Make commit history easier to scan and review (#2146)

* feat(app): improve commit history and diff review

* fix(app): keep commit timestamps current

* fix(app): pause hidden commit clocks

* fix(app): reopen commit diff in persistence test

packages/app/src/utils/time.test.ts

@@ -1,5 +1,20 @@
 import { describe, it, expect } from "vitest";
-import { formatDuration, formatMessageTimestamp } from "./time";
+import { formatDuration, formatMessageTimestamp, formatTimeAgo } from "./time";
+
+describe("formatTimeAgo", () => {
+  const now = new Date("2026-07-16T12:00:00.000Z");
+
+  it.each([
+    ["2026-07-16T11:59:55.000Z", "just now"],
+    ["2026-07-16T11:59:30.000Z", "30s ago"],
+    ["2026-07-16T11:55:00.000Z", "5m ago"],
+    ["2026-07-16T10:00:00.000Z", "2h ago"],
+    ["2026-07-13T12:00:00.000Z", "3d ago"],
+    ["2026-01-15T12:00:00.000Z", "Jan 15"],
+  ])("formats %s as %s", (date, expected) => {
+    expect(formatTimeAgo(new Date(date), now)).toBe(expected);
+  });
+});
 
 describe("formatDuration", () => {
   it("renders sub-minute durations as whole seconds", () => {

packages/app/src/utils/time.ts

@@ -2,8 +2,7 @@
  * Format a date as a human-friendly relative time string
  * Examples: "just now", "5m ago", "2h ago", "3d ago", "Jan 15"
  */
-export function formatTimeAgo(date: Date): string {
-  const now = new Date();
+export function formatTimeAgo(date: Date, now: Date = new Date()): string {
   const diffMs = now.getTime() - date.getTime();
   const diffSec = Math.floor(diffMs / 1000);
   const diffMin = Math.floor(diffSec / 60);