## Why
Holding the session MCP gate during `tools/list` blocks other runtime access. Releasing it requires preventing stale refresh results from publishing after configuration or authentication changes.
## What changed
- Capture the Apps client under the session gate, then release the gate before fetching tools.
- Validate runtime and authentication state before publishing the shared cache and client catalog; retry a superseded refresh once.
- Wait for in-flight Apps refreshes before capturing model tools, preparing Apps calls, or shutting down the runtime.
## Testing
Add regression coverage for stale refreshes after runtime invalidation or logout, publication validation after call preparation drains, and a model step that waits for refreshed Apps tools while MCP status queries remain available.
GitOrigin-RevId: 42d4be8c4a9218933f8e3d07fc7f32f2da9cbd9d
