## 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
## Why
Host-side truncation can bound Code Mode output before it crosses the transport, including script errors that would otherwise exceed the frame limit.
## What changed
- Negotiate server-side output truncation for stdio and gRPC sessions, with client-side fallback for older hosts.
- Forward output budgets for execution, waiting, and termination when server-side truncation is selected. Avoid truncating host-formatted output or appending script errors a second time.
- Preserve the negotiated mode across reconnects and reject hosts that cannot maintain it.
## Testing
Add transport and integration coverage for output budgets, oversized script errors, reconnect compatibility, and preservation of output-limit notices with a zero-token budget.
GitOrigin-RevId: 2075101e4845eca64f45491c27a3b326788645c8
## Why
Replacing a gRPC code-mode runtime loses stored values and running cells. Silently continuing after reconnection hides that loss, while prior external tool operations may already have completed.
## What changed
- Capture the runtime generation when `execute` and `wait` calls are created. If recovery replaces it, reject those calls with an explicit reset error, including concurrent calls and calls first polled after recovery.
- Explain the lost state and advise inspecting prior tool results before retrying. Allow a fresh `exec` call to continue on the replacement runtime.
- Keep `terminate` from reopening the runtime so cleanup cannot hide a reset from the next request.
## Testing
Extend gRPC recovery tests to cover reset errors after host restarts, missing sessions, and route loss, rejection of queued calls, and successful fresh execution with cleared stored state.
GitOrigin-RevId: 914cab3bb45e30a3f3b2afacb5631e42b18e21b0
## Why
Sessions sharing a transport can be admitted to different hosts. Each session needs its own routing token so subsequent RPCs reach the host holding its state.
## What changed
- Capture the optional `x-code-mode-route` metadata from successful `OpenSession` responses and attach it to subsequent session RPCs. Reject tokens longer than 256 bytes and keep new admission attempts free of existing session routes.
- Invalidate a routed session when an `Unavailable` response explicitly sets `x-code-mode-route-lost: true`, allowing a later operation to reopen it without replaying the failed execution. Ordinary `Unavailable` responses preserve the session.
- Allow up to five admission attempts for `Unavailable` and `ResourceExhausted`, with an immediate first retry followed by jittered exponential backoff.
- Order session failure with shutdown so late callback errors cannot cancel an in-flight `CloseSession` RPC.
## Testing
Add regression coverage for independent routing on a shared provider, route-loss recovery without execution replay, preservation of unaffected session state, and callback failures racing shutdown. Extend admission tests to verify the five-attempt limit and recovery tests to distinguish explicit route loss from ordinary unavailability.
GitOrigin-RevId: 5d60ef1afa56beb8c70ba7ab27865128225b0d3d
## Why
A host can reject a request for an unknown session while its lease streams remain open. Keeping that session binding prevents subsequent execution from recovering.
## What changed
Invalidate the session when `Execute` (including its response stream), `Wait`, or `Terminate` returns `NOT_FOUND`, allowing the next execution to open a fresh session. Return the failed call's error without replaying execution.
Document that these RPCs reserve `NOT_FOUND` for unknown sessions, while `CompleteToolCall` can use it for a missing invocation.
## Testing
Add regression coverage for recovery with lease streams still open, no replay of failed execution, and preservation of session state after `INVALID_ARGUMENT`. Add a cancellation-race test confirming that a late tool-completion `NOT_FOUND` leaves the session open.
GitOrigin-RevId: 85b38fdbd6d59268447b6aa6a85ea7c60ec869a7
Alex Kotliarskyi