Event Bus

Async pub/sub event system with wildcard support.

Lightweight async pub/sub event bus for decoupling system components.

The EventBus is the primary mechanism for loose coupling between the orchestrator, hook engine, and notification subsystem. Components subscribe to named event types (e.g., "task_completed", "agent_failed") and receive async callbacks when those events are emitted.

A special wildcard subscription ("*") receives every event regardless of type. The hook engine uses this to evaluate all events against its trigger conditions without needing individual subscriptions per event type.

See specs/event-bus.md for the full specification.

Classes

EventBus

EventBus()

Async event dispatcher with named channels and wildcard support.

Handlers are invoked sequentially in subscription order. Both sync and async handlers are supported — sync handlers are called directly while async handlers are awaited.

Source code in src/event_bus.py

def __init__(self):
    self._handlers: dict[str, list[Callable]] = defaultdict(list)