[bot] Legacy Google Generative AI SDK (`@google/generative-ai`) not instrumented — 3M weekly downloads with no tracing coverage

[braintrust-bot]

Summary

The legacy Google Generative AI JavaScript SDK (@google/generative-ai, v0.24.1, ~3 million weekly npm downloads) provides execution APIs for Gemini model generation and embeddings. This repository instruments only the newer unified SDK (@google/genai, covered by js/src/instrumentation/plugins/google-genai-plugin.ts), but not the older @google/generative-ai package. Users who have not yet migrated to @google/genai get no Braintrust spans.

What instrumentation is missing

The @google/generative-ai package exposes these execution surfaces, none of which are instrumented:

SDK Method	Description
model.generateContent(request)	Unary text and multimodal generation
model.generateContentStream(request)	Streaming generation
model.embedContent(request)	Single text embedding
model.batchEmbedContents(request)	Batch text embeddings
chat.sendMessage(request) / chat.sendMessageStream(request)	Multi-turn chat completions

These methods are accessible via const model = genAI.getGenerativeModel({ model: "gemini-..." }) and const chat = model.startChat(...).

No coverage in any instrumentation layer:

• No auto-instrumentation config in js/src/auto-instrumentations/configs/ targeting @google/generative-ai
• No plugin handler in js/src/instrumentation/plugins/ for @google/generative-ai
• No diagnostics channels for @google/generative-ai
• No e2e test scenarios

A search for @google/generative-ai across js/src/ returns zero matches.

Context

Google deprecated @google/generative-ai in favor of @google/genai, but the legacy package remains at v0.24.1 with approximately 3 million weekly npm downloads — far exceeding the @google/genai adoption rate. This means the majority of JavaScript Gemini SDK users currently receive no Braintrust instrumentation coverage, even though Braintrust fully supports the equivalent @google/genai API surface via wrapGoogleGenAI.

The existing google-genai plugin in this repo (js/src/auto-instrumentations/configs/google-genai.ts) exclusively targets @google/genai versions >=1.0.0 and does not patch any path from @google/generative-ai.

Braintrust docs status

supported for Google Gemini via @google/genai only. The Braintrust docs page at https://www.braintrust.dev/docs/integrations/ai-providers/gemini references @google/genai exclusively and does not mention @google/generative-ai.

Upstream references

• @google/generative-ai npm package: https://www.npmjs.com/package/@google/generative-ai
• API reference (generateContent): https://ai.google.dev/api/generate-content
• Migration guide to @google/genai: https://ai.google.dev/gemini-api/docs/migrate
• GitHub: https://github.com/google-gemini/generative-ai-js

Local files inspected

• js/src/auto-instrumentations/configs/google-genai.ts — instruments @google/genai versions >=1.0.0 only; no entry for @google/generative-ai
• js/src/instrumentation/plugins/google-genai-plugin.ts — handles @google/genai only
• js/src/instrumentation/plugins/google-genai-channels.ts — channels defined for @google/genai only
• e2e/scenarios/google-genai-instrumentation/ — test scenario targets @google/genai only
• Full repo grep for @google/generative-ai in js/src/ — zero matches