui >=0.13.0
Rewrites the apps documentation as a learning journey: overview → Prefab apps
→ FastMCPApp → patterns → dev tools → custom HTML. Adds a new FastMCPApp page
covering composable apps with @app.tool()/@app.ui(), CallTool, forms, actions,
and composition. Teaches Rx() and set_initial_state() as the primary state API.
Adds string-based CallTool resolution so CallTool("save_contact") resolves to
the tool's global key, matching callable ref behavior. Requires prefab-ui 0.13.0
which passes strings through the tool resolver.
* Detect ambiguous string CallTool resolution across apps
* Simplify string name registry to plain dict (last-write-wins)
* Add FastMCPApp — a Provider for composable MCP applications
* Wire Prefab callable resolver via to_json(tool_resolver=) parameter
* Remove inspect.signature compat check, use try/except until prefab 0.10.0
* Address review: fix add_tool registry gaps, normalize auth errors, bump prefab to 0.10.0
* Register global key after _add_component succeeds
* Simplify: extract decorator dispatch, use get_fastmcp_meta, expose get_global_tool
* Remove prek from Marvin workflows
These workflows run Claude to respond to /marvin mentions — linting
the repo is unnecessary and fails without renderer deps installed.
* Return ResolvedTool from callable resolver, add contacts example
The callable resolver now returns ResolvedTool (from prefab_ui) instead of a
plain string, carrying metadata like unwrap_result that the renderer needs to
correctly handle structuredContent envelopes. The unwrap_result flag is derived
from the tool's x-fastmcp-wrap-result output schema marker.
* Bump prefab-ui requirement to >=0.11.0
* Remove stale ty ignore comments now that prefab-ui 0.11 is published
* Add fastmcp dev apps command with browser UI preview
* Improve fastmcp dev apps: dropdown picker, reload flag, process cleanup
- Replace Tabs with Pages+Select for tool picker (Rx-based reactive state)
- Add --reload/--no-reload flag (default: True) to fastmcp dev apps
- Kill entire process group on shutdown so port 8000 is freed properly
- Suppress uvicorn websockets deprecation warning (websockets-sansio)
- Bump prefab-ui to >=0.11.1 (fixes get_renderer_head bug in 0.11.0)
- Add farewell tool to greet_server example for multi-tool testing
* Add docs for fastmcp dev apps command
* Fix orphaned server on startup failure, guard Unix-only signal handling
* Show tool title in picker, remove editable prefab source
* Bump prefab-ui to >=0.11.2
* Fail fast when prefab-ui is not installed
* Add apps/development docs, link from prefab and sidebar
* Fix optional field defaults, fail with non-zero on startup timeout
* Add FastMCPApp — a Provider for composable MCP applications
* Wire Prefab callable resolver via to_json(tool_resolver=) parameter
* Remove inspect.signature compat check, use try/except until prefab 0.10.0
* Address review: fix add_tool registry gaps, normalize auth errors, bump prefab to 0.10.0
* Register global key after _add_component succeeds
* Simplify: extract decorator dispatch, use get_fastmcp_meta, expose get_global_tool
* Remove prek from Marvin workflows
These workflows run Claude to respond to /marvin mentions — linting
the repo is unnecessary and fails without renderer deps installed.
* Return ResolvedTool from callable resolver, add contacts example
The callable resolver now returns ResolvedTool (from prefab_ui) instead of a
plain string, carrying metadata like unwrap_result that the renderer needs to
correctly handle structuredContent envelopes. The unwrap_result flag is derived
from the tool's x-fastmcp-wrap-result output schema marker.
* Bump prefab-ui requirement to >=0.11.0
* Remove stale ty ignore comments now that prefab-ui 0.11 is published
* Add tests for two-stage pattern, empty full-detail results, empty inputs
* Add ListTools, search limit, catalog size annotation; split tests
Co-authored-by: Claude <noreply@anthropic.com>
* Remove BM25 internal cap so Search.limit is the sole truncation point
* Pass default_limit to BM25 instead of arbitrary high cap
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Co-authored-by: Claude <noreply@anthropic.com>
* Add Google GenAI sampling handler
Co-authored-by: Bill Easton <strawgate@users.noreply.github.com>
* chore: Update SDK documentation
* Filter non-Gemini model hints in _get_model
Match the Anthropic/OpenAI handler pattern of only selecting
provider-compatible models from hints.
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Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Bill Easton <strawgate@users.noreply.github.com>
Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>
Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
* Replace vendored DI with uncalled-for
FastMCP vendored a minimal DI engine extracted from Docket (~164 lines)
with try/except fallback patterns everywhere. The `uncalled-for` package
is a clean, typed extraction of this same system, and since Docket will
also depend on it (chrisguidry/docket#353), `uncalled_for.Dependency`
becomes the single canonical base class.
This deletes the `_vendor/docket_di/` directory, replaces all the
try/except import patterns with direct `uncalled_for` imports, and
updates the `Dependency.execution` → `current_execution` ContextVar
references to match the Docket branch. The `Progress` class now
delegates to an internal impl and returns `self` from `__aenter__`
(matching Docket's pattern) so that ty's generic resolution works
without `type: ignore` suppressions.
Temporarily points pydocket at the `use-uncalled-for` branch so both
sides can be validated together in CI.
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Re-export Dependency from fastmcp.dependencies
Internal code like azure.py should import from the fastmcp namespace
rather than reaching into uncalled_for directly.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Import Dependency from fastmcp namespace in tests
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Add generic type parameters to Dependency subclasses
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Mention uncalled-for in DI docs
The DI engine now comes from uncalled-for, so the docs should credit
it alongside Docket. Also updates the Docket docs link to docket.lol.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Point docket dependency at main
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Bump uncalled-for pin to >=0.2.0
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Fix uncalled-for imports for 0.2.0 API changes
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Support Shared() dependencies without docket
Enters a SharedContext at server lifetime so that Shared() dependencies
from uncalled-for resolve once and are cached across tool/resource/prompt
calls. When running with docket, the Worker already handles this; this
covers the non-docket path and direct call_tool() usage.
Also re-exports Shared from fastmcp.dependencies.
Closes#3251
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Bump docket lockfile to latest main
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Remove duplicate test classes from rebase conflict resolution
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Point docket dependency at pydocket>=0.18.0 release
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Pair SharedContext __aenter__ with __aexit__ in Context lifecycle
The old `_ensure_shared_context` on the server called `__aenter__()` on a
lazy `SharedContext` but never `__aexit__()`, leaking the exit stack and
its resources. Moved the SharedContext management into Context's own
enter/exit so it's properly paired: when docket is available the lifespan
handles it, otherwise Context creates and cleans up a per-request one.
Updated Shared() tests to use Client (which runs the lifespan) rather
than calling server methods directly, since cross-request sharing
requires a lifespan.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Hoist SharedContext import to module level
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
* Add prefab auto-wiring for MCP Apps (#3119)
Tools that return prefab types (UIResponse, Component) automatically get
wired to the shared prefab renderer resource. Works via app=True,
return type inference, or both.
* Prefab compatibility updates
* Use published prefab-ui >=0.6.0, remove local source override
* Migrate UIResponse to PrefabApp for Prefab UI integration
PrefabApp is a pure data object with to_json(), html(), and csp()
methods. Tools can return PrefabApp, bare Components, or
ToolResult with structured_content for custom LLM fallback text.
* Add Prefab UI apps documentation
* Add mini apps and full apps documentation pages
Mini apps covers the common single-screen patterns: charts (bar, line,
area, pie), data tables with sorting/search/pagination, forms (manual
and Pydantic-generated), status displays, conditional content, and
layout composition with tabs and accordions.
Full apps covers multi-page applications using Pages/Page components,
shared state across pages, and using ToolCall with result_key for
server-driven state updates.
* Reframe apps docs around motivation, add generative UIs page
The docs now lead with the problem — MCP tools stuff data into the LLM
context window, and building HTML/JS/CSS frontends is a non-starter for
Python developers — before introducing Prefab as the solution. Mini apps
are framed as the primary use case: focused, single-purpose UIs that
present data visually and collect structured input.
New generative UIs page covers the concept of LLMs producing component
JSON directly, enabling adaptive dashboards, tailored forms, and
exploratory workflows.
* Tag Prefab docs pages as SOON instead of NEW
* Rename Low-Level API to Custom HTML Apps
The page is about using the MCP Apps extension directly, not a FastMCP
or Prefab internal API. Reframed to make clear this is the open MCP
protocol with FastMCP providing convenience wrappers.
* Tighten apps docs and widen content area
Strip editorial motivation from all app doc pages — let code examples
do the talking. Add content-area max-width override (44rem) to style.css.
* Restructure apps docs, fix code issues
Rename Prefab UI → Prefab Apps, mini-apps → patterns, remove
generative-uis and full-apps pages. Rewrite prefab page to lead with
what users do (declare a UI, return it) before explaining internals.
Patterns page now has fully self-contained copy-pasteable examples with
explicit imports and links to prefab docs. Forms show the two-tool
pattern (form + handler). Add patterns_server.py example.
Code fixes: move get_args to module-level import, remove dead
AuthCheckCallable type alias, fix ToolCall→CallTool in all docs.
* Remove unused ToolResult import from chart_server
* Handle composite Prefab types in type inference and schema suppression
_has_prefab_return_type and the output schema suppression logic only
checked bare classes, missing unions (Column | None) and Annotated
wrappers (Annotated[PrefabApp | None, ...]). Recurse through Union,
types.UnionType, and Annotated to detect Prefab types in composite
annotations.
* code mode
* update uv.lock for monty optional dep
🤖 Generated with Claude Code
* retry CI
* Address PR review comments on CodeMode transform
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Fix ty unresolved-attribute error on search_helper
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* more idiomacy
* harden
* fix docs
* harden
* fix red CI
* Refactor CodeMode to use CatalogTransform base class
Removes the duplicate ContextVar bypass pattern in favor of the shared
CatalogTransform machinery. Also fixes a pre-existing bug where
`from __future__ import annotations` caused NameError for Annotated
in nested function scopes at runtime.
* Remove redundant _get_visible_tools wrapper in CodeMode
* Rewrite CodeMode docs with proper motivation and structure
* Fix type narrowing in collision test
* Stop unwrapping tool results in CodeMode's call_tool
call_tool() inside execute blocks now returns structured content as-is,
preserving the {"result": value} wrapping. This means the output schema
shown in search results accurately describes what call_tool() returns,
so LLMs can trust the schema when writing code.
Also adds examples/code_mode/ with a server and narrated client demo.
* Simplify call_tool return type: dict | str
* Fix example client to unwrap structured results
* Let server resolve tool versions instead of pinning first match
* Rewrite CodeMode docs to match current behavior
* Rename optional extra from monty to code-mode
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
* Fix ty 0.0.19 type errors
🤖 Generated with Claude Code
* Fix ruff formatting in sampling/run.py
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https://claude.ai/code/session_01GWzbyF1vHvVeS4yJ5bhScf
---------
Co-authored-by: Claude <noreply@anthropic.com>
Points pydocket to the fix-cancellation-handling branch to validate
asyncio cancellation handling works correctly on the 3.x branch.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Adds opt-in distributed tracing via OpenTelemetry for observability into
FastMCP server and client operations.
Server spans are created for tool calls, resource reads, and prompt
renders with attributes like component key, component type, provider
type, session ID, and auth context. Client spans wrap outgoing calls
with trace context propagation via W3C headers in request meta.
Components provide their own span attributes through a `get_span_attributes()`
method that subclasses override - this lets LocalProvider, FastMCPProvider,
and ProxyProvider each include relevant context (original names, backend URIs).
To enable: configure an OpenTelemetry SDK with a TracerProvider before
importing fastmcp. Traces export to any OTLP-compatible backend.
Closes ENG-2813
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
