nxtgauge-backend-rust/docs/MIGRATION_MASTER_PLAN.md

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.