Fix live activity replay expiry and same-identity registration retry

- Skip replay delivery when the aggregate is null but non-terminal rows
  remain: an all-expired row set is ambiguous (dead environment vs. a
  healthy long-running agent whose meaningful state has not changed), so
  ending the Live Activity on foreground could kill a healthy activity.
- Only skip device re-registration for an unchanged identity when the
  previous attempt actually registered with the relay, so failed or
  stalled registrations retry when the auth effect re-runs.

Author: cursoragent

apps/mobile/src/features/agent-awareness/remoteRegistration.ts

@@ -186,7 +186,11 @@ export function setAgentAwarenessRelayTokenProvider(
     refreshActiveLiveActivityRemoteRegistration(),
     "active live activity registration after cloud sign-in failed",
   );
-  if (isExistingIdentity) {
+  // An unchanged identity only skips re-registration when the previous attempt
+  // actually reached the relay; a failed or stalled attempt must retry the next
+  // time the auth effect re-runs, or the device stays unregistered until an
+  // unrelated event (token rotation, environment link) happens to enqueue one.
+  if (isExistingIdentity && registrationStatus === "registered") {
     return;
   }
   enqueueDeviceRegistration({}, "device registration after cloud sign-in failed");

infra/relay/src/agentActivity/AgentActivityPublisher.ts

@@ -119,6 +119,16 @@ export const make = Effect.gen(function* () {
         terminalState: null,
         nowMs: now.epochMilliseconds,
       });
+      // A null aggregate is ambiguous while non-terminal rows still exist:
+      // they may belong to a dead environment, or to a healthy long-running
+      // agent whose meaningful state (and therefore updatedAt) has not changed
+      // within the TTL. Sending in that case would end a possibly-healthy Live
+      // Activity on every foreground, so replay only delivers when live rows
+      // remain or the rows are truly gone (the thread ended and its end push
+      // may have been lost).
+      if (aggregate === null && activeStates.some((state) => !isTerminalPhase(state))) {
+        return null;
+      }
       return yield* apnsDeliveries.sendForTarget({
         target,
         aggregate,