[Eduardo Villalpando Mello (edvilme)]

Fixes #139.

Summary

Restore the formatter fallback after the old client's stop settles and while replacement startup is pending, without adding it while the old client is still healthy.

• Add an optional synchronous onOldClientStopped notification to restartServer, called before replacement creation only when the old client is Stopped after its stop attempt settles.
• Restore the context-owned fallback through that notification only while the context is undisposed. Keep the existing healthy-replacement removal boundary, disposal guards, retry semantics, status behavior, and continue-on-stop-error behavior.
• Update the existing lifecycle characterization and add focused failure/disposal regressions using real createToolContext + restartServer orchestration, the shared client mock, and explicit deferred stop/start barriers. No shared mock changes.

The supported languageclient 8.1.0 implementation emits public Stopped when shutdown begins, before disposing feature registrations. Waiting for stop to settle avoids relying on that premature state event or keeping stale client/status listeners alive.

Validation

Runtime: Node 24.17.0 / npm 11.13.0.

• Reproduced the gap before the production fix: three regression failures, each observing one fallback registration instead of the expected second registration while replacement startup was held.
• Focused lifecycle tests: 47 passed.
• Full TypeScript suite: 160 passed.
• TypeScript build: passed.
• Production lint and changed-test ESLint: passed with existing warnings.
• git diff --check: passed.
• Changed-file Prettier check still reports formatting issues in all three changed files; each file also fails on the exact baseline. Unrelated formatting was left unchanged.

Live VS Code formatter-picker behavior was not verified in an extension host. These tests establish lifecycle/provider ownership, not visible picker behavior.

[Rich Chiodo (rchiodo)]

🔒 Automated review in progress — Rich Chiodo (@rchiodo) is auto-reviewing this PR.

[Rich Chiodo (rchiodo)]

Reviewed commit: 14d2e3c47c601beab7ea50055885aa661ad46be1

Result: 🔴 could-not-verify

Verification details

Verification: Automated verification is best effort. The PR author remains responsible for testing.

Summary: [unavailable] Container verification could not start and local execution was not authorized for this PR HEAD: Podman machine 'pyrx-automation' is not running.

Test runs: none recorded.

[Rich Chiodo (rchiodo)]

Approved via Review Center.