feat: a list from the cache says how old it is while it reloads

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/ui/app/persist_test.go

@@ -39,6 +39,9 @@ func TestCacheFileShowsLastRunAtOnce(t *testing.T) {
 	// Next run, with a backend too slow to answer during the test: the
 	// lists show from the file, and the cursor is where it was.
 	d2 := newDriverOpts(t, Options{CacheFile: file}, fake.Azure(time.Minute))
+	if strings.Contains(d2.screen(), "cached") {
+		t.Errorf("a fresh cache said its age:\n%s", d2.screen())
+	}
 	d2.keys("2")
 	if _, v, _ := d2.selected(); v != vault {
 		t.Errorf("vaults from the cache: selected %q, want %q\n%s", v, vault, d2.screen())
@@ -49,6 +52,29 @@ func TestCacheFileShowsLastRunAtOnce(t *testing.T) {
 	}
 }
 
+// Lists from an older cache say how old they are while they reload.
+func TestCacheFileSaysItsAge(t *testing.T) {
+	t.Parallel()
+	file := filepath.Join(t.TempDir(), "cache.json")
+	d := newDriverOpts(t, Options{CacheFile: file}, fake.Azure(0))
+	d.keys("3")
+	at := time.Now().Add(-3 * time.Hour)
+	for k, e := range d.m.cache.containers {
+		d.m.cache.containers[k] = entry[[]provider.Container]{e.value, at}
+	}
+	for id := range d.m.sourcesAt {
+		d.m.sourcesAt[id] = at
+	}
+	if err := d.m.Persist(); err != nil {
+		t.Fatal(err)
+	}
+	d2 := newDriverOpts(t, Options{CacheFile: file}, fake.Azure(time.Minute))
+	d2.keys("2")
+	if n := strings.Count(d2.screen(), "cached 3h ago"); n != 2 {
+		t.Errorf("Sources and Vaults should say they're from 3h ago (%d do):\n%s", n, d2.screen())
+	}
+}
+
 func TestCacheFileDropsOldAndSignedOut(t *testing.T) {
 	t.Parallel()
 	file := filepath.Join(t.TempDir(), "cache.json")