Cross-plugin agent-status accessor for use by Fabric.OpenclawPlugin's
presence-sync loop (and any future plugin needing 'is agent X busy
right now'). Backed by CalendarBridgeClient.getAgentStatus() with a
30s in-memory TTL cache to avoid hammering the HF backend.
Returns one of 'idle' | 'on_call' | 'busy' | 'exhausted' | 'offline'
or undefined when the agent isn't known to HF. Cache miss + bridge
failure returns the last cached value (stale-data better than no
data for delivery-decision use cases).
Part of DIALECTIC-V2 Phase 1 (Fabric announce channel + busy-discard).
See /home/hzhang/arch/DIALECTIC-V2-DESIGN.md sections 7+8.
hzhang
709f7e09ab