Per-agent SSE (metadata-only new_message events, id=message_id, 30s heartbeat, Last-Event-ID replay capped at 200 with resync_required, max 5 connections per agent, slow clients dropped). Mounted behind the agent API-key middleware. /api/events is unchanged. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>