🚨 CRITICAL FIX: Replace require() with dynamic imports for webpack compatibility

- Replace require('liquidjs') and require('mustache') with dynamic imports
- Fix webpack compatibility issues and ES module support
- Make template engine initialization lazy and async
- Add proper error handling for optional dependencies
- Use Function('return import(...)') pattern to avoid TypeScript issues
- Maintain backward compatibility with existing configurations

This resolves critical webpack bundling issues in client applications.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@xtr-dev/payload-mailing",
-  "version": "0.0.9",
+  "version": "0.0.10",
   "description": "Template-based email system with scheduling and job processing for PayloadCMS",
   "type": "module",
   "main": "dist/index.js",

pnpm-lock.yaml

@@ -8,9 +8,6 @@ importers:
 
   .:
     dependencies:
-      liquidjs:
-        specifier: ^10.19.0
-        version: 10.21.1
       nodemailer:
         specifier: ^6.9.8
         version: 6.10.1
@@ -117,6 +114,13 @@ importers:
       vitest:
         specifier: ^3.1.2
         version: 3.2.4(@types/debug@4.1.12)(@types/node@22.18.1)(sass@1.77.4)(tsx@4.20.3)
+    optionalDependencies:
+      liquidjs:
+        specifier: ^10.19.0
+        version: 10.21.1
+      mustache:
+        specifier: ^4.2.0
+        version: 4.2.0
 
 packages:
 
@@ -4190,6 +4194,10 @@ packages:
   ms@2.1.3:
     resolution: {integrity: sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA==}
 
+  mustache@4.2.0:
+    resolution: {integrity: sha512-71ippSywq5Yb7/tVYyGbkBggbU8H3u5Rz56fH60jGFgr8uHwxs+aSKeqmluIVzM0m0kB7xQjKS6qPfd0b2ZoqQ==}
+    hasBin: true
+
   nanoid@3.3.11:
     resolution: {integrity: sha512-N8SpfPUnUp1bK+PMYW8qSWdl9U+wwNWI4QKxOYDy9JAro3WMX7p2OeVRF9v+347pnakNevPmiHhNmZ2HbFA76w==}
     engines: {node: ^10 || ^12 || ^13.7 || ^14 || >=15.0.1}
@@ -8533,7 +8541,8 @@ snapshots:
 
   colorette@2.0.20: {}
 
-  commander@10.0.1: {}
+  commander@10.0.1:
+    optional: true
 
   commander@2.20.3: {}
 
@@ -10033,6 +10042,7 @@ snapshots:
   liquidjs@10.21.1:
     dependencies:
       commander: 10.0.1
+    optional: true
 
   locate-path@5.0.0:
     dependencies:
@@ -10421,6 +10431,9 @@ snapshots:
 
   ms@2.1.3: {}
 
+  mustache@4.2.0:
+    optional: true
+
   nanoid@3.3.11: {}
 
   napi-postinstall@0.3.3: {}

src/services/MailingService.ts

@@ -73,18 +73,22 @@ export class MailingService implements IMailingService {
     const engine = this.config.templateEngine || 'liquidjs'
 
     if (engine === 'liquidjs') {
-      this.initializeLiquidJS()
+      // LiquidJS will be initialized lazily on first use
+      this.liquid = null
     } else if (engine === 'mustache') {
-      // Mustache doesn't need initialization, we'll use it directly in renderTemplate
+      // Mustache will be loaded dynamically on first use
       this.liquid = null
     } else if (engine === 'simple') {
       this.liquid = null
     }
   }
 
-  private initializeLiquidJS(): void {
+  private async initializeLiquidJS(): Promise<void> {
+    if (this.liquid) return // Already initialized
+
     try {
-      const { Liquid: LiquidEngine } = require('liquidjs')
+      const liquidModule = await Function('return import("liquidjs")')() as any
+      const { Liquid: LiquidEngine } = liquidModule
       this.liquid = new LiquidEngine()
 
       // Register custom filters (equivalent to Handlebars helpers)
@@ -396,24 +400,27 @@ export class MailingService implements IMailingService {
 
     const engine = this.config.templateEngine || 'liquidjs'
 
-    // Use LiquidJS if available and configured
-    if (engine === 'liquidjs' && this.liquid) {
+    // Use LiquidJS if configured
+    if (engine === 'liquidjs') {
       try {
-        return await this.liquid.parseAndRender(template, variables)
+        await this.initializeLiquidJS()
+        if (this.liquid) {
+          return await this.liquid.parseAndRender(template, variables)
+        }
       } catch (error) {
         console.error('LiquidJS template rendering error:', error)
-        return template
       }
     }
 
     // Use Mustache if configured
     if (engine === 'mustache') {
       try {
-        const Mustache = require('mustache')
-        return Mustache.render(template, variables)
+        const mustacheResult = await this.renderWithMustache(template, variables)
+        if (mustacheResult !== null) {
+          return mustacheResult
+        }
       } catch (error) {
         console.warn('Mustache not available. Falling back to simple variable replacement. Install mustache package.')
-        return this.simpleVariableReplacement(template, variables)
       }
     }
 
@@ -421,6 +428,17 @@ export class MailingService implements IMailingService {
     return this.simpleVariableReplacement(template, variables)
   }
 
+  private async renderWithMustache(template: string, variables: Record<string, any>): Promise<string | null> {
+    try {
+      // Dynamic import with proper typing
+      const mustacheModule = await Function('return import("mustache")')() as any
+      const Mustache = mustacheModule.default || mustacheModule
+      return Mustache.render(template, variables)
+    } catch (error) {
+      return null
+    }
+  }
+
   private simpleVariableReplacement(template: string, variables: Record<string, any>): string {
     return template.replace(/\{\{(\w+)\}\}/g, (match, key) => {
       const value = variables[key]