feat(mobile): default messaging mode to steer (port #3983)

Ports desktop PR #3983 to the React Native app. Steer mode is stable in
cloud, and mobile only runs cloud sessions, so new sessions now default to
steer instead of queue.

Since `defaultMode` is persisted in AsyncStorage, existing installs would
otherwise keep queue forever. Bumps the `messaging-mode-storage` persist
version to 1 with a migrate that moves untouched installs to steer. Per-task
overrides are preserved and still win over the default. An explicit "queue"
default is indistinguishable from the old default in the single-key store, so
it is reset to steer too (one-time, disclosed tradeoff).

Generated-By: PostHog Code
Task-Id: 33d606bb-a1b4-48d4-9fb9-e5d26fa4a9f0

Author: Gilbert09

apps/mobile/src/app/settings/index.tsx

@@ -418,7 +418,7 @@ export default function SettingsScreen() {
           />
           <SettingsRow
             label="Messaging mode"
-            description="What happens when you send while a turn is running"
+            description="What new cloud sessions do when you send while a turn is running"
             onPress={() => setMessagingModeSheetOpen(true)}
             rightSlot={
               <>

apps/mobile/src/features/tasks/stores/messagingModeStore.test.ts

@@ -1,31 +1,36 @@
 import { beforeEach, describe, expect, it } from "vitest";
-import { useMessagingModeStore } from "./messagingModeStore";
+import {
+  migrateMessagingModeState,
+  useMessagingModeStore,
+} from "./messagingModeStore";
 
 const INITIAL_STATE = useMessagingModeStore.getState();
 
 describe("messagingModeStore", () => {
   beforeEach(() => {
     useMessagingModeStore.setState(
-      { ...INITIAL_STATE, modesByTaskId: {}, defaultMode: "queue" },
+      { ...INITIAL_STATE, modesByTaskId: {}, defaultMode: "steer" },
       true,
     );
   });
 
-  it("defaults to Queue", () => {
-    expect(useMessagingModeStore.getState().getEffectiveMode("t1")).toBe(
-      "queue",
-    );
-  });
-
-  it("falls back to the global default when a task has no override", () => {
-    useMessagingModeStore.getState().setDefaultMode("steer");
+  it("defaults to Steer", () => {
     expect(useMessagingModeStore.getState().getEffectiveMode("t1")).toBe(
       "steer",
     );
   });
 
+  it.each(["queue", "steer"] as const)(
+    "falls back to the global default (%s) when a task has no override",
+    (mode) => {
+      useMessagingModeStore.getState().setDefaultMode(mode);
+      expect(useMessagingModeStore.getState().getEffectiveMode("t1")).toBe(
+        mode,
+      );
+    },
+  );
+
   it("prefers a per-task override over the global default", () => {
-    useMessagingModeStore.getState().setDefaultMode("steer");
     useMessagingModeStore.getState().setMode("t1", "queue");
     expect(useMessagingModeStore.getState().getEffectiveMode("t1")).toBe(
       "queue",
@@ -37,9 +42,32 @@ describe("messagingModeStore", () => {
   });
 
   it("treats an undefined taskId as the global default", () => {
-    useMessagingModeStore.getState().setDefaultMode("steer");
     expect(useMessagingModeStore.getState().getEffectiveMode(undefined)).toBe(
       "steer",
     );
   });
 });
+
+describe("migrateMessagingModeState", () => {
+  it("moves v0 installs to steer while keeping per-task overrides", () => {
+    const migrated = migrateMessagingModeState(
+      { modesByTaskId: { t1: "queue" }, defaultMode: "queue" },
+      0,
+    );
+    expect(migrated).toEqual({
+      modesByTaskId: { t1: "queue" },
+      defaultMode: "steer",
+    });
+  });
+
+  it("leaves already-migrated state untouched", () => {
+    const state = { modesByTaskId: {}, defaultMode: "queue" as const };
+    expect(migrateMessagingModeState(state, 1)).toEqual(state);
+  });
+
+  it("tolerates missing persisted state", () => {
+    expect(migrateMessagingModeState(undefined, 0)).toEqual({
+      defaultMode: "steer",
+    });
+  });
+});

apps/mobile/src/features/tasks/stores/messagingModeStore.ts

@@ -13,11 +13,25 @@ interface MessagingModeState {
   getEffectiveMode: (taskId: string | undefined) => MessagingMode;
 }
 
+/**
+ * Mobile sessions are all cloud, where steer is stable, so the default moved to
+ * steer. Existing installs persisted "queue" under v0 and would keep it, so v1
+ * rehydrates them to steer. Per-task overrides are untouched; an explicit
+ * "queue" default is indistinguishable from the old default, so it is reset too.
+ */
+export function migrateMessagingModeState(
+  persisted: unknown,
+  version: number,
+): Partial<MessagingModeState> {
+  const state = (persisted ?? {}) as Partial<MessagingModeState>;
+  return version < 1 ? { ...state, defaultMode: "steer" } : state;
+}
+
 export const useMessagingModeStore = create<MessagingModeState>()(
   persist(
     (set, get) => ({
       modesByTaskId: {},
-      defaultMode: "queue",
+      defaultMode: "steer",
       setMode: (taskId, mode) =>
         set((state) => ({
           modesByTaskId: { ...state.modesByTaskId, [taskId]: mode },
@@ -34,6 +48,8 @@ export const useMessagingModeStore = create<MessagingModeState>()(
     {
       name: "messaging-mode-storage",
       storage: createJSONStorage(() => AsyncStorage),
+      version: 1,
+      migrate: migrateMessagingModeState,
       partialize: (state) => ({
         modesByTaskId: state.modesByTaskId,
         defaultMode: state.defaultMode,