feat(app): restore recent chat while reconnecting (#2206)

Keep a small non-authoritative view of the last focused chat so the app can paint it before the daemon finishes revalidation. Bound persistence to one focused agent per host and evict whole host entries to limit storage and serialization work.

packages/app/src/hooks/use-agent-screen-state-machine.ts

@@ -150,9 +150,11 @@ function resolveCatchingUpUi(args: {
   hasOptimisticCreateContinuity: boolean;
   isVisibilityCatchUpPending: boolean;
   hasHydratedHistoryBefore: boolean;
+  needsAuthoritativeSync: boolean;
   hadInitialSyncFailure: boolean;
 }): "overlay" | "silent" {
   if (args.hasOptimisticCreateContinuity) return "silent";
+  if (args.hasHydratedHistoryBefore && args.needsAuthoritativeSync) return "silent";
   if (args.isVisibilityCatchUpPending) return "overlay";
   if (args.hasHydratedHistoryBefore) return "silent";
   if (args.hadInitialSyncFailure) return "silent";
@@ -184,6 +186,7 @@ function resolveAgentScreenSync(args: {
         hasOptimisticCreateContinuity: hasOptimisticCreateContinuity(input),
         isVisibilityCatchUpPending: input.visibilityCatchUpStatus === "pending",
         hasHydratedHistoryBefore: input.hasHydratedHistoryBefore,
+        needsAuthoritativeSync: input.needsAuthoritativeSync,
         hadInitialSyncFailure,
       }),
     };