Events: pull answers carry latest_cursor (the head as an opaque cursor) (#45)

ddiff --git a/README.md b/README.md
iindex 310ffec..7c01a2d 100644
---- a/README.md
++++ b/README.md
@@@ -114,7 +114,7 @@ Each delivery is `POST <endpoint>` with body `{ "event": <envelope>, "seq": n }`
  
  Operators: `GET /api/v1/deliveries?status=dead` is the dead-letter queue; `POST /api/v1/deliveries/replay { subscription_id, event_ids: [...] }` or `{ subscription_id, from_seq }` requeues retained events (that is also how a new subscription catches up on history).
  
--Pull consumers: start with `GET /api/v1/events?topic=media.vod.*&limit=100`, then request `GET /api/v1/events?topic=media.vod.*&after=<next_cursor>&limit=100`, using the previous response's opaque `next_cursor` ([ADR-042](https://github.com/OpenVibers/OpenVibe.Contracts/blob/main/docs/adr/ADR-042-events-fabric.md) decision 7). The response carries `{ events: [{ seq, cursor, event }], next_cursor, next_after_seq, latest_seq }`, plus `gap: { from_seq, to_seq }` when the position is older than both the hot store and the replay tier (below) or from another retention epoch. Use `next_cursor` even when no events match, since it advances past scanned events. Numeric `after_seq=<position>` remains accepted for one release; when both are supplied, `after` takes precedence. The numeric `seq`, `next_after_seq` and `latest_seq` fields also remain for one release. `PUT /api/v1/checkpoints { topic, cursor }` stores a consumer's position here if it has nowhere better (an opaque cursor string is accepted in place of the integer; the answer carries its `epoch`, `carrier` and `next_cursor`).
++Pull consumers: start with `GET /api/v1/events?topic=media.vod.*&limit=100`, then request `GET /api/v1/events?topic=media.vod.*&after=<next_cursor>&limit=100`, using the previous response's opaque `next_cursor` ([ADR-042](https://github.com/OpenVibers/OpenVibe.Contracts/blob/main/docs/adr/ADR-042-events-fabric.md) decision 7). The response carries `{ events: [{ seq, cursor, event }], next_cursor, next_after_seq, latest_seq, latest_cursor }` (`latest_cursor` is the head as an opaque cursor, for a consumer that starts at "now" without history), plus `gap: { from_seq, to_seq }` when the position is older than both the hot store and the replay tier (below) or from another retention epoch. Use `next_cursor` even when no events match, since it advances past scanned events. Numeric `after_seq=<position>` remains accepted for one release; when both are supplied, `after` takes precedence. The numeric `seq`, `next_after_seq` and `latest_seq` fields also remain for one release. `PUT /api/v1/checkpoints { topic, cursor }` stores a consumer's position here if it has nowhere better (an opaque cursor string is accepted in place of the integer; the answer carries its `epoch`, `carrier` and `next_cursor`).
  
  ### Retention: three tiers
  
ddiff --git a/server/api/read.js b/server/api/read.js
iindex e601611..c9cacd4 100644
---- a/server/api/read.js
++++ b/server/api/read.js
@@@ -3,7 +3,9 @@
   * Pull consumers (service token with events.event.read):
   *
   *   GET /api/v1/events?topic=media.vod.*[,…]&after_seq=0&limit=100
-- *       -> { events: [{ seq, cursor, event }], next_after_seq, next_cursor, latest_seq, gap? }
++ *       -> { events: [{ seq, cursor, event }], next_after_seq, next_cursor, latest_seq, latest_cursor, gap? }
++ *       `latest_cursor` is the head as an opaque cursor: a consumer that starts at "now" (skipping history)
++ *       stores it, so it never needs the numeric latest_seq.
   *       `after=` takes an opaque cursor beside after_seq (ADR-042 decision 7); a cursor from another
   *       retention epoch answers `gap` — never a silent restart. `gap` ({ from_seq, to_seq }) means
   *       events after the position were already pruned by retention (or the epoch changed). The pull
@@@ -105,6 +107,7 @@ function readRouter({ store, auth, worker, limits }) {
          out.next_after_seq = scanned;
          out.next_cursor = cursor.encode(scanned, epoch);
          out.latest_seq = await store.lastSeq();
++        out.latest_cursor = cursor.encode(out.latest_seq, epoch);
          res.json(out);
      });
  
ddiff --git a/test/pull-health.test.js b/test/pull-health.test.js
iindex 48c42e5..d20114d 100644
---- a/test/pull-health.test.js
++++ b/test/pull-health.test.js
@@@ -71,6 +71,15 @@ t('pull: cursor, topic filter, internal events included for services', async ()
      r = await request(h.base, 'GET', `/api/v1/events?topic=live.vod.*&after_seq=${r.body.next_after_seq}`, { token: reader });
      assert.deepStrictEqual(r.body.events, []);
      assert.strictEqual(r.body.latest_seq, s3);
++    assert.match(r.body.latest_cursor, /^c1\./, 'the head as an opaque cursor');
++    {
++        // Starting at the head with latest_cursor reads nothing old, and the next event after it arrives.
++        const head = r.body.latest_cursor;
++        const fromHead = await request(h.base, "GET", `/api/v1/events?topic=live.vod.*&after=${encodeURIComponent(head)}`, { token: reader });
++        assert.strictEqual(fromHead.status, 200);
++        assert.deepStrictEqual(fromHead.body.events, []);
++        assert.strictEqual(fromHead.body.next_cursor, head);
++    }
  
      const id3 = (await h.db.prepare('SELECT id FROM events WHERE seq = ?').get(s3)).id;
      r = await request(h.base, 'GET', `/api/v1/events/${id3}`, { token: reader });