Mongoose ODM Patterns

Quick Guide: Use Mongoose as the ODM layer for MongoDB. Let TypeScript infer types from schema definitions instead of duplicating interfaces. Register all middleware before calling model() -- hooks added after compilation are silently ignored. Use .lean() for any read-only query. Pass { session } to every operation inside a transaction or enable transactionAsyncLocalStorage. Prefer session.withTransaction() over manual commit/abort. Use 127.0.0.1 instead of localhost in connection strings (Node.js 18+ IPv6 preference causes timeouts).

<critical_requirements>

CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST define all middleware (pre/post hooks) BEFORE calling model() -- hooks registered after model compilation are silently ignored with no error)

(You MUST pass { session } to EVERY operation inside a transaction -- missing session causes that operation to run outside the transaction silently)

(You MUST use .lean() for read-only queries returning API responses -- skipping lean wastes 3x memory on hydration overhead)

(You MUST use 127.0.0.1 instead of localhost in connection strings -- Node.js 18+ prefers IPv6 and localhost causes connection timeouts)