Reprobe once for health request

[RunningLeon]

Motivation

Reprobe once if the cached state is unhealthy

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[Copilot]

Pull request overview

This PR updates LMDeploy’s server health behavior so the /health endpoint can proactively refresh a cached unhealthy snapshot by triggering a new backend health probe, and adds unit tests for the new monitor and endpoint behavior.

Changes:

• Added EngineHealthMonitor.refresh_snapshot() and serialized probing via an internal asyncio lock.
• Updated the OpenAI API server /health route to refresh the snapshot when the cached status is not healthy/sleeping.
• Introduced new unit tests covering snapshot refresh, probe serialization, and /health refresh behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
lmdeploy/serve/core/health.py	Adds probe serialization and a refresh_snapshot() helper to update/return the cached health snapshot.
lmdeploy/serve/openai/api_server.py	Updates /health endpoint to optionally refresh cached health state before responding.
tests/test_lmdeploy/serve/test_health_monitor.py	Adds unit tests validating refreshed unhealthy snapshots, serialized probes, and refreshed /health responses.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.