Constant SERVER_EVENT_CHANNEL_CAPACITY 

pub const SERVER_EVENT_CHANNEL_CAPACITY: usize = 1024; // 1_024usize

Bounded broadcast capacity for the event-notification channel — mirrors crate::mcp::MCP_SSE_CHANNEL_CAPACITY’s bounded-buffering discipline (P5-2): a slow/absent subscriber can never make the sender block or grow memory unboundedly; a lagging receiver just misses old events (broadcast::error::RecvError::Lagged) rather than stalling the agent loop or accumulating unbounded backlog.