Flowlines SDK Integration Guide

Follow these steps to integrate the @flowlines/sdk into a Node.js/TypeScript application.

Step 1: Install the SDK

npm install @flowlines/sdk

Requires Node.js >= 20.

Step 2: Initialize the SDK

The SDK instruments AI libraries by monkey-patching their module exports. This means Flowlines.init() must run before those libraries are imported and before any AI client instances are created.

Choose the initialization approach based on the application's setup:

Standard Node.js app

Option A: Separate instrumentation file (recommended)

Create a dedicated file that runs before the application entry point:

// instrumentation.ts
import { Flowlines } from "@flowlines/sdk";

Flowlines.init({
  apiKey: process.env.FLOWLINES_API_KEY,
});

Start the app with:

# ESM
node --import ./instrumentation.ts app.ts

# CJS
node --require ./instrumentation.js app.js

This ensures init runs before any AI library imports.

Option B: Pass instrumentModules explicitly

If you cannot control the startup order (e.g., ESM hoists all imports), pass the AI modules directly — this works regardless of import order:

import OpenAI from "openai";
import { Flowlines } from "@flowlines/sdk";

Flowlines.init({
  apiKey: process.env.FLOWLINES_API_KEY,
  instrumentModules: { openAI: OpenAI },
});

const openai = new OpenAI();

Supported instrumentModules keys: openAI, anthropic, cohere, bedrock, google_vertexai, google_aiplatform, google_generativeai, pinecone, together, chromadb, qdrant, langchain, llamaIndex, mcp.

Import style matters. OpenAI requires a default import (import OpenAI from "openai"). Anthropic requires a namespace import (import * as AnthropicModule from "@anthropic-ai/sdk"). Using the wrong style causes instrumentation to silently fail.

Next.js app

Next.js supports an instrumentation file that runs before the application starts.

1. Create the instrumentation file:

// instrumentation.ts (project root)
import { Flowlines } from "@flowlines/sdk";

export function register() {
  Flowlines.init({
    apiKey: process.env.FLOWLINES_API_KEY,
  });
}

2. Configure webpack externals in next.config.mjs to prevent bundling the SDK and AI libraries (required for monkey-patching to work):

/** @type {import('next').NextConfig} */
const nextConfig = {
  experimental: {
    instrumentationHook: true,
  },
  webpack: (config, { isServer }) => {
    if (isServer) {
      config.externals.push("@flowlines/sdk", "openai");
    }
    return config;
  },
};

export default nextConfig;

Add every instrumented AI library to the externals array (e.g. "openai", "@anthropic-ai/sdk").

If auto-instrumentation still doesn't work despite externals, use instrumentModules in the register function (see Option B above).

App with existing OpenTelemetry setup

If the app already has its own NodeSDK, set hasExternalOtel: true so Flowlines does not create a second one. Then compose Flowlines' processor and instrumentations into the existing setup:

import { NodeSDK } from "@opentelemetry/sdk-node";
import { Flowlines } from "@flowlines/sdk";

Flowlines.init({
  apiKey: process.env.FLOWLINES_API_KEY,
  hasExternalOtel: true,
});

const sdk = new NodeSDK({
  spanProcessors: [Flowlines.createSpanProcessor()],
  instrumentations: Flowlines.getInstrumentations(),
});
sdk.start();

Step 3: Attach context to LLM calls

Wrap every AI/LLM call with Flowlines.context() to attach user and session metadata to spans:

await Flowlines.context({ userId: "user-123", sessionId: "sess-456" }, async () => {
  const response = await openai.chat.completions.create({
    model: "gpt-4",
    messages: [{ role: "user", content: "Hello!" }],
  });
});

userId (required): the end-user making the request
sessionId (required): the conversation or session ID
agentId (optional): the AI agent handling the request
The callback can be sync or async — the return value is forwarded
Supports nesting: inner calls override outer values

How to choose values:

If the codebase has obvious mappings (e.g. req.user.id, threadId), use them directly.
If mappings are unclear, ask the user which variables to use.
If no data is available yet, use placeholder values with TODO comments:

await Flowlines.context(
  {
    userId: "anonymous", // TODO: replace with actual user identifier
    sessionId: `sess-${Date.now()}`, // TODO: replace with actual session/conversation ID
  },
  async () => { ... }
);

Step 4: Fetch and use memory

Use Flowlines.getMemory() to retrieve memory context for a user. Inject the returned string into your LLM conversation (e.g. as a system message):

const memory = await Flowlines.getMemory({
  userId: "user_123",
  sessionId: "sess_456",
  agentId: "agent_1",     // optional
});

await Flowlines.context({ userId: "user_123", sessionId: "sess_456" }, async () => {
  const response = await openai.chat.completions.create({
    model: "gpt-4",
    messages: [
      { role: "system", content: `You are a helpful assistant.\n\n${memory}` },
      { role: "user", content: "What were we talking about last time?" },
    ],
  });
});

getMemory() returns a JSON string with the memory content, or an empty string if no memory is found.

Step 5: End a session

Look for places where a session or conversation naturally ends and call Flowlines.endSession() there. This flushes pending spans and notifies the backend. Common examples:

An explicit "end conversation" or "close session" action
A WebSocket close or disconnect event
A session cleanup or logout handler
A timeout that expires inactive sessions

await Flowlines.endSession({
  userId: "user_123",
  sessionId: "sess_456",
});

userId and sessionId must match the values passed to Flowlines.context().

If the app has no concept of sessions that start and end (e.g. a single-shot CLI tool), do not add endSession. If session boundaries are ambiguous, ask the user.

Verifying trace ingestion

If the user provides a Flowlines API key, you can verify that traces are being received by the backend:

curl -X GET 'http://api.flowlines.ai/v1/get-traces' -H 'x-flowlines-api-key: <FLOWLINES_API_KEY>'

Use this after the integration is complete and the application has made at least one LLM call, to confirm that traces are flowing correctly.

integrate-flowlines-sdk-js