Burn

What you get

• A cost chip under the prompt box, beside the context circle. It shows the thread's total and, while the thread works, what the last prompt added, for example $4.27 +$0.30. Click it for a card with where the money went (input, cache write, cache read and output), a bar for every model call, the models used, and the total with the thread's child threads, such as minions. From the card you can set a budget, open the Burn tab or copy a summary.
• A Burn tab in the side panel that lists every prompt with its cost, newest or costliest first, and every child thread with its model, calls and cost.
• A Burn page in bb's navigation with spend across all threads for today, the last 7 days or the last 30 days, for every project or one. It ranks by cost, tokens or calls, and shows spend per day by model, the token mix against what it cost, call times, the busiest hours, the costliest threads, a table of models, and spend by project and by harness.
• A Cost entry in every thread menu, and a red flame in the sidebar on threads over their budget.

Budgets

Set a budget for one thread from the chip, the thread menu or the Burn tab, or set one budget for every thread in the plugin settings. Burn sends a notification at 80% and at 100% of a thread's budget, and once a day when all threads together pass the daily budget you set. It never stops a thread unless you turn on Stop a thread at its budget, which is off by default. Another optional notification flags a prompt that cost at least three times the thread's median and at least $0.50.

Where the numbers come from

Burn counts every thread, whatever harness runs it. For pi threads it reads the session logs that bb's pi bridge keeps on each machine, where pi already records the cost of every call. For Codex, Claude Code and other harnesses it reads the token usage that bb records after each call or turn, and keeps its own copy, because bb deletes older usage events. When a harness reports no cost, Burn prices its tokens at list price and marks the amount as an estimate, such as ~$1.23. A model with no known price shows tokens instead of dollars.

The pi extension (optional)

The same repository ships a pi extension, installed separately with pi install git:github.com/kalindudc/burn. It adds a cost pill to pi's status line and a /burn overlay in the terminal, with or without bb. In a bb thread it also stops a run at its budget from inside pi, which is quicker than stopping it through bb. The bb plugin works without it.

Requirements and limits

• bb 0.46 or newer. No account and no outside service: Burn reads only what bb and pi already record.
• Dollar figures are list prices. They do not include discounts or what a proxy bills.
• Claude Code threads update once per turn, do not count Claude Code's subagents, and are never stopped at their budget, though budget alerts still fire.
• Call times and failed calls are recorded only for pi threads.
• A harness that sends bb no usage shows nothing.

Documentation and source: https://github.com/kalindudc/burn