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.test.ts

@@ -190,6 +190,25 @@ describe("deriveAgentScreenViewState", () => {
     expect(sync.ui).toBe("silent");
   });
 
+  it("keeps hydrated history visible while reconnect revalidation and visibility catch-up overlap", () => {
+    const memory = createBaseMemory({
+      hasRenderedReady: true,
+      lastReadyAgent: createAgent("agent-1"),
+    });
+    const input: AgentScreenMachineInput = {
+      ...createBaseInput(),
+      hasHydratedHistoryBefore: true,
+      needsAuthoritativeSync: true,
+      visibilityCatchUpStatus: "pending",
+    };
+
+    const result = deriveAgentScreenViewState({ input, memory });
+    const ready = expectReadyState(result.state);
+    const sync = expectCatchingUpSync(ready);
+
+    expect(sync.ui).toBe("silent");
+  });
+
   it("covers already-hydrated history while a newly visible agent catches up", () => {
     const memory = createBaseMemory({
       hasRenderedReady: true,

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,
       }),
     };