fix: Correct virtual SSR module invalidation and import side-effect logic (#587)

Follow-up to previous PR (#586) - there were some issues in it for establishing proper module graph linkage for virtual SSR modules.

Fixes:
* Corrected environment scope for invalidation: Virtual SSR modules must be invalidated in the worker environment, not client, to ensure proper propagation without triggering full reloads.
* Handled modules without code (e.g. CSS): CSS and other plugin-handled modules can return undefined from fetchModule(). We now avoid skipping these entirely and still extract specifiers to maintain accurate graph linkage.
* Replaced the switch-wrapped `ssrImport()` + return logic with direct inline injection of `import()` side effects. This change restores correct behaviour for some module types (notably CSS), though the exact cause of breakage in the previous version is not yet fully understood.

Author: justinvdm

sdk/src/vite/directivesPlugin.mts

@@ -6,7 +6,6 @@ import { transformClientComponents } from "./transformClientComponents.mjs";
 import { transformServerFunctions } from "./transformServerFunctions.mjs";
 import { normalizeModulePath } from "./normalizeModulePath.mjs";
 import type { ViteDevServer } from "vite";
-import { invalidateModule } from "./invalidateModule.mjs";
 
 const log = debug("rwsdk:vite:rsc-directives-plugin");
 const verboseLog = debug("verbose:rwsdk:vite:rsc-directives-plugin");
@@ -89,8 +88,6 @@ export const directivesPlugin = ({
           lookupModule,
           id,
         );
-
-        //invalidateModule(devServer, environment, `virtual:use-${kind}-lookup`);
       }
     }
   };

sdk/src/vite/miniflareHMRPlugin.mts

@@ -196,7 +196,7 @@ export const miniflareHMRPlugin = (givenOptions: {
         );
 
         if (virtualSSRModule) {
-          ctx.server.environments.client.moduleGraph.invalidateModule(
+          ctx.server.environments.worker.moduleGraph.invalidateModule(
             virtualSSRModule,
             new Set(),
             ctx.timestamp,

sdk/src/vite/ssrBridgePlugin.mts

@@ -148,20 +148,12 @@ export const ssrBridgePlugin = ({
 
           verboseLog("Fetch module result: id=%s, result=%O", realId, result);
 
-          if (!result) {
-            return;
-          }
-
           const code = "code" in result ? result.code : undefined;
           log("Fetched SSR module code length: %d", code?.length || 0);
 
-          if (!code) {
-            return;
-          }
-
           const { imports, dynamicImports } = findSsrImportSpecifiers(
             realId,
-            code,
+            code || "",
             verboseLog,
           );
 
@@ -176,17 +168,14 @@ export const ssrBridgePlugin = ({
 
           const transformedCode = `
 await (async function(__vite_ssr_import__, __vite_ssr_dynamic_import__) {${code}})(
-  (id, ...args) => ssrImport(id, false, ...args),
-  (id, ...args) => ssrImport(id, true, ...args)
+  (id, ...args) => {ssrImport(id); return __vite_ssr_import__('/@id/${VIRTUAL_SSR_PREFIX}' + id, ...args);},
+  (id, ...args) => {ssrImport(id); return __vite_ssr_dynamic_import__('/@id/${VIRTUAL_SSR_PREFIX}' + id, ...args);}
 );
 
-function ssrImport(id, isDynamic, ...args) {
+function ssrImport(id) {
   switch (id) {
 ${switchCases}
   }
-
-  const virtualId = '/@id/${VIRTUAL_SSR_PREFIX}' + id;
-  return isDynamic ? __vite_ssr_dynamic_import__(virtualId, ...args) : __vite_ssr_import__(virtualId, ...args);
 }
 `;