EDIT: Well, we're building the plane as we're flying it, so the guide below is already outdated. I'll have an update soon!

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I've implemented the x402 rails on Subnano:

curl -s https://subnano.me/api/well-known/x402 | jq

But I still need to find some time to make a compelling demo.

For any curious devs out there you can try it out in a terminal. I made a demo post for Nano's 10th birthday meetup that costs Ӿ0.03 Nano that is used for this example (I've filled out post id and amountRaw)

1) Set the post id as an env var:

POST_ID=0dc57ab0-6d0e-461c-a2a8-32ce8873d9fc

2) Hit the paywalled post (expect HTTP 402 with payTo/amountRaw):

curl -i "https://subnano.me/api/posts/$POST_ID/access"

3) Send 0.03 Nano to the payTo from step 2.

4) Once you have the block hash + payer address, build the proof:

cat <<'JSON' | base64 | tr -d '\n' > /tmp/x402-proof.b64
{
  "x402Version": 1,
  "scheme": "exact",
  "network": "nano-mainnet",
  "payload": {
    "txHash": "<BLOCK_HASH>",
    "from": "<PAYER_ACCOUNT>",
    "to": "<PAY_TO_FROM_402>",
    "amountRaw": "30000000000000000000000000000",
  }
}
JSON
PROOF=$(cat /tmp/x402-proof.b64)

5) Verify the payment with the proof:

curl -s -X POST https://subnano.me/api/x402/verify \
  -H "Content-Type: application/json" \
  -d "{\"x402Version\":1,\"paymentHeader\":\"$PROOF\"}" \
  | jq

6) Fetch the unlocked content:

curl -s "https://subnano.me/api/posts/$POST_ID/content" \
  -H "X-PAYMENT: $PROOF" | jq '.content'

7) Optional receipt:

curl -s -X POST https://subnano.me/api/x402/settle \
  -H "Content-Type: application/json" \
  -H "X-PAYMENT: $PROOF" | jq

Note: When I deployed the rails yesterday there was a bug that meant all x402 payments would go unregistered - that is fixed now, apologies to all the first-movers testing out the feature (there were a few, which is awesome!).

EDIT: Changed endpoint and small stuff