This is a confirmed bug. The root cause is that both mise run and mise prepare use InstallOptions::default() which sets missing_args_only: true — this means only tools passed as CLI arguments get installed before prepare runs, not tools from [tools] in your config file.

So in your case, uv from [tools] is skipped during the initial install phase, and the prepare step tries to run uv pip install before uv is available. It only gets installed later during the task-specific tool installation phase (after prepare has already run/failed).

A fix has been submitted in #8582.

This comment was generated by Claude Code.