feat: add onFallbackRequest handler to McpAppRenderer#7208
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alexhancock merged 2 commits intomainfrom Feb 13, 2026
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Upgrade @mcp-ui/client from ^6.0.0 to ^6.1.0 to get the new onFallbackRequest prop on AppRenderer. Add a fallback request handler that catches unhandled MCP requests from the app iframe. This is a stub that logs the request method and returns success, with a todo to implement sampling/createMessage per #7039. Changes: - Upgrade @mcp-ui/client to ^6.1.0 - Import RequestHandlerExtra from @mcp-ui/client - Import JSONRPCRequest from @modelcontextprotocol/sdk/types.js - Add handleFallbackRequest async callback - Wire onFallbackRequest prop to AppRenderer
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Pull request overview
Adds an onFallbackRequest handler to the desktop UI’s McpAppRenderer so unhandled MCP JSON-RPC requests coming from the embedded app iframe are caught instead of bubbling as unhandled behavior.
Changes:
- Extends imports to include
RequestHandlerExtraand the SDK’sJSONRPCRequesttype. - Introduces an async
handleFallbackRequestcallback (currently stubbed). - Wires
handleFallbackRequestintoAppRenderervia theonFallbackRequestprop.
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Update the handleFallbackRequest function to properly handle the 'sampling/createMessage' method. If the method is unrecognized, return an error status with a descriptive message. This improves error handling for unhandled JSON-RPC methods. Changes: - Implement specific handling for 'sampling/createMessage' - Return error status for unhandled methods
alexhancock
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…ntext * 'main' of github.com:block/goose: feat: add onFallbackRequest handler to McpAppRenderer (#7208) feat: add streaming support for Claude Code CLI provider (#6833) fix: The detected filetype is PLAIN_TEXT, but the provided filetype was HTML (#6885) Add prompts (#7212) Add testing instructions for speech to text (#7185) Diagnostic files copying (#7209) fix: allow concurrent tool execution within the same MCP extension (#7202) fix: handle missing arguments in MCP tool calls to prevent GUI crash (#7143) Filter Apps page to only show standalone Goose Apps (#6811) opt: use static for Regex (#7205) nit: show dir in title, and less... jank (#7138) feat(gemini-cli): use stream-json output and re-use session (#7118) chore(deps): bump qs from 6.14.1 to 6.14.2 in /documentation (#7191) Switch jsonwebtoken to use aws-lc-rs (already used by rustls) (#7189) chore(deps): bump qs from 6.14.1 to 6.14.2 in /evals/open-model-gym/mcp-harness (#7184) Add SLSA build provenance attestations to release workflows (#7097) fix save and run recipe not working (#7186) Upgraded npm packages for latest security updates (#7183) docs: reasoning effort levels for Codex provider (#6798)
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Summary
Add a fallback request handler to
McpAppRendererthat catches unhandled MCP requests from the app iframe.This is a stub implementation that logs the request method and returns success, with a todo to implement
sampling/createMessageper #7039.Changes
RequestHandlerExtrafrom@mcp-ui/clientJSONRPCRequestfrom@modelcontextprotocol/sdk/types.jshandleFallbackRequestasync callback usinguseCallbackonFallbackRequestprop toAppRendererType fixes
The original snippet had several type issues that are fixed here:
JSONRPCRequest(correct SDK type) instead of non-existentMcpUiFallbackRequestrequest.urlaccess (JSONRPCRequesthasmethod, noturl)asyncto match expectedPromise<Record<string, unknown>>return typeuseCallbackdependency array (was[extra]which would be aReferenceError)