UI: handle future timestamps in formatAgo

ui/src/ui/format.test.ts

@@ -1,5 +1,36 @@
-import { describe, expect, it } from "vitest";
-import { stripThinkingTags } from "./format.ts";
+import { describe, expect, it, vi } from "vitest";
+import { formatAgo, stripThinkingTags } from "./format.ts";
+
+describe("formatAgo", () => {
+  it("returns 'just now' for timestamps less than 60s in the future", () => {
+    expect(formatAgo(Date.now() + 30_000)).toBe("just now");
+  });
+
+  it("returns 'Xm from now' for future timestamps", () => {
+    expect(formatAgo(Date.now() + 5 * 60_000)).toBe("5m from now");
+  });
+
+  it("returns 'Xh from now' for future timestamps", () => {
+    expect(formatAgo(Date.now() + 3 * 60 * 60_000)).toBe("3h from now");
+  });
+
+  it("returns 'Xd from now' for future timestamps beyond 48h", () => {
+    expect(formatAgo(Date.now() + 3 * 24 * 60 * 60_000)).toBe("3d from now");
+  });
+
+  it("returns 'Xs ago' for recent past timestamps", () => {
+    expect(formatAgo(Date.now() - 10_000)).toBe("10s ago");
+  });
+
+  it("returns 'Xm ago' for past timestamps", () => {
+    expect(formatAgo(Date.now() - 5 * 60_000)).toBe("5m ago");
+  });
+
+  it("returns 'n/a' for null/undefined", () => {
+    expect(formatAgo(null)).toBe("n/a");
+    expect(formatAgo(undefined)).toBe("n/a");
+  });
+});
 
 describe("stripThinkingTags", () => {
   it("strips <think>…</think> segments", () => {

ui/src/ui/format.ts

@@ -12,23 +12,22 @@ export function formatAgo(ms?: number | null): string {
     return "n/a";
   }
   const diff = Date.now() - ms;
-  if (diff < 0) {
-    return "just now";
-  }
-  const sec = Math.round(diff / 1000);
+  const absDiff = Math.abs(diff);
+  const suffix = diff < 0 ? "from now" : "ago";
+  const sec = Math.round(absDiff / 1000);
   if (sec < 60) {
-    return `${sec}s ago`;
+    return diff < 0 ? "just now" : `${sec}s ago`;
   }
   const min = Math.round(sec / 60);
   if (min < 60) {
-    return `${min}m ago`;
+    return `${min}m ${suffix}`;
   }
   const hr = Math.round(min / 60);
   if (hr < 48) {
-    return `${hr}h ago`;
+    return `${hr}h ${suffix}`;
   }
   const day = Math.round(hr / 24);
-  return `${day}d ago`;
+  return `${day}d ${suffix}`;
 }
 
 export function formatDurationMs(ms?: number | null): string {