refactor(desktop): share relative timestamp formatting

desktop/src/renderer/src/lib/utils/time.test.ts

@@ -1,5 +1,5 @@
-import { afterEach, describe, expect, it, vi } from "vitest"
-import { formatTimestamp, timeAgo } from "./time.js"
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest"
+import { formatTimestamp, timeAgo, timeAgoMs } from "./time.js"
 
 describe("timeAgo", () => {
   afterEach(() => {
@@ -62,6 +62,135 @@ describe("timeAgo", () => {
   })
 })
 
+describe("relative timestamps with a frozen clock", () => {
+  const now = 864000000
+
+  beforeEach(() => {
+    vi.useFakeTimers()
+    vi.setSystemTime(now)
+  })
+
+  afterEach(() => {
+    vi.restoreAllMocks()
+    vi.unstubAllGlobals()
+    vi.useRealTimers()
+  })
+
+  it.each([
+    [0, "Just now"],
+    [59999, "Just now"],
+    [60000, "1m ago"],
+    [3599999, "59m ago"],
+    [3600000, "1h ago"],
+    [86399999, "23h ago"],
+    [86400000, "1d ago"],
+    [5 * 86400000 + 86399999, "5d ago"],
+    [-1, "Just now"],
+    [-86400000, "Just now"],
+  ])(
+    "formats %d milliseconds ago through both adapters",
+    (elapsed, expected) => {
+      const timestamp = now - elapsed
+      const clock = vi.spyOn(Date, "now")
+
+      expect(timeAgo(new Date(timestamp).toISOString())).toBe(expected)
+      expect(clock).toHaveBeenCalledTimes(1)
+      clock.mockClear()
+      expect(timeAgoMs(timestamp)).toBe(expected)
+      expect(clock).toHaveBeenCalledTimes(1)
+    },
+  )
+
+  it.each([
+    [0, "10d ago"],
+    [-86400000, "11d ago"],
+  ])(
+    "formats epoch timestamp %d through both adapters",
+    (timestamp, expected) => {
+      expect(timeAgo(new Date(timestamp).toISOString())).toBe(expected)
+      expect(timeAgoMs(timestamp)).toBe(expected)
+    },
+  )
+
+  it.each([undefined, ""])(
+    "avoids the clock for missing input %s",
+    (timestamp) => {
+      const clock = vi.spyOn(Date, "now").mockImplementation(() => {
+        throw new Error("Clock must not be read")
+      })
+
+      expect(timeAgo(timestamp)).toBe("Unknown")
+      expect(clock).not.toHaveBeenCalled()
+    },
+  )
+
+  it.each(["not-a-date", "NaN", "Infinity", "-Infinity"])(
+    "preserves invalid nonempty string %s",
+    (timestamp) => {
+      const clock = vi.spyOn(Date, "now")
+
+      expect(timeAgo(timestamp)).toBe("NaNd ago")
+      expect(clock).toHaveBeenCalledTimes(1)
+    },
+  )
+
+  it.each([
+    [NaN, "NaNd ago"],
+    [Infinity, "Just now"],
+    [-Infinity, "Infinityd ago"],
+    [now - 60000 + 0.5, "Just now"],
+    [now - 60000 - 0.5, "1m ago"],
+    [-0.5, "10d ago"],
+  ])("preserves numeric timestamp %s", (timestamp, expected) => {
+    const clock = vi.spyOn(Date, "now")
+
+    expect(timeAgoMs(timestamp)).toBe(expected)
+    expect(clock).toHaveBeenCalledTimes(1)
+  })
+
+  it("reads the clock before constructing and reading the parsed date", () => {
+    const events: string[] = []
+    const OriginalDate = Date
+    class ObservedDate extends OriginalDate {
+      constructor(timestamp: string) {
+        events.push("parse")
+        super(timestamp)
+      }
+
+      getTime(): number {
+        events.push("getTime")
+        return super.getTime()
+      }
+
+      static now(): number {
+        events.push("now")
+        return now
+      }
+    }
+    vi.stubGlobal("Date", ObservedDate)
+
+    expect(timeAgo("1970-01-10T23:59:00Z")).toBe("1m ago")
+    expect(events).toEqual(["now", "parse", "getTime"])
+  })
+
+  it("reads the clock before coercing the numeric timestamp", () => {
+    const events: string[] = []
+    vi.spyOn(Date, "now").mockImplementation(() => {
+      events.push("now")
+      return now
+    })
+    const timestamp = {
+      valueOf() {
+        events.push("timestamp")
+        return now - 60000
+      },
+    }
+
+    expect(timeAgoMs(timestamp as unknown as number)).toBe("1m ago")
+    expect(events).toEqual(["now", "timestamp"])
+  })
+})
+
 describe("formatTimestamp", () => {
   it("formats a valid ISO timestamp", () => {
     const result = formatTimestamp("2026-01-15T12:00:00Z")

desktop/src/renderer/src/lib/utils/time.ts

@@ -1,17 +1,15 @@
 export function timeAgo(timestamp?: string): string {
   if (!timestamp) return "Unknown"
   const diff = Date.now() - new Date(timestamp).getTime()
-  const minutes = Math.floor(diff / 60000)
-  if (minutes < 1) return "Just now"
-  if (minutes < 60) return `${minutes}m ago`
-  const hours = Math.floor(minutes / 60)
-  if (hours < 24) return `${hours}h ago`
-  const days = Math.floor(hours / 24)
-  return `${days}d ago`
+  return formatElapsedTime(diff)
 }
 
 export function timeAgoMs(ts: number): string {
   const diff = Date.now() - ts
+  return formatElapsedTime(diff)
+}
+
+function formatElapsedTime(diff: number): string {
   const minutes = Math.floor(diff / 60000)
   if (minutes < 1) return "Just now"
   if (minutes < 60) return `${minutes}m ago`