Remove legacy code for format conversion

tests/test_relay.py

@@ -402,27 +402,28 @@ class ConfigTests(unittest.TestCase):
         with self.assertRaises(ValueError):
             self.load('\n[http]\nbase_path="/../config"\n')
 
-    def test_history_account_settings_and_migration_from_query_api_keys(self):
+    def test_history_account_environment_settings(self):
         config, _ = self.load('\n[history]\nusername_env="BACKUP_USER"\npassword_env="BACKUP_PASSWORD"\n')
         self.assertEqual(config.history.username_env, "BACKUP_USER")
         self.assertEqual(config.history.password_env, "BACKUP_PASSWORD")
         self.assertFalse(config.history.enabled)
-        config, _ = self.load('\n[history]\naccess_key_id_env="OLD_ID"\naccess_key_value_env="OLD_KEY"\n')
-        self.assertEqual(config.history.username_env, "SOLARWEB_USERNAME")
-        self.assertEqual(config.history.password_env, "SOLARWEB_PASSWORD")
         for name in ("username_env", "password_env"):
             with self.subTest(name=name), self.assertRaisesRegex(ValueError, "environment variable"):
                 self.load(f'\n[history]\n{name}="invalid name"\n')
 
-    def test_history_uses_retention_instead_of_legacy_lookback_setting(self):
+    def test_history_uses_collector_retention(self):
         with tempfile.TemporaryDirectory() as directory:
             path = Path(directory) / "synthetic-test.toml"
             path.write_text('[collector]\nretention_days=2\n[history]\nenabled=true\n'
-                            'pv_system_id="73733052-6f10-47a5-9746-7f7e76ebcb8c"\nlookback_days=7\n')
+                            'pv_system_id="73733052-6f10-47a5-9746-7f7e76ebcb8c"\n')
             config = load_config(path)
         self.assertEqual(config.collector.retention_days, 2)
         self.assertTrue(config.history.enabled)
-        self.assertFalse(hasattr(config.history, "lookback_days"))
+
+    def test_obsolete_history_options_are_rejected(self):
+        for name in ("access_key_id_env", "access_key_value_env", "lookback_days"):
+            with self.subTest(name=name), self.assertRaisesRegex(ValueError, "Unknown history settings"):
+                self.load(f'\n[history]\n{name}=7\n')
 
     def test_private_config_accepts_credentials_and_redacts_them_from_repr(self):
         config, _ = self.load('\n[upload]\ntoken="synthetic-shared-token"\n'