fix(session-search): exclude current lineage root deterministically in recent mode

tests/tools/test_session_search.py

@@ -10,6 +10,7 @@ from tools.session_search_tool import (
     _format_conversation,
     _truncate_around_matches,
     _get_session_search_max_concurrency,
+    _list_recent_sessions,
     _HIDDEN_SESSION_SOURCES,
     MAX_SESSION_CHARS,
     SESSION_SEARCH_SCHEMA,
@@ -240,6 +241,54 @@ class TestSessionSearchConcurrency:
         assert max_seen["value"] == 1
 
 
+class TestRecentSessionListing:
+    def test_current_child_session_excludes_root_lineage_even_when_child_id_is_longer(self):
+        from unittest.mock import MagicMock
+
+        mock_db = MagicMock()
+        mock_db.list_sessions_rich.return_value = [
+            {
+                "id": "root",
+                "title": "Current conversation",
+                "source": "cli",
+                "started_at": 1709500000,
+                "last_active": 1709500100,
+                "message_count": 4,
+                "preview": "current root",
+                "parent_session_id": None,
+            },
+            {
+                "id": "other_session",
+                "title": "Other conversation",
+                "source": "cli",
+                "started_at": 1709400000,
+                "last_active": 1709400100,
+                "message_count": 3,
+                "preview": "other root",
+                "parent_session_id": None,
+            },
+        ]
+
+        def _get_session(session_id):
+            if session_id == "child_session_id_that_is_definitely_longer":
+                return {"parent_session_id": "root"}
+            if session_id == "root":
+                return {"parent_session_id": None}
+            return None
+
+        mock_db.get_session.side_effect = _get_session
+
+        result = json.loads(_list_recent_sessions(
+            mock_db,
+            limit=5,
+            current_session_id="child_session_id_that_is_definitely_longer",
+        ))
+
+        assert result["success"] is True
+        assert [item["session_id"] for item in result["results"]] == ["other_session"]
+        assert all(item["session_id"] != "root" for item in result["results"])
+
+
 # =========================================================================
 # session_search (dispatcher)
 # =========================================================================