diff --git a/strix/core/execution.py b/strix/core/execution.py
index 2d4ad5f7..ff60fee9 100644
--- a/strix/core/execution.py
+++ b/strix/core/execution.py
@@ -184,7 +184,7 @@ def _is_transient_model_error(exc: BaseException) -> bool:
         return True
     code = _model_error_status_code(exc)
     if code is not None:
-        return code >= 400
+        return code >= 400 and code not in (401, 402, 403)
     return isinstance(exc, APIError)
 
 
diff --git a/tests/test_execution_request_log.py b/tests/test_execution_request_log.py
index 28c330ff..426c4d47 100644
--- a/tests/test_execution_request_log.py
+++ b/tests/test_execution_request_log.py
@@ -96,12 +96,8 @@ async def test_blocked_provider_failure_text_carries_request_id(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     coordinator = AgentCoordinator()
-    # 4xx errors are retried, so the block repeats until retries run out.
-    streams = [
-        _FakeStream(exc=_blocked_error()) for _ in range(execution._MAX_TRANSIENT_MODEL_RETRIES + 1)
-    ]
     with pytest.raises(PermissionDeniedError):
-        await _run(monkeypatch, streams, coordinator)
+        await _run(monkeypatch, [_FakeStream(exc=_blocked_error())], coordinator)
     assert coordinator.statuses["root"] == "failed"
     error = coordinator.errors["root"]
     assert "Output blocked by policy" in error
diff --git a/tests/test_execution_transient_retry.py b/tests/test_execution_transient_retry.py
index a9200794..6b2fd336 100644
--- a/tests/test_execution_transient_retry.py
+++ b/tests/test_execution_transient_retry.py
@@ -84,8 +84,9 @@ def test_client_errors_are_transient() -> None:
         "bad", response=httpx.Response(400, request=_request()), body=None
     )
     assert execution._is_transient_model_error(bad_request) is True
-    for status in (401, 402, 403, 404):
-        assert execution._is_transient_model_error(_status_error(status)) is True
+    assert execution._is_transient_model_error(_status_error(404)) is True
+    for status in (401, 402, 403):
+        assert execution._is_transient_model_error(_status_error(status)) is False
     assert execution._is_transient_model_error(ValueError("nope")) is False