fix(desktop): keep pinned + recent sessions visible across compression

Long-running sessions auto-compress: the gateway ends the original session
and surfaces the live continuation under a new id (list_sessions_rich projects
the root forward to its tip). Two symptoms fell out of the id rotation:

- A pinned session "vanished" — the pin is stored as the pre-compression root
  id, but the sidebar only matched on the live id, so it was filtered out.
  Pins now resolve on the durable lineage-root id (`_lineage_root_id`, already
  surfaced by the projection): the sidebar indexes sessions by both ids, pin/
  unpin and reorder operate on the durable id, and `sessionPinId()` is shared
  with the Cmd+P toggle. Existing pins keep working with no migration.

- A freshly-continued session was missing from the list until you ungrouped +
  "load 50 more" — the list paginated by original start time, so an old-but-
  active conversation sat past the first page. The desktop now requests
  `order=recent` (GET /api/sessions gains an `order` param backed by the
  existing recency CTE), surfacing live continuations on the first page.

tests/hermes_cli/test_web_server.py

@@ -293,6 +293,49 @@ class TestWebServerEndpoints:
         resp = self.client.get("/api/sessions?archived=bogus")
         assert resp.status_code == 400
 
+    def test_get_sessions_rejects_unknown_order_value(self):
+        resp = self.client.get("/api/sessions?order=sideways")
+        assert resp.status_code == 400
+
+    def test_get_sessions_order_recent_surfaces_compression_tip(self):
+        """A long-running conversation that auto-compresses must stay on the
+        first page by recency, listed under its live continuation id."""
+        import time as _time
+
+        from hermes_state import SessionDB
+
+        db = SessionDB()
+        try:
+            old = _time.time() - 86_400
+            # Old conversation that later compresses into a fresh continuation.
+            # The continuation must start at/after the parent's ended_at to be
+            # recognised as a compression tip (not a sub-agent/branch).
+            db.create_session(session_id="root-old", source="cli")
+            db.append_message(session_id="root-old", role="user", content="kickoff")
+            db.end_session("root-old", "compression")
+            db._conn.execute(
+                "UPDATE sessions SET started_at = ?, ended_at = ? WHERE id = ?",
+                (old, old + 10, "root-old"),
+            )
+            db.create_session(session_id="tip-new", source="cli", parent_session_id="root-old")
+            db._conn.execute("UPDATE sessions SET started_at = ? WHERE id = ?", (old + 10, "tip-new"))
+            db.append_message(session_id="tip-new", role="user", content="continued just now")
+            # A brand-new unrelated session started after the root but before now.
+            db.create_session(session_id="mid", source="cli")
+            db._conn.execute("UPDATE sessions SET started_at = ? WHERE id = ?", (_time.time() - 3600, "mid"))
+            db.append_message(session_id="mid", role="user", content="hello")
+            db._conn.commit()
+        finally:
+            db.close()
+
+        rows = self.client.get("/api/sessions?order=recent&limit=5").json()["sessions"]
+        ids = [r["id"] for r in rows]
+        # The compressed conversation surfaces under its live tip id...
+        assert "tip-new" in ids
+        # ...carrying the durable lineage root so the desktop can match pins.
+        tip = next(r for r in rows if r["id"] == "tip-new")
+        assert tip.get("_lineage_root_id") == "root-old"
+
     def test_get_sessions_archived_is_boolean(self):
         from hermes_state import SessionDB