doctor

name	doctor
description	Detect and install the local prerequisites a managed repo needs before init/build/dev — git, mise (and the pnpm/uv/node it manages), and Docker — with per-OS guidance and confirmation-gated installs.
when_to_use	Use on a fresh machine, or whenever a tool is missing ("command not found", "tool not found", mise/docker errors), before /steer:init, /steer:build, or `mise run dev:setup`. /steer:build and /steer:init invoke it when prerequisites are absent.
allowed-tools	["Bash(git rev-parse *)","Bash(git --version)","Bash(mise --version)","Bash(mise doctor *)","Bash(mise ls *)","Bash(docker --version)","Bash(docker info *)","Bash(sh *scripts/scan-prereqs.sh*)"]
disallowed-tools	Edit, Write, NotebookEdit, EnterWorktree

Prerequisite doctor

Get a blank or half-set-up machine to the point where /steer:init, /steer:build, and mise run dev:setup actually work. This is the one place the toolchain-install logic lives; /steer:init and /steer:build call here rather than carrying their own copies.

What a skill cannot do — the manual floor. Installing Claude Code itself, adding the steer marketplace, and the Docker Desktop app are GUI/host steps no skill can perform (a skill can't run before its host exists). This skill detects and links them; for everything below the floor — mise and the runtimes it manages — it installs with your confirmation.

1. Detect — run the scan, don't eyeball

Run the read-only detector and act on its output (never guess what's installed):

sh "${CLAUDE_PLUGIN_ROOT}/scripts/scan-prereqs.sh" .

It prints an os fingerprint line, then one TAB line per tool — <tool>\t<status>\t<detail>. Statuses:

status	meaning	what to do
ok	installed (detail = version)	nothing
missing	not installed	resolve (§3) — a blocker for required tools
down	docker present, daemon not running	start the daemon (§3)
via-mise	runtime absent but mise present	one mise install provides it (§3)
unmanaged	runtime absent and mise absent	install mise first, then mise install
shadowed	runtime present but a non-mise copy (nvm/asdf/volta/fnm/system) is masking mise's pinned one	advisory — surface it and fix activation (§3)
n/a	not used by this repo's stack	nothing

The detail column carries requiredness for docker (required (compose.yaml) vs advisory), so a missing/down docker is only a blocker when this repo declares backing services.

2. Report

Summarize the state plainly. When you arrived here from /steer:build, speak in the PO's plain language (no git/stack jargon — see the "Who you are working with" rule); for a dev, the tool names are fine. Name what's green, what's a blocker, and what you're about to do.

3. Resolve — offer to install, gated on confirmation

Install scriptable tools only after the user says yes (Commit-autonomy applies to system changes too). GUI/host steps are always handed over as instructions — never automated. Use the os line to pick the right command; these mirror the scaffold README quickstart (the static source of the same commands).

• mise missing — the gateway; resolve this first.
  • macOS: brew install mise
  • Linux / WSL2: curl https://mise.run | sh
  • Then activate it in the shell and persist it to the rc file: eval "$(mise activate zsh)" (or bash), and add that line to ~/.zshrc / ~/.bashrc so new shells have it.
• node / pnpm / uv (via-mise or unmanaged) — do not install these separately. Once mise is present, run mise install from the repo (and cd infra && mise install if they'll touch infra); it provisions every pinned runtime. Then verify each mise.lock gained real [[tools.*]] entries (see /steer:init's lock-verification step — Path A step 4 / Path B step 5) and commit it.
• node / pnpm / uv shadowed — mise's pinned runtime exists but a global version manager (the detail names it: nvm/asdf/volta/fnm) or a system/Homebrew copy is ahead of it on PATH, so bare pnpm/node run the wrong version (this is what silently produces a node_modules built by the wrong pnpm). Advisory, not a blocker. Fix: ensure eval "$(mise activate …)" is sourced after the other manager in the rc file (mise must load last to win PATH), open a fresh shell, and confirm which <tool> now resolves under …/mise/…. Until then, run package-manager commands via mise exec -- <tool>.
• git missing — macOS: xcode-select --install; Debian/Ubuntu: sudo apt-get install git (a sudo command: present it, let the user run it).
• docker missing — manual (GUI app, can't be scripted): point them to https://www.docker.com/products/docker-desktop/, have them install and start it, then re-run this skill. Only a blocker when detail says required.
• docker down — offer to start it: macOS open -a Docker (then wait and re-scan until the daemon answers); Linux sudo systemctl start docker (present the command).
• Windows — the answer depends on the shell, not the OS. The hooks (and this detector) run via sh, so a POSIX shell must be present.
  • os = windows (the scan ran — it printed os = windows, i.e. under MINGW/MSYS via Git for Windows): this is a supported setup, not a blocker. steer's sh-invoked hooks run here, and it's the right environment for the Claude Desktop Code tab — /steer:build and mise run dev:setup build locally too (install Docker Desktop if the repo declares services). Proceed with the normal mise/runtime resolution above. WSL2 is optional here — only worth it for heavy CLI/IDE development.
  • No POSIX shell at all (this detector failed to run — native cmd/PowerShell, no Git Bash): install Git for Windows (winget install Git.Git or https://gitforwindows.org/), reopen the session, and re-scan — that alone gets the Desktop Code tab working, builds included. For CLI / IDE development, WSL2 is the recommended alternative: in elevated PowerShell run wsl --install, reboot, then re-run everything inside WSL2. Both are GUI/host steps — hand them over, don't automate. Full matrix: the Windows setup page in the docs.

4. Re-scan and confirm

After installing, re-run the detector and report the new state. Don't claim the machine is ready on the strength of a command that "looked like it worked" — let the scan say so. A tool still missing/down/unmanaged is not resolved.

Recommend the next action

Close with a ## Recommended next actions block per ${CLAUDE_PLUGIN_ROOT}/templates/reference/NEXT-ACTIONS.md, derived from the final scan.

Observed state	Category	Action / suggested command
A required tool still missing/down/unmanaged	Blocking now	Finish resolving it (§3), then re-scan
os = windows (Git Bash live)	Complete	Supported — hooks run; valid for the Desktop Code tab, builds included. WSL2 optional (CLI/IDE dev only)
Windows, no POSIX shell (detector couldn't run)	Blocking now	Install Git for Windows, reopen, re-scan — or WSL2 for CLI/IDE dev
A runtime is shadowed (and nothing above blocks)	Recommended	Fix activation ordering (§3) — not a hard blocker, but the wrong, un-pinned version is in use
All green, repo not yet set up (no /spec)	Recommended	Stand the repo up — /steer:init (dev) or /steer:build (PO)
All green, repo already set up	Recommended	mise run dev:setup, then start work
All green, nothing else pending	Complete	No action is currently required.

Pick one Current recommended action by precedence. Read-only on the repo — it detects and (with consent) installs host tools; it never edits repo files or commits.

Guardrails

• Never install without explicit confirmation. GUI/host steps (Docker Desktop, WSL2, Claude Code, the marketplace) are always manual instructions.
• Never edit repo files or commit from this skill; never touch secrets.
• The detector is plugin-internal — invoke it from ${CLAUDE_PLUGIN_ROOT}; it is not installed into the consumer repo.