fix: publish custom event polyfill

[davilima6]

Purpose

Ensure the custom event polyfill referenced by the SDK's generated declarations is included in the published package.

> tsc --noEmit

../../node_modules/.pnpm/@builder.io+sdk@6.3.1_encoding@0.1.13/node_modules/@builder.io/sdk/dist/src/bu
ilder.class.d.ts:2:8 - error TS2882: Cannot find module or type declarations for side-effect import of
'./polyfills/custom-event-polyfill'.

2 import './polyfills/custom-event-polyfill';
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Found 1 error in ../../node_modules/.pnpm/@builder.io+sdk@6.3.1_encoding@0.1.13/node_modules/@builder.i
o/sdk/dist/src/builder.class.d.ts:2

 ELIFECYCLE  Command failed with exit code 1.
ERROR: command (/Users/me/Projects/mypackage/apps/mcp-server) /Users/me/Library/p
npm/.tools/pnpm/10.4.1/bin/pnpm run check:types exited (1)
└─ @myorg/my-pkg#check:types ──

Approach and changes

• converted the custom event polyfill from JS to TS so the existing SDK compiler emits its runtime module and empty declaration alongside builder.class.d.ts
• preserved the browser fallback behavior: it only defines window.CustomEvent when it is missing

Testing instructions

1. Run yarn workspace @builder.io/sdk build
2. Confirm that packages/core/dist/src/polyfills/custom-event-polyfill.js and packages/core/dist/src/polyfills/custom-event-polyfill.d.ts exist
3. In a TS consumer that enables noUncheckedSideEffectImports, import @builder.io/sdk and run tsc --noEmit. The declaration import of ./polyfills/custom-event-polyfill should resolve

---

Note

Low Risk
Small packaging and typing fix for an existing browser polyfill with no auth, data, or API behavior changes.

Overview
Fixes a published package gap where builder.class.d.ts side-effect-imports ./polyfills/custom-event-polyfill, but consumers running tsc --noEmit (especially with strict side-effect import checks) could not resolve that module.

The polyfill is now TypeScript so the SDK build emits custom-event-polyfill.js and a matching .d.ts next to the generated declarations. Runtime behavior is unchanged: the IIFE still only patches window.CustomEvent when it is missing in the browser.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 726f9c6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@builder.io/sdk	Patch
@builder.io/react	Patch

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[nx-cloud]

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---

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☁️ Nx Cloud last updated this comment at 2026-08-04 20:45:02 UTC

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