The locked stack

Settled on 2026-09-09, one question at a time. Every entry has a matching entry in DECISIONS.md recording the options considered and what the choice costs.

Treat this as given. If you believe an entry is wrong, say so once, clearly, then follow it.

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Structural

Multi-tenancy	Only when the project is multi-tenant, because it is a third axis beside Type and Architecture, and a single-tenant project receives none of it. Then: tenant_id on every tenant-scoped table, isolated by a MikroORM filter. No schema-per-tenant. RLS is stronger and unmeasured; see docs/OPEN-QUESTIONS.md.
Primary keys	UUID v7, generated by the database: DEFAULT uuidv7(). Not by the application.
Delete	Hard delete is the default. deleted_at requires a stated reason: audit, user-facing recovery, legal retention.
Timezone	UTC in the database. timestamptz on every time column, without exception. Conversion at the edge only.
Database	PostgreSQL 18 or later. Not a variable.
Errors	Exceptions, handled Nest's way, with HttpException and exception filters. No Result type.

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Version floors

These accumulate. Every one is a machine a generated project will not run on.

Floor	Required by
PostgreSQL 18	uuidv7(), which shipped in September 2025
Node 22.17	MikroORM v7
TypeScript 6.0	nestjs/typescript-starter, which declares ^6.0.2. It supersedes the 5.8 floor MikroORM v7 required

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Core

Area	Choice
Monorepo	pnpm workspaces, with native catalog: for versions. No Turborepo. Applies only when the architecture is monorepo.
Language	TypeScript 6, based on nestjs/typescript-starter: module and moduleResolution nodenext, target ES2023, strict on, strictPropertyInitialization off. Plus noUncheckedIndexedAccess. Not exactOptionalPropertyTypes.
Quality	Biome. Pre-commit is .githooks/pre-commit running biome check --staged --write, wired by "prepare": "node .githooks/install.mjs", which sets core.hooksPath inside a Git repository and does nothing outside one. No husky, no lint-staged.
API	NestJS. DTOs are classes validated by class-validator + class-transformer through ValidationPipe; @nestjs/swagger reads the same decorators.
ORM	MikroORM v7, with @mikro-orm/postgresql, @mikro-orm/migrations, @mikro-orm/nestjs. Entities use defineEntity with a class: the schema is in the defineEntity call and carries no ORM decorators. The class carries @Exclude and @ApiProperty, for serialization and documentation.
Auth	Better Auth, mounted directly on a controller with @All('*path') passing the request to toNodeHandler(auth), plus a hand-written global guard. Own Postgres schema, own connection, own migration CLI, generateId: 'uuid'. httpOnly cookie on web and mobile, kept in expo-secure-store. No community Nest bridge.
Observability	Structured logs and a health check. No error reporting and no tracing by default. See Documented, not installed below.
Testing	Vitest, Testcontainers, Testing Library.
Web	Vite, React, TanStack Router, TanStack Query, Tailwind, shadcn/ui, react-hook-form with Zod as the resolver.
Mobile	Expo with prebuild, Expo Router, NativeWind, Reanimated, MMKV, expo-secure-store.
Site	Next with the App Router, never the Pages Router. Tailwind and shadcn/ui. Static by default, revalidated where content changes, dynamic only with a stated reason. Data is fetched on the server.

shadcn/ui is not a dependency, because components are copied into the project. Templates ship its plumbing and only the components their own screens use, installed by its CLI, on Base UI, which is shadcn's default primitive library.

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Documented, not installed

Prumo never installs a tool requiring a commercial account. Such a tool is documented (how it is wired, what it needs, what it changes) so it is ready the day the developer wants it, and absent until then. Installing a service that needs an account, a DSN and eventually a bill is a commercial decision made on the developer's behalf, inside a project they own.

Capability	Documented adapter	Default
Error reporting and tracing	@sentry/nestjs, see api/observability.md	not installed

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Deliberately dropped

Sixteen entries left the previous stack. Each was removed for a stated reason, not trimmed for taste.

Dropped	Because
Result / neverthrow	The restart removed Result. Nest's error model is exceptions, and two error models in one codebase is worse than either.
ts-pattern	Existed for the Result union. switch with a never default gives the same exhaustiveness for free.
dependency-cruiser	Enforced the hexagonal layering, which is gone. The restart measured it producing a useless file to satisfy no-circular.
Fastify + type provider + Scalar + Pino	Replaced by NestJS.
The porting rule	Removed explicitly by the restart.
Drizzle + drizzle-kit	Replaced by MikroORM. Still on 0.x with an unreleased breaking v1, and absent from Nest's documentation.
Turborepo	Its value is caching, and a two-package monorepo does not hurt yet.
syncpack	pnpm catalogs do the job natively.
knip	Finds nothing on a day-zero project.
husky + lint-staged	biome check --staged and core.hooksPath replace both, with no dependency.
@t3-oss/env-core	Zod-based, and Zod left the API. Its distinctive value, keeping server secrets out of a client bundle, does not apply to an API with no bundle.
Zustand	TanStack Query owns server state; what remains is usually context-sized.
FlashList	FlatList handles small lists, and the swap is local when they grow.
MSW	Mocks a network that does not exist yet.
Playwright	Downloads a browser to walk screens that do not exist yet.
exactOptionalPropertyTypes	The only strictness flag whose friction lands in library types rather than your own code.

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The two rules that decided most of this

The day-zero test. Does this have work on the day the project is born? It removed knip, MSW, Playwright, ts-pattern and Zustand.

Its limit. The test does not apply to anything that owns data, because arriving late is then a migration rather than a swap. That kept MMKV and Better Auth. Whatever owns data is decided at the start; whatever draws a screen can wait.