Burn

See what each agent thread has cost, while it runs.

Burn puts a cost pill such as $4.82 +$0.31 in pi's footer and in bb's prompt box: the thread's total, then what the last prompt added. Behind the pill is what every prompt, model and call cost, budgets that warn you before a thread gets expensive, and your spend across every thread.

What you get

In bb, for every thread, whatever harness runs it (pi, OpenCode, Codex, Claude Code or another):

• A chip beside the context circle, with a card behind it that breaks the cost down and charts every call.
• A Burn tab in the side panel that lists every prompt and adds the cost of child threads, such as minions.
• A Burn page in bb's navigation with spend across all threads by day, project, model and harness.

In pi, in the terminal, with or without bb:

• A pill in pi's status line.
• A /burn overlay with four views: an overview, what each prompt cost, cost by model, and this project's spend across sessions.

Budgets work in both. Burn warns at 80% and at 100% of a thread's budget. It never stops a thread unless you turn on the stop setting, which is off by default.

Install

The bb plugin alone is enough in bb. The pi extension is optional: it adds the pill and /burn in pi's terminal, and in a bb thread it stops a run at its budget from inside pi, which is faster than stopping it through bb.

# bb plugin
bb plugin install git:https://github.com/kalindudc/burn

# pi extension
pi install git:github.com/kalindudc/burn

From a local checkout instead:

git clone https://github.com/kalindudc/burn && cd burn
npm ci --ignore-scripts
bb plugin install path:"$PWD"
pi install "$PWD"

To update, run bb plugin update burn and pi update git:github.com/kalindudc/burn. A bare pi update updates pi itself, not its packages.

Requirements: bb 0.46 or newer. The pi extension needs pi 1.x, which provides ctx.mode.

Do not install the bb plugin from npm. The npm package ships only the pi extension, and bb needs the whole repository to build the plugin.

Threads that are already running show their cost as soon as the bb plugin is installed.

Documentation

• Burn in bb: the chip, the card, the Burn tab, the Burn page, and settings.
• Burn in pi: the pill, the /burn views, commands, and settings.
• How Burn works: where the numbers come from, and how the two halves talk.
• Troubleshooting and limits.
• Changelog: what changed in each release.

Development

npm install
npm test
npm run typecheck
bb plugin build

If you installed with npm ci --ignore-scripts (the local-checkout install above), run npm rebuild better-sqlite3 before npm test. The plugin SDK's test host uses its native binding, and without the rebuild 16 tests fail on a fresh checkout.

The shared report, formatting and budget code is in src/. The pi extension is in extensions/pi, and the bb plugin is in extensions/bb. test/layout.test.ts keeps the halves from importing each other's dependencies.

The screenshots come from a sandboxed bb and pi with made-up projects and threads.

Credits

Support for OpenCode threads, which Burn reads from opencode's own database, is by Nikolai Berezovskii (#1).

Subagent accounting, which reads Claude Code transcripts and separates Codex child counters, is by Artur Karapetyan (#2).

License

MIT