fix: Fix type mismatch in ContextFilterPlugin.custom_filter signature

[justinli34]

Link to Issue or Description of Change

Problem:
The ContextFilterPlugin.custom_filter parameter has an incorrect type signature. It's declared as Callable[[List[Event]], List[Event]] but is actually called with list[types.Content] from llm_request.contents in the before_model_callback method. This type mismatch could lead to runtime errors and prevents proper type checking.

Solution:
Changed the type signature of custom_filter to Callable[[list[types.Content]], list[types.Content]] to match its actual usage. This ensures type safety and allows static type checkers to properly validate code that uses this plugin.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Existing unit tests continue to pass. The change is a type annotation fix that doesn't alter runtime behavior, so existing test coverage validates the fix.

Pytest output:

3674 passed, 1 skipped, 2192 warnings in 101.27s (0:01:41)

Manual End-to-End (E2E) Tests:
Type checking validation:

• Ran mypy on the modified file to confirm no type errors
• Verified that custom filter implementations now receive correct type hints in IDEs

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

This is a type annotation fix that improves type safety without changing runtime behavior. Users who have implemented custom filters may need to update their type hints if they were following the incorrect signature, though the runtime behavior remains unchanged.

[gemini-code-assist]

Summary of Changes

Hello @justinli34, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical type inconsistency within the ContextFilterPlugin by correcting the signature of its custom_filter method. This ensures that the type hints accurately reflect the data types being processed, thereby enhancing type safety and enabling more robust static analysis without introducing any changes to the plugin's operational behavior at runtime.

Highlights

• Type Signature Correction: The type signature for ContextFilterPlugin.custom_filter has been updated from Callable[[List[Event]], List[Event]] to Callable[[list[types.Content]], list[types.Content]] to accurately reflect its actual usage.
• Improved Type Safety: This change resolves a type mismatch, ensuring proper type checking and enabling static type checkers to validate code using this plugin correctly.
• No Runtime Behavior Change: The fix is purely a type annotation update and does not alter the runtime behavior of the application.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a type mismatch in the ContextFilterPlugin.custom_filter signature, changing it from Callable[[List[Event]], List[Event]] to Callable[[List[types.Content]], List[types.Content]]. This aligns the type hint with its actual usage in before_model_callback, improving type safety. The change is well-described and necessary. I have one minor suggestion for consistency.

[gemini-code-assist]

For consistency with other parts of the codebase (e.g., llm_request.py which uses list[types.Content]) and to align with the PR description, it would be better to use the built-in list type hint instead of typing.List. This is the modern approach for Python 3.9+ and seems to be adopted in other files. Using list here would also allow for the removal of the from typing import List import, which would become unused.

Suggested change

	Callable[[List[types.Content]], List[types.Content]]
	Callable[[list[types.Content]], list[types.Content]]