fix: pre-bundle the server-function client runtime

.changeset/server-functions-client-runtime-prebundle.md

@@ -0,0 +1,5 @@
+---
+'@solidjs/vite-plugin': patch
+---
+
+With `serverFunctions` on, the dev server now pre-bundles the server-function client runtime even without `components` (`@solidjs/web/server-functions`, or `runtime.client` when it names a package), so a cold cache no longer re-optimizes and reloads on the first `"use server"` module. In Vitest browser mode that reload showed up as "Vite unexpectedly reloaded a test".

examples/start-ssr/test/components-warning.mjs

@@ -13,7 +13,13 @@
 //     derived serverComponents flag) matches `true` exactly, and stays off
 //     when the option is off,
 //   - under full SSR start mode `'external'` is redundant but harmless:
-//     silent, exactly like `true`.
+//     silent, exactly like `true`,
+//   - independent of server components: `serverFunctions` alone (with or
+//     without `ssr`) pre-bundles the server-function client runtime under
+//     `serve` (the dependency scan never runs the transform that adds its
+//     import), listed once when components also ask for it; not without
+//     `serverFunctions`, not in build, and a custom `runtime.client` only as
+//     a package specifier, beside the components entries when both are on.
 //
 // Pure resolveConfig — no dev server, no browser. Requires the plugin built
 // (pnpm build at the repo root). Usage: node test/components-warning.mjs
@@ -81,6 +87,14 @@ async function resolveWith(solidOptions) {
     config.optimizeDeps.include.includes('@solidjs/web/frames') &&
       config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
   );
+  const runtimeEntries = config.optimizeDeps.include.filter(
+    (dep) => dep === '@solidjs/web/server-functions',
+  );
+  record(
+    'enabled: server-function client runtime listed once',
+    runtimeEntries.length === 1,
+    config.optimizeDeps.include.join(', '),
+  );
 }
 
 // ---- `'external'` in the identical config: silent, still enabled ---------
@@ -123,6 +137,84 @@ async function resolveWith(solidOptions) {
       config.optimizeDeps.include.includes('@solidjs/web/performance-tracks'),
     config.optimizeDeps.include.join(', '),
   );
+  // Compiled server-function references import the client runtime, but the
+  // dependency scanner never runs the transform that adds that import.
+  // Without the entry, the first "use server" module the browser loads
+  // discovers it late: re-optimize and full reload.
+  record(
+    'serverFunctions without components: server-function client runtime pre-bundled',
+    config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
+
+// ---- serverFunctions without ssr: same entry -----------------------------
+{
+  const { config } = await resolveWith({ serverFunctions: true });
+  record(
+    'serverFunctions without ssr: server-function client runtime pre-bundled',
+    config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
+
+// ---- serverFunctions off: no server-function runtime pre-bundle -----------
+{
+  const { config } = await resolveWith({ ssr: true });
+  record(
+    'serverFunctions off: server-function client runtime not pre-bundled',
+    !config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
+
+// ---- custom runtime: only a package specifier is pre-bundled --------------
+{
+  const client = '@acme/server-runtime/client';
+  const { config } = await resolveWith({
+    ssr: true,
+    serverFunctions: { runtime: { server: '@acme/server-runtime/server', client } },
+  });
+  record(
+    'custom runtime (package): runtime.client pre-bundled instead of the default',
+    config.optimizeDeps.include.includes(client) &&
+      !config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
+{
+  const client = '@acme/server-runtime/client';
+  const { config } = await resolveWith({
+    ssr: true,
+    serverFunctions: {
+      components: true,
+      runtime: { server: '@acme/server-runtime/server', client },
+    },
+  });
+  record(
+    'components + custom runtime (package): runtime.client beside the components entries',
+    config.optimizeDeps.include.includes(client) &&
+      config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
+for (const client of [
+  './src/sf-client.ts',
+  '/src/sf-client.ts',
+  'virtual:sf-client',
+  '@/sf-client',
+  '~/sf-client',
+]) {
+  const { config } = await resolveWith({
+    ssr: true,
+    serverFunctions: { runtime: { server: client, client } },
+  });
+  record(
+    `custom runtime (${client}): neither it nor the default pre-bundled`,
+    !config.optimizeDeps.include.includes(client) &&
+      !config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
 }
 
 // ---- build: optimizeDeps is serve-only, the entries stay out --------------
@@ -138,6 +230,21 @@ async function resolveWith(solidOptions) {
     config.optimizeDeps.include.join(', '),
   );
 }
+{
+  const config = await resolveConfig(
+    {
+      root: exampleDir,
+      configFile: false,
+      plugins: [solidPlugin({ ssr: true, serverFunctions: true })],
+    },
+    'build',
+  );
+  record(
+    'build: server-function client runtime not in optimizeDeps.include',
+    !config.optimizeDeps.include.includes('@solidjs/web/server-functions'),
+    config.optimizeDeps.include.join(', '),
+  );
+}
 
 // ---- full SSR start mode: `'external'` is redundant but harmless ---------
 {

src/index.ts

@@ -582,6 +582,18 @@ function findPackageDir(name: string, root: string): string | undefined {
   }
 }
 
+/**
+ * Whether `id` looks like a package specifier (`name`, `name/sub`,
+ * `@scope/name/sub`), by syntax alone. Relative and absolute paths, ids with a
+ * protocol or drive (`virtual:`, `node:`, `C:`), subpath imports (`#x`) and
+ * aliases like `~/x` or `@/x` don't.
+ */
+function isPackageSpecifier(id: string): boolean {
+  if (!id || /^[./\\#~\0]/.test(id) || id.includes(':')) return false;
+  if (id.startsWith('@')) return /^@[^/]+\/[^/]/.test(id);
+  return true;
+}
+
 function getJestDomExport(setupFiles: string[], root: string) {
   if (setupFiles?.some((file) => /jest-dom/.test(file))) return undefined;
 
@@ -1057,6 +1069,21 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin[] {
   const serverComponentsOption =
     typeof options.serverFunctions === 'object' ? options.serverFunctions.components : undefined;
   const serverComponents = !!serverComponentsOption;
+  // The client runtime compiled server-function references import (the
+  // server-functions plugin's own default unless `runtime` is set), kept only
+  // when it names a package. A relative path or an alias is app source: the
+  // optimizer would bundle a copy nothing loads or, for `@/x`, serve that copy
+  // so edits stop showing up. A virtual id or `/src/x` doesn't resolve for
+  // `include` and only warns.
+  const serverFunctionsClientRuntime = options.serverFunctions
+    ? typeof options.serverFunctions === 'object' && options.serverFunctions.runtime
+      ? options.serverFunctions.runtime.client
+      : '@solidjs/web/server-functions'
+    : undefined;
+  const serverFunctionsClientDep =
+    serverFunctionsClientRuntime && isPackageSpecifier(serverFunctionsClientRuntime)
+      ? serverFunctionsClientRuntime
+      : undefined;
   // `start: true` is sugar for the empty options bag — one start mode,
   // two spellings — so normalize here and let everything downstream see a
   // single shape (`false` behaves exactly like omission).
@@ -1483,6 +1510,15 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin[] {
             ...(command === 'serve' && serverComponents
               ? ['@solidjs/web/frames', '@solidjs/web/server-functions']
               : []),
+            // Plain `serverFunctions` needs the runtime too: the scanner never
+            // runs the transform that adds its import, so the first "use server"
+            // module forces the same re-optimize + full reload (in Vitest
+            // browser mode, "Vite unexpectedly reloaded a test").
+            ...(command === 'serve' &&
+            serverFunctionsClientDep &&
+            !(serverComponents && serverFunctionsClientDep === '@solidjs/web/server-functions')
+              ? [serverFunctionsClientDep]
+              : []),
             // The attribution engine and the Chrome performance-tracks
             // recorder are subpaths the scanner only sees when the app's own
             // graph imports them; a consumer it never crawls (a linked