## Summary
Fixes#20219.
The `@tailwindcss/postcss` exports map serves the CJS-shaped
`dist/index.d.ts` (`export = _default`) for both the `import` and
`require` conditions, while the correct ESM declaration file
`dist/index.d.mts` (`export { _default as default }`) is built and
published but never referenced. Type checkers that treat the import
condition as ESM reject the default import with TS1192 — concretely,
`deno check` on Deno 2.8.3+ (which ships TypeScript 6.0) fails on
`import tailwindcss from "@tailwindcss/postcss"`.
This splits the export entry into per-condition `types` blocks so ESM
importers resolve `index.d.mts` and CJS consumers keep `index.d.ts` —
the same shape `@tailwindcss/vite` already uses (`"types":
"./dist/index.d.mts"`).
Two notes on the issue as filed:
- Stock `tsc` with NodeNext does **not** reproduce the error
(declaration file format follows the file extension and package `type`,
not the matched condition), so I didn't take the suggested `export =` →
`export default` change in `index.d.ts` — that would break CJS
consumers, and the correct ESM declarations already ship.
- `@tailwindcss/node` has the same single-`types` exports shape; happy
to follow up there if you want parity.
## Test plan
Against `@tailwindcss/postcss@4.3.0` with the published exports map,
then again with only this `package.json` change applied to the installed
package:
```sh
# Deno 2.8.3 (TypeScript 6.0), nodeModulesDir: auto
deno check main.ts # before: TS1192 "Module ... index.d.ts has no default export" — after: passes
```
```sh
# typescript@6.0.0-dev (NodeNext), one ESM importer + one .cts require importer
tsc --noEmit # passes both before and after (no regression for npm consumers)
```
`@arethetypeswrong/cli`:
| | published 4.3.0 | with this change |
|---|---|---|
| node16 (from ESM) | 🎭 Masquerading as CJS | 🟢 (ESM) |
| node16 (from CJS) | 🟢 (CJS) | 🟢 (CJS) |
| bundler | 🟢 | 🟢 |
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