Use https://x402-tokens.fly.dev as an OpenAI-compatible inference endpoint. There is no API key.

POST https://x402-tokens.fly.dev/v1/chat/completions
Content-Type: application/json

Body is a normal OpenRouter/OpenAI chat completion:
{"model":"google/gemini-2.5-flash","messages":[{"role":"user","content":"..."}],"max_tokens":256}

You will get HTTP 402. That is the product, not an error.

accepts[] will include one row per live rail. Pick ONE:
- yUSDCx  mint 6ZjjxcoicqM4nniddkuPVwew4PDwY3swbfHsGbCuLuTv  20bps tax  price $1 stable
- wTOKENx  mint Bo7xBF7SY8EyUBPUxRP66SFafxoPf2n5uqiLjbxEebx9  20bps tax  price Birdeye EVULoNF4DeMBN4dGiZiDfpiiTfNZgoCvXWWgaV3epump at the 402

Every row:
- network: solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
- payTo: WzMaL78srutrF6CsxEkWuhMaDF5HZA6jNRaEPengqpb
- feePayer: WzMaL78srutrF6CsxEkWuhMaDF5HZA6jNRaEPengqpb   ← tx feePayer MUST be this. you do not pay SOL.
- maxAmountRequired: already 3× OpenRouter USD, in that token's raw units, grossed up for its transfer tax. do not reprice it.
- facilitator: https://x402.accrue.fund

Build one Solana legacy Transaction:
1. feePayer = WzMaL78srutrF6CsxEkWuhMaDF5HZA6jNRaEPengqpb
2. exactly one Token-2022 TransferChecked: your ATA of the chosen mint → payTo's ATA, amount = maxAmountRequired, decimals = 6
3. you sign as the token owner. leave the feePayer signature empty.
4. serialize requireAllSignatures=false, base64 that bytes

X-PAYMENT header = base64 of this JSON (utf8):
{"x402Version":1,"scheme":"exact","network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","payload":{"transaction":"<base64-tx>"}}

POST the SAME body again with X-PAYMENT set. Do not change model/messages/max_tokens after the 402 — the quote is for that body.

On 200 you get a normal chat.completion.

Raw TOKEN (EVULoNF4DeMBN4dGiZiDfpiiTfNZgoCvXWWgaV3epump) and raw USDC will not settle. Wrap first:
- USDC → yUSDCx via FrSERTNCPvTtaDS9AvQp9u1nYGzXDb3kC9MdL8Xxn2NE escrow 2qLm8aCvn6gQVUFeQ7EC5J62Y95gFzc3vReHzD5d5Gj2
- TOKEN → wTOKENx via the same program, escrow 7j682FdwSdTkXNjbMrrLd5wcXQoh23UTZaDReqKXbL2q
Both wraps are Token-2022 with a 20bps transfer tax. Yield is that tax.

Do not use api.cdp.coinbase.com. This service names https://x402.accrue.fund. GET https://x402-tokens.fly.dev/.well-known/x402.json and https://x402-tokens.fly.dev/prompt.txt if you want this text again.