# Decisions

Implementation decisions not spelled out in `memory-bank/implementation-plan.md`. Design decisions from plan §0.5 are logged here as they are implemented.

## Step 1.1

- **Repo lives on an NTFS drive (`C:\Projects\...`).** The original location (G:) is exFAT, which cannot hold symlinks, so pnpm could not link workspace packages. Do not move the repo back to an exFAT drive.
- **TypeScript is pinned to `~6.0`.** TypeScript 7 is the latest release, but `typescript-eslint` (needed in Step 1.2) only supports `<6.1`. Upgrade once typescript-eslint supports 7.
- **Packages export TypeScript source directly** (`main`/`types` point at `src/index.ts`). There is no build step for internal packages; Vite, Vitest and the server's TS runner consume the source. The base config uses `moduleResolution: "Bundler"` and `noEmit`.
- **Node 24** is the required runtime (`engines` + `.nvmrc`).
- **Line endings are LF** everywhere (`.gitattributes`), overriding the machine's global `core.autocrlf`, to match Prettier and the Linux CI runner.

## Step 1.2

- **ESLint 10 flat config** with `typescript-eslint` recommended (not type-aware, to keep lint fast) and `eslint-config-prettier`. `pnpm lint` runs ESLint then `prettier --check`.
- **Purity rule** for `packages/sim` and `packages/content`: `no-restricted-properties` bans `Math.random` and `Date.now`; `no-restricted-syntax` bans `new Date()` with no arguments (`new Date(x)` is allowed).
- **Prettier skips `memory-bank/`** so tooling never rewrites the design docs.

## Step 1.3

- **Vitest projects**: the root `vitest.config.ts` treats each `apps/*` and `packages/*` folder as a project, so `pnpm test` runs every package's tests. Packages can add their own `vitest.config.ts` when they need a different environment.
- **Tests live in each package's `test/` folder** and are included in that package's tsconfig, so `pnpm typecheck` covers them.