# Backend Rust Migration Master Plan

## Goal
Re-implement backend services in Rust while preserving architecture, service boundaries, data flow, and runtime behavior.

## Current-to-Target Mapping
- NestJS gateway -> Rust gateway
- NestJS users -> Rust users
- NestJS companies -> Rust companies
- NestJS customers -> Rust customers
- NestJS professionals -> Rust professionals
- NestJS jobseekers -> Rust jobseekers

## Hard Constraints
1. Same microservice boundaries.
2. Same role/runtime-config flow.
3. Same onboarding state transitions and schema lookup behavior.
4. Same auth/session behavior at gateway boundary.
5. No contract-breaking change unless explicitly versioned.

## Stage Sequence
1. Freeze contracts and DB assumptions.
2. Implement Rust shared crates (`config`, `errors`, `db`, `auth`, `observability`, `contracts`).
3. Implement Rust gateway with parity adapters to existing services.
4. Migrate `users` service to Rust and switch gateway client to Rust users.
5. Migrate `companies` service to Rust.
6. Migrate `customers` service to Rust.
7. Migrate `professionals` service to Rust.
8. Migrate `jobseekers` service to Rust.
9. Remove legacy Nest services after full parity signoff.

## Phase Exit Checklist (Apply Every Stage)
- Build passes.
- Contract tests pass.
- Runtime-config and onboarding smoke tests pass.
- No P0/P1 behavior regressions.
- Rollback path validated.