refactor(rsc): restructure environmentImportMetaMap to key by sourceEnv

Change from `Record<resolvedId, meta>` to `Record<sourceEnv, Record<resolvedId, meta>>`.
This properly handles the case where the same module is imported from multiple
source environments, avoiding overwrites.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: hi-ogawa

packages/plugin-rsc/src/plugin.ts

@@ -125,7 +125,11 @@ class RscPluginManager {
     {}
   serverReferenceMetaMap: Record<string, ServerRerferenceMeta> = {}
   serverResourcesMetaMap: Record<string, { key: string }> = {}
-  environmentImportMetaMap: Record<string, EnvironmentImportMeta> = {}
+  // Keyed by [sourceEnv][resolvedId] to support same module imported from multiple environments
+  environmentImportMetaMap: Record<
+    string,
+    Record<string, EnvironmentImportMeta>
+  > = {}
 
   stabilize(): void {
     // sort for stable build
@@ -157,17 +161,10 @@ class RscPluginManager {
       return
     }
 
-    // Group imports by source environment
-    const bySourceEnv: Record<string, typeof this.environmentImportMetaMap> = {}
-    for (const [resolvedId, meta] of Object.entries(
+    // Write manifest to each source environment's output
+    for (const [sourceEnv, imports] of Object.entries(
       this.environmentImportMetaMap,
     )) {
-      bySourceEnv[meta.sourceEnv] ??= {}
-      bySourceEnv[meta.sourceEnv]![resolvedId] = meta
-    }
-
-    // Write manifest to each source environment's output
-    for (const [sourceEnv, imports] of Object.entries(bySourceEnv)) {
       const sourceOutDir = this.config.environments[sourceEnv]!.build.outDir
       const manifestPath = path.join(sourceOutDir, ENV_IMPORTS_MANIFEST_NAME)
 

packages/plugin-rsc/src/plugins/import-environment.ts

@@ -62,12 +62,20 @@ export function vitePluginImportEnvironment(
         // Emit discovered entries during build
         if (this.environment.mode !== 'build') return
 
-        for (const meta of Object.values(manager.environmentImportMetaMap)) {
-          if (meta.targetEnv === this.environment.name) {
-            this.emitFile({
-              type: 'chunk',
-              id: meta.resolvedId,
-            })
+        // Collect unique entries targeting this environment (may be imported from multiple sources)
+        const emitted = new Set<string>()
+        for (const imports of Object.values(manager.environmentImportMetaMap)) {
+          for (const meta of Object.values(imports)) {
+            if (
+              meta.targetEnv === this.environment.name &&
+              !emitted.has(meta.resolvedId)
+            ) {
+              emitted.add(meta.resolvedId)
+              this.emitFile({
+                type: 'chunk',
+                id: meta.resolvedId,
+              })
+            }
           }
         }
       },
@@ -124,11 +132,13 @@ export function vitePluginImportEnvironment(
               resolvedId = resolved.id
             }
 
-            // Track discovered entry (keyed by absolute path for generateBundle lookup)
-            manager.environmentImportMetaMap[resolvedId] = {
+            // Track discovered entry, keyed by [sourceEnv][resolvedId]
+            const sourceEnv = this.environment.name
+            manager.environmentImportMetaMap[sourceEnv] ??= {}
+            manager.environmentImportMetaMap[sourceEnv]![resolvedId] = {
               resolvedId,
               targetEnv: environmentName,
-              sourceEnv: this.environment.name,
+              sourceEnv,
               specifier,
             }
 
@@ -178,12 +188,17 @@ export function vitePluginImportEnvironment(
         if (this.environment.name === 'client') return
 
         // Track output filenames for discovered environment imports
-        // This runs in both RSC and SSR builds to capture all outputs
+        // Only set fileName when this bundle's environment matches the target
         for (const [fileName, chunk] of Object.entries(bundle)) {
           if (chunk.type === 'chunk' && chunk.isEntry && chunk.facadeModuleId) {
-            const meta = manager.environmentImportMetaMap[chunk.facadeModuleId]
-            if (meta) {
-              meta.fileName = fileName
+            const resolvedId = chunk.facadeModuleId
+            for (const imports of Object.values(
+              manager.environmentImportMetaMap,
+            )) {
+              const meta = imports[resolvedId]
+              if (meta && meta.targetEnv === this.environment.name) {
+                meta.fileName = fileName
+              }
             }
           }
         }