fix: keep $ServerOnly templates in client HMR transforms

.changeset/server-only-templates-hmr.md

@@ -0,0 +1,5 @@
+---
+'vite-plugin-solid': patch
+---
+
+Keep `$ServerOnly` templates in client transforms while HMR is active so hot updates of components using `$ServerOnly` no longer throw `template is not a function`. An explicit `solid.omitServerOnlyTemplates` setting still takes precedence.

README.md

@@ -145,6 +145,8 @@ Pass any additional [babel transform options](https://babeljs.io/docs/en/options
 Pass any additional [babel-plugin-jsx-dom-expressions](https://github.com/ryansolid/dom-expressions/tree/main/packages/babel-plugin-jsx-dom-expressions#plugin-options).
 They will be merged with the defaults sets by [babel-preset-solid](https://github.com/solidjs/solid/blob/main/packages/babel-preset-solid/index.js#L8-L25).
 
+In dev with HMR enabled, the plugin sets `omitServerOnlyTemplates: false` for client transforms so that components containing `$ServerOnly` elements can be re-created by Solid Refresh. Pass `omitServerOnlyTemplates` explicitly to override this.
+
 #### options.typescript
 
 - Type: [@babel/preset-typescript](https://babeljs.io/docs/en/babel-preset-typescript)

src/index.ts

@@ -105,6 +105,19 @@ export interface Options {
      */
     omitQuotes?: boolean;
 
+    /**
+     * Only applies when `hydratable` is `true`. When `true`, an element marked
+     * `$ServerOnly` registers no client template, so it can only be obtained by
+     * hydrating server-rendered DOM and throws if it is ever re-created on the client.
+     *
+     * The plugin sets this to `false` for client transforms in dev while HMR is
+     * enabled, since Solid Refresh re-runs components outside of hydration. Pass
+     * an explicit value to override that.
+     *
+     * @default true
+     */
+    omitServerOnlyTemplates?: boolean;
+
     /**
      * The name of the runtime module to import the methods from.
      *
@@ -397,11 +410,22 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin {
         plugins.push('typescript');
       }
 
+      // babel-plugin-jsx-dom-expressions >= 0.40.10 omits the client template of
+      // `$ServerOnly` elements by default, so re-creating such an element outside
+      // of hydration throws "template is not a function". Solid Refresh does
+      // exactly that on every hot update, so keep the templates in client HMR
+      // transforms. An explicit user setting still wins.
+      const presetOptions = {
+        ...solidOptions,
+        ...(needHmr && !isSsr ? { omitServerOnlyTemplates: false } : {}),
+        ...(options.solid || {}),
+      };
+
       const opts: babel.TransformOptions = {
         root: projectRoot,
         filename: id,
         sourceFileName: id,
-        presets: [[solid, { ...solidOptions, ...(options.solid || {}) }]],
+        presets: [[solid, presetOptions]],
         plugins: needHmr && !isSsr && !inNodeModules ? [[solidRefresh, { bundler: 'vite' }]] : [],
         ast: false,
         sourceMaps: true,