0002 — TypeScript version per app: TS 6 for NestJS services, TS 6 for Angular frontend

Status

Accepted — superseded the original TS-7-for-NestJS plan after hitting a concrete incompatibility.

Context

apps/bff and apps/realtime (NestJS) and apps/frontend (Angular) are independent pnpm workspace packages. TypeScript 7 is the new native/Go-based compiler line; TypeScript 6 is the last JS-hosted line.

The original plan (below, kept for the record) was TS 7 for the NestJS services. While scaffolding apps/bff (TS 7.0.2, @nestjs/cli 12.0.0), nest build failed with:

The installed TypeScript version (7.0.2) does not expose the programmatic compiler API that the Nest CLI requires. TypeScript 7.0 ships the "tsc" executable only; the compiler API is expected to return in 7.1.

This isn't a peer-dependency warning that can be ignored — the build cannot run at all under TS 7.0.x with the current Nest CLI.

Decision

• apps/bff, apps/realtime: TypeScript 6.x (downgraded from the original TS 7 plan — see Context).
• apps/frontend: TypeScript 6.x.
• packages/shared-types: authored and compiled independently to plain .js + .d.ts output (its own minimal tsconfig), so it is consumed as compiled output by both sides.
• No root tsconfig is shared across apps; each app keeps its own tsconfig.json.
• Revisit TS 7 for apps/bff/apps/realtime once TypeScript 7.1 restores the programmatic compiler API and @nestjs/cli confirms support.

Original decision (superseded)

• apps/bff, apps/realtime: TypeScript 7.x — blocked by the Nest CLI incompatibility above.

Consequences

• No TS-version split across the monorepo for now; all apps sit on TS 6.x until the Nest CLI/TS 7 story matures.
• packages/shared-types must still avoid syntax that isn't valid on TS 6, since Angular's peer range also gates it.