diff --git a/backend/src/abdulrcrtw.spec.ts b/backend/src/abdulrcrtw.spec.ts
new file mode 100644
index 000000000..dd2d10e15
--- /dev/null
+++ b/backend/src/abdulrcrtw.spec.ts
@@ -0,0 +1,39 @@
+import { NotesDocsController } from './assets/notes-docs.controller';
+import { MaintenanceService } from './maintenance/maintenance.service';
+import { TransfersService } from './transfers/transfers.service';
+
+describe('abdulrcrtw Modules (BE-92, BE-91, BE-90, BE-89)', () => {
+  it('NotesDocsController adds and lists asset notes and documents', () => {
+    const controller = new NotesDocsController();
+    const note = controller.addNote('ast-1', 'Need battery replacement', { user: { id: 'u-1' } } as any);
+    expect(note.content).toBe('Need battery replacement');
+    expect(controller.getNotes('ast-1').length).toBe(1);
+
+    const doc = controller.addDocument('ast-1', { title: 'Warranty.pdf', fileUrl: 'http://example.com/w.pdf' }, { user: { id: 'u-1' } } as any);
+    expect(doc.title).toBe('Warranty.pdf');
+    expect(controller.getDocuments('ast-1').length).toBe(1);
+  });
+
+  it('MaintenanceService creates maintenance records', async () => {
+    const mockRepo = {
+      create: jest.fn().mockImplementation((dto) => dto),
+      save: jest.fn().mockImplementation((dto) => Promise.resolve({ id: 'm-1', ...dto })),
+    };
+    const service = new MaintenanceService(mockRepo as any);
+    const rec = await service.create({ assetId: 'ast-1', title: 'Screen repair', cost: 15000 });
+    expect(rec.cost).toBe(15000);
+  });
+
+  it('TransfersService manages approval workflow', async () => {
+    const tr = { id: 'tr-1', status: 'PENDING' };
+    const mockRepo = {
+      findOne: jest.fn().mockResolvedValue(tr),
+      create: jest.fn().mockImplementation((dto) => dto),
+      save: jest.fn().mockImplementation((dto) => Promise.resolve(dto)),
+    };
+    const service = new TransfersService(mockRepo as any);
+    const approved = await service.approve('tr-1', 'manager-1');
+    expect(approved.status).toBe('APPROVED');
+    expect(approved.approvedByUserId).toBe('manager-1');
+  });
+});
diff --git a/backend/src/app.module.ts b/backend/src/app.module.ts
index 2dcad4bf0..50bb1c6fc 100644
--- a/backend/src/app.module.ts
+++ b/backend/src/app.module.ts
@@ -4,10 +4,35 @@ import { ConfigModule, ConfigService } from '@nestjs/config';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
+import { CommonModule } from './common/common.module';
+import { UsersModule } from './users/users.module';
+import { HealthModule } from './health/health.module';
+import { AuthModule } from './auth/auth.module';
+import { BranchesModule } from './branches/branches.module';
+import { DepartmentsModule } from './departments/departments.module';
+import { LocationsModule } from './locations/locations.module';
+import { CategoriesModule } from './categories/categories.module';
+import { AssetsLifecycleModule } from './assets/assets-lifecycle.module';
+import { AssetsModule } from './assets/assets.module';
+import { NotesDocsController } from './assets/notes-docs.controller';
+import { MaintenanceModule } from './maintenance/maintenance.module';
+import { TransfersModule } from './transfers/transfers.module';
 
 @Module({
   imports: [
     ConfigModule.forRoot({ isGlobal: true }),
+    CommonModule,
+    UsersModule,
+    HealthModule,
+    AuthModule,
+    BranchesModule,
+    DepartmentsModule,
+    LocationsModule,
+    CategoriesModule,
+    AssetsLifecycleModule,
+    AssetsModule,
+    MaintenanceModule,
+    TransfersModule,
     TypeOrmModule.forRootAsync({
       imports: [ConfigModule],
       useFactory: (configService: ConfigService) => ({
@@ -18,12 +43,12 @@ import { AppService } from './app.service';
         password: configService.get('DB_PASSWORD', 'password'),
         database: configService.get('DB_DATABASE', 'manage_assets'),
         autoLoadEntities: true,
-        synchronize: configService.get('NODE_ENV') === 'development',
+        synchronize: false,
       }),
       inject: [ConfigService],
     }),
   ],
-  controllers: [AppController],
+  controllers: [AppController, NotesDocsController],
   providers: [AppService],
 })
 export class AppModule {}
diff --git a/backend/src/assets/entities/asset-document.entity.ts b/backend/src/assets/entities/asset-document.entity.ts
new file mode 100644
index 000000000..270258205
--- /dev/null
+++ b/backend/src/assets/entities/asset-document.entity.ts
@@ -0,0 +1,28 @@
+import { Entity, Column, PrimaryGeneratedColumn, CreateDateColumn } from 'typeorm';
+
+@Entity('asset_documents')
+export class AssetDocument {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  assetId: string;
+
+  @Column()
+  title: string;
+
+  @Column()
+  fileUrl: string;
+
+  @Column({ nullable: true })
+  fileType?: string;
+
+  @Column({ type: 'integer', default: 0 })
+  fileSizeBytes: number;
+
+  @Column()
+  uploadedByUserId: string;
+
+  @CreateDateColumn()
+  createdAt: Date;
+}
diff --git a/backend/src/assets/entities/asset-note.entity.ts b/backend/src/assets/entities/asset-note.entity.ts
new file mode 100644
index 000000000..d09156a9c
--- /dev/null
+++ b/backend/src/assets/entities/asset-note.entity.ts
@@ -0,0 +1,19 @@
+import { Entity, Column, PrimaryGeneratedColumn, CreateDateColumn } from 'typeorm';
+
+@Entity('asset_notes')
+export class AssetNote {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  assetId: string;
+
+  @Column()
+  authorUserId: string;
+
+  @Column({ type: 'text' })
+  content: string;
+
+  @CreateDateColumn()
+  createdAt: Date;
+}
diff --git a/backend/src/assets/notes-docs.controller.ts b/backend/src/assets/notes-docs.controller.ts
new file mode 100644
index 000000000..3f03313a9
--- /dev/null
+++ b/backend/src/assets/notes-docs.controller.ts
@@ -0,0 +1,57 @@
+import { Controller, Get, Post, Delete, Param, Body, Req } from '@nestjs/common';
+import { ApiTags, ApiOperation } from '@nestjs/swagger';
+
+@ApiTags('assets')
+@Controller('assets/:id')
+export class NotesDocsController {
+  private notes = new Map<string, any[]>();
+  private docs = new Map<string, any[]>();
+
+  @Get('notes')
+  @ApiOperation({ summary: 'Get asset notes' })
+  getNotes(@Param('id') assetId: string) {
+    return this.notes.get(assetId) || [];
+  }
+
+  @Post('notes')
+  @ApiOperation({ summary: 'Add an asset note' })
+  addNote(@Param('id') assetId: string, @Body('content') content: string, @Req() req: any) {
+    const list = this.notes.get(assetId) || [];
+    const note = {
+      id: `n_${Date.now()}`,
+      assetId,
+      content,
+      authorUserId: req.user?.id || 'usr-1',
+      createdAt: new Date(),
+    };
+    list.unshift(note);
+    this.notes.set(assetId, list);
+    return note;
+  }
+
+  @Get('documents')
+  @ApiOperation({ summary: 'Get asset document attachments' })
+  getDocuments(@Param('id') assetId: string) {
+    return this.docs.get(assetId) || [];
+  }
+
+  @Post('documents')
+  @ApiOperation({ summary: 'Attach a document to an asset' })
+  addDocument(
+    @Param('id') assetId: string,
+    @Body() body: { title: string; fileUrl: string; fileType?: string; fileSizeBytes?: number },
+    @Req() req: any,
+  ) {
+    const list = this.docs.get(assetId) || [];
+    const doc = {
+      id: `d_${Date.now()}`,
+      assetId,
+      ...body,
+      uploadedByUserId: req.user?.id || 'usr-1',
+      createdAt: new Date(),
+    };
+    list.unshift(doc);
+    this.docs.set(assetId, list);
+    return doc;
+  }
+}
diff --git a/backend/src/maintenance/entities/maintenance-record.entity.ts b/backend/src/maintenance/entities/maintenance-record.entity.ts
new file mode 100644
index 000000000..9bafdfd57
--- /dev/null
+++ b/backend/src/maintenance/entities/maintenance-record.entity.ts
@@ -0,0 +1,47 @@
+import { Entity, Column, PrimaryGeneratedColumn, CreateDateColumn, UpdateDateColumn } from 'typeorm';
+
+export enum MaintenanceStatus {
+  SCHEDULED = 'SCHEDULED',
+  IN_PROGRESS = 'IN_PROGRESS',
+  COMPLETED = 'COMPLETED',
+  CANCELLED = 'CANCELLED',
+}
+
+@Entity('maintenance_records')
+export class MaintenanceRecord {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  assetId: string;
+
+  @Column()
+  title: string;
+
+  @Column({ nullable: true })
+  description?: string;
+
+  @Column({ type: 'enum', enum: MaintenanceStatus, default: MaintenanceStatus.SCHEDULED })
+  status: MaintenanceStatus;
+
+  @Column({ nullable: true })
+  vendorId?: string;
+
+  @Column({ type: 'integer', default: 0 })
+  cost: number;
+
+  @Column({ default: 'USD' })
+  currency: string;
+
+  @Column({ nullable: true })
+  scheduledDate?: Date;
+
+  @Column({ nullable: true })
+  completedDate?: Date;
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+}
diff --git a/backend/src/maintenance/maintenance.controller.ts b/backend/src/maintenance/maintenance.controller.ts
new file mode 100644
index 000000000..6c8865a17
--- /dev/null
+++ b/backend/src/maintenance/maintenance.controller.ts
@@ -0,0 +1,33 @@
+import { Controller, Get, Post, Patch, Body, Param } from '@nestjs/common';
+import { ApiTags, ApiOperation } from '@nestjs/swagger';
+import { MaintenanceService } from './maintenance.service';
+
+@ApiTags('maintenance')
+@Controller('maintenance')
+export class MaintenanceController {
+  constructor(private readonly maintenanceService: MaintenanceService) {}
+
+  @Get()
+  @ApiOperation({ summary: 'List all maintenance records' })
+  findAll() {
+    return this.maintenanceService.findAll();
+  }
+
+  @Post()
+  @ApiOperation({ summary: 'Create a maintenance record' })
+  create(@Body() dto: any) {
+    return this.maintenanceService.create(dto);
+  }
+
+  @Get(':id')
+  @ApiOperation({ summary: 'Get maintenance record details' })
+  findOne(@Param('id') id: string) {
+    return this.maintenanceService.findById(id);
+  }
+
+  @Patch(':id')
+  @ApiOperation({ summary: 'Update a maintenance record' })
+  update(@Param('id') id: string, @Body() dto: any) {
+    return this.maintenanceService.update(id, dto);
+  }
+}
diff --git a/backend/src/maintenance/maintenance.module.ts b/backend/src/maintenance/maintenance.module.ts
new file mode 100644
index 000000000..7d4439644
--- /dev/null
+++ b/backend/src/maintenance/maintenance.module.ts
@@ -0,0 +1,13 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { MaintenanceRecord } from './entities/maintenance-record.entity';
+import { MaintenanceService } from './maintenance.service';
+import { MaintenanceController } from './maintenance.controller';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([MaintenanceRecord])],
+  providers: [MaintenanceService],
+  controllers: [MaintenanceController],
+  exports: [MaintenanceService],
+})
+export class MaintenanceModule {}
diff --git a/backend/src/maintenance/maintenance.service.ts b/backend/src/maintenance/maintenance.service.ts
new file mode 100644
index 000000000..44ed1b913
--- /dev/null
+++ b/backend/src/maintenance/maintenance.service.ts
@@ -0,0 +1,33 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { MaintenanceRecord } from './entities/maintenance-record.entity';
+
+@Injectable()
+export class MaintenanceService {
+  constructor(
+    @InjectRepository(MaintenanceRecord)
+    private readonly maintenanceRepo: Repository<MaintenanceRecord>,
+  ) {}
+
+  async findAll() {
+    return this.maintenanceRepo.find();
+  }
+
+  async findById(id: string) {
+    const record = await this.maintenanceRepo.findOne({ where: { id } });
+    if (!record) throw new NotFoundException(`Maintenance record ${id} not found`);
+    return record;
+  }
+
+  async create(dto: Partial<MaintenanceRecord>) {
+    const record = this.maintenanceRepo.create(dto);
+    return this.maintenanceRepo.save(record);
+  }
+
+  async update(id: string, dto: Partial<MaintenanceRecord>) {
+    const record = await this.findById(id);
+    Object.assign(record, dto);
+    return this.maintenanceRepo.save(record);
+  }
+}
diff --git a/backend/src/transfers/entities/asset-transfer.entity.ts b/backend/src/transfers/entities/asset-transfer.entity.ts
new file mode 100644
index 000000000..f20999a6a
--- /dev/null
+++ b/backend/src/transfers/entities/asset-transfer.entity.ts
@@ -0,0 +1,42 @@
+import { Entity, Column, PrimaryGeneratedColumn, CreateDateColumn, UpdateDateColumn } from 'typeorm';
+
+export enum TransferStatus {
+  PENDING = 'PENDING',
+  APPROVED = 'APPROVED',
+  REJECTED = 'REJECTED',
+  COMPLETED = 'COMPLETED',
+  CANCELLED = 'CANCELLED',
+}
+
+@Entity('asset_transfers')
+export class AssetTransfer {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  assetId: string;
+
+  @Column()
+  fromDepartmentId: string;
+
+  @Column()
+  toDepartmentId: string;
+
+  @Column()
+  requestedByUserId: string;
+
+  @Column({ nullable: true })
+  approvedByUserId?: string;
+
+  @Column({ type: 'enum', enum: TransferStatus, default: TransferStatus.PENDING })
+  status: TransferStatus;
+
+  @Column({ nullable: true })
+  rejectionReason?: string;
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+}
diff --git a/backend/src/transfers/transfers.controller.ts b/backend/src/transfers/transfers.controller.ts
new file mode 100644
index 000000000..927fed139
--- /dev/null
+++ b/backend/src/transfers/transfers.controller.ts
@@ -0,0 +1,40 @@
+import { Controller, Get, Post, Param, Body, Req } from '@nestjs/common';
+import { ApiTags, ApiOperation } from '@nestjs/swagger';
+import { TransfersService } from './transfers.service';
+
+@ApiTags('transfers')
+@Controller('transfers')
+export class TransfersController {
+  constructor(private readonly transfersService: TransfersService) {}
+
+  @Get()
+  @ApiOperation({ summary: 'List all asset transfers' })
+  findAll() {
+    return this.transfersService.findAll();
+  }
+
+  @Post()
+  @ApiOperation({ summary: 'Request an asset transfer' })
+  create(@Body() dto: any) {
+    return this.transfersService.create(dto);
+  }
+
+  @Get(':id')
+  @ApiOperation({ summary: 'Get transfer request details' })
+  findOne(@Param('id') id: string) {
+    return this.transfersService.findById(id);
+  }
+
+  @Post(':id/approve')
+  @ApiOperation({ summary: 'Approve an asset transfer' })
+  approve(@Param('id') id: string, @Req() req: any) {
+    const approverId = req.user?.id || 'usr-1';
+    return this.transfersService.approve(id, approverId);
+  }
+
+  @Post(':id/reject')
+  @ApiOperation({ summary: 'Reject an asset transfer' })
+  reject(@Param('id') id: string, @Body('reason') reason: string) {
+    return this.transfersService.reject(id, reason || 'Rejected by manager');
+  }
+}
diff --git a/backend/src/transfers/transfers.module.ts b/backend/src/transfers/transfers.module.ts
new file mode 100644
index 000000000..76ff2c3ae
--- /dev/null
+++ b/backend/src/transfers/transfers.module.ts
@@ -0,0 +1,13 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { AssetTransfer } from './entities/asset-transfer.entity';
+import { TransfersService } from './transfers.service';
+import { TransfersController } from './transfers.controller';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([AssetTransfer])],
+  providers: [TransfersService],
+  controllers: [TransfersController],
+  exports: [TransfersService],
+})
+export class TransfersModule {}
diff --git a/backend/src/transfers/transfers.service.ts b/backend/src/transfers/transfers.service.ts
new file mode 100644
index 000000000..48b0e9fc4
--- /dev/null
+++ b/backend/src/transfers/transfers.service.ts
@@ -0,0 +1,47 @@
+import { Injectable, NotFoundException, BadRequestException } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { AssetTransfer, TransferStatus } from './entities/asset-transfer.entity';
+
+@Injectable()
+export class TransfersService {
+  constructor(
+    @InjectRepository(AssetTransfer)
+    private readonly transferRepo: Repository<AssetTransfer>,
+  ) {}
+
+  async findAll() {
+    return this.transferRepo.find();
+  }
+
+  async findById(id: string) {
+    const tr = await this.transferRepo.findOne({ where: { id } });
+    if (!tr) throw new NotFoundException(`Transfer ${id} not found`);
+    return tr;
+  }
+
+  async create(dto: Partial<AssetTransfer>) {
+    const tr = this.transferRepo.create({ ...dto, status: TransferStatus.PENDING });
+    return this.transferRepo.save(tr);
+  }
+
+  async approve(id: string, approverUserId: string) {
+    const tr = await this.findById(id);
+    if (tr.status !== TransferStatus.PENDING) {
+      throw new BadRequestException('Only pending transfers can be approved');
+    }
+    tr.status = TransferStatus.APPROVED;
+    tr.approvedByUserId = approverUserId;
+    return this.transferRepo.save(tr);
+  }
+
+  async reject(id: string, reason: string) {
+    const tr = await this.findById(id);
+    if (tr.status !== TransferStatus.PENDING) {
+      throw new BadRequestException('Only pending transfers can be rejected');
+    }
+    tr.status = TransferStatus.REJECTED;
+    tr.rejectionReason = reason;
+    return this.transferRepo.save(tr);
+  }
+}