- Added `concurrency` option to `AgentTool` interface supporting 'shared' (default, parallel execution) and 'exclusive' (solo execution) modes.
- Implemented parallel execution of shared tools within a single agent turn with ordered result emission.
- Refactored tool execution to support concurrent scheduling with interrupt handling via steering messages and AbortSignal.
- Added steering message checking mechanism that interrupts tool execution when user messages arrive during tool processing.
- Removed HTTP proxy setup code from stream.ts that was conditionally setting up undici global dispatcher.