API Overview

Orchestrator Service (FabricManagerService)

RPC	Description
QueryPhysicalTopology	Returns the aggregated physical topology (all ASICs, connectivity graph, host-to-rank mapping) from healthy agents. Request may set hosts to restrict to specific host IDs; empty means all healthy hosts. topo_source selects the connectivity source: PSD (default) uses the connectivity discovered by the agents, FSD derives connectivity from the controller-configured Factory System Descriptor (“golden state”) while keeping ASIC descriptors from the live PSD
GetValidPlacementsMGD	Accepts a Mesh Graph Descriptor (MGD textproto) and returns valid host-to-ASIC assignments using CSP-based mapping. Supports constraints: host ID filtering and ASIC pinning. topo_source selects whether placement uses the discovered Physical System Descriptor (PSD, default) or the configured Factory System Descriptor (FSD, “golden state”) for connectivity

Daemon Service (DaemonService)

RPC	Description
RegisterDaemon	Agent registers its host physical topology (ASICs, local connections, exit nodes) with the controller
HeartbeatStream	Bidirectional streaming RPC for keepalive. Controller NACKs trigger re-registration. Hosts are marked offline after timeout