feat: persist isolated utility export jobs

tests/test_config_contracts.py

@@ -82,6 +82,9 @@ class ConfigurationTests(unittest.TestCase):
         self.assertEqual(config.storage.uncertain_review_after_seconds, 900.0)
         self.assertEqual(config.mqtt.publish_ack_timeout_seconds, 2.0)
         self.assertEqual(config.mqtt.router_echo_grace_seconds, 2.0)
+        self.assertEqual(config.downloads.export_directory, Path("exports"))
+        self.assertEqual(config.downloads.export_max_height, 1080)
+        self.assertEqual(config.downloads.max_queued_exports, 20)
 
     def test_documented_environment_overrides_apply(self):
         env = {
@@ -175,6 +178,34 @@ class ConfigurationTests(unittest.TestCase):
                 with self.assertRaisesRegex(ConfigError, f"{field} must be an absolute path"):
                     load_config(path, environ={})
 
+    def test_export_directory_must_stay_relative_to_media_root(self):
+        invalid = ("/tmp/exports", "../exports", "nested/../exports", r"nested\\exports")
+        for value in invalid:
+            with self.subTest(value=value), tempfile.TemporaryDirectory() as directory:
+                path = Path(directory) / "config.yaml"
+                path.write_text(
+                    f"downloads:\n  export_directory: {value!r}\n",
+                    encoding="utf-8",
+                )
+                with self.assertRaisesRegex(ConfigError, "safe relative directory"):
+                    load_config(path, environ={})
+
+    def test_export_limits_are_bounded_positive_integers(self):
+        cases = (
+            ("export_max_height", 0),
+            ("max_queued_exports", 0),
+            ("max_queued_exports", 1001),
+        )
+        for field, value in cases:
+            with self.subTest(field=field), tempfile.TemporaryDirectory() as directory:
+                path = Path(directory) / "config.yaml"
+                path.write_text(
+                    f"downloads:\n  {field}: {value}\n",
+                    encoding="utf-8",
+                )
+                with self.assertRaisesRegex(ConfigError, field):
+                    load_config(path, environ={})
+
 
 class ImportLifecycleTests(unittest.TestCase):
     def test_controller_core_import_does_not_connect_or_create_runtime_paths(self):