The last post in this series looked at why hand-rolled NestJS auth tends to accumulate glue code as real requirements pile up, and introduced brkpt-auth: full source code installed into your project, structured around interfaces (ports) you implement (adapters), so your database and token logic stay separate from the auth logic itself.
This post is the walkthrough: the same password + Google sign-in flow from the last post, built with brkpt-auth from scratch. Roughly, the shape of it is: install brkpt-auth's core feature, implement an adapter that connects it to Prisma, then add credentials and oauth the same way.
This post was written against NestJS v11 (a default CommonJS project from nest new) and Prisma 7.10.0. If your versions differ, some commands or config may not match, especially Prisma's CLI, which has changed flags across major versions. Check the Prisma releases page if something here doesn't work as shown.
Validation here uses class-validator, the same library NestJS's own docs default to, and what most NestJS tutorials still use. Worth noting up front: brkpt-auth doesn't require it. It doesn't ship with any validation library baked in, so class-validator, Zod, or nothing at all are all equally valid choices. class-validator is used here because it needs zero extra wiring with @Body(); Zod works too, but needs a small custom pipe to hook into NestJS's request pipeline, which would add a step this post doesn't need.
