Color Convert

{
  "background": {
    "alpha": 1,
    "cmyk": {
      "c": 0,
      "k": 0,
      "m": 0,
      "note": "naive RGB to CMYK formula (no ICC profile, no ink limits): not a print proof",
      "y": 0
    },
    "hex": "#ffffff",
    "hex8": "#ffffffff",
    "hsl": {
      "css": "hsl(0 0% 100%)",
      "h": 0,
      "l": 100,
      "s": 0
    },
    "hsv": {
      "h": 0,
      "s": 0,
      "v": 100
    },
    "names": [
      "white"
    ],
    "oklch": {
      "c": 0,
      "css": "oklch(100% 0 none)",
      "h": null,
      "l": 1
    },
    "relative_luminance": 1,
    "rgb": {
      "b": 255,
      "css": "rgb(255 255 255)",
      "g": 255,
      "r": 255
    }
  },
  "color": {
    "alpha": 1,
    "cmyk": {
      "c": 0,
      "k": 53.33,
      "m": 0,
      "note": "naive RGB to CMYK formula (no ICC profile, no ink limits): not a print proof",
      "y": 0
    },
    "hex": "#777777",
    "hex8": "#777777ff",
    "hsl": {
      "css": "hsl(0 0% 46.67%)",
      "h": 0,
      "l": 46.67,
      "s": 0
    },
    "hsv": {
      "h": 0,
      "s": 0,
      "v": 46.67
    },
    "names": [],
    "oklch": {
      "c": 0,
      "css": "oklch(56.93% 0 none)",
      "h": null,
      "l": 0.5693
    },
    "relative_luminance": 0.184475,
    "rgb": {
      "b": 119,
      "css": "rgb(119 119 119)",
      "g": 119,
      "r": 119
    }
  },
  "contrast": {
    "aa_large_text": true,
    "aa_normal_text": false,
    "aa_ui_components": true,
    "aaa_large_text": false,
    "aaa_normal_text": false,
    "composited": false,
    "note": "WCAG 2.x contrast; pass/fail compares the unrounded ratio. Large text: at least 18 pt (24 px), or 14 pt (about 18.7 px) bold. Thresholds: AA 4.5 normal / 3 large, AAA 7 / 4.5, UI components and graphics 3 (SC 1.4.11).",
    "ratio": 4.48,
    "ratio_text": "4.48:1",
    "ratio_unrounded": 4.478089
  }
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://tanod.dev/v1/color/convert' \
  -H 'content-type: application/json' \
  --data-raw '{"background":"white","color":"#777"}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://tanod.dev/v1/color/convert' \
  -H 'content-type: application/json' \
  --data-raw '{"background":"white","color":"#777"}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.001 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.001" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.001 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Ftanod.dev%2Fv1%2Fcolor%2Fconvert&method=POST
const res = await pay("https://tanod.dev/v1/color/convert", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "background": "white",
    "color": "#777"
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.001 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.001"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://tanod.dev/v1/color/convert",
        json={
            "background": "white",
            "color": "#777",
        },
    )
    print(res.status_code, res.text)