feat(task): undo toast for completing — mis-taps are one tap to take back

completeTask returns an undo closure that restores status + sort slot and
trashes the occurrence a repeat spawned. One global snackbar (5s,
replace-on-new) mounted in the root layout; every checkbox and Clarify's
save-as-done go through completeWithUndo. bun tests for the store.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YE5FmDZmFnWxH6RXCZLcjj

app/src/app/_layout.tsx

@@ -6,6 +6,7 @@ import { AppState, Pressable } from "react-native";
 import { GestureHandlerRootView } from "react-native-gesture-handler";
 import { getState, hydrate, subscribe, sync } from "../lib/store";
 import Icon from "../components/Icon";
+import { ToastHost } from "../components/Toast";
 import { C, space } from "../lib/theme";
 import { refreshNextUpWidget } from "../widget/refresh";
 
@@ -74,6 +75,7 @@ export default function RootLayout() {
         <Stack.Screen name="review" options={{ title: "Weekly review" }} />
         <Stack.Screen name="settings" options={{ title: "Settings", presentation: "modal" }} />
       </Stack>
+      <ToastHost />
     </GestureHandlerRootView>
   );
 }

app/src/app/project/[id].tsx

@@ -4,7 +4,8 @@ import { FlatList, Pressable, StyleSheet, Text, TextInput, View } from "react-na
 import Icon from "../../components/Icon";
 import { Button, cardEdges, Chips, Empty, Separator } from "../../components/ui";
 import { haptic } from "../../lib/haptics";
-import { createTask, dropProject, updateProject, updateTask } from "../../lib/store";
+import { createTask, dropProject, updateProject } from "../../lib/store";
+import { completeWithUndo } from "../../lib/undo";
 import { C, radius, space, type } from "../../lib/theme";
 import { useStore } from "../../lib/useStore";
 import type { ProjectStatus } from "../../lib/types";
@@ -68,10 +69,7 @@ export default function ProjectDetail() {
             <Pressable
               style={s.checkbox}
               hitSlop={10}
-              onPress={() => {
-                haptic.success();
-                updateTask(item.id, { status: "done" });
-              }}
+              onPress={() => completeWithUndo(item)}
             />
             <View style={{ flex: 1 }}>
               <Text style={s.title} numberOfLines={2}>

app/src/app/review.tsx

@@ -10,6 +10,7 @@ import { haptic } from "../lib/haptics";
 import { PRIORITY_COLOR } from "../lib/priority";
 import { daysSince, markReviewed, useLastReview } from "../lib/review";
 import { reviewBuckets, trashTask, updateTask } from "../lib/store";
+import { completeWithUndo } from "../lib/undo";
 import { C, radius, space, type } from "../lib/theme";
 import { useStore } from "../lib/useStore";
 import type { Task } from "../lib/types";
@@ -34,10 +35,7 @@ function ReviewRow({
       <Pressable
         style={s.check}
         hitSlop={8}
-        onPress={act(() => {
-          haptic.success();
-          updateTask(task.id, { status: "done" });
-        })}
+        onPress={() => completeWithUndo(task)}
       >
         <View style={[s.checkbox, { borderColor: PRIORITY_COLOR[task.priority] }]} />
       </Pressable>

app/src/app/task/[id].tsx

@@ -5,6 +5,7 @@ import TaskForm, { CAPTURE_BOXES, type TaskDraft } from "../../components/TaskFo
 import { Button, Empty } from "../../components/ui";
 import { haptic } from "../../lib/haptics";
 import { trashTask, updateTask } from "../../lib/store";
+import { completeWithUndo } from "../../lib/undo";
 import { C, space, type } from "../../lib/theme";
 import { useStore } from "../../lib/useStore";
 import type { Task, TaskStatus } from "../../lib/types";
@@ -37,8 +38,13 @@ export default function TaskDetail() {
   if (!original || !draft) return <Empty>Task not found.</Empty>;
 
   const save = () => {
-    updateTask(original.id, { ...draft, priority: draft.priority ?? 3 });
-    haptic.success();
+    const { status, ...rest } = draft;
+    const completing = status === "done" && original.status !== "done";
+    // Completing from Clarify gets the same Undo as a checkbox; the toast
+    // lives in the root layout so it outlives this modal.
+    updateTask(original.id, { ...rest, ...(completing ? {} : { status }), priority: draft.priority ?? 3 });
+    if (completing) completeWithUndo(original, original.status);
+    else haptic.success();
     router.back();
   };
 

app/src/components/TaskRow.tsx

@@ -6,6 +6,7 @@ import { haptic } from "../lib/haptics";
 import { formatEstimate, PRIORITY_COLOR } from "../lib/priority";
 import { updateTask } from "../lib/store";
 import { C, radius, space, type } from "../lib/theme";
+import { completeWithUndo } from "../lib/undo";
 import type { Task, TaskStatus } from "../lib/types";
 
 export default function TaskRow({
@@ -13,6 +14,7 @@ export default function TaskRow({
   uncheckTo = "next",
   showStatus,
   onLongPress,
+  emphasized,
 }: {
   task: Task;
   /** Status to revert to when un-checking a done task. */
@@ -20,6 +22,8 @@ export default function TaskRow({
   showStatus?: boolean;
   /** Drag handle for reorderable lists. */
   onLongPress?: () => void;
+  /** The one thing to do now — bigger, tinted, labelled. */
+  emphasized?: boolean;
 }) {
   const router = useRouter();
   const done = task.status === "done";
@@ -41,16 +45,18 @@ export default function TaskRow({
   const flag = PRIORITY_COLOR[task.priority];
 
   const toggle = () => {
-    const next = task.status !== "done";
-    if (next) haptic.success();
-    else haptic.tap();
-    updateTask(task.id, { status: next ? "done" : uncheckTo });
+    if (!done) {
+      completeWithUndo(task);
+      return;
+    }
+    haptic.tap();
+    updateTask(task.id, { status: uncheckTo });
   };
 
   return (
     <Animated.View entering={FadeIn.duration(150)}>
       <Pressable
-        style={({ pressed }) => [s.row, pressed && s.rowPressed]}
+        style={({ pressed }) => [s.row, emphasized && s.rowEmphasized, pressed && s.rowPressed]}
         onPress={() => router.push(`/task/${task.id}`)}
         onLongPress={onLongPress}
         delayLongPress={200}
@@ -59,14 +65,20 @@ export default function TaskRow({
             The border carries the priority colour, so priority is legible at a
             glance without spending a whole column on a flag. */}
         <Pressable
-          style={[s.checkbox, { borderColor: done ? C.done : flag }, done && s.checkboxDone]}
+          style={[
+            s.checkbox,
+            emphasized && s.checkboxEmphasized,
+            { borderColor: done ? C.done : flag },
+            done && s.checkboxDone,
+          ]}
           hitSlop={10}
           onPress={toggle}
         >
           {done && <Text style={s.check}>✓</Text>}
         </Pressable>
         <View style={{ flex: 1 }}>
-          <Text style={[s.title, done && s.titleDone]} numberOfLines={2}>
+          {emphasized && <Text style={s.nowLabel}>NOW</Text>}
+          <Text style={[s.title, emphasized && s.titleEmphasized, done && s.titleDone]} numberOfLines={2}>
             {task.title}
           </Text>
           {!!meta && (
@@ -92,6 +104,10 @@ const s = StyleSheet.create({
     backgroundColor: C.surface,
   },
   rowPressed: { backgroundColor: C.surface2 },
+  rowEmphasized: { backgroundColor: C.accentSoft, paddingVertical: space.lg + 2 },
+  checkboxEmphasized: { width: 26, height: 26, borderRadius: 8 },
+  nowLabel: { fontSize: 10, fontWeight: "700", letterSpacing: 1.2, color: C.accent, marginBottom: 2 },
+  titleEmphasized: { fontSize: 19, fontWeight: "600", lineHeight: 24 },
   checkbox: {
     width: 22,
     height: 22,

app/src/components/Toast.tsx

@@ -0,0 +1,98 @@
+// One app-wide snackbar, mounted once in the root layout. `showToast` is a
+// plain function so stores and rows can call it without a context hop. A new
+// toast replaces the current one (last action wins) and the timer restarts.
+import { useEffect, useState } from "react";
+import { Pressable, StyleSheet, Text } from "react-native";
+import Animated, { FadeInDown, FadeOutDown } from "react-native-reanimated";
+import { useSafeAreaInsets } from "react-native-safe-area-context";
+import { haptic } from "../lib/haptics";
+import { C, radius, shadow, space, type } from "../lib/theme";
+
+export interface ToastSpec {
+  message: string;
+  action?: { label: string; onPress: () => void };
+}
+
+const DURATION_MS = 5000;
+// Sits on the home FAB's baseline (index.tsx `fab.bottom`) — above the
+// launcher bar, and the right padding leaves the FAB itself uncovered.
+const FAB_BOTTOM = 104;
+const FAB_CLEARANCE = space.xl + 56 + space.md;
+
+let setCurrent: ((t: ToastSpec | null) => void) | null = null;
+
+export function showToast(spec: ToastSpec) {
+  setCurrent?.(spec);
+}
+
+export function ToastHost() {
+  const [toast, setToast] = useState<ToastSpec | null>(null);
+  const insets = useSafeAreaInsets();
+
+  useEffect(() => {
+    setCurrent = setToast;
+    return () => {
+      if (setCurrent === setToast) setCurrent = null;
+    };
+  }, []);
+
+  useEffect(() => {
+    if (!toast) return;
+    const timer = setTimeout(() => setToast(null), DURATION_MS);
+    return () => clearTimeout(timer);
+  }, [toast]);
+
+  if (!toast) return null;
+  const { action } = toast;
+  return (
+    <Animated.View
+      entering={FadeInDown.duration(180)}
+      exiting={FadeOutDown.duration(150)}
+      style={[s.wrap, { bottom: FAB_BOTTOM + insets.bottom }]}
+      pointerEvents="box-none"
+    >
+      <Pressable style={s.toast} onPress={() => setToast(null)}>
+        <Text style={s.message} numberOfLines={1}>
+          {toast.message}
+        </Text>
+        {action && (
+          <Pressable
+            hitSlop={12}
+            onPress={() => {
+              haptic.tap();
+              setToast(null);
+              action.onPress();
+            }}
+            style={({ pressed }) => [s.action, pressed && { opacity: 0.6 }]}
+          >
+            <Text style={s.actionText}>{action.label}</Text>
+          </Pressable>
+        )}
+      </Pressable>
+    </Animated.View>
+  );
+}
+
+const s = StyleSheet.create({
+  wrap: {
+    position: "absolute",
+    left: space.lg,
+    right: FAB_CLEARANCE,
+    alignItems: "flex-start",
+  },
+  toast: {
+    flexDirection: "row",
+    alignItems: "center",
+    gap: space.lg,
+    maxWidth: 420,
+    paddingVertical: space.md,
+    paddingLeft: space.lg,
+    paddingRight: space.md,
+    borderRadius: radius.pill,
+    backgroundColor: C.text,
+    ...shadow.fab,
+  },
+  message: { ...type.row, color: C.bg, flexShrink: 1 },
+  action: { paddingVertical: space.xs, paddingHorizontal: space.sm },
+  actionText: { ...type.row, color: C.accentSoft, fontWeight: "600" },
+});

app/src/lib/store.test.ts

@@ -0,0 +1,63 @@
+// Store unit tests — run with `bun test src/lib`. Expo/native modules are
+// mocked so the local-first mutations run in plain Bun.
+import { beforeEach, describe, expect, mock, test } from "bun:test";
+
+const storage = new Map<string, string>();
+mock.module("@react-native-async-storage/async-storage", () => ({
+  default: {
+    getItem: async (k: string) => storage.get(k) ?? null,
+    setItem: async (k: string, v: string) => void storage.set(k, v),
+  },
+}));
+let seq = 0;
+mock.module("expo-crypto", () => ({
+  randomUUID: () => `00000000-0000-4000-8000-${String(++seq).padStart(12, "0")}`,
+}));
+mock.module("./api", () => ({ api: {} }));
+mock.module("./config", () => ({ getConfig: async () => ({ token: "" }) }));
+
+const store = await import("./store");
+
+beforeEach(async () => {
+  storage.clear();
+  await store.hydrate();
+});
+
+const find = (id: string) => store.getState().tasks.find((t) => t.id === id)!;
+
+describe("completeTask", () => {
+  test("marks done and undo restores the original status in place", () => {
+    const a = store.createTask({ title: "a", status: "waiting", sort_order: 5 });
+    const undo = store.completeTask(a.id);
+    expect(find(a.id).status).toBe("done");
+    expect(find(a.id).completed_at).not.toBeNull();
+    undo!();
+    expect(find(a.id).status).toBe("waiting");
+    expect(find(a.id).completed_at).toBeNull();
+    expect(find(a.id).sort_order).toBe(5);
+  });
+
+  test("revertTo overrides the status undo returns to", () => {
+    const a = store.createTask({ title: "a", status: "next" });
+    store.completeTask(a.id, "someday")!();
+    expect(find(a.id).status).toBe("someday");
+  });
+
+  test("undo of a repeating task trashes the spawned occurrence", () => {
+    const a = store.createTask({ title: "rent", repeat: "monthly", due_date: "2026-09-01" });
+    const known = new Set(store.getState().tasks.map((t) => t.id));
+    const undo = store.completeTask(a.id)!;
+    const spawned = store.getState().tasks.filter((t) => !known.has(t.id));
+    expect(spawned).toHaveLength(1);
+    expect(spawned[0].status).toBe("next");
+    undo();
+    expect(find(a.id).status).toBe("next");
+    expect(find(spawned[0].id).status).toBe("trashed");
+  });
+
+  test("returns null for an already-done or unknown task", () => {
+    const a = store.createTask({ title: "a", status: "done" });
+    expect(store.completeTask(a.id)).toBeNull();
+    expect(store.completeTask("nope")).toBeNull();
+  });
+});

app/src/lib/store.ts

@@ -136,6 +136,11 @@ export function createTask(data: Partial<Task> & { title: string }): Task {
 }
 
 export function updateTask(id: string, patch: Partial<Task>) {
+  applyTaskUpdate(id, patch);
+}
+
+/** Applies a patch; returns the next occurrence if completing spawned one. */
+function applyTaskUpdate(id: string, patch: Partial<Task>): Task | null {
   const before = state.tasks.find((t) => t.id === id);
   setState({
     tasks: state.tasks.map((t) => {
@@ -152,11 +157,28 @@ export function updateTask(id: string, patch: Partial<Task>) {
   // done row later leaves the spawn in place — it's one tap to trash, versus
   // silently deleting a row the user may have edited.
   if (before && before.repeat && before.status !== "done" && patch.status === "done") {
-    spawnNextOccurrence(before);
+    return spawnNextOccurrence(before);
   }
+  return null;
 }
 
-function spawnNextOccurrence(t: Task) {
+/**
+ * Complete a task and hand back an undo. Undo puts the task back where it was
+ * (same status and sort slot) and trashes the occurrence a repeat spawned, so
+ * a mis-tap leaves no trace. Returns null when there's nothing to complete.
+ */
+export function completeTask(id: string, revertTo?: Task["status"]): (() => void) | null {
+  const before = state.tasks.find((t) => t.id === id);
+  if (!before || before.status === "done") return null;
+  const spawned = applyTaskUpdate(id, { status: "done" });
+  const back = revertTo ?? before.status;
+  return () => {
+    updateTask(id, { status: back });
+    if (spawned) trashTask(spawned.id);
+  };
+}
+
+function spawnNextOccurrence(t: Task): Task {
   const today = todayIso();
   const due = t.due_date ? nextOccurrence(t.due_date, t.repeat!, today) : null;
   // Keep the same lead time between defer and due (e.g. "surfaces 3 days before").
@@ -168,7 +190,7 @@ function spawnNextOccurrence(t: Task) {
         : t.defer_date
           ? nextOccurrence(t.defer_date, t.repeat!, today)
           : null;
-  createTask({
+  return createTask({
     title: t.title,
     notes: t.notes,
     status: t.status,

app/src/lib/undo.ts

@@ -0,0 +1,13 @@
+// Complete + "Undo" toast, shared by every checkbox in the app so a mis-tap
+// is one tap to take back wherever it happened.
+import { showToast } from "../components/Toast";
+import { haptic } from "./haptics";
+import { completeTask } from "./store";
+import type { Task, TaskStatus } from "./types";
+
+export function completeWithUndo(task: Pick<Task, "id" | "title">, revertTo?: TaskStatus) {
+  const undo = completeTask(task.id, revertTo);
+  if (!undo) return;
+  haptic.success();
+  showToast({ message: `Completed “${task.title}”`, action: { label: "Undo", onPress: undo } });
+}

app/tsconfig.json

@@ -16,5 +16,8 @@
     "**/*.tsx",
     ".expo/types/**/*.ts",
     "expo-env.d.ts"
+  ],
+  "exclude": [
+    "**/*.test.ts"
   ]
 }