- SsePayloadSigner signs JSON payloads and adds signature field before SSE delivery - SseConnectionManager signs all command payloads via SsePayloadSigner before sendEvent - Signed payload parsed to JsonNode for correct SseEmitter serialization - Integration tests use bootstrap token + JWT auth (adapts to Plan 02 security layer) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>