diff --git a/packages/artemis-client/src/artemis_client/transport.py b/packages/artemis-client/src/artemis_client/transport.py
index b4196414..814d6045 100644
--- a/packages/artemis-client/src/artemis_client/transport.py
+++ b/packages/artemis-client/src/artemis_client/transport.py
@@ -97,7 +97,8 @@ def request(
                 except (UnicodeDecodeError, json.JSONDecodeError) as exc:
                     raise ProtocolError(f"Artemis host returned invalid JSON from {path}") from exc
         except urllib.error.HTTPError as exc:
-            payload = self._decode_error_payload(exc)
+            with exc:
+                payload = self._decode_error_payload(exc)
             detail = self._error_detail(payload, exc.reason)
             error_type = {
                 401: AuthenticationError,
diff --git a/packages/artemis-client/tests/test_transport_cleanup.py b/packages/artemis-client/tests/test_transport_cleanup.py
new file mode 100644
index 00000000..96e6986e
--- /dev/null
+++ b/packages/artemis-client/tests/test_transport_cleanup.py
@@ -0,0 +1,98 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+
+"""Regression controls for ownership of urllib HTTP error response bodies."""
+
+from __future__ import annotations
+
+import io
+import unittest
+import urllib.error
+from email.message import Message
+from unittest.mock import patch
+
+from artemis_client import (
+    ApiError,
+    AuthenticationError,
+    ConflictError,
+    JsonTransport,
+    NotFoundError,
+)
+
+
+class BrokenBody(io.BytesIO):
+    def read(self, *args, **kwargs):
+        raise OSError("read failed")
+
+
+class UnexpectedFailureBody(io.BytesIO):
+    def read(self, *args, **kwargs):
+        raise RuntimeError("unexpected decoder failure")
+
+
+class ErrorResponseOwnershipTests(unittest.TestCase):
+    def test_translated_http_error_closes_body_and_preserves_details(self):
+        for status, error_type in (
+            (401, AuthenticationError),
+            (403, AuthenticationError),
+            (404, NotFoundError),
+            (409, ConflictError),
+            (503, ApiError),
+        ):
+            with self.subTest(status=status):
+                body = io.BytesIO(b'{"detail":"denied"}')
+                http_error = urllib.error.HTTPError(
+                    "https://host.example/api/status", status, "fallback", Message(), body
+                )
+                with patch("urllib.request.urlopen", side_effect=http_error):
+                    with self.assertRaises(error_type) as caught:
+                        JsonTransport("https://host.example").request("GET", "/api/status")
+                self.assertEqual(caught.exception.status_code, status)
+                self.assertEqual(caught.exception.payload, {"detail": "denied"})
+                self.assertIn("denied", str(caught.exception))
+                self.assertIs(caught.exception.__cause__, http_error)
+                self.assertTrue(body.closed)
+
+    def test_text_and_empty_error_bodies_are_closed(self):
+        for payload, detail in ((b"plain failure", "plain failure"), (b"", "fallback")):
+            with self.subTest(payload=payload):
+                body = io.BytesIO(payload)
+                http_error = urllib.error.HTTPError(
+                    "https://host.example/api/status", 503, "fallback", Message(), body
+                )
+                with patch("urllib.request.urlopen", side_effect=http_error):
+                    with self.assertRaisesRegex(ApiError, detail):
+                        JsonTransport("https://host.example").request("GET", "/api/status")
+                self.assertTrue(body.closed)
+
+    def test_read_error_keeps_http_status_and_closes_body(self):
+        body = BrokenBody()
+        http_error = urllib.error.HTTPError(
+            "https://host.example/api/status", 503, "fallback", Message(), body
+        )
+        with patch("urllib.request.urlopen", side_effect=http_error):
+            with self.assertRaises(ApiError) as caught:
+                JsonTransport("https://host.example").request("GET", "/api/status")
+        self.assertEqual(caught.exception.status_code, 503)
+        self.assertIsNone(caught.exception.payload)
+        self.assertIs(caught.exception.__cause__, http_error)
+        self.assertTrue(body.closed)
+
+    def test_unexpected_read_failure_is_not_swallowed_but_body_is_closed(self):
+        body = UnexpectedFailureBody()
+        http_error = urllib.error.HTTPError(
+            "https://host.example/api/status", 503, "fallback", Message(), body
+        )
+        with patch("urllib.request.urlopen", side_effect=http_error):
+            with self.assertRaisesRegex(RuntimeError, "unexpected decoder failure"):
+                JsonTransport("https://host.example").request("GET", "/api/status")
+        self.assertTrue(body.closed)
+
+
+if __name__ == "__main__":
+    unittest.main()