Firebase Genkit

​

Setup

pnpm add braintrust genkit @genkit-ai/googleai

npm install braintrust genkit @genkit-ai/googleai

​

Auto-instrumentation

import { initLogger } from "braintrust";
import { genkit } from "genkit";
import { googleAI } from "@genkit-ai/googleai";

initLogger({
  projectName: "my-genkit-project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const ai = genkit({
  plugins: [googleAI()],
});

const { text } = await ai.generate({
  model: googleAI.model("gemini-2.5-flash"),
  prompt: "What is the capital of France?",
});

console.log(text);

node --import braintrust/hook.mjs trace-genkit-auto.js

​

Manual instrumentation

import { initLogger, wrapGenkit } from "braintrust";
import { genkit } from "genkit";
import { googleAI } from "@genkit-ai/googleai";

initLogger({
  projectName: "my-genkit-project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const ai = wrapGenkit(
  genkit({
    plugins: [googleAI()],
  }),
);

const { text } = await ai.generate({
  model: googleAI.model("gemini-2.5-flash"),
  prompt: "What is the capital of France?",
});

console.log(text);

​

What Braintrust traces

• Generate spans (genkit.generate), with the prompt and messages as input, model and request parameters in metadata, and the response as output.
• Streaming generate spans (genkit.generateStream), with streamed text output and time_to_first_token.
• Embedding spans (genkit.embed and genkit.embedMany), with input as input and a summarized result (embedding count and dimensions).
• Action spans (genkit.<action_type>: <name>) for flows, tools, and other Genkit actions, with input, output, and duration, plus action type, name, and key in metadata.
• Token usage metrics (prompt, completion, total, plus cached and reasoning tokens when reported).
• Errors captured on every call.

​

Tracing resources

• Firebase Genkit documentation
• Genkit JS on GitHub