# Architecture

Internal architecture notes for major runtime mechanisms and subsystem design.

- [Steering](steering.md): injecting messages into a running agent loop between tool calls.
- [SubTurn Mechanism](subturn.md): sub-agent coordination, concurrency control, and lifecycle handling.
- [Hook System Guide](hooks/README.md): current hook architecture and protocol details.
- [Agent Refactor](agent-refactor/README.md): notes and checkpoints for the agent refactor work.

For proposal-style or exploratory docs, also see [`../design/`](../design/).