Skip unchanged materialization and expire only open occurrences

src/habits/performance.test.ts

@@ -44,3 +44,16 @@ test('calendar summaries omit editor payloads and mutation versions cover histor
     expect((await f.json(`/habits/${habit.id}/days/2026-09-04`)).tasks[0].done).toBe(true);
   } finally { f.close(); }
 });
+
+test('unchanged dashboard and calendar reads write no rows after synchronization', async () => {
+  const f = fixture();
+  try {
+    const habit = await f.json('/habits', 'POST', {name:'Tasks', method:'tasks', tasks:[{name:'Read'}]}, 201);
+    f.setTime('2027-09-04T12:00:00Z');
+    await f.json('/today');
+    const before = (f.sqlite.query('SELECT total_changes() AS n').get() as {n:number}).n;
+    await f.json('/today');
+    await f.json(`/habits/${habit.id}/calendar?from=2027-09-01&to=2027-09-04&compact=true`);
+    expect((f.sqlite.query('SELECT total_changes() AS n').get() as {n:number}).n).toBe(before);
+  } finally {f.close();}
+});