style: ruff's own fixes, mechanically applied

`ruff check .` had gone unrun long enough to report 568 errors, which is the
same as having no linter: the next real finding would have been invisible in the
noise. This is the 521 it fixes by itself, in 173 files, and nothing else — the
98 it cannot fix are the next commit.

What actually changed: import sorting (225), imports nobody used (87, none of
them a re-export — no `__init__.py` is touched, which was the one way this could
have broken an import elsewhere), `datetime.timezone.utc` to `datetime.UTC` (69)
and `asyncio.TimeoutError` to `TimeoutError` (18), both plain aliases on the 3.12
this project requires, `Optional[X]` to `X | None` (24), and f-strings with
nothing to interpolate (19).

Checked rather than assumed: every module in the three packages still imports,
and the suite is 2893 passed — the same count, test for test, as the merge
before it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

6 files changed, 15 insertions, 19 deletions

diff --git a/packages/meshbay-common/tests/test_background_tasks.py b/packages/meshbay-common/tests/test_background_tasks.py
index 4f0ac59..d01235b 100644
--- a/packages/meshbay-common/tests/test_background_tasks.py
+++ b/packages/meshbay-common/tests/test_background_tasks.py
@@ -28,7 +28,6 @@ import logging
 from pathlib import Path
 
 import pytest
-
 from meshbay_common import background
 
 REPO = Path(__file__).resolve().parents[3]
diff --git a/packages/meshbay-common/tests/test_handshake.py b/packages/meshbay-common/tests/test_handshake.py
index d4f6d2b..11313aa 100644
--- a/packages/meshbay-common/tests/test_handshake.py
+++ b/packages/meshbay-common/tests/test_handshake.py
@@ -12,7 +12,6 @@ import jwt
 import pytest
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
-
 from meshbay_common.handshake import (
     HANDSHAKE_PREFIX,
     NONCE_LEN,
@@ -207,8 +206,8 @@ def test_membership_refusal_carries_a_code_a_client_can_act_on():
     is exactly the kind of coupling that breaks when someone improves a message.
     """
     import jwt as _jwt
-    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
     from cryptography.hazmat.primitives import serialization
+    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 
     sk = Ed25519PrivateKey.generate()
     pem_priv = sk.private_bytes(
@@ -234,8 +233,8 @@ def test_a_group_this_node_does_not_host_is_refused_with_a_code():
     dark on 2026-09-11 with its real host online — or had to match on wording.
     """
     import jwt as _jwt
-    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
     from cryptography.hazmat.primitives import serialization
+    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 
     sk = Ed25519PrivateKey.generate()
     pem_priv = sk.private_bytes(
diff --git a/packages/meshbay-common/tests/test_js_python_parity.py b/packages/meshbay-common/tests/test_js_python_parity.py
index 9893a9f..3887414 100644
--- a/packages/meshbay-common/tests/test_js_python_parity.py
+++ b/packages/meshbay-common/tests/test_js_python_parity.py
@@ -21,7 +21,6 @@ import tempfile
 from pathlib import Path
 
 import pytest
-
 from meshbay_common.adminop import admin_transcript
 from meshbay_common.handshake import handshake_transcript, webrtc_binding
 from meshbay_common.join import join_transcript
@@ -312,7 +311,6 @@ def _groupbox_payload(idx: int) -> dict:
 @pytest.fixture(scope="module")
 def groupbox_js(tmp_path_factory):
     import msgpack
-
     from meshbay_common.groupbox import seal
 
     d = tmp_path_factory.mktemp("groupbox-parity")
@@ -486,7 +484,6 @@ def chatbox_js(tmp_path_factory):
     from cryptography.hazmat.primitives.asymmetric.ed25519 import (
         Ed25519PrivateKey,
     )
-
     from meshbay_common.chatbox import seal
 
     d = tmp_path_factory.mktemp("chatbox-parity")
@@ -537,7 +534,6 @@ def test_browser_opens_a_chat_message_python_sealed(idx, vector, chatbox_js):
 @pytest.mark.parametrize("idx,vector", list(enumerate(CHAT_VECTORS)))
 def test_python_opens_a_chat_message_the_browser_sealed(idx, vector, chatbox_js):
     import msgpack
-
     from meshbay_common.chatbox import open_message
 
     js, vectors = chatbox_js
@@ -580,7 +576,6 @@ def test_a_message_does_not_open_under_another_epoch(chatbox_js):
     would round-trip against itself and pass every other test here.
     """
     import pytest as _pytest
-
     from meshbay_common.chatbox import open_message
 
     _js, vectors = chatbox_js
@@ -598,7 +593,6 @@ def test_a_message_does_not_open_under_another_devices_key(chatbox_js):
     any coordination — the property per-device ratchet chains were wanted for.
     """
     import pytest as _pytest
-
     from meshbay_common.chatbox import open_message
 
     _js, vectors = chatbox_js
diff --git a/packages/meshbay-common/tests/test_keyderive.py b/packages/meshbay-common/tests/test_keyderive.py
index 0aa6201..40b3c71 100644
--- a/packages/meshbay-common/tests/test_keyderive.py
+++ b/packages/meshbay-common/tests/test_keyderive.py
@@ -1,12 +1,12 @@
 """Tests for password-based key derivation."""
 
 import pytest
+from meshbay_common.crypto import pk_to_b64
 from meshbay_common.keyderive import (
+    decrypt_keypair_bundle,
     derive_keys_from_password,
     encrypt_keypair_bundle,
-    decrypt_keypair_bundle,
 )
-from meshbay_common.crypto import pk_to_b64
 
 
 def test_deterministic():
diff --git a/packages/meshbay-common/tests/test_paths.py b/packages/meshbay-common/tests/test_paths.py
index b9052e3..223a2a6 100644
--- a/packages/meshbay-common/tests/test_paths.py
+++ b/packages/meshbay-common/tests/test_paths.py
@@ -7,7 +7,6 @@ one file, and whether a member can save what they downloaded.
 """
 
 import pytest
-
 from meshbay_common.paths import (
     find_fold_collisions,
     fold,
@@ -18,7 +17,6 @@ from meshbay_common.paths import (
     sanitize_for_download,
 )
 
-
 # ── Same file or not ─────────────────────────────────────────────────────────
 
 def test_case_differences_fold_together():
diff --git a/packages/meshbay-common/tests/test_webcrypto.py b/packages/meshbay-common/tests/test_webcrypto.py
index 2ed6405..fbffdc1 100644
--- a/packages/meshbay-common/tests/test_webcrypto.py
+++ b/packages/meshbay-common/tests/test_webcrypto.py
@@ -1,10 +1,11 @@
 """Tests for AES-256-GCM webcrypto variant."""
 
 import os
-import pytest
+
 import blake3
+import pytest
 from meshbay_common.crypto import generate_gek
-from meshbay_common.webcrypto import chunk_key_aes, encrypt_chunk_aes, decrypt_chunk_aes
+from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes, encrypt_chunk_aes
 
 
 def test_aes_roundtrip():
@@ -49,7 +50,10 @@ def test_aes_chunk_keys_unique_per_chunk():
 def test_aes_gek_wrap_unwrap_roundtrip():
     from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
     from meshbay_common.crypto import (
-        wrap_gek_aes, unwrap_gek_aes, sk_to_raw, pk_to_raw,
+        pk_to_raw,
+        sk_to_raw,
+        unwrap_gek_aes,
+        wrap_gek_aes,
     )
     gek = generate_gek()
     sk = X25519PrivateKey.generate()
@@ -63,7 +67,7 @@ def test_aes_gek_wrap_unwrap_roundtrip():
 
 def test_aes_gek_wrap_wrong_key_rejected():
     from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
-    from meshbay_common.crypto import wrap_gek_aes, unwrap_gek_aes, sk_to_raw, pk_to_raw
+    from meshbay_common.crypto import pk_to_raw, sk_to_raw, unwrap_gek_aes, wrap_gek_aes
 
     gek = generate_gek()
     sk_a = X25519PrivateKey.generate()
@@ -77,7 +81,9 @@ def test_aes_gek_wrap_wrong_key_rejected():
 def test_aes_gek_wrap_differs_from_chacha_wrap():
     from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
     from meshbay_common.crypto import (
-        wrap_gek, wrap_gek_aes, pk_to_raw,
+        pk_to_raw,
+        wrap_gek,
+        wrap_gek_aes,
     )
     gek = generate_gek()
     sk = X25519PrivateKey.generate()