- Remove redundant ChannelSender interface, use *bus.MessageBus directly - Consolidate two handlers (onHeartbeat, onHeartbeatWithTools) into one - Move HEARTBEAT.md and heartbeat.log to workspace root - Simplify NewHeartbeatService signature (remove handler param) - Add SetBus and SetHandler methods for dependency injection Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>