feat(mcp): expose the existing thread search query

[juliusmarminge]

Part 11/16 of the shared-core and MCP stack. Based on #10560. Next: #10562.

Expose the existing bounded searchThreads query and return only matches from the calling project.

This filters the global top results, so a project can underfill the requested limit. It is not exhaustive or paginated. Project-first SQL pagination and search-service correctness changes belong in a separate service PR.

MCP-only rebuild of #8721, #8722, preserving attribution to Julius Marminge's original work. Original branches remain available for separate service follow-ups.

Validation: The composed stack passes 94 tests across 12 focused files, including shared core MCP and real MCP/V2 integration, attachment intake, project RPC/service contracts, and client model command selection. Server/contracts/shared/client-runtime typechecks and targeted format/lint/diff checks pass. New behavior coverage lives with the shared operation; no per-tool mock suite was added. Current-head CI is shown below.

Layer size: 4 files, +32/-1. No domain-service production implementation or documentation files change in this MCP layer.

Prepared with Codex in the OpenAI agent runtime.

[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for 6342c1c.

This comment will update automatically after the next completed run.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds a production MCP capability that exposes thread-content search and broadens the default read-only Claude tool allowlist. The query is bounded and project-scoped, but the default capability change warrants human review.

No code changes detected at 6342c1c. Prior analysis still applies.

^{You can add or adjust custom eligibility rules. Learn more.}

[cursor]

Bugbot is paused — on-demand spend limit reached

Bugbot uses usage-based billing for this team and has hit its on-demand spend limit.

A team admin can raise the spend limit in the Cursor dashboard, or wait for the next billing cycle to continue.