## What changed
- Cache an `McpBinding` on each published MCP runtime once server startup has
settled and the tool catalog revision is stable.
- Reuse the cached binding while the catalog revision remains unchanged, and
rebuild it after a runtime publish or catalog change.
- Treat terminal failures from optional servers as stable, while continuing to
wait for required servers and reconnecting Codex Apps servers.
## Testing
- Cover binding reuse within one published runtime and invalidation after a
republish.
- Cover stability checks for pending, failed optional, required, and
reconnected servers.
GitOrigin-RevId: 783a6b04897f6c484a6d56fd9cee542814041759