fix(ui): restore responsive session switching

Keep the experimental persistent message cache disabled in desktop restore flows. The bounded cache could expose only a transcript suffix while progressive IndexedDB hydration repeatedly copied and measured large histories on the renderer thread, preventing responsive session changes.

Tab restoration and in-memory session eviction remain enabled; selected sessions now use the established authoritative HTTP load path. Add a regression check and validate request authority, memory eviction, UI typechecking, and the production build.

Author: pascalandr

packages/ui/src/stores/client-state.test.ts

@@ -34,6 +34,12 @@ const boot = async (api?: NativeApi, storage?: MemoryStorage) => {
 const transact = (state: ClientState, kind: TransactionKind) => kind === "clear"
   ? state.clearRestoredClientState() : state.setRestorePreviousStateEnabled(false)
 describe("client state ownership and persistence", () => {
+  it("keeps persistent message caching disabled during desktop restore", async () => {
+    const cache = await import("../lib/session-message-cache.ts")
+    cache.setSessionMessageCacheEnabled(false)
+    await boot({ loadClientState: async () => loadResult(snapshot("project")) })
+    assert.equal(cache.isSessionMessageCacheEnabled(), false)
+  })
   it("treats a rejected access claim as secondary without loading", async () => {
     let loads = 0
     const state = await boot({

packages/ui/src/stores/client-state.ts

@@ -272,7 +272,8 @@ export async function setRestorePreviousStateEnabled(enabled: boolean): Promise<
       if (!await setNativeRestoreEnabled(true)) throw new Error("Native restore preference update was rejected")
       writeBlock = false
       setRestorePreviousStateEnabledSignal(true)
-      setSessionMessageCacheEnabled(true)
+      // ponytail: keep message caching off until restore no longer blocks the renderer on large sessions.
+      setSessionMessageCacheEnabled(false)
       return
     }
     setRestorePreviousStateEnabledSignal(false)
@@ -287,7 +288,7 @@ export async function setRestorePreviousStateEnabled(enabled: boolean): Promise<
       await executeDestructiveTransaction(() => setNativeRestoreEnabled(false), "Native restore preference update was rejected")
     } catch (error) {
       setRestorePreviousStateEnabledSignal(true)
-      setSessionMessageCacheEnabled(!isSessionMessageCacheUnsafe())
+      setSessionMessageCacheEnabled(false)
       throw error
     }
     cacheClearPending = true
@@ -341,7 +342,7 @@ export function initializeClientState(): Promise<void> {
       writeBlock = isFutureClientSnapshot(loaded.snapshot) ? "snapshot" : false
       const snapshot = decodeClientSnapshot(loaded.snapshot)
       resetLoadedState(snapshot, true)
-      setSessionMessageCacheEnabled(!writeBlock)
+      setSessionMessageCacheEnabled(false)
       if (!writeBlock && migrateLegacyLayoutValues()) scheduleSave()
     } catch (error) {
       initialized = true