Extend Gemini configuration options in order to allow Vertex AI authentication via googleAuthOptions

[Tehnix]

Problem

I ran into an issue instrumenting the Gemini SDK with PostHog since I'm using Vertex AI and that doesn't support authentication via API Key, but instead via googleAuthOptions.

This config option wasn't exposed, so typescript would fail, but since all options are already passed directly into the Gemini client for initialization, it was really just a type issue and not any other code changes required.

I've extended the config options using the client's GoogleGenAIOptions, which should ensure that changes to the Gemini SDK in the future are immediately exposed and available to consumers using the @posthog/ai wrapper.

Relevant thread in the PostHog docs https://posthog.com/questions/vertex-ai-support

Changes

Extended the Gemini wrappers MonitoringGeminiConfig config with GoogleGenAIOptions which ensures all client configuration is available, and unblocks Vertex AI usage.

Release info Sub-libraries affected

Libraries affected

• All of them
• posthog-js (web)
• posthog-js-lite (web lite)
• posthog-node
• posthog-react-native
• @posthog/react
• @posthog/ai
• @posthog/nextjs-config

Checklist

• Tests for new code
• Accounted for the impact of any changes across different platforms
• Accounted for backwards compatibility of any changes (no breaking changes!)
• Took care not to unnecessarily increase the bundle size

If releasing new changes

• Ran pnpm changeset to generate a changeset file
• Added the "release" label to the PR to indicate we're publishing new versions for the affected packages

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[Tehnix]

This is still very much relevant, I'm running a locally patched version of @posthog/ai currently that adds this in order to use Gemini with Vertex AI