diff --git a/dap-gateway/src/main/java/io/shinhanlife/dap/mcg/presentation/ScaffoldingController.java b/dap-gateway/src/main/java/io/shinhanlife/dap/mcg/presentation/ScaffoldingController.java
index e1e5448e..21b00739 100644
--- a/dap-gateway/src/main/java/io/shinhanlife/dap/mcg/presentation/ScaffoldingController.java
+++ b/dap-gateway/src/main/java/io/shinhanlife/dap/mcg/presentation/ScaffoldingController.java
@@ -155,6 +155,21 @@ public class ScaffoldingController {
                 .sorted().toList();
     }
 
+    @GetMapping("/categories")
+    public List<String> listCategories(@RequestParam String moduleName) {
+        if (moduleName == null || !moduleName.matches("^dap-was-[a-z0-9-]+$")) {
+            throw new IllegalArgumentException("Invalid target module.");
+        }
+        String sourceDir = System.getenv("AXHUB_SOURCE_DIR");
+        if (sourceDir == null || sourceDir.isBlank()) sourceDir = System.getProperty("user.dir");
+        File bizDir = new File(sourceDir, moduleName + "/src/main/java/io/shinhanlife/dap/mcc/biz");
+        File[] dirs = bizDir.listFiles(File::isDirectory);
+        if (dirs == null) return List.of();
+        return Arrays.stream(dirs).map(File::getName)
+                .filter(name -> name.matches("^[a-z0-9]{3}$"))
+                .sorted().toList();
+    }
+
     @PostMapping("/field-draft")
     public ResponseEntity<?> generateFieldDraft(@RequestBody Map<String, String> req) {
         String description = req.getOrDefault("description", "").trim();
diff --git a/dap-gateway/src/main/resources/static/admin/scaffold.html b/dap-gateway/src/main/resources/static/admin/scaffold.html
index c334afd3..ec270593 100644
--- a/dap-gateway/src/main/resources/static/admin/scaffold.html
+++ b/dap-gateway/src/main/resources/static/admin/scaffold.html
@@ -824,6 +824,50 @@
                 <!-- Tool Creation Form -->
                 <div class="tab-pane fade" id="tool" role="tabpanel">
                     <form id="toolForm">
+                        <div class="row mb-4">
+                            <div class="col-md-6">
+                                <label class="form-label">Target Module</label>
+                                <select class="form-select" name="moduleName" id="targetModuleSelect" required>
+                                    <option value="dap-was-cus">dap-was-cus</option>
+                                    <option value="dap-was-hr">dap-was-hr</option>
+                                    <option value="dap-was-sal">dap-was-sal</option>
+                                    <option value="dap-was-pro">dap-was-pro</option>
+                                    <option value="dap-was-sys">dap-was-sys</option>
+                                </select>
+                                <div class="input-hint">Destination Pod directory.</div>
+                            </div>
+                            <div class="col-md-6 mt-3 mt-md-0">
+                                <label class="form-label">Gateway Registration</label>
+                                <select class="form-select" name="register">
+                                    <option value="true" selected>True (Public)</option>
+                                    <option value="false">False (Private)</option>
+                                </select>
+                                <div class="input-hint">Controls dynamic routing exposure.</div>
+                            </div>
+                        </div>
+
+                        <div class="row mb-3">
+                            <div class="col-md-6">
+                                <label class="form-label mb-1">Domain Category</label>
+                                <div class="row g-2">
+                                    <div class="col-md-5">
+                                        <select id="domainCategorySelect" class="form-select">
+                                            <option value="">새 도메인 생성</option>
+                                        </select>
+                                    </div>
+                                    <div class="col-md-7">
+                                        <input type="text" id="domainCategoryName" class="form-control" name="categoryKey" pattern="^[a-z0-9]{3}$" maxlength="3" minlength="3" placeholder="e.g. cmm (3글자 영소문자)" oninput="this.value = this.value.toLowerCase()" required>
+                                    </div>
+                                </div>
+                            </div>
+                            <div class="col-md-6 mt-3 mt-md-0">
+                                <label class="form-label">Protocol</label>
+                                    <select class="form-select" name="routingType">
+                                        <option value="HTTP">HTTP (REST)</option>
+                                        <option value="MCI">MCI (Legacy)</option>
+                                    </select>
+                            </div>
+                        </div>
                         <div class="mb-4 p-3 rounded" style="background:#18181b; border:1px solid #3f3f46;">
                             <div class="d-flex justify-content-between align-items-center gap-3">
                                 <div>
@@ -920,26 +964,6 @@
                             </div>
                         </div>
                         
-                        <div class="row mb-3">
-                            <div class="col-md-6">
-                                <label class="form-label">Domain Category</label>
-                                <input type="text" class="form-control" name="categoryKey" pattern="^[a-z0-9]{3}$" maxlength="3" minlength="3" list="groupList" placeholder="e.g. cmm, smp, pay" oninput="this.value = this.value.toLowerCase()" required>
-                                <datalist id="groupList">
-                                    <option value="smp">smp</option>
-                                    <option value="cmm">cmm</option>
-                                    <option value="cus">cus</option>
-                                    <option value="cnt">cnt</option>
-                                    <option value="clm">clm</option>
-                                </datalist>
-                            </div>
-                            <div class="col-md-6 mt-3 mt-md-0">
-                                <label class="form-label">Protocol</label>
-                                    <select class="form-select" name="routingType">
-                                        <option value="HTTP">HTTP (REST)</option>
-                                        <option value="MCI">MCI (Legacy)</option>
-                                    </select>
-                            </div>
-                        </div>
 
                         <div class="row mb-3">
                             <div class="col-md-6">
@@ -977,27 +1001,6 @@
                             </div>
                         </div>
 
-                        <div class="row mb-4">
-                            <div class="col-md-6">
-                                <label class="form-label">Target Module</label>
-                                <select class="form-select" name="moduleName" id="targetModuleSelect" required>
-                                    <option value="dap-was-cus">dap-was-cus</option>
-                                    <option value="dap-was-hr">dap-was-hr</option>
-                                    <option value="dap-was-sal">dap-was-sal</option>
-                                    <option value="dap-was-pro">dap-was-pro</option>
-                                    <option value="dap-was-sys">dap-was-sys</option>
-                                </select>
-                                <div class="input-hint">Destination Pod directory.</div>
-                            </div>
-                            <div class="col-md-6 mt-3 mt-md-0">
-                                <label class="form-label">Gateway Registration</label>
-                                <select class="form-select" name="register">
-                                    <option value="true" selected>True (Public)</option>
-                                    <option value="false">False (Private)</option>
-                                </select>
-                                <div class="input-hint">Controls dynamic routing exposure.</div>
-                            </div>
-                        </div>
 
                         <div class="row mb-4">
                             <div class="col-md-6">
@@ -1483,6 +1486,9 @@
                 if (modules && modules.length > 0) {
                     select.innerHTML = modules.map(m => `<option value="${m}" ${m === 'dap-was-cus' ? 'selected' : ''}>${m}</option>`).join('');
                 }
+                if (typeof loadCategoriesForSelection === 'function') {
+                    loadCategoriesForSelection();
+                }
             })
             .catch(err => console.error('Failed to load modules:', err));
     });
@@ -1569,8 +1575,37 @@
         }
     }
 
-    document.querySelector('#toolForm [name="categoryKey"]').addEventListener('change', loadUseCasesForSelection);
-    document.getElementById('targetModuleSelect').addEventListener('change', loadUseCasesForSelection);
+    async function loadCategoriesForSelection() {
+        const moduleName = document.getElementById('targetModuleSelect').value;
+        const select = document.getElementById('domainCategorySelect');
+        const nameInput = document.getElementById('domainCategoryName');
+        select.innerHTML = '<option value="">새 도메인 생성</option>';
+        try {
+            const response = await fetch(`/api/v1/scaffold/categories?moduleName=${encodeURIComponent(moduleName)}`);
+            if (!response.ok) throw new Error('Category 목록 조회 실패');
+            const categories = await response.json();
+            categories.forEach(cat => select.add(new Option(`기존 ${cat} 도메인`, cat)));
+        } catch (error) {
+            console.warn(error);
+        }
+        nameInput.value = '';
+        nameInput.readOnly = false;
+        loadUseCasesForSelection();
+    }
+
+    document.getElementById('domainCategoryName').addEventListener('input', loadUseCasesForSelection);
+    document.getElementById('targetModuleSelect').addEventListener('change', loadCategoriesForSelection);
+    document.getElementById('domainCategorySelect').addEventListener('change', function() {
+        const nameInput = document.getElementById('domainCategoryName');
+        if (this.value) {
+            nameInput.value = this.value;
+            nameInput.readOnly = true;
+        } else {
+            nameInput.value = '';
+            nameInput.readOnly = false;
+        }
+        loadUseCasesForSelection();
+    });
     document.getElementById('toolGroupUseCaseSelect').addEventListener('change', function() {
         const nameInput = document.getElementById('toolGroupUseCaseName');
         if (this.value) {