diff --git a/frontend/app/(admin)/admin/migration/page.tsx b/frontend/app/(admin)/admin/migration/page.tsx
index 2c54072..9b7c4d9 100644
--- a/frontend/app/(admin)/admin/migration/page.tsx
+++ b/frontend/app/(admin)/admin/migration/page.tsx
@@ -49,7 +49,7 @@ export default function MigrationReviewQueuePage() {
     if (selectedIds.length === items.length) {
       setSelectedIds([]);
     } else {
-      setSelectedIds(items.map((i) => i.id));
+      setSelectedIds(items.map((i) => i.id).filter((id): id is number => id !== undefined));
     }
   };
 
@@ -63,6 +63,7 @@ export default function MigrationReviewQueuePage() {
       setSubmitting(true);
 
       const batchItems = items
+        .filter((i): i is typeof i & { id: number } => i.id !== undefined)
         .filter((i) => selectedIds.includes(i.id))
         .map((item) => ({
           queueId: item.id,
@@ -165,12 +166,12 @@ export default function MigrationReviewQueuePage() {
                 </TableHeader>
                 <TableBody>
                   {items.map((item) => (
-                    <TableRow key={item.id}>
+                    <TableRow key={item.id || item.publicId}>
                       <TableCell>
                         <Checkbox
-                          checked={selectedIds.includes(item.id)}
-                          onCheckedChange={() => handleToggleSelect(item.id)}
-                          aria-label={`Select item ${item.id}`}
+                          checked={item.id !== undefined && selectedIds.includes(item.id)}
+                          onCheckedChange={() => item.id !== undefined && handleToggleSelect(item.id)}
+                          aria-label={`Select item ${item.id || item.publicId}`}
                         />
                       </TableCell>
                       <TableCell className="font-medium">{item.documentNumber}</TableCell>
@@ -205,7 +206,7 @@ export default function MigrationReviewQueuePage() {
                       </TableCell>
                       <TableCell>{format(new Date(item.createdAt), 'dd MMM yyyy, HH:mm')}</TableCell>
                       <TableCell className="text-right">
-                        <Link href={`/admin/migration/review/${item.id}`}>
+                        <Link href={`/admin/migration/review/${item.id || item.publicId}`}>
                           <Button size="sm" variant="ghost">
                             <EyeIcon className="h-4 w-4 mr-2" /> Review
                           </Button>
diff --git a/frontend/app/(admin)/admin/migration/review/[id]/page.tsx b/frontend/app/(admin)/admin/migration/review/[id]/page.tsx
index 5a5594e..927f0aa 100644
--- a/frontend/app/(admin)/admin/migration/review/[id]/page.tsx
+++ b/frontend/app/(admin)/admin/migration/review/[id]/page.tsx
@@ -125,6 +125,10 @@ export default function MigrationReviewPage() {
         },
       };
 
+      if (!item?.id) {
+        toast.error('Invalid item ID');
+        return;
+      }
       // Mock idempotency key based on timestamp to ensure uniqueness per approval retry
       const idempotencyKey = `review-${item.id}-${Date.now()}`;
       await migrationService.approveQueueItem(item.id, payload, idempotencyKey);
@@ -140,7 +144,7 @@ export default function MigrationReviewPage() {
   };
 
   const onReject = async () => {
-    if (!item || !confirm('Are you sure you want to REJECT this document? It will not be imported.')) return;
+    if (!item || !item.id || !confirm('Are you sure you want to REJECT this document? It will not be imported.')) return;
 
     try {
       setSubmitting(true);
diff --git a/frontend/app/(admin)/admin/monitoring/audit-logs/page.tsx b/frontend/app/(admin)/admin/monitoring/audit-logs/page.tsx
index 1352c1c..84e5654 100644
--- a/frontend/app/(admin)/admin/monitoring/audit-logs/page.tsx
+++ b/frontend/app/(admin)/admin/monitoring/audit-logs/page.tsx
@@ -31,7 +31,7 @@ export default function AuditLogsPage() {
                   <div className="flex-1">
                     <div className="flex items-center gap-3 mb-2">
                       <span className="font-medium text-sm">
-                        {log.user?.fullName || log.user?.username || `User #${log.user?.userId || 'System'}`}
+                        {log.user?.fullName || log.user?.username || `User #${log.userId || 'System'}`}
                       </span>
                       <Badge
                         variant={log.severity === 'ERROR' ? 'destructive' : 'outline'}
diff --git a/frontend/components/admin/security/rbac-matrix.tsx b/frontend/components/admin/security/rbac-matrix.tsx
index 1be56d8..5017ed4 100644
--- a/frontend/components/admin/security/rbac-matrix.tsx
+++ b/frontend/components/admin/security/rbac-matrix.tsx
@@ -10,7 +10,8 @@ import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import apiClient from '@/lib/api/client';
 
 interface Role {
-  roleId: number;
+  publicId?: string; // ADR-019: public identifier
+  roleId?: number;   // Internal INT
   roleName: string;
   permissions?: Permission[];
 }
@@ -151,16 +152,17 @@ export function RbacMatrix() {
                   <div className="text-xs text-muted-foreground">{perm.description}</div>
                 </TableCell>
                 {roleList.map((role) => {
+                  const roleId = role.roleId ?? 0;
                   // Assume role.permissions is populated
                   const currentRolePerms = role.permissions?.map((p) => p.permissionId) || [];
-                  const activePerms = pendingChanges[role.publicId] || currentRolePerms;
+                  const activePerms = pendingChanges[roleId] || currentRolePerms;
                   const isChecked = activePerms.includes(perm.permissionId);
 
                   return (
-                    <TableCell key={`${role.publicId}-${perm.permissionId}`} className="text-center">
+                    <TableCell key={`${roleId}-${perm.permissionId}`} className="text-center">
                       <Checkbox
                         checked={isChecked}
-                        onCheckedChange={() => handleToggle(role.publicId, perm.permissionId, currentRolePerms)}
+                        onCheckedChange={() => handleToggle(roleId, perm.permissionId, currentRolePerms)}
                       />
                     </TableCell>
                   );
diff --git a/frontend/components/admin/user-dialog.tsx b/frontend/components/admin/user-dialog.tsx
index 22aba33..b08798f 100644
--- a/frontend/components/admin/user-dialog.tsx
+++ b/frontend/components/admin/user-dialog.tsx
@@ -108,7 +108,7 @@ export function UserDialog({ open, onOpenChange, user }: UserDialogProps) {
         isActive: user.isActive,
         lineId: user.lineId || '',
         primaryOrganizationId: user.primaryOrganizationId?.toString() || ALL_ORGANIZATIONS_VALUE,
-        roleIds: user.roles?.map((r: { publicId: string }) => r.publicId) || [],
+        roleIds: user.roles?.map((r: { roleId?: number }) => r.roleId).filter((id): id is number => id !== undefined) || [],
         password: '',
         confirmPassword: '',
       });
@@ -297,23 +297,26 @@ export function UserDialog({ open, onOpenChange, user }: UserDialogProps) {
                 <p className="text-sm text-muted-foreground">Loading roles...</p>
               )}
               {Array.isArray(roles) &&
-                roles.map((role: { publicId: string; roleName: string; description?: string }) => (
-                  <div key={role.publicId} className="flex items-start space-x-2">
-                    <Checkbox
-                      id={`role-${role.publicId}`}
-                      checked={selectedRoleIds.includes(role.publicId)}
-                      onCheckedChange={(checked) => {
-                        const current = selectedRoleIds;
-                        if (checked) {
-                          setValue('roleIds', [...current, role.publicId]);
-                        } else {
-                          setValue(
-                            'roleIds',
-                            current.filter((id) => id !== role.publicId)
-                          );
-                        }
-                      }}
-                    />
+                roles.map((role: { publicId?: string; roleId?: number; roleName: string; description?: string }) => {
+                  const roleId = role.roleId;
+                  if (roleId === undefined) return null;
+                  return (
+                    <div key={role.publicId ?? roleId} className="flex items-start space-x-2">
+                      <Checkbox
+                        id={`role-${role.publicId ?? roleId}`}
+                        checked={selectedRoleIds.includes(roleId)}
+                        onCheckedChange={(checked) => {
+                          const current = selectedRoleIds;
+                          if (checked) {
+                            setValue('roleIds', [...current, roleId]);
+                          } else {
+                            setValue(
+                              'roleIds',
+                              current.filter((id) => id !== roleId)
+                            );
+                          }
+                        }}
+                      />
                     <div className="grid gap-1.5 leading-none">
                       <label
                         htmlFor={`role-${role.publicId}`}
@@ -323,8 +326,9 @@ export function UserDialog({ open, onOpenChange, user }: UserDialogProps) {
                       </label>
                       <p className="text-xs text-muted-foreground">{role.description}</p>
                     </div>
-                  </div>
-                ))}
+                    </div>
+                  );
+                })}
             </div>
           </div>
 
diff --git a/frontend/components/numbering/template-tester.tsx b/frontend/components/numbering/template-tester.tsx
index 056ff26..e92512d 100644
--- a/frontend/components/numbering/template-tester.tsx
+++ b/frontend/components/numbering/template-tester.tsx
@@ -158,7 +158,7 @@ export function TemplateTester({ open, onOpenChange, template }: TemplateTesterP
                       <SelectContent>
                         <SelectItem value="0">Default (All Types)</SelectItem>
                         {(correspondenceTypes as CorrespondenceType[])?.map((type) => (
-                          <SelectItem key={type.publicId} value={type.publicId.toString()}>
+                          <SelectItem key={type.id} value={type.id.toString()}>
                             {type.typeCode} - {type.typeName}
                           </SelectItem>
                         ))}
@@ -179,7 +179,7 @@ export function TemplateTester({ open, onOpenChange, template }: TemplateTesterP
                       <SelectContent>
                         <SelectItem value="0">None</SelectItem>
                         {(disciplines as Discipline[])?.map((disc) => (
-                          <SelectItem key={disc.publicId} value={disc.publicId.toString()}>
+                          <SelectItem key={disc.id} value={disc.id.toString()}>
                             {disc.disciplineCode}
                           </SelectItem>
                         ))}
diff --git a/frontend/components/rfas/form.tsx b/frontend/components/rfas/form.tsx
index 95436c0..76b6a91 100644
--- a/frontend/components/rfas/form.tsx
+++ b/frontend/components/rfas/form.tsx
@@ -403,7 +403,7 @@ export function RFAForm() {
                 onValueChange={(val) => {
                   setValue('contractId', val);
                   setValue('disciplineId', 0);
-                  setValue('rfaTypeId', 0);
+                  setValue('rfaTypeId', '');
                   setValue('shopDrawingRevisionIds', []);
                   setValue('asBuiltDrawingRevisionIds', []);
                 }}
diff --git a/frontend/hooks/use-correspondence.ts b/frontend/hooks/use-correspondence.ts
index f6e8d3c..d4b25b3 100644
--- a/frontend/hooks/use-correspondence.ts
+++ b/frontend/hooks/use-correspondence.ts
@@ -142,7 +142,7 @@ export function useAddTag() {
 
   return useMutation({
     mutationFn: ({ uuid, tagId }: { uuid: string; tagId: number | string }) =>
-      correspondenceService.addTag(uuid, tagId),
+      correspondenceService.addTag(uuid, Number(tagId)),
     onSuccess: (_, { uuid }) => {
       toast.success('Tag added');
       queryClient.invalidateQueries({ queryKey: [...correspondenceKeys.detail(uuid), 'tags'] });
@@ -160,7 +160,7 @@ export function useRemoveTag() {
 
   return useMutation({
     mutationFn: ({ uuid, tagId }: { uuid: string; tagId: number | string }) =>
-      correspondenceService.removeTag(uuid, tagId),
+      correspondenceService.removeTag(uuid, Number(tagId)),
     onSuccess: (_, { uuid }) => {
       toast.success('Tag removed');
       queryClient.invalidateQueries({ queryKey: [...correspondenceKeys.detail(uuid), 'tags'] });
diff --git a/frontend/lib/api/admin.ts b/frontend/lib/api/admin.ts
index f09eca3..7d03dbe 100644
--- a/frontend/lib/api/admin.ts
+++ b/frontend/lib/api/admin.ts
@@ -3,27 +3,30 @@ import { User, CreateUserDto, Organization, AuditLog } from '@/types/admin';
 // Mock Data
 const mockUsers: User[] = [
   {
+    publicId: 'user-001',
     userId: 1,
     username: 'admin',
     email: 'admin@example.com',
     firstName: 'System',
     lastName: 'Admin',
     isActive: true,
-    roles: [{ roleId: 1, roleName: 'ADMIN', description: 'Administrator' }],
+    roles: [{ publicId: 'role-001', roleId: 1, roleName: 'ADMIN', description: 'Administrator' }],
   },
   {
+    publicId: 'user-002',
     userId: 2,
     username: 'jdoe',
     email: 'john.doe@example.com',
     firstName: 'John',
     lastName: 'Doe',
     isActive: true,
-    roles: [{ roleId: 2, roleName: 'USER', description: 'Regular User' }],
+    roles: [{ publicId: 'role-002', roleId: 2, roleName: 'USER', description: 'Regular User' }],
   },
 ];
 
 const mockOrgs: Organization[] = [
   {
+    publicId: 'org-001',
     orgId: 1,
     orgCode: 'PAT',
     orgName: 'Port Authority of Thailand',
@@ -31,6 +34,7 @@ const mockOrgs: Organization[] = [
     description: 'Owner',
   },
   {
+    publicId: 'org-002',
     orgId: 2,
     orgCode: 'CNPC',
     orgName: 'CNPC Consortium',
@@ -40,6 +44,7 @@ const mockOrgs: Organization[] = [
 
 const mockLogs: AuditLog[] = [
   {
+    publicId: 'log-001',
     auditLogId: 1,
     userName: 'admin',
     action: 'CREATE',
@@ -49,6 +54,7 @@ const mockLogs: AuditLog[] = [
     createdAt: new Date(Date.now() - 1000 * 60 * 60 * 24).toISOString(),
   },
   {
+    publicId: 'log-002',
     auditLogId: 2,
     userName: 'jdoe',
     action: 'UPDATE',
@@ -67,14 +73,17 @@ export const adminApi = {
 
   createUser: async (data: CreateUserDto): Promise<User> => {
     await new Promise((resolve) => setTimeout(resolve, 800));
+    const maxId = mockUsers.length > 0 ? Math.max(...mockUsers.map((u) => u.userId ?? 0)) : 0;
     const newUser: User = {
-      userId: Math.max(...mockUsers.map((u) => u.userId)) + 1,
+      publicId: `user-${String(maxId + 1).padStart(3, '0')}`,
+      userId: maxId + 1,
       username: data.username,
       email: data.email,
       firstName: data.firstName,
       lastName: data.lastName,
       isActive: data.isActive,
       roles: data.roles.map((id) => ({
+        publicId: `role-${String(id).padStart(3, '0')}`,
         roleId: id,
         roleName: id === 1 ? 'ADMIN' : 'USER',
         description: '',
@@ -91,7 +100,8 @@ export const adminApi = {
 
   createOrganization: async (data: Omit<Organization, 'orgId'>): Promise<Organization> => {
     await new Promise((resolve) => setTimeout(resolve, 600));
-    const newOrg = { ...data, orgId: Math.max(...mockOrgs.map((o) => o.orgId)) + 1 };
+    const maxId = mockOrgs.length > 0 ? Math.max(...mockOrgs.map((o) => o.orgId ?? 0)) : 0;
+    const newOrg: Organization = { ...data, publicId: data.publicId || `org-${String(maxId + 1).padStart(3, '0')}`, orgId: maxId + 1 };
     mockOrgs.push(newOrg);
     return newOrg;
   },
diff --git a/frontend/lib/api/drawings.ts b/frontend/lib/api/drawings.ts
index c892f1d..ae8d813 100644
--- a/frontend/lib/api/drawings.ts
+++ b/frontend/lib/api/drawings.ts
@@ -3,7 +3,7 @@ import { Drawing } from '@/types/drawing';
 // Mock Data
 const mockDrawings: Drawing[] = [
   {
-    drawingId: 1,
+    publicId: 'dwg-001',
     drawingNumber: 'S-201-A',
     title: 'Structural Foundation Plan',
     discipline: 'Structural',
@@ -13,7 +13,7 @@ const mockDrawings: Drawing[] = [
     updatedAt: new Date(Date.now() - 1000 * 60 * 60 * 24).toISOString(),
   },
   {
-    drawingId: 2,
+    publicId: 'dwg-002',
     drawingNumber: 'A-101-B',
     title: 'Architectural Floor Plan - Level 1',
     discipline: 'Architectural',
@@ -30,12 +30,12 @@ export const drawingApi = {
     return { data: mockDrawings, meta: { total: mockDrawings.length } };
   },
 
-  getById: async (id: number): Promise<Drawing | undefined> => {
+  getById: async (_id: string): Promise<Drawing | undefined> => {
     await new Promise((resolve) => setTimeout(resolve, 300));
-    return mockDrawings.find((d) => d.drawingId === id);
+    return mockDrawings.find((d) => d.publicId === _id);
   },
 
-  getByContract: async (_contractId: number): Promise<{ data: Drawing[] }> => {
+  getByContract: async (_contractId: string): Promise<{ data: Drawing[] }> => {
     await new Promise((resolve) => setTimeout(resolve, 400));
     // Mock: return all drawings for any contract
     return { data: mockDrawings };
diff --git a/frontend/lib/api/workflows.ts b/frontend/lib/api/workflows.ts
index 801c3bc..4772e53 100644
--- a/frontend/lib/api/workflows.ts
+++ b/frontend/lib/api/workflows.ts
@@ -3,6 +3,7 @@ import { Workflow, CreateWorkflowDto, ValidationResult } from '@/types/workflow'
 // Mock Data
 let mockWorkflows: Workflow[] = [
   {
+    publicId: 'wf-001',
     workflowId: 1,
     workflowName: 'Standard RFA Workflow',
     description: 'Default approval process for RFAs',
@@ -22,6 +23,7 @@ steps:
     updatedAt: new Date().toISOString(),
   },
   {
+    publicId: 'wf-002',
     workflowId: 2,
     workflowName: 'Correspondence Review',
     description: 'Incoming correspondence review flow',
@@ -44,15 +46,17 @@ export const workflowApi = {
     return [...mockWorkflows];
   },
 
-  getWorkflow: async (id: number): Promise<Workflow | undefined> => {
+  getWorkflow: async (id: string): Promise<Workflow | undefined> => {
     await new Promise((resolve) => setTimeout(resolve, 300));
-    return mockWorkflows.find((w) => w.workflowId === id);
+    return mockWorkflows.find((w) => w.publicId === id);
   },
 
   createWorkflow: async (data: CreateWorkflowDto): Promise<Workflow> => {
     await new Promise((resolve) => setTimeout(resolve, 800));
+    const maxId = mockWorkflows.length > 0 ? Math.max(...mockWorkflows.map((w) => Number(w.workflowId ?? 0))) : 0;
     const newWorkflow: Workflow = {
-      workflowId: Math.max(...mockWorkflows.map((w) => Number(w.workflowId))) + 1,
+      publicId: `wf-${String(maxId + 1).padStart(3, '0')}`,
+      workflowId: maxId + 1,
       ...data,
       version: 1,
       isActive: true,
@@ -63,9 +67,9 @@ export const workflowApi = {
     return newWorkflow;
   },
 
-  updateWorkflow: async (id: number, data: Partial<CreateWorkflowDto>): Promise<Workflow> => {
+  updateWorkflow: async (id: string, data: Partial<CreateWorkflowDto>): Promise<Workflow> => {
     await new Promise((resolve) => setTimeout(resolve, 600));
-    const index = mockWorkflows.findIndex((w) => w.workflowId === id);
+    const index = mockWorkflows.findIndex((w) => w.publicId === id);
     if (index === -1) throw new Error('Workflow not found');
 
     const updatedWorkflow = { ...mockWorkflows[index], ...data, updatedAt: new Date().toISOString() };
diff --git a/frontend/lib/services/audit-log.service.ts b/frontend/lib/services/audit-log.service.ts
index 7e034b8..9fff064 100644
--- a/frontend/lib/services/audit-log.service.ts
+++ b/frontend/lib/services/audit-log.service.ts
@@ -2,6 +2,7 @@ import apiClient from '@/lib/api/client';
 import { AuditQueryParams } from '@/types/dto/numbering.dto';
 
 export interface AuditLog {
+  publicId?: string; // ADR-019: public identifier
   auditId: string;
   userId?: number | null;
   user?: {
diff --git a/frontend/lib/services/contract.service.ts b/frontend/lib/services/contract.service.ts
index 9a78cc1..355c759 100644
--- a/frontend/lib/services/contract.service.ts
+++ b/frontend/lib/services/contract.service.ts
@@ -3,11 +3,11 @@ import { CreateContractDto, UpdateContractDto, SearchContractDto } from '@/types
 import { Contract } from '@/types/contract';
 
 const normalizeContract = (record: Contract): Contract => {
-  const publicId = record.publicId ?? record.id;
+  const publicId = record.publicId;
   const project = record.project
     ? {
         ...record.project,
-        publicId: record.project.publicId ?? record.project.id,
+        publicId: record.project.publicId,
       }
     : undefined;
 
diff --git a/frontend/lib/services/workflow-engine.service.ts b/frontend/lib/services/workflow-engine.service.ts
index 0814b40..3d01e61 100644
--- a/frontend/lib/services/workflow-engine.service.ts
+++ b/frontend/lib/services/workflow-engine.service.ts
@@ -99,6 +99,7 @@ const normalizeWorkflowType = (workflowCode?: string): WorkflowType => {
 const mapWorkflow = (backendObj: BackendWorkflowShape): Workflow => {
   if (!backendObj) throw new Error('Workflow not found');
   return {
+    publicId: String(backendObj.id ?? ''),
     workflowId: backendObj.id ?? backendObj.workflow_code ?? '',
     workflowName:
       (typeof backendObj.dsl === 'object' ? backendObj.dsl?.workflowName : undefined) ||
diff --git a/frontend/types/user.ts b/frontend/types/user.ts
index 8273f38..e376937 100644
--- a/frontend/types/user.ts
+++ b/frontend/types/user.ts
@@ -1,5 +1,6 @@
 export interface Role {
-  roleId: number;
+  publicId?: string; // ADR-019: public identifier
+  roleId?: number;   // Internal INT
   roleName: string;
   description: string;
 }