fix(mobile): stop double-scaling commit timestamps in history rows (#17731)

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Jinwoo-H <jinwoo0825@gmail.com>

mobile/src/source-control/MobileGitHistoryList.test.tsx

@@ -27,11 +27,24 @@ vi.mock('react-native', () => ({
 vi.mock('lucide-react-native', () => ({ ChevronDown: 'ChevronDown', ChevronRight: 'ChevronRight' }))
 vi.mock('../transport/client-context', () => ({ useForceReconnect: () => vi.fn() }))
 
+// Captured at module scope: the list renders rows against Date.now() a few ms later,
+// so a 3h offset stays inside the '3h' relative-time bucket.
+const RENDER_NOW = Date.now()
+
 function historyResponse(subject: string) {
   return {
     ok: true,
     result: {
-      items: [{ id: 'commit-1', displayId: 'c0mm1t1', subject, author: 'Ada', parentIds: [] }]
+      items: [
+        {
+          id: 'commit-1',
+          displayId: 'c0mm1t1',
+          subject,
+          author: 'Ada',
+          parentIds: [],
+          timestamp: RENDER_NOW - 3 * 3_600_000
+        }
+      ]
     }
   }
 }
@@ -92,6 +105,9 @@ describe('MobileGitHistoryList', () => {
 
     await render(client, 'connected')
     expect(tree()).toContain('first load')
+    // Rows format the RPC timestamp (epoch ms); a regression to seconds-scaling
+    // renders every commit as 'just now' instead.
+    expect(tree()).toContain('3h')
 
     await update(client, 'reconnecting')
     expect(tree()).toContain('first load')

mobile/src/source-control/mobile-git-history.test.ts

@@ -11,20 +11,21 @@ function item(overrides: Partial<GitHistoryItem> = {}): GitHistoryItem {
     subject: 'feat: thing',
     message: 'feat: thing\n\nbody',
     author: 'Jane',
-    timestamp: NOW / 1000 - 3600,
+    timestamp: NOW - 3_600_000,
     ...overrides
   }
 }
 
 describe('formatCommitTime', () => {
-  it('formats across thresholds', () => {
-    const s = NOW / 1000
-    expect(formatCommitTime(s - 30, NOW)).toBe('just now')
-    expect(formatCommitTime(s - 5 * 60, NOW)).toBe('5m')
-    expect(formatCommitTime(s - 3 * 3600, NOW)).toBe('3h')
-    expect(formatCommitTime(s - 2 * 86400, NOW)).toBe('2d')
-    expect(formatCommitTime(s - 60 * 86400, NOW)).toBe('2mo')
-    expect(formatCommitTime(s - 800 * 86400, NOW)).toBe('2y')
+  it('formats across thresholds from epoch-millisecond timestamps', () => {
+    // GitHistoryItem.timestamp is epoch ms (git-history-log-parser scales git %at by 1000).
+    const ms = { min: 60_000, hour: 3_600_000, day: 86_400_000 }
+    expect(formatCommitTime(NOW - 3 * ms.hour, NOW)).toBe('3h')
+    expect(formatCommitTime(NOW - 30_000, NOW)).toBe('just now')
+    expect(formatCommitTime(NOW - 5 * ms.min, NOW)).toBe('5m')
+    expect(formatCommitTime(NOW - 2 * ms.day, NOW)).toBe('2d')
+    expect(formatCommitTime(NOW - 60 * ms.day, NOW)).toBe('2mo')
+    expect(formatCommitTime(NOW - 800 * ms.day, NOW)).toBe('2y')
   })
 
   it('returns empty for missing timestamp', () => {

mobile/src/source-control/mobile-git-history.ts

@@ -12,12 +12,13 @@ export type MobileCommitRow = {
 }
 
 // Short relative time for a commit list (just now / Xm / Xh / Xd / Xmo / Xy).
-export function formatCommitTime(timestampSeconds: number | undefined, nowMs: number): string {
+// `timestampMs` is epoch ms, the unit GitHistoryItem.timestamp already carries.
+export function formatCommitTime(timestampMs: number | undefined, nowMs: number): string {
   // Nullish — not falsy — so a real epoch-0 timestamp still formats.
-  if (timestampSeconds == null) {
+  if (timestampMs == null) {
     return ''
   }
-  const delta = nowMs - timestampSeconds * 1000
+  const delta = nowMs - timestampMs
   if (delta < 60_000) {
     return 'just now'
   }

src/shared/git-history-types.ts

@@ -48,6 +48,7 @@ export type GitHistoryItem = {
   displayId?: string
   author?: string
   authorEmail?: string
+  /** Epoch milliseconds (git %at seconds × 1000). */
   timestamp?: number
   statistics?: GitHistoryItemStatistics
   references?: GitHistoryItemRef[]

src/shared/git-history.test.ts

@@ -115,7 +115,9 @@ describe('git history parsing', () => {
       message: 'feat: add graph\n\nbody line',
       author: 'Ada Lovelace',
       authorEmail: 'ada@example.com',
-      displayId: HEAD_OID.slice(0, 7)
+      displayId: HEAD_OID.slice(0, 7),
+      // The format feeds %at seconds; consumers get epoch milliseconds.
+      timestamp: 1_700_000_000_000
     })
     expect(item?.references?.map((ref) => [ref.id, ref.name, ref.category])).toEqual([
       ['refs/heads/feature', 'feature', 'branches'],