diff --git a/studio/backend/core/inference/codex_availability.py b/studio/backend/core/inference/codex_availability.py
index 8ae57deadd..bbb78bef64 100644
--- a/studio/backend/core/inference/codex_availability.py
+++ b/studio/backend/core/inference/codex_availability.py
@@ -182,7 +182,9 @@ async def _detect_logged_in() -> bool:
     # Negative prefixes win, regardless of rc. We anchor on word
     # boundaries so "not logged in" / "not authenticated" both match
     # without being fooled by the substring "logged in" inside them.
-    negative = re.compile(r"\b(not logged in|not authenticated|please log in|run\s+`?codex login`?)\b")
+    negative = re.compile(
+        r"\b(not logged in|not authenticated|please log in|run\s+`?codex login`?)\b"
+    )
     if negative.search(combined):
         return False
 
diff --git a/studio/backend/core/inference/codex_provider.py b/studio/backend/core/inference/codex_provider.py
index 299de46be3..55cda300f5 100644
--- a/studio/backend/core/inference/codex_provider.py
+++ b/studio/backend/core/inference/codex_provider.py
@@ -353,8 +353,7 @@ async def _stream_codex_single(
     async_codex_cls = getattr(sdk, "AsyncCodex", None)
     if async_codex_cls is None:
         raise CodexUnavailableError(
-            "Codex SDK is installed but AsyncCodex is missing -- "
-            "upgrade the SDK."
+            "Codex SDK is installed but AsyncCodex is missing -- " "upgrade the SDK."
         )
 
     completion_text_chars = 0
@@ -746,7 +745,9 @@ async def stream_codex_device_login() -> AsyncGenerator[dict[str, Any], None]:
     # Anchor on the upstream URL shape: ``.../codex/device`` (optionally
     # with a query string). The pattern accepts any host because some
     # builds redirect via a staging host.
-    url_re = re.compile(r"https?://[^\s\x1b]+?/codex/device(?:\?[^\s\x1b]*)?", re.IGNORECASE)
+    url_re = re.compile(
+        r"https?://[^\s\x1b]+?/codex/device(?:\?[^\s\x1b]*)?", re.IGNORECASE
+    )
     # One-time-code format from upstream device_code_auth.rs: 4 chars,
     # dash, 4 chars. Pattern is tolerant of any uppercase alphanum.
     code_re = re.compile(r"\b([A-Z0-9]{4}-[A-Z0-9]{4})\b")
diff --git a/studio/backend/routes/codex.py b/studio/backend/routes/codex.py
index 5570706646..60b0d3b18e 100644
--- a/studio/backend/routes/codex.py
+++ b/studio/backend/routes/codex.py
@@ -88,11 +88,17 @@ async def codex_device_login(
                 exc_type = type(exc).__name__,
                 error = str(exc),
             )
-            yield "data: " + json.dumps({
-                "type": "error",
-                "message": "Codex login failed",
-                "exception_type": type(exc).__name__,
-            }) + "\n\n"
+            yield (
+                "data: "
+                + json.dumps(
+                    {
+                        "type": "error",
+                        "message": "Codex login failed",
+                        "exception_type": type(exc).__name__,
+                    }
+                )
+                + "\n\n"
+            )
             yield "data: " + json.dumps({"type": "done", "ok": False}) + "\n\n"
         # Frontend treats the trailing [DONE] the same way it does for
         # chat streams, so we emit it for parity.
diff --git a/studio/backend/tests/test_codex_provider.py b/studio/backend/tests/test_codex_provider.py
index 1943bcf7ad..b6a255a785 100644
--- a/studio/backend/tests/test_codex_provider.py
+++ b/studio/backend/tests/test_codex_provider.py
@@ -521,10 +521,11 @@ class TestCodexHardenedRegressions:
 
         monkeypatch.setattr("importlib.util.find_spec", _shim)
         from core.inference.codex_availability import _sdk_importable
+
         assert _sdk_importable() is False
-        assert calls and calls[0] == "openai_codex", (
-            f"availability probe must check openai_codex first; saw {calls}"
-        )
+        assert (
+            calls and calls[0] == "openai_codex"
+        ), f"availability probe must check openai_codex first; saw {calls}"
 
     def test_login_status_uses_login_subcommand(self):
         """Upstream is `codex login status`, NOT `codex auth status`."""
@@ -533,9 +534,9 @@ class TestCodexHardenedRegressions:
             "studio/backend/core/inference/codex_availability.py"
         )
         text = open(src).read()
-        assert '"auth", "status"' not in text, (
-            "_detect_logged_in must use `codex login status`, not `codex auth status`"
-        )
+        assert (
+            '"auth", "status"' not in text
+        ), "_detect_logged_in must use `codex login status`, not `codex auth status`"
         assert '"login", "status"' in text
 
     def test_device_login_uses_login_subcommand(self):
@@ -544,9 +545,9 @@ class TestCodexHardenedRegressions:
             "studio/backend/core/inference/codex_provider.py"
         )
         text = open(src).read()
-        assert '"auth", "login", "--device-auth"' not in text, (
-            "stream_codex_device_login must use `codex login --device-auth`"
-        )
+        assert (
+            '"auth", "login", "--device-auth"' not in text
+        ), "stream_codex_device_login must use `codex login --device-auth`"
         assert '"login", "--device-auth"' in text
 
     def test_not_logged_in_not_misparsed_as_logged_in(self):
@@ -594,9 +595,9 @@ class TestCodexHardenedRegressions:
         ]
         prompt = _last_user_prompt(msgs)
         assert "and germany?" in prompt
-        assert "Paris" in prompt, (
-            f"PRIOR ASSISTANT TURN DROPPED — multi-turn broken. Prompt:\n{prompt}"
-        )
+        assert (
+            "Paris" in prompt
+        ), f"PRIOR ASSISTANT TURN DROPPED — multi-turn broken. Prompt:\n{prompt}"
         assert "capital of france" in prompt.lower()
 
     def test_single_turn_prompt_unchanged(self):
@@ -611,9 +612,9 @@ class TestCodexHardenedRegressions:
         from core.inference.providers import PROVIDER_REGISTRY
 
         codex = PROVIDER_REGISTRY["codex"]
-        assert "o3" not in codex["default_models"], (
-            "o3 is not a Codex model; remove from default_models"
-        )
+        assert (
+            "o3" not in codex["default_models"]
+        ), "o3 is not a Codex model; remove from default_models"
         assert "gpt-5.5" in codex["default_models"]
 
     def test_inference_route_no_raw_exc_leak(self):