[javadtavakoli]

Summary

• Emit {"type":"module"} into src/_types/package.json during build:types, matching the existing _esm / _cjs markers
• Fixes declaration files resolving as CommonJS under TypeScript module: node16 (TS1479 / TS1541)

This is the same fix that was accepted in viem: wevm/viem#4903. That change came out of wevm/viem#4843, which fixed viem's own _types/ marker and explicitly identified the bundled ox 0.14.x as the remaining source of the leftover TS1479s. This PR is that remaining half.

The problem

scripts/prepublish.ts does delete packageJson.type, so the published root package.json has no "type" field and defaults to CommonJS. build:esm and build:cjs each write a marker into the folder they emit, but build:types does not:

emitted folder	package.json "type"
_esm/	"module" ✅
_cjs/	"commonjs" ✅
_types/	missing ❌

So every _types/**/*.d.ts is resolved as CommonJS. Those files use ESM syntax and import abitype, which is "type": "module" — a CJS file importing ESM:

node_modules/ox/_types/core/AbiFunction.d.ts(1,26): error TS1479: The current file is a CommonJS
module whose imports will produce 'require' calls; however, the referenced file is an ECMAScript
module and cannot be imported with 'require'.

This survives ox's own CI because check:types typechecks the source, never the emitted _types/ as a consumer resolves it through the exports map. It only appears downstream.

Reproduction

mkdir ox-repro && cd ox-repro
npm init -y && npm pkg set type=module
npm i ox@0.14.45 typescript@5.9.3

index.ts:

import * as AbiFunction from 'ox/AbiFunction'
export const f = AbiFunction.from('function approve(address, uint256)')

npx tsc --noEmit --strict --skipLibCheck false --module node16 --moduleResolution node16 index.ts
# 4x TS1479 + 3x TS1541, all inside node_modules/ox/_types/**

Verify the fix is exactly the missing marker:

printf '{"type":"module"}' > node_modules/ox/_types/package.json
npx tsc --noEmit --strict --skipLibCheck false --module node16 --moduleResolution node16 index.ts
# clean

Which configurations are affected

TypeScript	module: node16	module: nodenext
5.7.3	❌ fails	❌ fails
5.9.3	❌ fails	✅ passes

TypeScript 5.8 taught nodenext that Node 22+ permits require(esm), so nodenext on current TypeScript no longer surfaces it — please reproduce with node16, which is still a fully supported setting and is what pins Node 16 CJS/ESM semantics.

I also hit this on a larger module: node16 project consuming ox through viem, where it produced 12 × TS1479 across 7 declaration files (Abi, AbiConstructor, AbiError, AbiEvent, AbiFunction, AbiItem, AbiParameters); adding the marker cleared all 12.

Why it's worth patching the 0.x line

viem@2.56.8 pins "ox": "0.14.45" exactly, so this reaches every viem consumer on node16 resolution, not just direct ox users. The workarounds today are turning on skipLibCheck or patching ox in node_modules — and library authors who re-export these types with declaration: true can't use skipLibCheck to hide it, since the mismatch propagates into their own emitted declarations.

ox@1.x is unaffected — it keeps "type": "module" on the published root and emits to dist/ — so this targets 0.x only.

Test plan

• pnpm build:types writes src/_types/package.json containing {"type":"module"}
• Marker present → the repro above typechecks clean with skipLibCheck: false; absent → TS1479/TS1541 as listed
• Verified against both ox@0.14.45 and the current ox@0.14.47 tarball, neither of which ships _types/package.json

[vercel]

@javadtavakoli is attempting to deploy a commit to the Wevm Team on Vercel.

A member of the Team first needs to authorize it.

[javadtavakoli]

Friendly ping @jxom — this is the ox half of wevm/viem#4903 (which you merged; wevm/viem#4843 identified the bundled ox@0.14.x as the remaining source of the TS1479s). It's a one-line build:types change targeting 0.x, and it affects every viem consumer on module: node16 since viem pins ox@0.14.x.

CI hasn't run yet — looks like the workflows need approval for a first-time contributor. Happy to adjust anything.

[jxom]

Thanks @javadtavakoli! Superseded by #579, which lands this change on 0.x with you credited as co-author and a changeset that notes the CommonJS node16 tradeoff. main (1.x) is ESM-only and already resolves its types as ESM.