diff --git a/studio/backend/run.py b/studio/backend/run.py
index d6b5dd8c74..b83198626a 100644
--- a/studio/backend/run.py
+++ b/studio/backend/run.py
@@ -937,7 +937,11 @@ def _per_port_records() -> "list[tuple[int, float | None, str | None] | None]":
         return []
 
 
-def _resolve_port(host: str, port: int, avoid_own_studio: bool = True) -> int:
+def _resolve_port(
+    host: str,
+    port: int,
+    avoid_own_studio: bool = True,
+) -> int:
     """The requested port, or the next free one.
 
     With ``avoid_own_studio`` this aborts rather than falling back past one of our
diff --git a/studio/backend/tests/test_studio_pid_files.py b/studio/backend/tests/test_studio_pid_files.py
index 0b18cec680..a5d8d1257c 100644
--- a/studio/backend/tests/test_studio_pid_files.py
+++ b/studio/backend/tests/test_studio_pid_files.py
@@ -476,11 +476,14 @@ def test_bind_addresses_keeps_every_family_a_hostname_resolves_to(monkeypatch):
     # Independent oracle: the sibling test derives its expectation from this
     # function's own output, so dropping a family would pass it.
     import socket
-
-    monkeypatch.setattr(socket, "getaddrinfo", lambda *a, **k: [
-        (socket.AF_INET, socket.SOCK_STREAM, 6, "", ("127.0.0.1", 8889)),
-        (socket.AF_INET6, socket.SOCK_STREAM, 6, "", ("::1", 8889, 0, 0)),
-    ])
+    monkeypatch.setattr(
+        socket,
+        "getaddrinfo",
+        lambda *a, **k: [
+            (socket.AF_INET, socket.SOCK_STREAM, 6, "", ("127.0.0.1", 8889)),
+            (socket.AF_INET6, socket.SOCK_STREAM, 6, "", ("::1", 8889, 0, 0)),
+        ],
+    )
 
     assert run._bind_addresses("localhost", 8889) == {"127.0.0.1", "::1"}
 
@@ -491,8 +494,9 @@ def test_the_legacy_file_is_written_even_when_the_per_port_record_fails(tmp_path
     # overwrite of an existing path, so it can still succeed and must be tried.
     blocked = tmp_path / "not-a-directory"
     blocked.write_text("", encoding = "utf-8")
-    monkeypatch.setattr(run, "_pid_file_for_port",
-                        lambda port: blocked / f"studio-{port}-{os.getpid()}.pid")
+    monkeypatch.setattr(
+        run, "_pid_file_for_port", lambda port: blocked / f"studio-{port}-{os.getpid()}.pid"
+    )
 
     run._write_pid_file(8901, "127.0.0.1")
 
diff --git a/tests/studio/test_studio_pid_file_contract.py b/tests/studio/test_studio_pid_file_contract.py
index 5901fbf259..fbc981e485 100644
--- a/tests/studio/test_studio_pid_file_contract.py
+++ b/tests/studio/test_studio_pid_file_contract.py
@@ -54,12 +54,16 @@ def test_stop_finds_a_pid_file_named_the_way_the_backend_writes_it(tmp_path, mon
 def test_the_legacy_file_stays_a_bare_pid_an_older_cli_can_parse(tmp_path, monkeypatch):
     # An older `unsloth studio stop` reads studio.pid and requires str.isdigit(),
     # so the compatibility file must never gain the extra metadata lines.
-    ns = {"os": os, "Path": Path, "_studio_root": lambda: tmp_path,
-          "_PID_FILE": tmp_path / "studio.pid",
-          "_pid_file_for_port": lambda port: _backend_pid_path(tmp_path, port),
-          "_process_create_time": lambda pid: None,
-          "_bind_addresses": lambda host, port: {host},
-          "_OWN_PID_FILE": None}
+    ns = {
+        "os": os,
+        "Path": Path,
+        "_studio_root": lambda: tmp_path,
+        "_PID_FILE": tmp_path / "studio.pid",
+        "_pid_file_for_port": lambda port: _backend_pid_path(tmp_path, port),
+        "_process_create_time": lambda pid: None,
+        "_bind_addresses": lambda host, port: {host},
+        "_OWN_PID_FILE": None,
+    }
     exec(_func_source(_RUN_SRC, "_write_pid_file"), ns)
     ns["_write_pid_file"](8901, "127.0.0.1")
 
diff --git a/unsloth_cli/tests/test_studio_stop.py b/unsloth_cli/tests/test_studio_stop.py
index 752a7f2c2e..7e9efb26da 100644
--- a/unsloth_cli/tests/test_studio_stop.py
+++ b/unsloth_cli/tests/test_studio_stop.py
@@ -453,8 +453,8 @@ def test_stop_keeps_a_record_it_cannot_read(monkeypatch, tmp_path):
 def test_stop_reaches_every_server_when_one_record_cannot_be_removed(monkeypatch, tmp_path):
     # One undeletable stale record must not end the loop before the live servers.
     studio_mod, _live, killed = _install(monkeypatch, tmp_path, alive = {8600})
-    _write_pid(tmp_path, "studio-8901-8550.pid", 8550)   # dead -> stop prunes it
-    _write_pid(tmp_path, "studio-8902-8600.pid", 8600)   # live -> stop signals it
+    _write_pid(tmp_path, "studio-8901-8550.pid", 8550)  # dead -> stop prunes it
+    _write_pid(tmp_path, "studio-8902-8600.pid", 8600)  # live -> stop signals it
     real_unlink = Path.unlink
 
     def deny(self, *args, **kwargs):