Fix Codex replacement turn idle flash

packages/app/src/contexts/session-stream-lifecycle.test.ts

@@ -13,10 +13,17 @@ const turnFailedEvent: AgentStreamEventPayload = {
   error: "failed",
 };
 
+const turnCanceledEvent: AgentStreamEventPayload = {
+  type: "turn_canceled",
+  provider: "codex",
+  reason: "interrupted",
+};
+
 describe("session stream lifecycle helpers", () => {
   it("derives optimistic terminal lifecycle only when current status is running", () => {
     expect(deriveOptimisticLifecycleStatus("running", turnCompletedEvent)).toBe("idle");
     expect(deriveOptimisticLifecycleStatus("running", turnFailedEvent)).toBe("error");
+    expect(deriveOptimisticLifecycleStatus("running", turnCanceledEvent)).toBe(null);
     expect(deriveOptimisticLifecycleStatus("initializing", turnCompletedEvent)).toBe(null);
     expect(deriveOptimisticLifecycleStatus("idle", turnFailedEvent)).toBe(null);
   });