---
status: proposed
---

# Bun Runtime and Native Tooling

VacOptimizer will use Bun as the runtime for project-owned JavaScript in
development, CI, and production, adopting its native test runner, linter,
formatter, type checker, and HTTP server even without measured performance gains.
This deliberately accepts Bun-specific tooling and migration work while retaining
Angular's standard compiler and build pipeline, including TypeScript 6 for
Angular compilation alongside `bun check` for standalone TypeScript checking.

Verification on stable Bun 1.4.3 narrowed this: ESLint and Prettier stay,
run by Bun, until a stable release ships the native linter and formatter;
Angular builds a client-only bundle, because its server build relies on Node
loader hooks Bun does not apply, and a small `Bun.serve` server delivers it,
giving up `@angular/ssr`; coverage is line-level, converted from lcov to the
existing HTML and Cobertura reports; and the benchmark's heap cap becomes a
container memory limit.

Existing behavior, tests, lint rules, coverage reporting, and benchmark budgets
must be preserved; incompatibilities must be fixed or reported as blockers before
declaring completion, and a Node.js fallback does not meet the runtime requirement.
The [development spec](../bun-adoption.md) records the agreed boundaries,
acceptance criteria, and remaining verification.