Update dependency @mcp-b/webmcp-polyfill to v5

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
@mcp-b/webmcp-polyfill (source)	4.0.0 → 5.1.0

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Release Notes

WebMCP-org/npm-packages (@​mcp-b/webmcp-polyfill)

v5.1.0

Compare Source

Patch Changes

• @​mcp-b/webmcp-types@5.1.0

v5.0.3

Compare Source

Patch Changes

• @​mcp-b/webmcp-types@5.0.3

v5.0.1

Patch Changes

• @​mcp-b/webmcp-types@5.0.1

v5.0.0

Major Changes

• de0b41c: Adopt the current strict WebMCP lifecycle. ESM initialization is explicit,
  testing support is opt-in, unsupported cross-document options fail closed, and
  declarative forms stay synchronized with the document and open shadow roots.

• f80daeb: Return RegisteredTool.inputSchema from getTools() as a JSON Schema object
  instead of a serialized string, following webmcp#241 and Chrome 154.0.8013.
  The polyfill and the standalone BrowserMcpServer both parse a fresh object
  per call, exactly like Blink parsing its serialized copy; a schema whose
  custom toJSON serializes to non-object JSON is omitted rather than surfaced
  as a value consumers would mistake for a pre-154 serialized string.

  Consumers stay compatible with both generations of Chrome: the browser-server
  native backfill and the relay embed accept the object shape from new Chrome and
  the string shape that the 149–156 Origin Trial population still returns. The
  RegisteredTool.inputSchema type widens to InputSchema | string to make that
  branching explicit.

  Before this, Chrome ≥154.0.8013 broke native tool mirroring entirely:
  JSON.parse on the new object threw, and every native tool — including
  child-frame tools — was dropped as malformed.

Patch Changes

• de0b41c: Match Chrome's observable API shape, so webmcp/idlharness.https.window.html
  now passes 20/20 subtests against the polyfill.

  document.modelContext is a getter on Document.prototype rather than a value
  property on the document instance, as WebIDL's [SameObject] readonly attribute
  requires. Feature detection with 'modelContext' in document and reads of
  document.modelContext are unaffected; code that inspected the document's own
  property descriptor — Object.hasOwn(document, 'modelContext') or
  Object.keys(document) — must look at Document.prototype instead.

  The context object also stops leaking its internals: bookkeeping fields and
  helpers are #private or static, so only registerTool, getTools,
  executeTool and ontoolchange appear on the prototype, and the polyfill's own
  marker property is non-enumerable so instances spread and stringify like
  Chrome's. registerTool, getTools and executeTool report the length
  WebIDL specifies (1, 0, 2); their behavior is unchanged.

• de0b41c: Report SubmitEvent.agentInvoked only for submissions a declarative tool call
  started. Ordinary user submissions no longer claim agent attribution, so
  respondWith() throws InvalidStateError outside a running tool call. Submit
  listeners now share the per-root lifecycle that already owns reset listeners.

• de0b41c: Require Node 20 or newer. @mcp-b/global, @mcp-b/mcp-iframe,
  @mcp-b/webmcp-polyfill and @mcp-b/webmcp-ts-sdk previously allowed Node 18;
  the rest declared no engines range at all and now state the same floor. Node 18
  reached end of life in April 2025. Browser builds are unaffected — this governs
  build tooling and the relay CLI.

• de0b41c: Stop emitting declaration source maps, and ship the MIT LICENSE text these
  packages already declared. Each package shipped dist without src, so every
  published .d.ts.map pointed at a file that was not in the tarball; editors
  already fall back to the .d.ts itself. @mcp-b/webmcp-types keeps its maps —
  it is the one package that ships src, so its maps resolve.

• f1dbaa0: Align declarative form execution with Chromium and the upstream Web Platform
  Tests. Autosubmit now preserves native event ordering, opaque documents report
  their effective origin, and the composed runtime forwards behavior-only form
  registration changes.

• Updated dependencies [de0b41c]

• Updated dependencies [de0b41c]

• Updated dependencies [de0b41c]

• Updated dependencies [f80daeb]

  • @​mcp-b/webmcp-types@5.0.0

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