Feature: Savings Product A/B Testing

backend/src/migrations/1791200000000-CreateSavingsExperimentTables.ts

@@ -0,0 +1,98 @@
+import { MigrationInterface, QueryRunner, Table, TableIndex } from 'typeorm';
+
+export class CreateSavingsExperimentTables1791200000000 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.createTable(
+      new Table({
+        name: 'savings_experiments',
+        columns: [
+          {
+            name: 'id',
+            type: 'uuid',
+            isPrimary: true,
+            isGenerated: true,
+            generationStrategy: 'uuid',
+          },
+          { name: 'key', type: 'varchar', isUnique: true },
+          { name: 'name', type: 'varchar' },
+          { name: 'description', type: 'text', isNullable: true },
+          { name: 'productId', type: 'uuid', isNullable: true },
+          { name: 'variants', type: 'jsonb' },
+          { name: 'configuration', type: 'jsonb', isNullable: true },
+          { name: 'status', type: 'varchar', default: "'DRAFT'" },
+          { name: 'minSampleSize', type: 'int', default: 100 },
+          {
+            name: 'confidenceLevel',
+            type: 'decimal',
+            precision: 4,
+            scale: 2,
+            default: 0.95,
+          },
+          { name: 'startedAt', type: 'timestamp', isNullable: true },
+          { name: 'endedAt', type: 'timestamp', isNullable: true },
+          { name: 'createdAt', type: 'timestamp', default: 'now()' },
+          { name: 'updatedAt', type: 'timestamp', default: 'now()' },
+        ],
+      }),
+    );
+
+    await queryRunner.createTable(
+      new Table({
+        name: 'savings_experiment_assignments',
+        columns: [
+          {
+            name: 'id',
+            type: 'uuid',
+            isPrimary: true,
+            isGenerated: true,
+            generationStrategy: 'uuid',
+          },
+          { name: 'experimentId', type: 'uuid' },
+          { name: 'userId', type: 'uuid' },
+          { name: 'variantKey', type: 'varchar' },
+          { name: 'convertedAt', type: 'timestamp', isNullable: true },
+          {
+            name: 'conversionValue',
+            type: 'decimal',
+            precision: 14,
+            scale: 2,
+            default: 0,
+          },
+          { name: 'metadata', type: 'jsonb', isNullable: true },
+          { name: 'createdAt', type: 'timestamp', default: 'now()' },
+          { name: 'updatedAt', type: 'timestamp', default: 'now()' },
+        ],
+      }),
+    );
+
+    await queryRunner.createIndex(
+      'savings_experiment_assignments',
+      new TableIndex({
+        name: 'IDX_savings_experiment_user_unique',
+        columnNames: ['experimentId', 'userId'],
+        isUnique: true,
+      }),
+    );
+
+    await queryRunner.createIndex(
+      'savings_experiment_assignments',
+      new TableIndex({
+        name: 'IDX_savings_experiment_variant',
+        columnNames: ['experimentId', 'variantKey'],
+      }),
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.dropIndex(
+      'savings_experiment_assignments',
+      'IDX_savings_experiment_variant',
+    );
+    await queryRunner.dropIndex(
+      'savings_experiment_assignments',
+      'IDX_savings_experiment_user_unique',
+    );
+    await queryRunner.dropTable('savings_experiment_assignments');
+    await queryRunner.dropTable('savings_experiments');
+  }
+}

backend/src/modules/admin/admin-savings.controller.ts

@@ -26,6 +26,7 @@ import { JwtAuthGuard } from '../../auth/guards/jwt-auth.guard';
 import { RolesGuard } from '../../common/guards/roles.guard';
 import { Roles } from '../../common/decorators/roles.decorator';
 import { Role } from '../../common/enums/role.enum';
+import { ExperimentsService } from '../savings/experiments.service';
 import { CurrentUser } from '../../common/decorators/current-user.decorator';
 import { ProductCapacitySnapshot } from '../savings/savings.service';
 import { PageOptionsDto } from '../../common/dto/page-options.dto';
@@ -39,6 +40,10 @@ import { AdminSavingsService } from './admin-savings.service';
 @Roles(Role.ADMIN)
 @Controller({ path: 'admin/savings/products', version: '1' })
 export class AdminSavingsController {
+  constructor(
+    private readonly savingsService: SavingsService,
+    private readonly experimentsService: ExperimentsService,
+  ) {}
   constructor(private readonly adminSavingsService: AdminSavingsService) {}
 
   @Post()
@@ -83,6 +88,67 @@ export class AdminSavingsController {
     return this.adminSavingsService.getSubscribers(id, opts);
   }
 
+  @Post('experiments')
+  @ApiOperation({ summary: 'Create a savings product experiment (admin)' })
+  @ApiResponse({ status: 201, description: 'Experiment created' })
+  async createExperiment(
+    @Body()
+    body: {
+      key: string;
+      name: string;
+      description?: string;
+      productId?: string;
+      variants: Array<{
+        key: string;
+        weight: number;
+        config: Record<string, any>;
+      }>;
+      configuration?: Record<string, any>;
+      minSampleSize?: number;
+      confidenceLevel?: number;
+      status?: 'DRAFT' | 'ACTIVE' | 'PAUSED' | 'COMPLETED';
+    },
+  ) {
+    return await this.experimentsService.createExperiment(body);
+  }
+
+  @Post('experiments/:id/assignments')
+  @ApiOperation({ summary: 'Assign a user to an experiment variant (admin)' })
+  @ApiResponse({ status: 200, description: 'User assigned to a variant' })
+  async assignExperimentUser(
+    @Param('id') id: string,
+    @Body() body: { userId: string },
+  ) {
+    return await this.experimentsService.assignUser(id, body.userId);
+  }
+
+  @Post('experiments/:id/conversions')
+  @ApiOperation({ summary: 'Track an experiment conversion event (admin)' })
+  @ApiResponse({ status: 200, description: 'Conversion tracked' })
+  async trackExperimentConversion(
+    @Param('id') id: string,
+    @Body()
+    body: {
+      userId: string;
+      value?: number;
+      metadata?: Record<string, any>;
+    },
+  ) {
+    return await this.experimentsService.trackConversion(
+      id,
+      body.userId,
+      body.value ?? 1,
+      body.metadata,
+    );
+  }
+
+  @Post('experiments/:id/dashboard')
+  @ApiOperation({ summary: 'Get experiment dashboard statistics (admin)' })
+  @ApiResponse({ status: 200, description: 'Experiment dashboard' })
+  async getExperimentDashboard(
+    @Param('id') id: string,
+  ): Promise<Record<string, unknown>> {
+    return await this.experimentsService.getDashboard(id);
   @Post('products/:id/migrations')
   @ApiOperation({
     summary: 'Migrate active subscriptions to another product version (admin)',

backend/src/modules/savings/entities/savings-experiment-assignment.entity.ts

@@ -0,0 +1,40 @@
+import {
+  Entity,
+  Column,
+  PrimaryGeneratedColumn,
+  CreateDateColumn,
+  UpdateDateColumn,
+  Index,
+} from 'typeorm';
+
+@Entity('savings_experiment_assignments')
+@Index(['experimentId', 'userId'], { unique: true })
+@Index(['experimentId', 'variantKey'])
+export class SavingsExperimentAssignment {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column('uuid')
+  experimentId: string;
+
+  @Column('uuid')
+  userId: string;
+
+  @Column()
+  variantKey: string;
+
+  @Column({ type: 'timestamp', nullable: true })
+  convertedAt: Date | null;
+
+  @Column('decimal', { precision: 14, scale: 2, default: 0 })
+  conversionValue: number;
+
+  @Column({ type: 'jsonb', nullable: true })
+  metadata: Record<string, any> | null;
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+}

backend/src/modules/savings/entities/savings-experiment.entity.ts

@@ -0,0 +1,62 @@
+import {
+  Entity,
+  Column,
+  PrimaryGeneratedColumn,
+  CreateDateColumn,
+  UpdateDateColumn,
+  Index,
+} from 'typeorm';
+
+export type ExperimentStatus = 'DRAFT' | 'ACTIVE' | 'PAUSED' | 'COMPLETED';
+
+export interface ExperimentVariant {
+  key: string;
+  weight: number;
+  config: Record<string, any>;
+}
+
+@Entity('savings_experiments')
+@Index(['status', 'createdAt'])
+export class SavingsExperiment {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ unique: true })
+  key: string;
+
+  @Column()
+  name: string;
+
+  @Column({ type: 'text', nullable: true })
+  description: string | null;
+
+  @Column({ type: 'uuid', nullable: true })
+  productId: string | null;
+
+  @Column({ type: 'jsonb' })
+  variants: ExperimentVariant[];
+
+  @Column({ type: 'jsonb', nullable: true })
+  configuration: Record<string, any> | null;
+
+  @Column({ type: 'varchar', default: 'DRAFT' })
+  status: ExperimentStatus;
+
+  @Column({ type: 'int', default: 100 })
+  minSampleSize: number;
+
+  @Column({ type: 'decimal', precision: 4, scale: 2, default: 0.95 })
+  confidenceLevel: number;
+
+  @Column({ type: 'timestamp', nullable: true })
+  startedAt: Date | null;
+
+  @Column({ type: 'timestamp', nullable: true })
+  endedAt: Date | null;
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+}