fix: add ruff check to CI and fix all lint errors

- Add 'Lint with ruff' step to CI workflow (was only running format check)
- Fix F401: Add explicit re-exports for public API types in __init__.py
- Fix F811: Rename duplicate test_openai_reasoning_tokens to test_openai_reasoning_tokens_o4_mini
- Fix E731: Convert lambda to def function in test_middleware.py
- Fix unused imports in client.py and test files (auto-fixed)

Without ruff check in CI, lint errors were accumulating on master undetected.

Author: webjunkie

.github/workflows/ci.yml

@@ -36,6 +36,10 @@ jobs:
               run: |
                   ruff format --check .
 
+            - name: Lint with ruff
+              run: |
+                  ruff check .
+
             - name: Check types with mypy
               run: |
                   mypy --no-site-packages --config-file mypy.ini  . | mypy-baseline filter

posthog/__init__.py

@@ -18,8 +18,15 @@
     DEFAULT_CODE_VARIABLES_IGNORE_PATTERNS,
     DEFAULT_CODE_VARIABLES_MASK_PATTERNS,
 )
-from posthog.feature_flags import InconclusiveMatchError, RequiresServerEvaluation
-from posthog.types import FeatureFlag, FlagsAndPayloads, FeatureFlagResult
+from posthog.feature_flags import (
+    InconclusiveMatchError as InconclusiveMatchError,
+    RequiresServerEvaluation as RequiresServerEvaluation,
+)
+from posthog.types import (
+    FeatureFlag,
+    FlagsAndPayloads,
+    FeatureFlagResult as FeatureFlagResult,
+)
 from posthog.version import VERSION
 
 __version__ = VERSION

posthog/test/ai/langchain/test_callbacks.py

@@ -1716,7 +1716,7 @@ def test_combined_reasoning_and_cache_tokens(mock_client):
 
 
 @pytest.mark.skipif(not OPENAI_API_KEY, reason="OPENAI_API_KEY is not set")
-def test_openai_reasoning_tokens(mock_client):
+def test_openai_reasoning_tokens_o4_mini(mock_client):
     model = ChatOpenAI(
         api_key=OPENAI_API_KEY, model="o4-mini", max_completion_tokens=10
     )

posthog/test/integrations/test_middleware.py

@@ -315,7 +315,9 @@ def test_sync_middleware_with_filter(self):
         get_response = Mock(return_value=mock_response)
 
         # Create middleware with request filter that filters all requests
-        request_filter = lambda req: False
+        def request_filter(req):
+            return False
+
         middleware = PosthogContextMiddleware.__new__(PosthogContextMiddleware)
         middleware.get_response = get_response
         middleware._is_coroutine = False