fix(core): guard isFunctionCall/isFunctionResponse against empty parts

[amitesh0303]

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Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
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    • Docker
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  • Windows
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  • Linux
    • npm run
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[gemini-code-assist]

Summary of Changes

Hello, 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 improves the reliability of message inspection utilities by adding explicit length checks to function call and response validation. By ensuring that message parts are not empty, the code avoids potential logical errors where an empty array would otherwise return true, while also introducing safer property access patterns.

Highlights

• Added length validation: Updated isFunctionResponse and isFunctionCall to ensure content.parts has at least one element, preventing vacuous truth issues with Array.every.
• Improved safety: Added optional chaining to part access within the every callback to ensure robust handling of message parts.

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[gemini-code-assist]

Code Review

This pull request updates the isFunctionResponse and isFunctionCall helper functions in messageInspectors.ts to avoid vacuous truth on empty arrays by ensuring parts.length > 0, and adds optional chaining for safety. Feedback suggests using Array.prototype.some instead of every for identifying function calls, as Gemini 2.0 models often return other parts (such as thoughts) alongside function calls in the same turn.

[gemini-code-assist]

Gemini 2.0 models (such as Gemini 2.0 Flash/Pro) frequently return thought parts (part.thought) alongside functionCall parts in the same model turn. Using Array.prototype.every will cause isFunctionCall to return false if any thought parts (or text parts) are present, which can prevent tool execution. Changing this to Array.prototype.some ensures that any model response containing at least one function call is correctly identified, and it also naturally avoids vacuous truth for empty arrays without needing an explicit length check.

    content.parts.some((part) => !!part?.functionCall)