fix: fall back to node when bun and tsx are not installed

[jlaustill]

Problem

Three separate issues cause tsci dev (and build/snapshot) to fail hard on Node-only systems:

1. cli/entrypoint.js — no fallback beyond tsx

const runner = commandExists("bun") ? "bun" : "tsx"

If neither bun nor tsx is installed the spawned process fails. tsx isn't a guaranteed dependency on every dev machine, and it shouldn't be a hard requirement just to run compiled JS.

2 & 3. cli/build/worker-pool.ts and cli/snapshot/worker-pool.ts — import.meta.dir is Bun-only

path.join(import.meta.dir, "build.worker.ts")

import.meta.dir is a Bun extension; it is undefined in Node, causing path.join to throw once the worker entrypoint path is resolved.

Fix

entrypoint.js: chain a final process.execPath fallback so the current Node binary is always available:

const runner = commandExists("bun") ? "bun" : commandExists("tsx") ? "tsx" : process.execPath

worker-pool.ts (both): add a one-time cross-runtime __metaDir shim at the top of each file, then replace all import.meta.dir usages:

const __metaDir: string =
  (import.meta as unknown as { dir?: string }).dir ?? // Bun
  import.meta.dirname ??                              // Node >=21.2
  dirname(fileURLToPath(import.meta.url))             // Node <21.2

Tested

Verified tsci dev starts and serves the preview on a system with Node 24 and no Bun installed.

🤖 Generated with Claude Code