New subsection under client-federation.md's origin-aware routing section
covering dmAlternatives, failoverDmOriginsFromDisconnected, rekey flow,
trigger points, the intentional cache-flush trade-off, voice-out-of-scope,
no-re-home policy, and the WS routing contract. dm-system.md gets a
one-line cross-reference from the Client routing bullet.
The client-side federation model (instanceStore, federated accounts,
multi-instance connections, origin-aware routing) was completely
undocumented. An agent reading only federation.md would understand S2S
relay but have no knowledge of how the client connects to multiple
instances, creates federated accounts with real credentials, or routes
API/WS calls to the correct instance.
New spec covers: instanceStore architecture, federated account creation
(username@instance format), Connections UI, auto-connect lifecycle,
channelOriginMap routing, WebSocket multiplexing, cross-instance
identity resolution, and the relationship between client-side and S2S
federation.
CLAUDE.md subsystem table updated. Both federation docs cross-reference
each other.