chore: retire the @sei-js x402 fork packages

[alexander-sei]

Summary

Sei is now supported natively in the upstream x402 SDK, so this fork has no remaining purpose. x402-foundation/x402#3227 landed the Sei default stablecoins upstream in the v2 line, and the v1 legacy line already carried them.

This retires all seven @sei-js/* x402 packages and points users at the upstream v2 @x402/* packages.

Why this is a correctness fix, not just housekeeping

The fork defaults Sei mainnet (chain 1329) to an IBC-bridged USDC that does not implement EIP-3009. Since the exact scheme settles via transferWithAuthorization, payments cannot settle against that asset. The code has carried a TODO about this since it was written:

"1329": {
  // This USDC is an IBC Bridged one and does not support EIP3009
  // TODO: Substitute with a native USDC when available
  usdcAddress: "0x3894085Ef7Ff0f0aeDf52E2A2704928d1Ec074F1",

Upstream uses native USDC 0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf42392 (mainnet) and 0x4fCF1784B31630811181f670Aea7A7bEF803eaED (testnet), both of which do implement EIP-3009.

What changed

• MIGRATION.md mapping every package to its v2 replacement, with before/after code for the four breaking changes users will hit: CAIP-2 network identifiers ("sei" becomes "eip155:1329"), the restructured paymentMiddleware plus x402ResourceServer setup, the new client wrapper config shape, and the USDC address swap.
• Deprecation banners on the root README and all seven package READMEs.
• private: true on all seven packages, so npm publish refuses outright.
• Release automation disabled. release.yml no longer triggers on push to main (it previously auto-published on any change under typescript/**), and all eight release/publish workflows now fail fast with an explanatory error.
• scripts/deprecate-sei-x402-packages.sh to apply the npm deprecations, supporting DRY_RUN=1.

Package mapping

Deprecated	Replacement
@sei-js/x402	@x402/core + @x402/evm
@sei-js/x402-fetch	@x402/fetch
@sei-js/x402-axios	@x402/axios
@sei-js/x402-express	@x402/express
@sei-js/x402-hono	@x402/hono
@sei-js/x402-next	@x402/next
@sei-js/coinbase-x402	@coinbase/x402

Follow-ups after merge

1. Run ./scripts/deprecate-sei-x402-packages.sh with npm publish rights on the @sei-js scope.
2. Archive sei-protocol/x402 and sei-protocol/sei-x402-obsolete.

Test plan

• All eight workflow YAML files parse, carry no automatic triggers, and have the refusal guard as their first step.
• All eight edited JSON files parse and the seven packages report private: true.
• npm publish --dry-run reports Skipping workspace @sei-js/x402-fetch, marked as private.
• DRY_RUN=1 ./scripts/deprecate-sei-x402-packages.sh prints the expected message for all seven packages.

Notes

Scope check: the @sei-js npm scope has 12 packages, but only these seven are x402-related. create-sei, mcp-server, precompiles, registry, and sei-global-wallet are actively maintained and untouched. The python/, go/, and java/ trees in this repo contain no Sei-specific code and were never customised.

Made with Cursor

Made with Cursor

Tracking

PLT-1062, a follow-up to PLT-1046 which tracked the upstream Sei default stablecoin work in x402-foundation/x402#3227.