security: enforce 0600/0700 file permissions on sensitive files (inspired by openclaw)

Enforce owner-only permissions on files and directories that contain
secrets or sensitive data:

- cron/jobs.py: jobs.json (0600), cron dirs (0700), job output files (0600)
- hermes_cli/config.py: config.yaml (0600), .env (0600), ~/.hermes/* dirs (0700)
- cli.py: config.yaml via save_config_value (0600)

All chmod calls use try/except for Windows compatibility.

Includes _secure_file() and _secure_dir() helpers with graceful fallback.
8 new tests verify permissions on all file types.

Inspired by openclaw v2026.3.7 file permission enforcement.

tests/test_file_permissions.py

@@ -0,0 +1,135 @@
+"""Tests for file permissions hardening on sensitive files."""
+
+import json
+import os
+import stat
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import patch
+
+
+class TestCronFilePermissions(unittest.TestCase):
+    """Verify cron files get secure permissions."""
+
+    def setUp(self):
+        self.tmpdir = tempfile.mkdtemp()
+        self.cron_dir = Path(self.tmpdir) / "cron"
+        self.output_dir = self.cron_dir / "output"
+
+    def tearDown(self):
+        import shutil
+        shutil.rmtree(self.tmpdir, ignore_errors=True)
+
+    @patch("cron.jobs.CRON_DIR")
+    @patch("cron.jobs.OUTPUT_DIR")
+    @patch("cron.jobs.JOBS_FILE")
+    def test_ensure_dirs_sets_0700(self, mock_jobs_file, mock_output, mock_cron):
+        mock_cron.__class__ = Path
+        # Use real paths
+        cron_dir = Path(self.tmpdir) / "cron"
+        output_dir = cron_dir / "output"
+
+        with patch("cron.jobs.CRON_DIR", cron_dir), \
+             patch("cron.jobs.OUTPUT_DIR", output_dir):
+            from cron.jobs import ensure_dirs
+            ensure_dirs()
+
+            cron_mode = stat.S_IMODE(os.stat(cron_dir).st_mode)
+            output_mode = stat.S_IMODE(os.stat(output_dir).st_mode)
+            self.assertEqual(cron_mode, 0o700)
+            self.assertEqual(output_mode, 0o700)
+
+    @patch("cron.jobs.CRON_DIR")
+    @patch("cron.jobs.OUTPUT_DIR")
+    @patch("cron.jobs.JOBS_FILE")
+    def test_save_jobs_sets_0600(self, mock_jobs_file, mock_output, mock_cron):
+        cron_dir = Path(self.tmpdir) / "cron"
+        output_dir = cron_dir / "output"
+        jobs_file = cron_dir / "jobs.json"
+
+        with patch("cron.jobs.CRON_DIR", cron_dir), \
+             patch("cron.jobs.OUTPUT_DIR", output_dir), \
+             patch("cron.jobs.JOBS_FILE", jobs_file):
+            from cron.jobs import save_jobs
+            save_jobs([{"id": "test", "prompt": "hello"}])
+
+            file_mode = stat.S_IMODE(os.stat(jobs_file).st_mode)
+            self.assertEqual(file_mode, 0o600)
+
+    def test_save_job_output_sets_0600(self):
+        output_dir = Path(self.tmpdir) / "output"
+        with patch("cron.jobs.OUTPUT_DIR", output_dir), \
+             patch("cron.jobs.CRON_DIR", Path(self.tmpdir)), \
+             patch("cron.jobs.ensure_dirs"):
+            output_dir.mkdir(parents=True, exist_ok=True)
+            from cron.jobs import save_job_output
+            output_file = save_job_output("test-job", "test output content")
+
+            file_mode = stat.S_IMODE(os.stat(output_file).st_mode)
+            self.assertEqual(file_mode, 0o600)
+
+            # Job output dir should also be 0700
+            job_dir = output_dir / "test-job"
+            dir_mode = stat.S_IMODE(os.stat(job_dir).st_mode)
+            self.assertEqual(dir_mode, 0o700)
+
+
+class TestConfigFilePermissions(unittest.TestCase):
+    """Verify config files get secure permissions."""
+
+    def setUp(self):
+        self.tmpdir = tempfile.mkdtemp()
+
+    def tearDown(self):
+        import shutil
+        shutil.rmtree(self.tmpdir, ignore_errors=True)
+
+    def test_save_config_sets_0600(self):
+        config_path = Path(self.tmpdir) / "config.yaml"
+        with patch("hermes_cli.config.get_config_path", return_value=config_path), \
+             patch("hermes_cli.config.ensure_hermes_home"):
+            from hermes_cli.config import save_config
+            save_config({"model": "test/model"})
+
+            file_mode = stat.S_IMODE(os.stat(config_path).st_mode)
+            self.assertEqual(file_mode, 0o600)
+
+    def test_save_env_value_sets_0600(self):
+        env_path = Path(self.tmpdir) / ".env"
+        with patch("hermes_cli.config.get_env_path", return_value=env_path), \
+             patch("hermes_cli.config.ensure_hermes_home"):
+            from hermes_cli.config import save_env_value
+            save_env_value("TEST_KEY", "test_value")
+
+            file_mode = stat.S_IMODE(os.stat(env_path).st_mode)
+            self.assertEqual(file_mode, 0o600)
+
+    def test_ensure_hermes_home_sets_0700(self):
+        home = Path(self.tmpdir) / ".hermes"
+        with patch("hermes_cli.config.get_hermes_home", return_value=home):
+            from hermes_cli.config import ensure_hermes_home
+            ensure_hermes_home()
+
+            home_mode = stat.S_IMODE(os.stat(home).st_mode)
+            self.assertEqual(home_mode, 0o700)
+
+            for subdir in ("cron", "sessions", "logs", "memories"):
+                subdir_mode = stat.S_IMODE(os.stat(home / subdir).st_mode)
+                self.assertEqual(subdir_mode, 0o700, f"{subdir} should be 0700")
+
+
+class TestSecureHelpers(unittest.TestCase):
+    """Test the _secure_file and _secure_dir helpers."""
+
+    def test_secure_file_nonexistent_no_error(self):
+        from cron.jobs import _secure_file
+        _secure_file(Path("/nonexistent/path/file.json"))  # Should not raise
+
+    def test_secure_dir_nonexistent_no_error(self):
+        from cron.jobs import _secure_dir
+        _secure_dir(Path("/nonexistent/path"))  # Should not raise
+
+
+if __name__ == "__main__":
+    unittest.main()