fix(client): keep tool metadata intact when a listTools() refresh fails (v1.x)

[harshasiddartha]

Fixes #2614.

What's broken

cacheToolMetadata() clears _cachedToolOutputValidators, _cachedKnownTaskTools and _cachedRequiredTaskTools before it starts compiling the replacement catalog. If a later tool's outputSchema fails to compile, listTools() rejects as expected — but the caches have already been wiped or partially overwritten.

The client is then left in a worse state than before the refresh: callTool() finds no validator for tools that previously had one and silently skips output validation, and tools marked taskSupport: "required" are no longer recognised as such.

Change

Build the replacement Map/Set locally and assign them only after every tool has been processed. A failed refresh now leaves the metadata from the last successful listTools() in effect.

Test

Added a regression test to test/client/index.test.ts under outputSchema validation: it lists a catalog containing a tool with an output schema and a taskSupport: "required" tool, then serves a second catalog whose output schema fails to compile, and asserts both pieces of metadata are still enforced afterwards.

Without the source change it fails with:

AssertionError: promise resolved "{ content: [], …(1) }" instead of rejecting

npm test (1640 tests), npm run typecheck, npm run lint and npm run build all pass.

Scope

This is deliberately limited to the failure-atomicity of the cache write. The separate validator-lookup ordering issue in #2612 (callTool() resolving the validator after awaiting the response) is untouched — the two changes are in different methods and don't conflict.

Targeting v1.x since the reported behaviour is in the v1 client; main no longer has this code path.

[pkg-pr-new]

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npm i https://pkg.pr.new/@modelcontextprotocol/sdk@2618

commit: a0350ac

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