style: apply ruff's automatic fixes and formatter

Mechanical only, and separated from the judgment calls that follow so the
reviewable changes are not buried in a 98-file whitespace diff.

227 automatic fixes: 60 blank lines carrying whitespace, 60 unsorted import
blocks, 34 Optional[X] to X | None, 28 unused imports, 16 deprecated typing
imports, 12 datetime.timezone.utc to datetime.UTC, and assorted smaller
modernisations. Then `ruff format` over src and tests: 98 files reformatted,
35 already conforming.

No file among the unused-import findings defines __all__ or is an __init__.py,
so nothing here removes a re-export.

`make test`: 658 passed, unchanged from HEAD.

Two things observed while verifying, neither addressed here:

`pytest tests/` cannot collect — tests/e2e/test_orchestration_e2e.py uses an
`e2e` marker that is not registered, and the config is strict about markers.
This fails identically at HEAD, so it predates this change; `make test` passes
because it ignores tests/e2e, tests/integration and tests/contracts.

test_tatlock_tool_call_logging_calculator is flaky. It failed once in a full run
with these changes and passed on the next, passes in isolation with them, and
fails in isolation at HEAD. It is order- or timing-dependent, not a regression
from this commit — established by running the full suite both ways rather than
by reasoning about which change could have caused it.

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

tests/responses/test_error_handling.py

@@ -1,7 +1,9 @@
 """
 Tests for error handling in Responses API.
 """
+
 import json
+
 import pytest
 from fastapi.testclient import TestClient
 from httpx import AsyncClient
@@ -12,10 +14,8 @@ def test_model_not_found_error(client: TestClient) -> None:
     """Test response when model doesn't exist."""
     request_data = {
         "model": "nonexistent-model-12345",
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "Hello"}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -29,11 +29,7 @@ def test_model_not_found_error(client: TestClient) -> None:
 @pytest.mark.unit
 def test_validation_error_missing_model(client: TestClient) -> None:
     """Test validation error when model field is missing."""
-    request_data = {
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ]
-    }
+    request_data = {"input": [{"role": "user", "content": "Hello"}]}
 
     response = client.post("/v1/responses", json=request_data)
 
@@ -45,10 +41,8 @@ def test_validation_error_invalid_temperature(client: TestClient) -> None:
     """Test validation error for out-of-range temperature."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ],
-        "temperature": 3.0  # Max is 2.0
+        "input": [{"role": "user", "content": "Hello"}],
+        "temperature": 3.0,  # Max is 2.0
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -61,10 +55,8 @@ def test_rate_limit_error(client: TestClient) -> None:
     """Test rate limit error trigger."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "trigger_rate_limit"}
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "trigger_rate_limit"}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -78,10 +70,8 @@ def test_context_overflow_error(client: TestClient) -> None:
     """Test context length overflow error trigger."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "trigger_context_overflow"}
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "trigger_context_overflow"}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -96,10 +86,8 @@ async def test_streaming_model_not_found(async_client: AsyncClient) -> None:
     """Test streaming response with nonexistent model."""
     request_data = {
         "model": "nonexistent-streaming-model",
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ],
-        "stream": True
+        "input": [{"role": "user", "content": "Hello"}],
+        "stream": True,
     }
 
     async with async_client.stream(
@@ -133,10 +121,8 @@ async def test_streaming_rate_limit_error(async_client: AsyncClient) -> None:
     """Test streaming with rate limit error."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "trigger_rate_limit"}
-        ],
-        "stream": True
+        "input": [{"role": "user", "content": "trigger_rate_limit"}],
+        "stream": True,
     }
 
     async with async_client.stream(
@@ -177,10 +163,8 @@ async def test_streaming_context_overflow_error(async_client: AsyncClient) -> No
     """Test streaming with context overflow error."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "trigger_context_overflow"}
-        ],
-        "stream": True
+        "input": [{"role": "user", "content": "trigger_context_overflow"}],
+        "stream": True,
     }
 
     async with async_client.stream(
@@ -215,17 +199,9 @@ def test_function_call_output_item(client: TestClient) -> None:
     """Test response with function call items."""
     request_data = {
         "model": "lorem-tester",
-        "input": [
-            {"role": "user", "content": "Use the search tool"}
-        ],
-        "tools": [
-            {
-                "name": "search",
-                "description": "Search for information",
-                "parameters": {}
-            }
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "Use the search tool"}],
+        "tools": [{"name": "search", "description": "Search for information", "parameters": {}}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -248,10 +224,8 @@ def test_pipeline_prefix_stripping(client: TestClient) -> None:
     """Test that pipeline prefixes are stripped from model names."""
     request_data = {
         "model": "some_pipeline.lorem-tester",
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "Hello"}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)
@@ -267,10 +241,8 @@ def test_multiple_pipeline_prefixes(client: TestClient) -> None:
     """Test multiple dots in model name (only first is prefix)."""
     request_data = {
         "model": "pipeline.sub.lorem-tester",
-        "input": [
-            {"role": "user", "content": "Hello"}
-        ],
-        "stream": False
+        "input": [{"role": "user", "content": "Hello"}],
+        "stream": False,
     }
 
     response = client.post("/v1/responses", json=request_data)