> ## Documentation Index
> Fetch the complete documentation index at: https://docs.relayer.fi/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent Kit

> Budget-enforced AI agents that can sign transactions and pay for on-chain resources

The Agent Kit lets you ship AI agents that can hold a wallet, spend USDC, and sign Solana transactions — without ever being able to spend money they were not authorized to spend.

## Core guarantee

**Budget enforcement that cannot be bypassed.** If the SDK says "no budget", the payment does not happen. Enforcement is server-side and atomic — three independent budget layers plus a kill switch.

## What you get

* **Programmable agent lifecycle** — create, fund, pause, resume, rotate, and kill an agent
* **Per-agent USDC wallet** — an isolated wallet workspace on Solana, signed by passkey at provisioning time
* **3-layer budget guard** — infrastructure spend, token usage, and on-chain payments — enforced independently
* **Kill switch** — global stop that fails-safe (blocks payments, lets infra/tokens fail-open)
* **x402-pay** — pay HTTP 402 protected endpoints with USDC, with approval flow for amounts above threshold
* **Event batching** — `llm_call`, `api_call`, `payment` telemetry batched and flushed every 10s

## Authentication

Two modes coexist on `/v1/agents/*`:

| Caller           | Header                                                            | Used by                           |
| ---------------- | ----------------------------------------------------------------- | --------------------------------- |
| Integrator (you) | `Authorization: Bearer <jwt>` or `ApiKey <key>`                   | Dashboard, your backend           |
| Agent (the SDK)  | `X-Agent-Auth: <agentId>:<HMAC-SHA256(method+path+body, secret)>` | `@relayerfi/agent-sdk` at runtime |

The HMAC header is built inside `HttpClient.buildAuthHeaders(method, path, body)` — agents never pass the plain `agentId:secret` outside that boundary.

## SDK

The agent runtime is `@relayerfi/agent-sdk` — `RelayerSDK` facade, `HttpClient`, `BudgetGuard`, `KillSwitch`, `EventBatcher`, `X402Handler`, `ApprovalHandler`, `x402fetch`, and LLM wrappers for Anthropic / OpenAI / Google.

See [Flow Guide](/agent/flow-guide) for the create-agent → fund → spend lifecycle, and [Endpoints](/agent/endpoints) for the API surface.