## Why
Some hosts assign a worker per connection. Idle connection eviction can prevent a quiet session from reaching the worker holding its lease, while retaining a connection after the last session closes unnecessarily keeps that worker allocated.
## What changed
- Disable the HTTP connection pool idle timeout for gRPC code-mode connections.
- Cache URL-based clients weakly and let live sessions own the shared client, releasing their ownership on closure or failure even while the provider remains alive.
- Acquire clients for deferred RPCs only when needed and return the session error if the client has already been released.
## Testing
Add regression tests that verify connection reuse and stored state after 120 seconds of inactivity, and connection closure after the last shared session fails while the provider and session handles remain alive.
GitOrigin-RevId: bd1ff00c4003c03ed173c23dd2ed373ed354ab65
Alex Kotliarskyi
f6a69b5873