feat(federation): dmOriginFailover utility (rekey + failover)

failoverDmOriginsFromDisconnected(origin) walks pinned DMs and re-keys them to a connected sibling origin's local channel id (via dmAlternatives federatedId lookup). Preference: home first, then any connected remote in insertion order. rekeyDmChannel performs the atomic rename across spaceStore (dmChannels / channelOriginMap / channelLastMessageIds / dmAlternatives), chatStore (via rekeyChannelState), and the URL (via history.replaceState when viewing the rekeyed DM). Voice state is intentionally untouched — LiveKit sessions can't migrate across origins. Old origin's local id is retained in dmAlternatives for possible later fail-back without another ready round-trip.
2026-04-23 01:13:48 +02:00
parent 678790b88b
commit d393a870c2
2 changed files with 441 additions and 0 deletions
@@ -0,0 +1,127 @@
+import { useSpaceStore } from '../stores/spaceStore';
+import { useChatStore } from '../stores/chatStore';
+import { useInstanceStore } from '../stores/instanceStore';
+
+/**
+ * DM origin failover: when a remote instance disconnects mid-session,
+ * re-point every DM pinned to it onto a connected sibling that holds the
+ * same federated DM (via S2S mirroring). See
+ * `docs/superpowers/specs/2026-04-23-dm-origin-failover-design.md`.
+ *
+ * No-op when:
+ *  - no DMs are pinned to the disconnected origin
+ *  - pinned DMs have no `federatedId` (never-federated)
+ *  - no alternative origin is currently connected
+ *
+ * Voice state (activeDmCall / outgoingCall / incomingCall) is intentionally
+ * NOT rewritten — a LiveKit session bound to the disconnected origin cannot
+ * migrate; voice cleans up through its own disconnect paths.
+ */
+export function failoverDmOriginsFromDisconnected(disconnectedOrigin: string): void {
+  const spaceState = useSpaceStore.getState();
+  const { dmChannels, channelOriginMap, dmAlternatives } = spaceState;
+
+  // Build the set of connected-origin candidates (home is always considered
+  // connected while auth is live — its WS disconnect path doesn't go through
+  // instanceStore at all).
+  const instances = useInstanceStore.getState().instances;
+  const connectedRemotes = new Set(
+    instances.filter(i => i.status === 'connected').map(i => i.origin),
+  );
+  const isOriginConnected = (o: string): boolean => o === '' || connectedRemotes.has(o);
+
+  type Rekey = { oldId: string; newId: string; newOrigin: string; federatedId: string };
+  const rekeys: Rekey[] = [];
+
+  for (const dm of dmChannels) {
+    if (channelOriginMap.get(dm.id) !== disconnectedOrigin) continue;
+    if (!dm.federatedId) continue;
+
+    const byOrigin = dmAlternatives.get(dm.federatedId);
+    if (!byOrigin) continue;
+
+    // Preference order: home ('') first, then any connected remote in
+    // insertion order (Map preserves insertion order in ES2015+).
+    let chosenOrigin: string | null = null;
+    let chosenLocalId: string | null = null;
+    if (byOrigin.has('') && isOriginConnected('') && '' !== disconnectedOrigin) {
+      chosenOrigin = '';
+      chosenLocalId = byOrigin.get('')!;
+    } else {
+      for (const [altOrigin, altLocalId] of byOrigin) {
+        if (altOrigin === disconnectedOrigin) continue;
+        if (!isOriginConnected(altOrigin)) continue;
+        chosenOrigin = altOrigin;
+        chosenLocalId = altLocalId;
+        break;
+      }
+    }
+    if (chosenOrigin === null || chosenLocalId === null) continue;
+    if (chosenLocalId === dm.id) continue; // shouldn't happen, but guard
+
+    rekeys.push({
+      oldId: dm.id,
+      newId: chosenLocalId,
+      newOrigin: chosenOrigin,
+      federatedId: dm.federatedId,
+    });
+  }
+
+  if (rekeys.length === 0) return;
+
+  for (const r of rekeys) {
+    rekeyDmChannel(r.oldId, r.newId, r.newOrigin, r.federatedId);
+  }
+}
+
+/**
+ * Atomic rename of a DM across spaceStore + chatStore + URL.
+ * Exported for unit tests; not part of the public failover API.
+ */
+export function rekeyDmChannel(
+  oldId: string,
+  newId: string,
+  newOrigin: string,
+  federatedId: string,
+): void {
+  useSpaceStore.setState((state) => {
+    const dmChannels = state.dmChannels.map(dm =>
+      dm.id === oldId ? { ...dm, id: newId } : dm,
+    );
+
+    const channelOriginMap = new Map(state.channelOriginMap);
+    channelOriginMap.delete(oldId);
+    channelOriginMap.set(newId, newOrigin);
+
+    const channelLastMessageIds = new Map(state.channelLastMessageIds);
+    channelLastMessageIds.delete(oldId); // old id's stored last-message id is origin-local
+
+    // dmAlternatives update: remove the chosen origin's entry from the inner map
+    // (it IS the primary now — not an alternative), but RETAIN every other origin's
+    // entry including the old origin (so a later fail-back can use it without
+    // needing another ready round-trip).
+    const dmAlternatives = new Map<string, Map<string, string>>();
+    for (const [fid, byOrigin] of state.dmAlternatives) {
+      const next = new Map(byOrigin);
+      if (fid === federatedId) next.delete(newOrigin);
+      if (next.size > 0) dmAlternatives.set(fid, next);
+    }
+
+    return { dmChannels, channelOriginMap, channelLastMessageIds, dmAlternatives };
+  });
+
+  useChatStore.getState().rekeyChannelState(oldId, newId);
+
+  // URL update: if the user is viewing the DM whose id just changed, swap the
+  // last path segment in place. No router navigation — the chat view re-renders
+  // from the updated currentChannelId.
+  if (typeof window !== 'undefined') {
+    const path = window.location.pathname;
+    const marker = `/channels/@me/`;
+    const idx = path.indexOf(marker);
+    if (idx !== -1 && path.slice(idx + marker.length) === oldId) {
+      const nextPath = path.slice(0, idx + marker.length) + newId;
+      window.history.replaceState(window.history.state, '', nextPath + window.location.search);
+    }
+  }
+}