Worker Protocol

1. Orient: Call kanban_show() first to get task state and prior attempts
2. Work: Execute in $HERMES_KANBAN_WORKSPACE
3. Heartbeat: Call kanban_heartbeat(note=...) every few minutes for long operations
4. Block or Complete:
   • kanban_block(reason=...) for genuine blockers
   • kanban_complete(summary=..., metadata=...) when done
5. Never exit silently - always call block or complete