dzakwannajmi · Oct 8, 2026 · Oct 5, 2026 · Oct 5, 2026 · Oct 5, 2026
diff --git a/.env.example b/.env.example
@@ -29,6 +29,16 @@ EVM_PRIVATE_KEY=
 # Only needed to run the bundled fixture.
 EVM_PAYEE_ADDRESS=
 
+# --- x402 payment checks on Solana devnet -----------------------------------
+# Payer keypair for --network solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1, base58
+# of its 64 bytes as wallets export it. It needs devnet USDC and no SOL: the
+# facilitator signs as fee payer.
+SVM_PRIVATE_KEY=
+
+# Recipient address (base58) the Solana fixture server charges to. Its devnet
+# USDC account must already exist. Only needed to run the bundled fixture.
+SVM_PAYEE_ADDRESS=
+
 # --- MPP charge mode (MPP-01) ------------------------------------------------
 # Payer secret key (S...) for the charge check. Settles a real payment on every
 # run; repeated runs spend repeatedly.

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -63,16 +63,33 @@ Sepolia, the lying modes fail both checks
 the default; MPP is Stellar only. Under the hood, the payment checks now go through a
 per-chain adapter, and the x402 SDK moves from 2.19 to 2.28.
 
+**Added — the x402 payment checks pay on Solana devnet.** `--network
+solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` (MCP: `network`) runs `X402-06` to `X402-10`
+there, with the payer key in `SVM_PRIVATE_KEY` (base58 of the 64-byte keypair, as
+wallets export it). The payer signs a transaction with one `TransferChecked`, and the
+facilitator signs as fee payer, so a payer needs devnet USDC and no SOL. `X402-06` holds
+the settlement to the confirmed transaction's token balances: exactly one transfer, of
+the advertised amount and mint, to an account `payTo` owns, from this run's payer.
+`X402-07` forges only the payer's signature; `X402-10` builds the payment on a blockhash
+the RPC confirms has expired, since on Solana the blockhash, not `maxTimeoutSeconds`,
+sets a payment's lifetime. Against Wasit's own Solana fixture, all ten pass with the
+settlement read back independently and the payer holding no SOL; against `wasit serve`
+on devnet, the lying modes fail
+([evidence](docs/evidence/2026-10-05-solana-devnet-verification-run.md)). The payee's
+token account must exist before the payment. Library users with TypeScript 6 or 7 see
+npm peer warnings from `@solana/kit` 5 at install; the install succeeds and core runs.
+
 **Added — three negative payment checks: `X402-08` Payment Replay Rejected, `X402-09`
 Underpayment Rejected, `X402-10` Expired Authorization Rejected.** Each sends a payment the
 target must refuse: the exact payment `X402-06` was accepted for, sent again; a validly
 signed payment for half the price that still claims the full price; and a payment signed
-with a one-second lifetime, sent once it has expired. They run on Stellar and Base
-Sepolia. A refusal now shows the target's stated reason, when it gives one. Against
-Wasit's own fixtures all three pass on both chains, refused for the reason each is about
+with a one-second lifetime, sent once it has expired (on Solana, one built on an expired
+blockhash). They run on Stellar, Base Sepolia and Solana devnet. A refusal now shows the
+target's stated reason, when it gives one. Against Wasit's own fixtures all three pass on
+all three chains, refused for the reason each is about
 (`invalid_exact_stellar_payload_wrong_amount`, `invalid_exact_evm_payload_authorization_value_mismatch`,
-`invalid_exact_evm_payload_authorization_valid_before`, ...); against `wasit serve
---mode no-settle` all three fail. `X402-08` is skipped when the challenge advertises the
+`invalid_exact_evm_payload_authorization_valid_before`, `invalid_exact_svm_payload_amount_mismatch`,
+...); against `wasit serve --mode no-settle` all three fail. `X402-08` is skipped when the challenge advertises the
 `payment-identifier` extension, whose cached replies are legitimate. The catalogue grows
 from 13 to 16 checks. `X402-10` waits about 20 seconds on Stellar for the authorization
 to expire.
@@ -95,7 +112,8 @@ what the agent did. It never settles or forwards anything, so no funds move.
 Every mode's challenge is well-formed (`wasit test --read-only` passes it), and
 the two settlement modes reproduce the servers built for the 0.6.0 A/B:
 `X402-06` and `X402-07` fail against them. `--network eip155:84532` poses the same
-modes on Base Sepolia.
+modes on Base Sepolia, and `--network solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` on Solana
+devnet.
 
 **Changed — the CLI's payment warning says when it applies.** It said funds
 would move before every payment run, including runs where the target offered

diff --git a/docs/CHECKS.md b/docs/CHECKS.md
diff --git a/docs/evidence/2026-10-05-solana-devnet-verification-run.md b/docs/evidence/2026-10-05-solana-devnet-verification-run.md
@@ -0,0 +1,148 @@
+# x402 Payment Checks on Solana Devnet — A/B Against Lying Servers, and a Real Settlement
+
+**Date:** 2026-10-05
+**Wasit:** builds of the local `release/0.7.0` branch (`165e23c` for the Solana adapter
+and fixture, `7ea229f` for `wasit serve` on Solana devnet), not yet published.
+**Targets:** `wasit serve --network solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1`, the
+paywall that misbehaves on purpose, in three modes; and Wasit's own Solana devnet x402
+fixture (`packages/core/test/fixtures/x402-svm-server.ts`), settling through the public
+`x402.org` facilitator. Both ran on our machine; the chain is Solana devnet.
+**Environment:** macOS, Node `v26.8.1`.
+
+**What this is for.** `X402-06` to `X402-10` now also pay on Solana devnet, with the
+`exact` scheme: the payer signs a transaction carrying one `TransferChecked` to the
+payee's token account, and the sponsor named in `extra.feePayer`, here the facilitator,
+signs as fee payer and submits it (`scheme_exact_svm.md`). As on Stellar and Base
+Sepolia, the checks are only worth having if they fail servers that get this wrong and
+pass one that gets it right.
+
+**Authorization.** None was needed or sought. Every target was Wasit's own code on our
+machine. No service operated by anyone else was tested.
+
+## Servers that lie
+
+Payer and payee: throwaway keypairs generated for the run, holding nothing. That is
+enough here: signing needs no balance, and `wasit serve` never settles, so nothing moved.
+
+| `wasit serve` mode | What it does | `X402-06` | `X402-07`–`10` |
+|---|---|---|---|
+| `no-settle` | Serves any payment with 200, without settling and without `PAYMENT-RESPONSE` | **FAIL** | **FAIL** |
+| `wrong-settlement` | Serves with a `PAYMENT-RESPONSE` naming a random signature that exists nowhere | **FAIL** | **FAIL** |
+| `wrong-network` | Asks to be paid on Solana mainnet (`solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp`) | SKIP, nothing sent | SKIP |
+
+Output, quoted as printed:
+
+```
+FAIL  X402-06  Signature Resubmit Accepted
+      Valid payment accepted (HTTP 200), but the response carried no
+      PAYMENT-RESPONSE header, which the x402 v2 HTTP transport uses to report
+      settlement. Whether the payment settled cannot be verified.
+```
+
+```
+FAIL  X402-06  Signature Resubmit Accepted
+      Target reported settlement as tx 5BjTpgSQ…bLVRq, but the chain advanced 152
+      more slots without it. Either it was never broadcast, or the target
+      referenced a transaction that does not exist.
+```
+
+The second was decided against Solana devnet itself, through its public RPC
+(`https://api.devnet.solana.com`): the whole run took 38 seconds, most of it waiting for
+150 slots to pass without the cited signature.
+
+## An honest server
+
+Payer: a devnet account holding 20 USDC of the SDK's default devnet mint
+(`4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU`) and **no SOL**. Payee: a second account
+whose USDC token account already existed (the payment's transaction does not create
+one).
+
+`wasit test --target http://localhost:3007/protected --network
+solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1`: **10/10**, in 4 seconds.
+
+```
+PASS  X402-06  Signature Resubmit Accepted
+      Valid payment accepted (HTTP 200) and settled on-chain for exactly the
+      advertised 10000 base units of 4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU
+      to HzrAfDD9vQ7jjywai5dgiZbEzFumwNhWw3LLbXViHdBS, verified from the
+      transaction's token balances (tx 3QJCb8Z8…M7B1w).
+PASS  X402-07  Invalid Signature Rejected
+      Payment with a corrupted authorization signature correctly rejected
+      (HTTP 402: invalid_exact_svm_payload_signature_invalid).
+PASS  X402-08  Payment Replay Rejected
+      The same payment, sent again, was refused
+      (HTTP 402: invalid_exact_svm_transaction_simulation_failed).
+PASS  X402-09  Underpayment Rejected
+      A validly signed payment for 5000 of the advertised 10000 base units was
+      refused (HTTP 402: invalid_exact_svm_payload_amount_mismatch).
+PASS  X402-10  Expired Authorization Rejected
+      A payment whose authorization had expired was refused
+      (HTTP 402: invalid_exact_svm_transaction_simulation_failed).
+```
+
+[`3QJCb8Z8…M7B1w`](https://explorer.solana.com/tx/3QJCb8Z88QFRByCjCqb7JXvyTFZEGsSDBYqsrBmaqtZg1N3semLEm6R6McCwSNaNph33UUDttFvs3H8Ye5fM7B1w?cluster=devnet)
+
+Read back independently afterwards, outside Wasit, with raw JSON-RPC against the same
+endpoint:
+
+| | |
+|---|---|
+| Status | succeeded (`err` null), slot 507717163 |
+| Fee payer (account 0) | `CKPKJWNd…WYp5`, the facilitator's account, which paid the 10001-lamport fee |
+| Signers | the facilitator and the payer `Dya3U1bb…oQ9m`, nobody else |
+| Instructions | two ComputeBudget, one `spl-token` `transferChecked` of 10000 (6 decimals) from the payer's token account to the payee's, authority the payer; one memo carrying a random nonce; no inner instructions |
+| Token balances | payer 20000000 → 19990000, payee 20000000 → 20010000 |
+| Payer afterwards | 19.99 USDC, **still 0 SOL** |
+
+The payer's history holds two transactions: the deposit that funded it, and this
+settlement. So the settlement Wasit verified is the one that happened, the four
+payments the target had to refuse moved nothing, and a Solana devnet payer needs the
+token and nothing else.
+
+A second run on the same build, after the dependency checks below, passed 10/10 again
+([`3FomjFsz…WG8B`](https://explorer.solana.com/tx/3FomjFszTTivLg876SJopURcZTGJPaSnAsdKu2sJVULe53Qt4K6J9vYc3S29fyXmcMDSmDMBe8E9MC9Tka6XWG8B?cluster=devnet)).
+
+## How each payment was built
+
+- **Corrupted signature (`X402-07`):** before the sponsor signs, the transaction carries
+  one signature, the payer's; its first byte is flipped, and the message, transfer and
+  blockhash are untouched.
+- **Replay (`X402-08`):** the headers `X402-06`'s accepted payment was sent with, byte for
+  byte. Solana executes a transaction once, so this costs nothing.
+- **Underpayment (`X402-09`):** signed by the official SDK client for half the advertised
+  amount, then sent with `accepted` set back to the advertised terms.
+- **Expired (`X402-10`):** on Solana a payment's lifetime is its recent blockhash, which
+  the SDK client does not derive from `maxTimeoutSeconds`. The payment is built on a
+  blockhash from 300 slots back, through the client's `extra.recentBlockhash` hint, after
+  the RPC confirms that blockhash is no longer valid. So it had expired before it was
+  sent, without holding a fresh payment for the minute or more it takes to expire.
+
+## What did not change
+
+On the same build, Wasit's other x402 fixtures each passed 10/10: Stellar testnet
+(port 3001), Base Sepolia with EIP-3009 (3005) and with Permit2 (3006). `X402-10`'s
+expiry moved into each chain's adapter in this change, and was refused there for the
+same reasons as before (`invalid_exact_stellar_payload_simulation_failed`,
+`invalid_exact_evm_payload_authorization_valid_before`, `permit2_deadline_expired`). 221
+core and 63 CLI offline tests pass.
+
+## Installing alongside TypeScript
+
+`@x402/svm` 2.28 requires `@solana/kit` 5, whose packages declare an optional peer
+`typescript ^5`. The packed `@wasit-dev/core` was installed into fresh projects with
+TypeScript 5.8.3, 6.0.3, 7.0.2 and none: every install succeeded. Under TypeScript 7, npm
+printed 110 `ERESOLVE overriding peer dependency` warnings, and core then ran in that
+project: Solana's settlement check verified `3QJCb8Z8…M7B1w` against devnet and the read
+checks passed against the fixture. The CLI and MCP server installed globally or through
+npx carry no TypeScript, so the warnings do not arise there.
+
+## Limits
+
+- One Solana network: devnet. The payee's token account must exist before the payment.
+- The honest target is Wasit's own fixture on the official SDK. No third-party Solana
+  service was tested.
+- `X402-08`'s and `X402-10`'s refusals both read `transaction_simulation_failed`: the
+  facilitator's simulation fails for a transaction already executed and for an expired
+  blockhash alike. Both keep the resource from being served.
+- Unreleased: this ran from the branch, not from npm. Registry parity follows the 0.7.0
+  release.
diff --git a/docs/evidence/README.md b/docs/evidence/README.md
@@ -92,6 +92,7 @@ and what it does and does not establish. Newest first.
 
 | Date | File | What it shows | Deliverable |
 |---|---|---|---|
+| 2026-10-05 | [solana-devnet-verification-run](2026-10-05-solana-devnet-verification-run.md) | The x402 payment checks on Solana devnet (unreleased 0.7.0 branch): `wasit serve`'s lying modes fail `X402-06`–`10` and a mainnet request gets nothing sent; Wasit's own fixture passes 10/10 with `X402-06` settled on-chain and read back independently, the payer holding no SOL; the packed core installs and runs alongside TypeScript 5.8, 6 and 7 | Beyond the SOW |
 | 2026-10-05 | [x402-negative-checks-run](2026-10-05-x402-negative-checks-run.md) | `X402-08` replay, `X402-09` underpayment and `X402-10` expired authorization (unreleased 0.7.0 branch): Wasit's fixtures pass 10/10 on Stellar and Base Sepolia, each refusal for the reason the check is about; `wasit serve --mode no-settle` fails all of them on both chains | Beyond the SOW |
 | 2026-10-05 | [base-sepolia-verification-run](2026-10-05-base-sepolia-verification-run.md) | The x402 payment checks on Base Sepolia (unreleased 0.7.0 branch): servers that skip settlement or cite a missing transaction fail `X402-06` and `X402-07`; a mainnet request gets nothing sent; Wasit's own fixture passes 7/7 with `X402-06` settled on-chain and read back independently, the payer holding no ETH | Beyond the SOW |
 | 2026-09-30 | [x402-0.6.0-verification-run](2026-09-30-x402-0.6.0-verification-run.md) | 0.6.0's stricter `X402-06` and `X402-07`, A/B against 0.5.0: servers built to skip settlement, misreport it or skip signature checks pass 0.5.0 and fail 0.6.0. `stellar/x402-stellar`'s reference still passes 7/7, with `X402-06` verified on-chain. Registry parity for the published 0.6.0 | D1 |

diff --git a/docs/guides/cli.md b/docs/guides/cli.md
@@ -158,9 +158,9 @@ wasit test --target <url> [options]
 | Option | Default | Notes |
 |---|---|---|
 | `--target <url>` | required | Must include the scheme |
-| `--network <id>` | `stellar:testnet` | Network the payment checks pay on: `stellar:testnet`, `stellar:pubnet` or `eip155:84532` (Base Sepolia). `X402-01`–`05` apply to a challenge on any chain |
-| `--payer-key <key>` | `STELLAR_PRIVATE_KEY`, or `EVM_PRIVATE_KEY` on Base Sepolia | A Stellar secret (`S...`), or an EVM private key (`0x` + 64 hex) |
-| `--rpc-url <url>` | the network's default | RPC used to verify `X402-06`'s settlement: Soroban RPC on Stellar, required for pubnet; JSON-RPC on Base Sepolia (default `https://sepolia.base.org`) |
+| `--network <id>` | `stellar:testnet` | Network the payment checks pay on: `stellar:testnet`, `stellar:pubnet`, `eip155:84532` (Base Sepolia) or `solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` (Solana devnet). `X402-01`–`05` apply to a challenge on any chain |
+| `--payer-key <key>` | `STELLAR_PRIVATE_KEY`, `EVM_PRIVATE_KEY` on Base Sepolia, or `SVM_PRIVATE_KEY` on Solana devnet | A Stellar secret (`S...`), an EVM private key (`0x` + 64 hex), or a Solana keypair (base58 of its 64 bytes) |
+| `--rpc-url <url>` | the network's default | RPC used to verify `X402-06`'s settlement: Soroban RPC on Stellar, required for pubnet; JSON-RPC on Base Sepolia (default `https://sepolia.base.org`) and on Solana devnet (default `https://api.devnet.solana.com`) |
 | `--method <verb>` | `GET` | HTTP method the paid endpoint uses. Endpoints that compute something usually take `POST` |
 | `--body <json>` | — | Request body, sent verbatim; implies `Content-Type: application/json` |
 | `--header <name:value>` | — | Extra request header the endpoint needs before it will issue a challenge. Repeatable |
@@ -249,8 +249,8 @@ wasit serve --mode no-settle
 | `--mode <mode>` | required | One of the four 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` or `eip155:84532` (Base Sepolia). On Base Sepolia the paywall uses the SDK's USDC, `wrong-network` asks for Base mainnet (`eip155:8453`), and `overprice` one million USDC in its 6 decimals |
-| `--pay-to <address>` | `STELLAR_PAYEE_ADDRESS`, or `EVM_PAYEE_ADDRESS` on Base Sepolia | A testnet account (`G...`) with a trustline for the asset, or an EVM address (`0x...`) |
+| `--network <id>` | `stellar:testnet` | `stellar:testnet`, `eip155:84532` (Base Sepolia) or `solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` (Solana devnet). On Base Sepolia and Solana devnet the paywall uses the SDK's USDC, `wrong-network` asks for that chain's mainnet (`eip155:8453`, `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 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 |

diff --git a/docs/guides/configuration.md b/docs/guides/configuration.md
@@ -13,6 +13,7 @@ keys in this file.
 | `X402-01`–`05` | nothing |
 | `X402-06`–`10` on Stellar | `STELLAR_PRIVATE_KEY` |
 | `X402-06`–`10` on Base Sepolia (`--network eip155:84532`) | `EVM_PRIVATE_KEY` |
+| `X402-06`–`10` on Solana devnet (`--network solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1`) | `SVM_PRIVATE_KEY` |
 | `MPP-01` | `MPP_PAYER_SECRET`, `MPP_STELLAR_NETWORK` |
 | `MPP-10`–`12`, `14` | `COMMITMENT_SECRET_HEX`, `MPP_STELLAR_NETWORK` |
 | `MPP-13` | the above, plus `CHANNEL_CONTRACT_DISPOSABLE` and an explicit opt-in |
@@ -33,7 +34,10 @@ third-party node.
 The x402 payment checks also pay on Base Sepolia (`eip155:84532`), through
 `--network` (MCP: `network`), with the payer key in `EVM_PRIVATE_KEY`. Its
 default RPC endpoint is Base's public `https://sepolia.base.org`, overridable
-with `--rpc-url`. Any other network gets the read-only checks only.
+with `--rpc-url`. They pay on Solana devnet too
+(`solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1`), with the payer key in `SVM_PRIVATE_KEY`
+and the public `https://api.devnet.solana.com` as the default RPC endpoint. Any other
+network gets the read-only checks only.
 
 ## Getting testnet keys
 
@@ -62,6 +66,14 @@ once on-chain, which needs gas, and a run without that approval reports
 `ERROR (setup)`. A wrong or malformed key is reported at `PREFLIGHT` before
 anything is sent, without echoing it.
 
+For Solana devnet, `SVM_PRIVATE_KEY` is the base58 encoding of the keypair's 64
+bytes (seed, then public key), the form wallets export. The payer needs devnet USDC
+of the SDK's default mint, `4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU`, and **no
+SOL**: the facilitator signs as fee payer and pays the fee. The payee's USDC token
+account must exist before the first payment, since the payment's transaction does
+not create it. A keypair whose public half does not belong to its seed, or any
+malformed key, is reported at `PREFLIGHT` without echoing it.
+
 ## The disposable channel
 
 `MPP-13` closes a channel permanently. `CHANNEL_CONTRACT_DISPOSABLE` should name