- Create gateway/sync.go with initialSync method on WSClient
- Fetch agents via agents.list RPC, persist to AgentRepo
- Fetch sessions via sessions.list RPC, map status to AgentStatus
- Merge session state (status, sessionKey, tokens) into AgentCardData
- Broadcast merged fleet as fleet.update via SSE broker
- Trigger initialSync after hello-ok handshake
- Re-sync automatically on reconnect (connectAndRun calls initialSync)
- Handle unknown gateway fields gracefully via typed extraction