Imported from comp4020-agentic-coding-studio/core (comp4020-statusline/skills/statusline/SKILL.md). Install upstream with npx skills add comp4020-agentic-coding-studio/core --skill statusline. Copyright stays with the author.

COMP4020 budget status line

This plugin ships the script; the student's settings.json points at it. Both halves have to be in place, which is the source of nearly every "it isn't working" report.

Opus · comp4020 $41.20/$100 (41%)

Green through amber to red as the weekly cap approaches. In a session that isn't running on course credits — a personal subscription or key, or no key at all — it shows a dim own plan instead, so which wallet a session draws from is always visible. For a student running the course key alongside their own Claude plan, that flip is the main reason to want it.

The model leads either rendering (Opus · own plan), since which model a session is on is the other thing that moves what it costs. On course credits an Opus model is picked out in magenta rather than dimmed — an Opus request costs several times a Sonnet one — and that colour deliberately sits outside the budget figure's green-amber-red, so it reads as a price rather than a warning about the cap. On someone's own plan the spend isn't the course's to flag, so the model stays dim there whatever it is.

Install

It needs jq (and curl, which every supported platform already has). Check with command -v jq; if it's missing, install it first with mise use -g jq (the course's install path — see onboard step 2). Without jq the segment just reads comp4020 budget: needs jq.

It's a Unix shell script, so macOS, Linux and WSL. On native Windows there is nothing to install — that's the WSL2 nudge /comp4020:doctor already gives.

1. The plugin is installed (you're running its skill), and its SessionStart hook copies the script to ~/.claude/comp4020/statusline.sh at the start of the next session. If it isn't there yet, don't hunt for it — carry on and tell them it lights up when they restart.

2. Merge this into ~/.claude/settings.json — read the file first and add just this key, preserving everything else verbatim. Installing the plugin never writes it: a plugin cannot set statusLine, which is exactly why the student's consent is needed here.

   {
     "statusLine": {
       "type": "command",
       "command": "$HOME/.claude/comp4020/statusline.sh"
     }
   }

   If they already have a statusLine, leave it alone and say so — their existing one can append this one's output instead:

   printf ' %s' "$(printf '%s' "$input" | "$HOME/.claude/comp4020/statusline.sh")"

   where $input is the session JSON their script has already read from stdin. Feeding it </dev/null instead is also fine and prints everything but the model name — which a hand-rolled status line usually shows already.

3. Tell them it appears in new sessions, not this one.

When it isn't working

The script always prints one of two tags, so the first question is which of three states they're in. Work down in this order:

• completely empty segment — the script isn't running at all. Check, in order: command -v jq; claude plugin list shows comp4020-statusline; test -x ~/.claude/comp4020/statusline.sh (if the plugin is installed but the script is missing, its SessionStart hook hasn't run yet — restarting Claude Code installs it); and statusLine.command in ~/.claude/settings.json actually points at that path. That last one is the step people miss, because installing the plugin does not write it. An enabledPlugins entry naming the plugin while claude plugin list doesn't show it means it was never installed: enabling is not installing, and only claude plugin install comp4020-statusline@comp4020 fetches it.
• own plan — the script works, but the session isn't routed through strproxy. It shows the budget only when ANTHROPIC_BASE_URL names the strproxy host and ANTHROPIC_AUTH_TOKEN holds a virtual key, by design, so it never sends a credential to a host it wasn't given. Whether that's correct depends on the setup: on someone's own Claude subscription outside course work it's exactly right, and for a student running both plans it's right everywhere except inside a course repo. Seeing it there means the repo's .claude/settings.local.json is missing — usually a fresh weekly clone. Fix: /comp4020:onboard, the dual-plan branch.
• comp4020 with a stale or missing figure — not a broken setup. budget: ? means the script has never reached /api/me, nearly always the ANU VPN; a number that won't move is the 60-second cache, which off the VPN sits on the last figure it fetched indefinitely. Their Claude sessions are unaffected either way.
• the right tag but no model name — the script isn't being handed the session JSON. Nearly always a status line of their own calling ours with </dev/null; the append recipe above pipes it through instead. Everything else works without it, by design.

A student who already had their own status line may have it pointing elsewhere — that's fine and deliberate; check whether their script calls ours (the append recipe above).

What it is, and isn't

It reads a figure cached and refreshed at most once a minute in the background: an indicator, not a ledger. The authoritative number is /comp4020:balance — say so if the two disagree, rather than trusting the bar.

Turning it off

Delete the statusLine block from ~/.claude/settings.json. To also stop the hook reinstalling the script:

claude plugin uninstall comp4020-statusline@comp4020
rm -rf ~/.claude/comp4020

The comp4020 skills plugin is unaffected either way.