cairn-statusline-setup

Skill: cairn-statusline-setup

You are wiring the operator's user-level Claude Code statusline to the cairn bundle. Once configured, every Claude Code session shows a one-line ⬡ cairn decisions:N inv:N <state> summary in the prompt's status row.

Trigger gate

This skill runs only on explicit operator request, or when the SessionStart context included a statusline_unset warning. Do not auto-invoke on session start without that signal.

Step 1 — surface the inline prompt

Render:

Wire the cairn statusline into your user-level settings? It shows a one-line ground-state summary in every Claude Code session. [a] set it up now [b] skip — you can run this skill later

AskUserQuestion. The question is the entire turn.

Step 2 — locate the shim file

The plugin's SessionStart hook writes the bundle's current path to ~/.claude/plugins/cache/isaacriehm-cairn/.active-version-path on every session open. The shim file is a single line: the absolute path to the active dist/cli.mjs.

Verify it exists:

test -f ~/.claude/plugins/cache/isaacriehm-cairn/.active-version-path \
  && echo OK \
  || echo MISSING

If MISSING, the plugin hasn't run a SessionStart yet for this project — surface:

Cairn's plugin hasn't fired SessionStart yet on this project. Open Claude Code in a cairn-adopted repo first; the shim file appears after the first session. Re-run this skill afterward.

End the turn.

Step 3 — patch user settings.json

Read ~/.claude/settings.json (create with {} if missing). Set the statusLine entry to:

{
  "statusLine": {
    "type": "command",
    "command": "node \"$(cat ~/.claude/plugins/cache/isaacriehm-cairn/.active-version-path)\" status-line"
  }
}

Preserve any other top-level fields. Use the Edit tool with the existing file content as old_string to do the merge atomically.

Step 4 — confirm + suggest restart

Statusline configured. Restart Claude Code to see the badge appear. ⬡ cairn decisions:N inv:N ready (or ⚑ when attention pending, ◐ during GC, ● for active task).

Hard rules

• Never hardcode the plugin's version-specific cache path (e.g. ~/.claude/plugins/cache/isaacriehm-cairn/cairn/0.2.0/). Plugin upgrades change the version dir; the shim file abstracts that away.
• Never modify ~/.claude/settings.json outside the statusLine field. Other fields are operator-owned.
• The skill is idempotent — re-running rewrites the same statusLine entry without breaking existing config.
• Caveman-ultra style for chat; full English in any code the skill writes (settings.json values are JSON, not chat).