milestone 27: diagnostics — operational failures land in one curated log, resolved history purgeable

admin/src/lib/format.test.ts

@@ -1,4 +1,4 @@
-import { formatAge, formatBytes, formatMicros, formatTime } from "@/lib/format";
+import { formatAge, formatBytes, formatDuration, formatMicros, formatTime } from "@/lib/format";
 
 test("formatTime renders unix seconds in the given locale and zone", () => {
 	// 2024-01-01T00:00:00Z; ICU emits U+202F before AM/PM in recent Node.
@@ -27,6 +27,15 @@ test("formatAge steps up a unit at each boundary and truncates", () => {
 	expect(formatAge(400000)).toBe("4d ago");
 });
 
+test("formatDuration is the same span without the 'ago', and never negative", () => {
+	expect(formatDuration(0)).toBe("0s");
+	expect(formatDuration(59)).toBe("59s");
+	expect(formatDuration(3600)).toBe("1h");
+	expect(formatDuration(86400)).toBe("1d");
+	// Clock skew between the server's timestamps and the browser's clock.
+	expect(formatDuration(-5)).toBe("0s");
+});
+
 test("formatMicros renders milliseconds with one decimal", () => {
 	expect(formatMicros(0)).toBe("0.0 ms");
 	expect(formatMicros(1234)).toBe("1.2 ms");