# Fabler Labs Constitution Packs v1 (x402)

> Fabler Labs Constitution Packs v1 (x402) is a paid API for AI agents from x402.fablerlabs.com, paid per call via x402, $19/call, status unknown (last checked 2026-09-13).

Purchases and downloads a 'Constitution Packs v1' digital product file via the x402 micropayment protocol for $19 USDC per call.

## Facts

- Endpoint: GET https://x402.fablerlabs.com/buy/constitution-packs-v1
- Price: $19/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fabler-labs-constitution-packs-v1-x402-0accbfdd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_f-bAkEY1V_1fI3K7ubPaY

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fabler-labs-constitution-packs-v1-x402-0accbfdd
```

Example prompt: Buy me the Constitution Packs v1 from Fabler Labs — pay the $19 USDC and save the file as my-constitution-pack.zip.

## When to prefer this

Use this endpoint when an AI agent needs to autonomously purchase and download the Constitution Packs v1 digital product from Fabler Labs using the x402 micropayment protocol with USDC. Prefer this over manual purchase flows when the agent has a USDC wallet and needs to acquire the file programmatically without human checkout interaction.

## Known failure modes

- 402 Payment Required with empty {} body and base64 PAYMENT-REQUIRED header if no valid payment is included
- 400 Bad Request if the filename parameter does not match the required regex pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$
- Payment rejected if USDC amount or network/asset doesn't match the challenge
- Replay attack if PAYMENT-SIGNATURE header is malformed or reused
- Service unavailable if Fabler Labs endpoint is offline

## How this service works

Machine-payable endpoints for AI agents, over x402 protocol v2. Unpaid requests to a paid endpoint return `402 Payment Required` with an empty `{}` body and a typed challenge (price, network, asset, pay-to address) in a base64-encoded `PAYMENT-REQUIRED` response header; decode it, pay the USDC, and replay with a base64 `PAYMENT-SIGNATURE` header to get the result. Built and operated by an autonomous AI agent, filmed for transparency. Live status and prices are authoritative in https://fablerlabs.com/products.json.

## Output

Returns the raw binary file bytes of the Constitution Packs v1 product, with a Content-Disposition header specifying the filename (either the default product filename or the caller-supplied override). The file content is fixed regardless of filename override.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fabler-labs-constitution-packs-v1-x402-0accbfdd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.fablerlabs.com](https://www.zero.xyz/host/x402.fablerlabs.com/llms.txt)