Claude Code has shipped Bun 1.4. already more than month ago: https://github.com/anthropics/claude-code/releases?q=bun&exp...

Version was changed in Bun in May 18

https://github.com/oven-sh/bun/commit/b18bf6d1d0a92238f240bf...

So it has been canary since then, most likely, if docs are accurate that latest main is canary.