Build the Signals AI integration using the Vercel AI SDK

The next step is to connect Signals to your AI agent, via the Vercel AI SDK.

Fetch Signals context

Create the module that fetches and formats user attributes from Signals:

tsx

// lib/signals-context.ts
import { Signals } from "@snowplow/signals-node";

let signalsInstance: Signals | null = null;

function getSignalsClient(): Signals | null {
  if (signalsInstance) return signalsInstance;

  const baseUrl = process.env.SNOWPLOW_SIGNALS_BASE_URL;
  const apiKey = process.env.SNOWPLOW_SIGNALS_API_KEY;
  const apiKeyId = process.env.SNOWPLOW_SIGNALS_API_KEY_ID;
  const organizationId = process.env.SNOWPLOW_SIGNALS_ORG_ID;

  if (!baseUrl || !apiKey || !apiKeyId || !organizationId) {
    return null;
  }

  signalsInstance = new Signals({ baseUrl, apiKey, apiKeyId, organizationId });
  return signalsInstance;
}

const SERVICE_NAME = "web-agent-context";

function formatAttributes(attributes: Record<string, unknown>): string {
  const lines = Object.entries(attributes).map(
    ([key, value]) => `- ${key}: ${JSON.stringify(value)}`,
  );
  return [
    "## Real-Time User Context (Snowplow Signals)",
    "The following attributes describe the current user's session behavior on this application:",
    ...lines,
  ].join("\n");
}

export async function getSignalsContext(
  domainSessionId: string,
): Promise<string> {
  const signals = getSignalsClient();
  if (!signals) return "";

  try {
    const attributes = await signals.getServiceAttributes({
      name: SERVICE_NAME,
      attribute_key: "domain_sessionid",
      identifier: domainSessionId,
    });

    if (!attributes || Object.keys(attributes).length === 0) {
      return "";
    }

    return formatAttributes(attributes);
  } catch (error) {
    console.error(
      "[signals-context] Failed to fetch signals attributes:",
      error,
    );
    return "";
  }
}

The raw response format from the service, pulled using signals.getServiceAttributes(), looks like this:

json

{
  "page_views_count": 12,
  "unique_pages_viewed": 5,
  "first_event_timestamp": "2026-04-09T14:23:01.000Z",
  "last_event_timestamp": "2026-04-09T14:41:03.000Z"
}

The formatAttributes() function converts that into a markdown section that can be appended to the agent's system prompt, for example:

markdown

## Real-Time User Context (Snowplow Signals)
The following attributes describe the current user's session behavior on this application:
- page_views_count: 12
- unique_pages_viewed: 5
- first_event_timestamp: "2026-04-09T14:23:01.000Z"
- last_event_timestamp: "2026-04-09T14:41:03.000Z"

If Signals isn't configured or a fetch fails, the getSignalsContext() function returns an empty string. The agent still works without the Signals context.

Build the agent

Create the function that constructs the system prompt with the Signals context appended:

tsx

// lib/agent.ts
const BASE_INSTRUCTIONS = `You are a helpful assistant for this application.
Help users understand features, answer questions, and guide them through their journey.

When you have real-time user context available (provided below), use it to personalize
your responses. Reference what the user has been looking at to give more relevant answers.`;

export function createAgent(signalsContext?: string) {
  const systemPrompt =
    BASE_INSTRUCTIONS + (signalsContext ? "\n\n" + signalsContext : "");

  return { systemPrompt };
}

The model treats the Signals block as factual context about the current user. No special prompting is needed beyond including it: LLMs naturally incorporate provided context when formulating responses.

Build the chat API route

Create the API route that ties everything together:

tsx

// app/api/chat/route.ts
import { streamText, UIMessage, convertToModelMessages, gateway } from "ai";
import { createAgent } from "@/lib/agent";
import { getSignalsContext } from "@/lib/signals-context";

export async function POST(request: Request) {
  const {
    messages,
    pageContext,
  }: {
    messages: UIMessage[];
    pageContext?: { snowplowDomainSessionId?: string };
  } = await request.json();

  // Extract the Snowplow session ID passed from the frontend
  const snowplowDomainSessionId = pageContext?.snowplowDomainSessionId || "";

  // Fetch real-time user attributes from Signals
  let signalsContext = "";
  if (snowplowDomainSessionId) {
    signalsContext = await getSignalsContext(snowplowDomainSessionId);
  }

  // Build the agent system prompt with Signals context injected
  const { systemPrompt } = createAgent(signalsContext);

  // Stream the response
  const result = streamText({
    model: gateway("openai/gpt-4o-mini"),
    system: systemPrompt,
    messages: await convertToModelMessages(messages),
  });

  return result.toUIMessageStreamResponse();
}

Model providers

This example uses Vercel AI Gateway, which routes requests to any supported model provider with a single API key.

To use a different model, change the model string e.g. gateway("anthropic/claude-sonnet-4.5") or gateway("google/gemini-2.5-pro").

See the full list of supported models. The Signals integration works identically regardless of which model you choose.

Build the chat frontend

Create a floating chat widget using AI Elements components. The widget renders as a button in the bottom-right corner that expands into a chat panel.

The widget accesses the current Snowplow session ID using the helper from lib/snowplow.ts.

tsx

// components/chat-widget.tsx
"use client";

import { useState } from "react";
import { useChat } from "@ai-sdk/react";
import { DefaultChatTransport } from "ai";
import { getDomainSessionId } from "@/lib/snowplow";
import {
  Conversation,
  ConversationContent,
} from "@/components/ai-elements/conversation";
import {
  Message,
  MessageContent,
  MessageResponse,
} from "@/components/ai-elements/message";

export function ChatWidget() {
  const [open, setOpen] = useState(false);
  const [input, setInput] = useState("");

  const { messages, sendMessage } = useChat({
    // Pass the Snowplow session ID as body on every request.
    // We use a function so it reads the current session ID at send time.
    transport: new DefaultChatTransport({
      api: "/api/chat",
      body: () => ({
        pageContext: { snowplowDomainSessionId: getDomainSessionId() },
      }),
    }),
  });

  return (
    <div className="fixed bottom-4 right-4 z-50">
      {open ? (
        <div className="w-[400px] h-[500px] rounded-xl border shadow-lg bg-white flex flex-col overflow-hidden">
          {/* Header */}
          <div className="flex items-center justify-between px-4 py-2 border-b">
            <span className="font-semibold text-sm">Chat</span>
            <button
              onClick={() => setOpen(false)}
              className="text-gray-500 hover:text-gray-700 text-lg leading-none"
            >
              &times;
            </button>
          </div>

          {/* Conversation */}
          <Conversation className="flex-1 overflow-hidden">
            <ConversationContent className="p-4">
              {messages.map((message) => (
                <Message key={message.id} from={message.role}>
                  <MessageContent>
                    <MessageResponse>
                      {message.parts
                        .filter((part) => part.type === "text")
                        .map((part) => part.text)
                        .join("")}
                    </MessageResponse>
                  </MessageContent>
                </Message>
              ))}
            </ConversationContent>
          </Conversation>

          {/* Input */}
          <form
            onSubmit={(e) => {
              e.preventDefault();
              if (!input.trim()) return;
              sendMessage({ text: input });
              setInput("");
            }}
            className="flex gap-2 border-t p-2"
          >
            <input
              value={input}
              onChange={(e) => setInput(e.target.value)}
              placeholder="Ask me anything..."
              className="flex-1 border rounded-lg px-3 py-2 text-sm"
            />
            <button
              type="submit"
              className="bg-blue-500 text-white px-4 py-2 rounded-lg text-sm"
            >
              Send
            </button>
          </form>
        </div>
      ) : (
        <button
          onClick={() => setOpen(true)}
          className="w-12 h-12 rounded-full bg-blue-500 text-white shadow-lg hover:bg-blue-600 flex items-center justify-center text-xl"
          aria-label="Open chat"
        >
          &#x1f4ac;
        </button>
      )}
    </div>
  );
}

Load the widget

Since the chat widget floats over page content, the best place to render it is in your root layout, alongside SnowplowTracker. This way the widget is available on every page:

tsx

// app/layout.tsx — add the ChatWidget import and render it inside <body>:

// 1. Add this import alongside the SnowplowTracker import
import { ChatWidget } from "@/components/chat-widget";

// 2. Render it inside the <body> tag, alongside SnowplowTracker:
<body className={/* ...keep existing classes... */}>
  <SnowplowTracker />
  {children}
  <ChatWidget />
</body>

The ChatWidget sits alongside SnowplowTracker in the layout.