Fix DocumentationSearch asset compatibility recovery

[lynnswap]

Purpose

Recover DocumentationSearch when Xcode advertises the tool but its selected documentation asset cannot initialize the text embedding model.

The proxy previously treated the latest installed documentation asset as universally executable and passed through Text encoding failed tool errors without attempting the installed-asset recovery path.

Changes

• Classify confirmed text encoder and embedding-model initialization failures as documentation provider failures.
• Exclude assets that require a newer host OS, rank the remaining assets for the target Xcode and host OS, retry only the confirmed model-initialization failure family within the original request deadline, and remember the successful candidate.
• Use the same host-compatible selection when repairing Xcode's documentation search configuration, and skip the persistent defaults write when no eligible asset exists.
• Reject nonpositive search timeouts before invoking the helper.
• Preserve an installed-asset fallback when a concurrent stale native response completes later, and retire stale routes only after their canonical owner changes.
• Add regression coverage for asset eligibility, selection, retry boundaries, success caching, provider replacement, and concurrent promotion.

Testing

• swift test --filter DocumentationProviderTests -Xswiftc -strict-concurrency=minimal (126 tests)
• scripts/check.sh:
  • swift test --no-parallel -Xswiftc -strict-concurrency=minimal (1,033 tests)
  • XCODE_MCP_RUN_PROCESS_TESTS=1 swift test --no-parallel --filter XcodeMCPProcessRuntimeTests -Xswiftc -strict-concurrency=minimal (24 tests)
  • XCODE_MCP_RUN_PROCESS_TESTS=1 swift test --no-parallel --filter ProxyStdioAdapterTests -Xswiftc -strict-concurrency=minimal (13 tests)
• git diff --check
• Two live EstimationTechnique searches against an isolated branch server; both returned OK with the Vision documentation result.
• Branch-wide Codex review against the pinned main base completed with no findings after four rounds.

[chatgpt-codex-connector]

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Reviewed commit: cfc4319c28

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[lynnswap]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: 2c0710c3c7

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".