fix: emit valid codex stop-hook cleanup output

src/serena/hooks.py

@@ -516,8 +516,22 @@ def execute(self) -> None:
 
 
 class SessionEndCleanupHook(Hook):
+    def __init__(self, client: HookClient):
+        raw = sys.stdin.read()
+        input_data = json.loads(raw) if raw else {}
+        self._input_data = input_data
+        self._client = client
+
+        session_id = input_data.get("session_id") or input_data.get("sessionId")
+        self._session_id = str(session_id) if session_id else None
+        self.session_persistence_dir = os.path.join(serena_home_dir, "hook_data", self._session_id) if self._session_id is not None else ""
+        self.triggered_at_timestamp = datetime.now()
+
     def execute(self) -> None:
-        shutil.rmtree(self.session_persistence_dir, ignore_errors=True)
+        if self._session_id is not None:
+            shutil.rmtree(self.session_persistence_dir, ignore_errors=True)
+        if self._client == HookClient.CODEX:
+            click.echo(json.dumps({"continue": True}))
 
 
 class PreToolUseAutoApproveSerenaHook(PreToolUseHook):

test/serena/test_hooks.py

@@ -677,6 +677,24 @@ def test_cleanup_is_idempotent(self, tmp_path: Path):
         with patch("sys.stdin", _make_stdin(stdin_data)), patch("serena.hooks.serena_home_dir", str(tmp_path)):
             SessionEndCleanupHook(HookClient.CLAUDE_CODE).execute()
 
+    def test_codex_cleanup_emits_continue_json(self, tmp_path: Path, capsys: pytest.CaptureFixture[str]):
+        session_dir = tmp_path / "hook_data" / "codex-cleanup"
+        session_dir.mkdir(parents=True)
+        (session_dir / "tool_use_counter.pkl").write_bytes(pickle.dumps(ToolUseCounter()))
+
+        stdin_data = {"session_id": "codex-cleanup"}
+        with patch("sys.stdin", _make_stdin(stdin_data)), patch("serena.hooks.serena_home_dir", str(tmp_path)):
+            SessionEndCleanupHook(HookClient.CODEX).execute()
+
+        assert not session_dir.exists()
+        assert json.loads(capsys.readouterr().out.strip()) == {"continue": True}
+
+    def test_codex_cleanup_without_session_id_is_noop(self, tmp_path: Path, capsys: pytest.CaptureFixture[str]):
+        with patch("sys.stdin", _make_stdin({})), patch("serena.hooks.serena_home_dir", str(tmp_path)):
+            SessionEndCleanupHook(HookClient.CODEX).execute()
+
+        assert json.loads(capsys.readouterr().out.strip()) == {"continue": True}
+
 
 class TestHookCli:
     """Tests for the Click CLI entry point (serena-hooks)."""
@@ -693,6 +711,19 @@ def test_cleanup_command(self, tmp_path: Path):
         assert result.exit_code == 0
         assert not session_dir.exists()
 
+    def test_cleanup_command_codex(self, tmp_path: Path):
+        session_dir = tmp_path / "hook_data" / "cli-cleanup-codex"
+        session_dir.mkdir(parents=True)
+        (session_dir / "somefile").write_text("data")
+
+        stdin_json = json.dumps({"session_id": "cli-cleanup-codex"})
+        runner = CliRunner()
+        with patch("serena.hooks.serena_home_dir", str(tmp_path)):
+            result = runner.invoke(hook_commands, ["cleanup", "--client", "codex"], input=stdin_json)
+        assert result.exit_code == 0
+        assert not session_dir.exists()
+        assert json.loads(result.output) == {"continue": True}
+
     def test_remind_command(self, tmp_path: Path):
         """Invoke the remind command enough times to trigger a deny."""
         runner = CliRunner()