Runtime versions

Manage language runtimes with one manager — mise — and end the nvm/asdf/pyenv/rbenv/fnm/homebrew-node sprawl where every tool has its own shims, its own PATH entry, and its own opinion about which node you get. mise is a single fast shim layer that reads the .tool-versions/.nvmrc/mise.toml files the others left behind, so migration is additive.

Route to a workflow

The scripts (prefer these over ad-hoc bash)

Stable, tested, read-only helpers live in scripts/ — call them instead of re-composing the command -v / which -a / mise which / env -i blocks each session. Run by absolute path from this skill's directory. They handle a missing manager/shell/mise gracefully.

Full contract + a worked example: scripts/README.md. The inline bash snippets in this file and the reference .mds show what the scripts run under the hood — reach for them for novel one-off checks, not to re-type the routine diagnostics.

Discovery (always run first)

Run scripts/detect_managers.py (which managers, rc hooks, brew runtimes, shim dirs), then scripts/tool_resolve.py (what each tool resolves to now) and, for the per-shell truth, scripts/shell_resolve.py both. Under the hood, that is:

mise --version 2>/dev/null || echo "mise NOT installed"
command -v mise nvm asdf pyenv rbenv fnm                  # which managers are present
brew list --formula 2>/dev/null | grep -E '^(node|python|ruby|go)(@|$)'  # homebrew runtimes
mise which node python go 2>/dev/null                     # what mise would resolve (if active)
command -v node python go                                 # what THIS shell actually resolves

• Multiple managers present, or a runtime installed via both brew and a manager, is the sprawl this skill fixes — different shells silently get different versions. Review it in optimize.md; an active per-shell divergence is repair.md.
• Shells activate these managers, so the truth is per-shell. Always check zsh and fish (scripts/shell_resolve.py both).

Core principles

1. mise-first, additive migration. mise reads existing .tool-versions/.nvmrc, so adopting it doesn't break projects. Set up mise, verify it, then neutralize the old managers.
2. Verify in a CLEAN environment. A shell spawned inside your current session inherits a polluted PATH. Prove resolution with scripts/shell_resolve.py both (clean env -i in each shell) — see verification.md.
3. Don't remove old managers until mise is verified working in both zsh and fish. Back up shell config first; shell edits are owned by the shell-sync skill (below), not reimplemented here.
4. Don't assume state. Re-run discovery each time — which manager wins depends on shim PATH order.

Cross-skill coordination (reference, don't reimplement)

• shell-sync — mise activation adds shims to PATH; the canonical shell owns the mise activate line and the mirror is regenerated. Route all shell-config edits through it.
• dotfiles — track ~/.config/mise/config.toml via chezmoi so global versions are reproducible.
• brew-doctor — install mise via brew; uninstall nvm/asdf/node@x after migration verifies.
• nvim-config — LSP servers run on the mise-managed runtime; a version change can move them.

Settings

Read ~/.config/devenv/config.toml before prompting; if a [runtime-versions] section exists, use it as defaults (precedence: explicit answer this session > config.toml > ask). Had to ask? Offer to save the answer back. Managed by the devenv skill. Keys honored:

• manager — the version manager to standardize on (e.g. "mise").
• tools — map of global runtime versions, e.g. node = "lts", python = "3.13", go = "latest".

Safety

• Switching managers changes which runtime a project resolves — verify per-project .tool-versions/.nvmrc are still honored under mise before trusting the switch.
• Back up shell config (~/.zshrc, ~/.config/fish/config.fish) before neutralizing a manager.
• Do not remove nvm/asdf/pyenv/node@x until mise is verified in a clean env in BOTH shells — a half-migrated PATH silently falls back to the old manager (or to no runtime at all).
• Confirm before editing shell config, mise use -g (changes global default), or any uninstall.