Testing an agent that pays

The other commands test a service that sells. wasit serve tests the other side, an agent that pays: it runs a local x402 paywall that misbehaves in one chosen way, so you can point your agent at it and watch what the agent does.

bash

wasit serve --mode no-settle

Mode	What the paywall does	What a careful agent does
`no-settle`	Issues an honest challenge, then serves the resource for any payment without settling it and without a `PAYMENT-RESPONSE` header	Finds no `PAYMENT-RESPONSE` and does not count the payment as made
`wrong-settlement`	Issues an honest challenge, then serves the resource with a `PAYMENT-RESPONSE` reporting success for a transaction that is not this payment	Looks the transaction up on-chain before trusting it
`wrong-network`	Asks to be paid on `stellar:pubnet` (mainnet) instead of `stellar:testnet`	Refuses before signing anything
`overprice`	Asks for one million USDC (`10000000000000` base units)	Refuses a price above its spending limit
`v1-challenge`	Issues its challenge only in the x402 v1 form, a JSON body with v1 field names and network name (`base-sepolia`, `solana-devnet`) and no `PAYMENT-REQUIRED` header, as a paywall on the old SDK does. Base Sepolia and Solana devnet only: v1 names no Stellar network	Pays it as v1, in an `X-PAYMENT` header, or declines; does not answer it with a v2 payment
`malformed-header`	Sends a `PAYMENT-REQUIRED` header that does not decode: base64 of the challenge's JSON, cut short	Reports the challenge as unreadable and pays nothing

Option	Default	Notes
`--mode <mode>`	required	One of the six above
`--port <port>`	`4020`	The server answers on every path
`--host <host>`	`127.0.0.1`	Local only unless you bind another interface
`--network <id>`	`stellar:testnet`	`stellar:testnet`, `eip155:84532` (Base Sepolia), `eip155:11155111` (Ethereum Sepolia) or `solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` (Solana devnet). Elsewhere than Stellar the paywall uses that network's USDC (the SDK's, or Circle's on Ethereum Sepolia), `wrong-network` asks for that chain's mainnet (`eip155:8453`, `eip155:1`, `solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp`), and `overprice` one million USDC in its 6 decimals. On Solana the challenge names the payee as `extra.feePayer`, which the spec allows; nothing is ever submitted
`--pay-to <address>`	`STELLAR_PAYEE_ADDRESS`, `EVM_PAYEE_ADDRESS` on Base or Ethereum Sepolia, or `SVM_PAYEE_ADDRESS` on Solana devnet	A testnet account (`G...`) with a trustline for the asset, an EVM address (`0x...`), or a Solana address (base58)
`--amount <units>`	`10000`	Price in base units, for every mode except `overprice`
`--asset <contract>`	testnet USDC	`CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA`
`--settlement-tx <hash>`	a random hash	`wrong-settlement` only. The default cites a transaction that exists nowhere; pass a real, unrelated transaction to test an agent that finds it on-chain but must notice it is not this payment

Nothing is settled or forwarded in any mode, so no payment the server receives can move funds. Your agent still needs a funded testnet wallet: payment clients build and simulate the transfer to --pay-to before signing, which is also why the payee must exist on testnet with a trustline for the asset.

The server prints one line per request: the challenge it sent, or the payment it received and what that says about the agent:

text

wasit serve: no-settle on http://127.0.0.1:4020/ (any path)
01:02:46  GET /paid: payment received for 10000 base units on stellar:testnet.
          Served 200 without settling and without PAYMENT-RESPONSE. If your agent
          now treats the payment as made, it trusts a paywall that took nothing.

The first four modes' challenges are well-formed x402 v2 challenges (wasit test --read-only passes them), so an agent that falls for one fell for the misbehaviour, not for a malformed message. Pointing wasit test itself at no-settle or wrong-settlement shows what a non-conformant paywall looks like from the checks' side: X402-06 and X402-07 fail. The last two are about the challenge itself: v1-challenge is a complete v1 challenge (X402-04 reports every v1 field present) and malformed-header fails X402-03. They answer any payment with 402 and log which header it came in. The official x402 SDK client pays v1-challenge as v1 and refuses malformed-header without paying (evidence).