Pattern: How should shared schemas be consumed by NestJS modules?

Documentation for Sessions

🎨 Pattern: How should shared schemas be consumed by NestJS modules?

Date: 2026-01-31
Time: 18:32:10 UTC
Session: editor2-75.21
Agent: backend
Confidence: 95%
Status: ✅ Documented

📋 Decision Context

Question:

How should shared schemas be consumed by NestJS modules?

Task: Session 75.15: Two-Layer Agent Intelligence & Preference Override System

🎯 Decision Made

Chosen:

Export schema class and SchemaFactory from backend-core, consumer registers with MongooseModule.forFeature() and adds service to providers

Options Considered:

Create a BackendCoreModule that registers everything
Export only types, keep services in each app
Export schemas and services separately, consumer registers (chosen)

💭 Reasoning

This matches the existing pattern used by User schema and PlatformUserService. The key insight is that services using @InjectModel cannot be provided by a shared module - the schema must be registered in the consuming module's MongooseModule.forFeature(). This is because Mongoose binds models to specific connections, and each app has its own connection. The pattern ensures proper DI while keeping business logic in the shared service.

📁 Files Involved

libs/libs-api/backend-core/src/index.ts
apis/backend-api/src/app/users/users.module.ts

🔗 Related

Decision ID: dev_1769884330376_2dc1t4m
Session: 75
Workspace: editor2

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