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
Hosts (Goose, MCP Jam) don't forward _meta on callServerTool, which
broke app tool routing entirely. Encode the app identity in the tool
name on the wire instead: the resolver writes "AppName___tool_name",
and the server parses it to route via get_app_tool.
Adds Provider.get_app_tool(app_name, tool_name) — a dedicated method for
finding app-visible tools by their original name, bypassing transforms.
AggregateProvider queries children, WrappedProvider delegates to inner,
FastMCPProvider delegates to nested server. The default implementation
checks _get_tool and matches meta.fastmcp.app.
This replaces the process-level _APP_TOOLS registry. Tool routing now
works through the provider tree, which exists in every process — no
shared state needed for horizontal scaling.
* Replace UUID global keys with (app_name, tool_name) registry
Collapses three module-level registries (_APP_TOOL_REGISTRY,
_FN_TO_GLOBAL_KEY, _NAME_TO_GLOBAL_KEY) into one: _APP_TOOLS keyed by
(app_name, tool_name). Removes UUID generation, global key stamping in
metadata, and the complex resolver that mapped callables and strings
through multiple fallback paths.
The server now reads _meta.fastmcp.app from the MCP request (set by the
Prefab renderer) and routes directly to the named app's tool. Two apps
with the same tool name are disambiguated by app name, not by UUID.
The resolver is simplified to pass-through: CallTool("save") serializes
as "save", and the server resolves it at call time using the app context.
* Read app name from _meta.prefab.app to match Prefab renderer
* Inject _meta.fastmcp.app into @app.ui() structured content
The @app.ui() decorator stores the FastMCPApp name in the tool's metadata.
When the tool result is serialized, _prefab_to_json injects it as
_meta.fastmcp.app in the structured content. The Prefab renderer reads
this on init and echoes it back as _meta.fastmcp.app on every
callServerTool call, completing the routing loop.
* 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)
* pin pydantic-monty to 0.0.8
* rename tool/prompt/resource base modules to avoid decorator name shadow
* add sys.modules shims for old submodule import paths
* preserve original module paths in deprecation warnings
* clarify when sys.modules shims can be removed
* 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
