test(mcp): many slow initialize roots share one discovery budget

[ScriptedAlchemy]

Summary

• MCP initialize already shares one repository-discovery deadline across roots. This test proves three slow roots cannot stack a fresh timeout each.
• The shared miss is deadline exceeded, not an unregistered project.

Test plan

• cargo test -p tracedecay --lib mcp::server::routing::tests::many_slow_initialize_roots_share_one_discovery_budget -- --exact passed, 1 test in 3.77s (cc-23361)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 601c7ac

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-17T17:10:30.699643Z	601c7ac	PR opened

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" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.