fix(web): summarize session titles, sort by activity, and paginate history (BUG-553)

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/tests/session-cursor.test.ts

@@ -0,0 +1,57 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  clampSessionLimit,
+  compareSessionCursor,
+  encodeSessionCursor,
+  nextSessionCursor,
+  parseSessionCursor,
+  SESSION_PAGE_SIZE,
+} from "../src/lib/session-cursor.ts";
+
+const leftId = "11111111-1111-4111-8111-111111111111";
+const rightId = "22222222-2222-4222-8222-222222222222";
+const stamp = "2026-09-06T04:00:00.000Z";
+
+test("encodeSessionCursor round-trips a valid pair", () => {
+  const encoded = encodeSessionCursor(stamp, leftId);
+  assert.deepEqual(parseSessionCursor(encoded), { updatedAt: stamp, id: leftId });
+});
+
+test("parseSessionCursor returns null for illegal strings", () => {
+  assert.equal(parseSessionCursor(null), null);
+  assert.equal(parseSessionCursor(""), null);
+  assert.equal(parseSessionCursor("not-a-date,11111111-1111-4111-8111-111111111111"), null);
+  assert.equal(parseSessionCursor(`${stamp},not-a-uuid`), null);
+  assert.equal(parseSessionCursor(stamp), null);
+});
+
+test("compareSessionCursor uses id when the timestamp is the same", () => {
+  const sameTime = compareSessionCursor(
+    { updatedAt: stamp, id: leftId },
+    { updatedAt: stamp, id: rightId },
+  );
+  assert.ok(sameTime > 0);
+  const newerTime = compareSessionCursor(
+    { updatedAt: "2026-09-06T05:00:00.000Z", id: leftId },
+    { updatedAt: stamp, id: rightId },
+  );
+  assert.ok(newerTime < 0);
+});
+
+test("clampSessionLimit defaults to 40 and clamps 1–100", () => {
+  assert.equal(clampSessionLimit(null), SESSION_PAGE_SIZE);
+  assert.equal(clampSessionLimit("0"), 1);
+  assert.equal(clampSessionLimit("101"), 100);
+  assert.equal(clampSessionLimit("40"), 40);
+});
+
+test("nextSessionCursor is null when the page is short, else encodes the limit-th row", () => {
+  const rows = [
+    { id: leftId, updated_at: stamp },
+    { id: rightId, updated_at: stamp },
+  ];
+  assert.equal(nextSessionCursor(rows, 40), null);
+  assert.equal(nextSessionCursor(rows, 1), encodeSessionCursor(stamp, leftId));
+});