Fastify
02 Setup Anvia
Create a reusable Anvia agent module for Fastify.
Create provider clients and shared agents outside Fastify route handlers. Register request-local tools inside routes.
1. Create src/ai/support-agent.ts
import { AgentBuilder, createTool } from "@anvia/core";
import { OpenAIClient } from "@anvia/openai";
import { z } from "zod";
const apiKey = process.env.OPENAI_API_KEY;
if (!apiKey) {
throw new Error("OPENAI_API_KEY is required");
}
const client = new OpenAIClient({ apiKey });
export const model = client.completionModel("gpt-5.5");
const lookupPolicy = createTool({
name: "lookup_policy",
description: "Look up a support policy by key.",
input: z.object({
key: z.enum(["password_reset", "priority_support"]),
}),
output: z.object({
text: z.string(),
}),
async execute({ key }) {
const policies = {
password_reset: "Password reset links expire after 30 minutes.",
priority_support: "Enterprise customers receive priority support.",
};
return { text: policies[key] };
},
});
export const supportAgent = new AgentBuilder("support", model)
.name("Support Agent")
.instructions("Answer clearly. Use tools when policy detail is needed.")
.tool(lookupPolicy)
.defaultMaxTurns(3)
.build();2. Keep The Fastify Instance Separate
The agent module should not import FastifyInstance. This keeps it reusable from routes, jobs, Studio, and tests.
3. Swap Providers Later
import { GeminiClient } from "@anvia/gemini";
const client = new GeminiClient({ apiKey: process.env.GEMINI_API_KEY });
const model = client.completionModel("gemini-2.5-pro");Next
Expose the agent through a Fastify plugin in Route Handler. Related guides: Creating Agents and Tools.
