## Why
A temporary exec-server transport loss could emit a thread environment disconnect notification while the session was still recovering.
## What changed
- Add `EnvironmentConnectionState::Recovering` for interrupted transports and pending session recovery.
- Suppress thread lifecycle notifications during recovery, emit a connected notification after successful recovery, and report disconnection when recovery fails.
- Ignore recovery callbacks from retired clients so they cannot overwrite the connection state during refresh.
## Testing
Add coverage for fast and near-deadline recovery, recovery timeout, rejected session resume, and retired-client callbacks. Extend app-server coverage to verify one lifecycle notification per selected thread and usable `environment/info` after recovery.
GitOrigin-RevId: d6dce5cc5264af29b6f993daa209b93102122e40
## What changed
Add the `codex-multi-env-copy-file` extension, exposing `multi_env_copy_file` when registered by the host. Copy files between distinct selected environments without loading their contents into model context, and return `bytes_copied` on completion.
Require absolute paths in each environment's native path convention and enforce each endpoint's sandbox policy and permission grants. Stream file contents where supported, with a buffered fallback for older executors. Reject same-environment copies and report I/O error kinds without exposing connection details. Warn that failed writes may leave a truncated or partially written target.
## Testing
Add integration tests for binary transfers in both directions, local and remote executors, path validation, opt-in tool visibility, endpoint permissions and grants, and unavailable or disconnected executors. Verify that copied contents stay outside model context.
GitOrigin-RevId: f5d9e423d105019834e0288828cb68c5711b3a49
richardopenai