Build/Test Tools: Restore React Refresh scripts for hot reloading #10725

youknowriad · 2026-01-13T10:17:01Z

Summary

Restores the wp_register_development_scripts() function and associated build infrastructure to enable hot module replacement (HMR) when using @wordpress/scripts with the --hot flag.

The React Refresh scripts were removed in [61438] as part of the Gutenberg build restructuring, but they are still needed for plugin developers using wp-scripts start --hot for block development.

Changes

Adds react-refresh and @pmmmwh/react-refresh-webpack-plugin npm dependencies
Creates tools/webpack/development.js to build the development scripts
Restores wp_register_development_scripts() in script-loader.php
Removes the deprecated stub from deprecated.php

The scripts are only registered when SCRIPT_DEBUG is true and are not loaded during Core tests.

Trac Ticket

https://core.trac.wordpress.org/ticket/64393

Test Plan

Set SCRIPT_DEBUG to true in wp-config.php
Create a plugin using @wordpress/scripts
Run wp-scripts start --hot
Verify hot module replacement works when editing React components

🤖 Generated with Claude Code

Restores the `wp_register_development_scripts()` function and associated build infrastructure to enable hot module replacement (HMR) when using `@wordpress/scripts` with the `--hot` flag. The React Refresh scripts were removed in [61438] as part of the Gutenberg build restructuring, but they are still needed for plugin developers using `wp-scripts start --hot` for block development. This commit: - Adds `react-refresh` and `@pmmmwh/react-refresh-webpack-plugin` npm dependencies - Creates `tools/webpack/development.js` to build the development scripts - Restores `wp_register_development_scripts()` in `script-loader.php` - Removes the deprecated stub from `deprecated.php` The scripts are only registered when `SCRIPT_DEBUG` is true and are not loaded during Core tests. Props youknowriad. Fixes #64393. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

github-actions · 2026-01-13T10:17:11Z

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Props youknowriad, wildworks, manzoorwanijk.

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youknowriad · 2026-01-13T10:20:11Z

Hot reloading has proven to be not very valuable in Gutenberg and WordPress in general since it's not a typical SPA. That said, this PR restores the previous behavior so we can make an informed decision about whether we still want it or not.

github-actions · 2026-01-13T10:26:04Z

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youknowriad · 2026-01-13T10:33:19Z

I tested this with an example plugin, it works but I understand why no one really uses this, it's not the seamless experience that you get with SPAs. Anyone, we can see whether to commit or not this PR.

youknowriad · 2026-01-14T09:47:09Z

@t-hamano What do you think we should do here? Maybe we can just merge this PR to restore previous status quo even if imperfect.

t-hamano

Thanks for the PR!

There is WordPress/gutenberg#74618 to replace @pmmmwh/react-refresh-webpack-plugin with react-refresh. Perhaps we need to align the two PR approaches.

I was the first to suggest keeping hot reload, but is keeping react-refresh a major blocker to improving build tooling? If so, I'm starting to think that it might be a good time to remove all the hot-reload libraries and code now. What do you think?

cc @manzoorwanijk @jsnajdr @aduth

manzoorwanijk · 2026-01-15T08:56:01Z

tools/webpack/development.js

+		// React Refresh entry - injects runtime into global hook before React loads.
+		[ buildTarget + 'wp-includes/js/dist/development/react-refresh-entry.js' ]:
+			'@pmmmwh/react-refresh-webpack-plugin/client/ReactRefreshEntry.js',
+		[ buildTarget + 'wp-includes/js/dist/development/react-refresh-entry.min.js' ]:
+			'@pmmmwh/react-refresh-webpack-plugin/client/ReactRefreshEntry.js',


We already have these in Gutenberg, why not use them from there?

We have them only when we have the built files in build. But that's not always true. The webpack dev server serves files from memory, and needs to build the entire self-contained set of Gutenberg JS assets.

manzoorwanijk · 2026-01-15T08:57:35Z

src/wp-includes/script-loader.php

+ *
+ * @param WP_Scripts $scripts WP_Scripts object.
+ */
+function wp_register_development_scripts( $scripts ) {


Should we backport this to Gutenberg to avoid 404 errors as mentioned in WordPress/gutenberg#74618 (comment)?

No need, this is only missing in WordPress trunk, which will get updated once this commit lands.

But we don't register those in Gutenberg to override the Core scripts. Which means that the ones in Gutenberg are never actually loaded. That is the reason I had to write Step 10 in the Testing Instructions in WordPress/gutenberg#74618 to load the scripts from Gutenberg to be able to test them.

But we don't register those in Gutenberg to override the Core scripts. Which means that the ones in Gutenberg are never actually loaded. That is the reason I had to write Step 10 in the Testing Instructions in WordPress/gutenberg#74618 to load the scripts from Gutenberg to be able to test them.

I think we should remove the ones in Gutenberg entirely.

youknowriad · 2026-01-15T11:17:53Z

My thinking is that we should ship this PR to "fix" things for folks using the previous version of wp-scripts but I won't be against removing this entirely from wp-scripts in Gutenberg.

jsnajdr

Looks good 🙂

I wouldn't mind removing React Refresh completely. With esbuild it doesn't work at all. In npm run dev we would have to run our own dev server with esbuild.serve. We currently don't do that, we only recompile files in watch mode.

youknowriad · 2026-01-15T13:02:11Z

This was committed.

youknowriad requested a review from t-hamano January 13, 2026 10:33

t-hamano mentioned this pull request Jan 15, 2026

Replace @pmmmwh/react-refresh-webpack-plugin with react-refresh WordPress/gutenberg#74618

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youknowriad closed this Jan 15, 2026

Build/Test Tools: Restore React Refresh scripts for hot reloading #10725

Build/Test Tools: Restore React Refresh scripts for hot reloading #10725

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youknowriad commented Jan 13, 2026

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Test using WordPress Playground

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