10.1.0: dist/package.json is missing the `exports` field (breaks /scope subpath and scope in bundlers)

[Olovyannikov]

Summary

@effector/reflect@10.1.0 is published without the exports field in its package.json. Version 10.0.2 had it.

// 10.0.2 package.json
"exports": {
  ".":       { "types": "./index.d.ts", "import": "./index.mjs", "require": "./index.cjs", "default": "./index.mjs" },
  "./scope": { "types": "./scope.d.ts", "import": "./scope.mjs", "require": "./scope.js",  "default": "./scope.mjs" }
}
// 10.1.0 package.json — no `exports` at all

Root cause

build.mjs, which generates dist/package.json, uses a typo — export: Existing.export (singular, non-existent) instead of exports: Existing.exports:

const Dist = {
  ...
  export: Existing.export, // ← typo; Existing.export is undefined
  ...
};

Introduced in commit cef40e6 ("ci: include over exclude fields for dist/package.json"). The source package.json still has a correct exports, but it never reaches the built artifact.

Impact

• The @effector/reflect/scope subpath no longer resolves via exports.
• Bundlers fall back to main (CJS). The CJS entry requires its own copy of effector-react, producing a dual-package hazard: <Provider> (ESM) and the useUnit used inside variant/reflect (CJS) end up referencing different effector-react instances. The forked scope is then lost — variant/reflect read the store's default value instead of the scoped one.

Reproduction

React 19 app, bundler resolving the package entry (Vite/Vitest):

const Cmp = variant({ if: $flag, then: Then, else: Else });
render(
  <Provider value={fork({ values: [[$flag, false]] })}>
    <Cmp />
  </Provider>,
);
// expected: <Else/>; actual on 10.1.0: <Then/> (reads default `true`, not scoped `false`)

Pinning back to 10.0.2 (which still ships exports) fixes it.

Fix

build.mjs: export → exports. PR incoming. Also adding a guard in validate_dist.mjs so a missing exports fails dist validation (the current attw/publint calls swallow their errors).