Bun

The runtime — single executable bundling runtime, package manager, bundler, and test runner; native TypeScript, no transpile step. Lives inside the v10r container, never on the host. See CLAUDE.md "Local Development" for the container-first rule.

Why was it chosen?

• Native .ts execution and a built-in test runner — fewer dev dependencies inside the container.

Known limitations

SvelteKit dev gotcha (load-bearing):

• Vite dev server runs Node-compat under bun run dev (Bun as script runner). The bun --bun run dev mode (Vite on Bun's runtime) is disabled — oven-sh/bun#23523, a known Vite restart hang. Production SSR runs on the Node.js 22 Vercel runtime (adapter-vercel, runtime: 'nodejs22.x'); Bun runs the build and the local dev container. A Bun production target (adapter-bun / Vercel bunVersion) is blueprint-only, not wired.
• svelte-adapter-bun is community-maintained; ORIGIN header isn't passed correctly (breaks form CSRF). Fallback: adapter-node via a single config change.

Node.js API gaps: node:http2 server, node:cluster, node:inspector, node:repl, node:sqlite missing or partial. Packages relying on Node internals may fail.

Related

• sveltekit.md - Framework integration
• podman.md - Container setup
• ../ops/deployment.md - Deployment targets