Add WebMCP registration, discovery, and execution - #1
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Match the published official types with a document-local implementation and real-browser, package-consumer, and pinned WPT checks. Resolve package dependencies with fresh registry metadata so clean CI runners do not depend on a warm offline cache. Allow only the downloaded Chrome executable to create user namespaces on Ubuntu, keeping its sandbox enabled, and expose WPT startup logs. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Implement executeTool() against the current draft: object input, JSON-serialized results, and abort handling that gives the callback its own signal and a default AbortError while the caller receives its own reason. Extend the WPT selection from 13 files to 18, and from 27 assertions to 56, now that the interface is complete enough for the IDL harness. Record as per-subtest expected failures in wpt-metadata the four upstream files that disagree with the draft on omitted input and on result serialization, rather than patching tests or relaxing the implementation. Carry a temporary ModelContext augmentation mirroring webmcp-types#3 until that ships. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Thank you @MiguelsPizza for starting this effort! See comments below
| "imperative/non-secure.html", | ||
| "imperative/register-tool-title.https.html", | ||
| "imperative/register_tool_with_empty_annotation.https.html", | ||
| "imperative/getTools-imperative-annotations.https.html", |
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Why is imperative/getTools.https.html not covered? I may have missed others as well. Can you explain which ones you picked?
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No reason other than things were (are) still in WIP. They should all be covered now
Use released webmcp-types 0.1.8 and remove the temporary executeTool augmentation. Shorten comments and test setup while preserving Web IDL conversion, cancellation, and native-installation behavior. Run every pinned WebMCP testharness file with standard WPT expectations instead of a selected list. Record failures, timeouts, and blocked subtests separately so the supported scope is visible. Apply the review's fixture, header, and Chrome flag corrections. Validate blob URLs using their inherited origin; a browser regression demonstrates the former SecurityError for trustworthy blob origins. Validated with pnpm test (100 browser tests), pnpm test:package, and pnpm test:wpt (58 files; all results match their explicit expectations). References: #1 #2 https://github.com/webmachinelearning/webmcp-types/releases/tag/v0.1.8 https://url.spec.whatwg.org/#concept-url-origin
Browser tests and their type checks used separate filename allowlists, so a new test could be silently omitted. Discover test files by convention while keeping the native Chromium test in its own project. Share execution-test setup and use resolved promises instead of definitely-assigned test state. CI and the local WPT runner now read one unchanged revision from wpt-revision.txt. Preserve the full testharness selection and reviewed expectations established after Francois's review: #1 (comment) Use URL.parse for invalid-origin handling, keeping the same security errors without exception-driven parsing. Expand the installer's public JSDoc with its no-op cases, frame scope, example, and first-party references. Keep Web IDL boundary checks and document the native validation behind their casts. https://url.spec.whatwg.org/#dom-url-parse https://webmachinelearning.github.io/webmcp/#document-extension Validation: pnpm test (100 passes), pnpm test:package, formatting, and pnpm test:wpt on Canary 156.0.8062.0. All 58 WPT files match expectations: 72 PASS, 23 expected FAIL, 25 expected TIMEOUT, and 19 expected NOTRUN.
The implementation was compact but made readers unpack argument conversion, security checks, and asynchronous execution at the same time. Put installation and public operations first, move Web IDL conversion into named local helpers, and distinguish the caller's settlement from the callback's completion. Make discovery an explicit copy, sort, and return sequence. Preserve optional member omission and Web IDL property order, with an assertion in the existing metadata test. Expand guards and give stored schemas and signals names that explain their roles. This deliberately favors reading order over line count. Flatten browser tests so each action finishes before its outcome is asserted. Record the readability convention for future edits. No public API, dependency, WPT selection, or expectation changes. References: https://webidl.spec.whatwg.org/#es-dictionary https://webmachinelearning.github.io/webmcp/ Validation: pnpm test (100 passes), pnpm test:package, formatting, and pnpm test:wpt on Canary 156.0.8062.0. All 58 WPT files match expectations: 72 PASS, 23 expected FAIL, 25 expected TIMEOUT, and 19 expected NOTRUN.
Expand dense test phases, fixture code, and the WPT runner so the combined registration and execution work is easier to follow. Review every tracked file and comment; explain actual WPT blockers without changing expectations. Replace Reflect.get/apply in origin conversion while retaining a single iterator lookup and the original receiver. Cover both registration and discovery with an iterator whose function properties cannot be read. Run all 15 Rook anti-slop rules externally without adding the plugin here. Keep required Web IDL boundary types and browser checks. Document the schema JSON/type mismatch instead of claiming an unchecked cast is safe. Reference: https://webidl.spec.whatwg.org/#es-sequence Validation: 100 browser tests, lint, build, typecheck, packed consumer, formatting, and diff checks pass. WPT: 58 files / 139 subtests, no unexpected results (72 pass, 23 expected fail, 25 expected timeout, 19 expected notrun).
Use plain conditionals for schema serialization, title conversion, and the Permissions Policy fallback. Each step now reads in execution order without mixing an optional value, conversion, and fallback into one expression. Preserve the existing undefined/null checks and property access order. Validation: lint, build, typecheck, 100 browser tests, packed consumer, formatting, and WPT pass with no unexpected results. All 29 previously documented anti-slop diagnostics are unchanged.
Calling a toolchange handler through its own call property skips valid callbacks when authors shadow that property. Invoke it with Reflect.apply, and honor a false return value by cancelling cancelable events. Both bugs were reproduced against native Chromium and are covered by browser tests. Use the same direct invocation for origin iterators instead of the less readable Function.prototype.call.bind workaround. Keep concise conditional assignments and remove workflow labels from the remaining comments. References: https://html.spec.whatwg.org/multipage/webappapis.html#event-handler-processing-algorithm https://webidl.spec.whatwg.org/#es-sequence Validation: pnpm test (106 browser tests), pnpm test:package, formatting, and git diff --check passed. Pinned WPT ran 58 files and 139 subtests with no unexpected results: 72 PASS, 23 expected FAIL, 25 expected TIMEOUT, and 19 expected NOTRUN. All 22 IDL subtests passed.
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Separate the implementation, local tests, and upstream WPT runner into src/, tests/, and wpt/ so contributors can find each part without scanning the repository root. Run the Node scripts directly as TypeScript on Node 24 and include them, plus the browser fixture JavaScript, in strict type checking. Update CI, documentation, and ignored cache paths while keeping the package entry points and WPT expectations unchanged. Use the caller signal and native promise settlement instead of duplicate execution state. Share USVString conversion and load the official global types through the test config. Preserve a reflexive sort comparator and cover cancellation during result serialization, before queued delivery. References: https://nodejs.org/docs/latest-v24.x/api/typescript.html#type-stripping https://webidl.spec.whatwg.org/#es-USVString https://tc39.es/ecma262/multipage/indexed-collections.html#sec-sortindexedproperties https://webmachinelearning.github.io/webmcp/#dom-modelcontext-executetool Validation: lint, type checking, formatting, 109 browser tests, and the packed-consumer checks passed. Pinned WPT ran 58 files and 139 subtests with no unexpected results: 72 PASS, 23 expected FAIL, 25 expected TIMEOUT, and 19 expected NOTRUN. All 22 IDL subtests passed.
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Still in WIP but getting closer to something ready for review. Below is AI generated and will change:
This adds document-local WebMCP registration, discovery, and execution, combining the original implementation with the execution work in #2. It follows the Community Group draft and uses released
webmcp-types@0.1.8after the upstream execution types merged; the temporary type augmentation is removed.The package provides
registerTool(),getTools(),executeTool(), andontoolchangeondocument.modelContext. Registration signals unregister tools. Execution takes object input, returns JSON-serialized results, and gives each callback a separate cancellation signal. Installation preserves existing native implementations. Event handlers and iterators are invoked without consulting author-defined function properties. A handler returning false cancels cancelable events, matching native behavior.Review follow-ups
WebMCPin both browser runners; remove the obsoleteWebMCPTestingflag. WPT comment, Playwright commentimperative/getTools.https.html, with standard WPT expectation files. Unexpected passes and failures fail the run. Coverage comment, expectations commentValidation and scope
1a21db9on Chrome Canary 156.0.8062.0 runs 58 files and 139 subtests: 72 PASS, 23 expected FAIL, 25 expected TIMEOUT, and 19 expected NOTRUN. All 22 IDL subtests pass; there are no unexpected results. Non-testharness tests are outside this lane.df2d824.Tools remain in their registering document. Cross-document routing, declarative forms, lifecycle events, and exact native task/policy behavior are unsupported or approximated. Known draft/WPT disagreements and all limitations are recorded in TESTING.md; this does not claim full conformance.
Extension integration remains separate in #3.