`bun = true` config is not working as expected. Node runtime is still being used if `--bun` flag is not added

[aabuhijleh]

What version of Bun is running?

1.2.9

What platform is your computer?

Darwin 24.3.0 arm64 arm

What steps can reproduce the bug?

• Have an old node version installed on your machine e.g. v14.17.0 using nvm
• Create a vite react app using bun create vite
• Create bunfig.toml and add run.bun config
• Run it using bun dev

What is the expected behavior?

My goal is to make bun the default runtime without having to keep adding --bun flag

I want to avoid doing this

bun --bun run dev  

After adding the configuration, the dev script should run using the bun runtime without errors without having to add the --bun flag

What do you see instead?

bun runtime is not used no matter what I do if I do not use the --bun flag. Node runtime is used which leads to errors ❌

Additional information

From the bun docs I can see this,

but running this command gives me this error ❌

❯ bun --bun which node
error: Script not found "which"