bug: isFunctionCall and isFunctionResponse return true for empty parts arrays

[PewterZz]

What happened?

isFunctionCall() and isFunctionResponse() in messageInspectors.ts return true for messages with empty parts arrays. This happens because Array.every([]) is vacuously true in JavaScript.

This means any message with role: "model" and parts: [] is incorrectly classified as a function call, and any message with role: "user" and parts: [] is incorrectly classified as a function response.

// Current behavior:
[].every((part) => !!part.functionCall) // => true (vacuous truth)

What did you expect to happen?

Both functions should return false when parts is an empty array, since there are no actual function call or function response parts present.

Client information

Found via code review. The file has no existing test coverage.

Login information

No response

Anything else we need to know?

No response

[gemini-cli]

Found possible duplicate issues:

• fix(core): empty parts array causes false positives in messageInspectors #22912

If you believe this is not a duplicate, please remove the status/possible-duplicate label.

[Nagajyothi-tammisetti]

Hi, I’d like to work on this issue.

It seems the problem is caused by the condition allowing empty arrays to pass as valid. I’m planning to update the check to ensure the array contains elements before returning true.

Please let me know if that approach works.

[gemini-cli]

A localized logic error causing empty arrays to be incorrectly classified as function calls or responses.

Effort Analysis:
The functions isFunctionCall and isFunctionResponse in packages/core/src/utils/messageInspectors.ts incorrectly return true for empty arrays due to JavaScript's Array.every behavior. The fix involves adding a simple check for array length (e.g., parts.length > 0), which is a localized bug fix in a single file.