1.1.0: execution AbortSignals + document.modelContext consumer API - #54
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AGENTS.md still named navigator.modelContextTesting as the external-call path
in the architecture note and the Testing section, which would steer new tests
at a surface that is removed in 2.0.0. Name document.modelContext.getTools() /
executeTool() instead and mention the shim only as deprecated.
Drop the unused `{ signal }` destructure from the README quick start — it
trips noUnusedParameters for anyone copying the first snippet. The 1.1.0
section still shows the two-argument handler.
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kashishhora
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naji247
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What changed
Built on #53 (the 1.0.0 release, now merged) — this is the 1.1.0 delta on top of it.
Chrome's WebMCP implementation moved in three steps (per the Chrome WebMCP team's EPP announcements, checked against Chromium source):
navigator.modelContextTesting. The consumer API isdocument.modelContext.getTools()/executeTool()(shipping since 150.0.7861.0).executeasexecute(input, { signal })— webmcp issue #48, spec PR #247. From 153.0.8008.0, unregistering a tool no longer cancels its in-flight executions (issue #218).RegisteredTool.inputSchemafrom a JSON string to an object (spec PR #241).Library
src/types.ts—ToolDescriptor.executeand the confighandlertake(input, { signal }). NewToolExecuteCallbackOptions,ExecuteToolOptions,RegisteredTool(inputSchema: InputSchema | string, since 153 and 154 differ),ModelContextGetToolOptions;ModelContextgains optionalgetTools/executeTool. One-argument handlers still type-check.src/hooks/useMcpTool.ts— the directexecute()path and the registered descriptor now share onerunHandler. Handlers always receive a realAbortSignal; on Chrome <=152 (which passes no options) a never-aborting one is substituted. When an aborted execution's handler rejects it's treated as cancellation:isExecutingclears,state.errorandonErrorare left alone.execute(input?, { signal }?)accepts a caller signal.src/polyfill/execute.ts(new) — one execution engine behind bothexecuteTooland the shim: per-executionAbortController, a caller abort rejects withsignal.reasonwhile the tool-side signal aborts with a genericAbortError(what 153 does), late settlement after abort is ignored, tool failures rejectUnknownError, results serialize the way native does. Input is still validated againstinputSchema(OperationError); native doesn't validate yet (issue #92).src/polyfill/index.ts—document.modelContext.getTools()/executeTool()on the polyfill: fresh sorted objects, deep-copied objectinputSchema(the 154 shape),fromOriginsvalidation,UnknownErrorfor a stale tool. In-flight executions survive unregistration.src/polyfill/testing-shim.ts— now a thin wrapper over the engine that warns once thatnavigator.modelContextTestingis deprecated (removal planned for 2.0.0). Keeps its historicalNotFoundError/OperationErrorinput errors.docs/api.md(Cancellation section and a Chrome compat table), AGENTS.md, both skills, CHANGELOG. Version bump to 1.1.0.Test plan
pnpm typecheck/pnpm lint(zero warnings) /pnpm buildpnpm test— 205 passing: both execution paths, cancellation semantics, engine abort races and serialization, consumer API, shim parityThe extension and examples migration is stacked on this branch in a follow-up PR.