fix: replay completion motion reliably

frontend/src/style.test.ts

@@ -1,5 +1,6 @@
 import { readFileSync } from 'node:fs'
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it, vi } from 'vitest'
+import { createCompletionPulse } from './lib/completion-motion'
 
 const css = readFileSync('src/style.css', 'utf8')
 const app = readFileSync('src/App.vue', 'utf8')
@@ -58,14 +59,23 @@ describe('completion feedback motion', () => {
     expect(css).toContain('@media(prefers-reduced-motion:reduce){.task-row.just-completed,.habit-row.just-completed,.task-row.just-completed .task-check-mark,.habit-row.just-completed .task-check-mark{animation:none}}')
   })
 
-  it('adds transient completion classes only for incomplete to complete transitions', () => {
-    expect(app).toContain("const justCompletedTaskIds = ref(new Set<string>())")
-    expect(app).toContain("if (completing) markTaskJustCompleted(task.id)")
-    expect(app).toContain("'just-completed': justCompletedTaskIds.has(node.task.id)")
-    expect(app).toContain("'just-completed': justCompletedTaskIds.has(subtask.id)")
-    expect(mvpPanel).toContain("const justCompletedHabitIds = ref(new Set<string>())")
-    expect(mvpPanel.match(/if \(!wasDone && isHabitComplete\(h\.kind, next, h\.target \?\? 1\)\) markHabitJustCompleted\(h\.id\)/g)).toHaveLength(2)
-    expect(mvpPanel.match(/'just-completed': justCompletedHabitIds\.has\(h\.id\)/g)).toHaveLength(2)
+  it('restarts the pulse and ignores a stale timer on rapid repeat completion', () => {
+    vi.useFakeTimers()
+    const active = new Set<string>()
+    const pulse = createCompletionPulse((id) => active.add(id), (id) => active.delete(id), 420)
+    pulse('item-1')
+    vi.advanceTimersByTime(16)
+    expect(active.has('item-1')).toBe(true)
+    vi.advanceTimersByTime(200)
+    pulse('item-1')
+    expect(active.has('item-1')).toBe(false)
+    vi.advanceTimersByTime(16)
+    expect(active.has('item-1')).toBe(true)
+    vi.advanceTimersByTime(220)
+    expect(active.has('item-1')).toBe(true)
+    vi.advanceTimersByTime(200)
+    expect(active.has('item-1')).toBe(false)
+    vi.useRealTimers()
   })
 })