run esbuild wasm

package-lock.json

@@ -1197,6 +1197,18 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/esbuild-wasm": {
+      "version": "0.25.12",
+      "resolved": "https://registry.npmjs.org/esbuild-wasm/-/esbuild-wasm-0.25.12.tgz",
+      "integrity": "sha512-rZqkjL3Y6FwLpSHzLnaEy8Ps6veCNo1kZa9EOfJvmWtBq5dJH4iVjfmOO6Mlkv9B0tt9WFPFmb/VxlgJOnueNg==",
+      "license": "MIT",
+      "bin": {
+        "esbuild": "bin/esbuild"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/escalade": {
       "version": "3.2.0",
       "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.2.0.tgz",
@@ -2851,7 +2863,8 @@
       "license": "MIT",
       "dependencies": {
         "@mcp-ui/server": "^5.15.0",
-        "esbuild": "^0.25.0"
+        "esbuild": "^0.25.0",
+        "esbuild-wasm": "^0.25.0"
       },
       "devDependencies": {
         "@types/node": "^20.10.0",

packages/library/package.json

@@ -47,7 +47,8 @@
   "license": "MIT",
   "dependencies": {
     "@mcp-ui/server": "^5.15.0",
-    "esbuild": "^0.25.0"
+    "esbuild": "^0.25.0",
+    "esbuild-wasm": "^0.25.0"
   },
   "peerDependencies": {
     "react": ">=18.0.0",

packages/library/server/bundle.ts

@@ -1,4 +1,4 @@
-import * as esbuild from 'esbuild';
+import type * as EsbuildType from 'esbuild';
 
 // Cache bundled JS per entry path (only used in production)
 const bundleCache = new Map<string, string>();
@@ -6,12 +6,51 @@ const bundleCache = new Map<string, string>();
 // In development mode, skip cache to allow hot-reloading of component changes
 const isDev = process.env.NODE_ENV !== 'production';
 
-async function runBuild(entryPath: string): Promise<esbuild.BuildResult<{ write: false }>> {
+// Esbuild instance - lazily loaded
-    console.log('[mcp-ui-kit] runBuild called for:', entryPath);
+let esbuild: typeof EsbuildType | null = null;
+let usingWasm = false;
+
+async function getEsbuild(): Promise<typeof EsbuildType> {
+    if (esbuild) return esbuild;
+
+    // Try native esbuild first
+    try {
+        console.log('[mcp-ui-kit] Trying native esbuild...');
+        const native = await import('esbuild');
+        // Test if native works by running a simple transform
+        await native.transform('const x = 1', { loader: 'js' });
+        console.log('[mcp-ui-kit] Native esbuild works!');
+        esbuild = native;
+        return esbuild;
+    } catch (nativeError) {
+        console.log('[mcp-ui-kit] Native esbuild failed:', nativeError instanceof Error ? nativeError.message : String(nativeError));
+        
+        // Fall back to wasm
+        try {
+            console.log('[mcp-ui-kit] Falling back to esbuild-wasm...');
+            const wasm = await import('esbuild-wasm');
+            await wasm.initialize({
+                wasmURL: `https://unpkg.com/esbuild-wasm@${wasm.version}/esbuild.wasm`,
+            });
+            console.log('[mcp-ui-kit] esbuild-wasm initialized!');
+            esbuild = wasm as typeof EsbuildType;
+            usingWasm = true;
+            return esbuild;
+        } catch (wasmError) {
+            console.log('[mcp-ui-kit] esbuild-wasm also failed:', wasmError instanceof Error ? wasmError.message : String(wasmError));
+            throw wasmError;
+        }
+    }
+}
+
+async function runBuild(entryPath: string): Promise<EsbuildType.BuildResult<{ write: false }>> {
+    const esbuild = await getEsbuild();
+    console.log('[mcp-ui-kit] runBuild using', usingWasm ? 'wasm' : 'native', 'for:', entryPath);
+    
     return esbuild.build({
         entryPoints: [entryPath],
         bundle: true,
-        write: false,  // No disk I/O - keep everything in memory
+        write: false,
         format: 'iife',
         target: 'es2020',
         jsx: 'automatic',
@@ -25,45 +64,33 @@ async function runBuild(entryPath: string): Promise<esbuild.BuildResult<{ write:
 
 export async function bundleComponent(entryPath: string): Promise<string> {
     console.log('[mcp-ui-kit] bundleComponent called for:', entryPath);
-    console.log('[mcp-ui-kit] isDev:', isDev, 'NODE_ENV:', process.env.NODE_ENV);
-    console.log('[mcp-ui-kit] Cache has entry:', bundleCache.has(entryPath));
     
     if (!isDev && bundleCache.has(entryPath)) {
         console.log('[mcp-ui-kit] Returning cached bundle');
         return bundleCache.get(entryPath)!;
     }
 
-    let result: esbuild.BuildResult<{ write: false }>;
+    let result: EsbuildType.BuildResult<{ write: false }>;
     
     try {
-        console.log('[mcp-ui-kit] Attempting first build...');
         result = await runBuild(entryPath);
-        console.log('[mcp-ui-kit] First build succeeded');
+        console.log('[mcp-ui-kit] Build succeeded');
     } catch (error) {
         const errorMessage = error instanceof Error ? error.message : String(error);
-        const errorStack = error instanceof Error ? error.stack : '';
+        console.log('[mcp-ui-kit] Build failed:', errorMessage);
-        console.log('[mcp-ui-kit] ========== BUILD ERROR ==========');
-        console.log('[mcp-ui-kit] Error message:', errorMessage);
-        console.log('[mcp-ui-kit] Error stack:', errorStack);
-        console.log('[mcp-ui-kit] Full error:', JSON.stringify(error, Object.getOwnPropertyNames(error || {}), 2));
-        console.log('[mcp-ui-kit] ================================');
         
-        // Handle esbuild service errors in serverless environments (Vercel, Lambda, etc.)
+        // Handle service errors for native esbuild in serverless
-        // This happens when the serverless runtime freezes/stops the esbuild subprocess.
+        const isServiceError = !usingWasm && error instanceof Error && (
-        const isServiceError = error instanceof Error && (
             errorMessage.includes('service was stopped') ||
             errorMessage.includes('service is no longer running') ||
-            errorMessage.includes('The service') ||
+            errorMessage.includes('The service')
-            errorMessage.includes('could not be found')
         );
-        console.log('[mcp-ui-kit] Is service error:', isServiceError);
         
         if (isServiceError) {
-            // Force stop the dead service, then retry - esbuild will start fresh
+            console.log('[mcp-ui-kit] Service error, stopping and retrying...');
-            console.log('[mcp-ui-kit] Stopping esbuild service and retrying...');
+            const esbuild = await getEsbuild();
             await esbuild.stop();
             result = await runBuild(entryPath);
-            console.log('[mcp-ui-kit] Retry succeeded');
         } else {
             throw error;
         }
@@ -72,10 +99,8 @@ export async function bundleComponent(entryPath: string): Promise<string> {
     const bundledJS = result.outputFiles[0].text;
     console.log('[mcp-ui-kit] Bundle size:', bundledJS.length, 'bytes');
 
-    // Only cache in production mode
     if (!isDev) {
         bundleCache.set(entryPath, bundledJS);
-        console.log('[mcp-ui-kit] Bundle cached');
     }
 
     return bundledJS;

yarn.lock

@@ -713,6 +713,11 @@ es-object-atoms@^1.0.0, es-object-atoms@^1.1.1:
   dependencies:
     es-errors "^1.3.0"
 
+esbuild-wasm@^0.25.0:
+  version "0.25.12"
+  resolved "https://registry.npmjs.org/esbuild-wasm/-/esbuild-wasm-0.25.12.tgz"
+  integrity sha512-rZqkjL3Y6FwLpSHzLnaEy8Ps6veCNo1kZa9EOfJvmWtBq5dJH4iVjfmOO6Mlkv9B0tt9WFPFmb/VxlgJOnueNg==
+
 esbuild@^0.25.0:
   version "0.25.12"
   resolved "https://registry.npmjs.org/esbuild/-/esbuild-0.25.12.tgz"
@@ -1042,6 +1047,7 @@ mcp-ui-kit@*, "mcp-ui-kit@file:/Users/fedjens/projects/mcp-ui-kit/packages/libra
   dependencies:
     "@mcp-ui/server" "^5.15.0"
     esbuild "^0.25.0"
+    esbuild-wasm "^0.25.0"
 
 media-typer@^1.1.0:
   version "1.1.0"