Stop finding out you're rate-limited mid-task. Check the headroom first.

A developer released blackbox-bill v0.3.0, an open-source, zero-dependency Python tool that reports per-account quota headroom before a task is dispatched, rather than diagnosing the bill afterward. The tool subtracts observed usage from user-declared caps in a limits.json file, flags each quota pool as OK, LOW, EXHAUSTED or UNLIMITED, and with --task-in/--task-out re-prices a planned task under each account's rate card to recommend which account can absorb it. It remains a read-only billing-attribution ledger with no enforcement or blocking.

One sentence from a Show HN thread stuck with me: "Thing I'd want surfaced is per account rate limit headroom before I dispatch, not after I'm stuck mid task." blackbox-bill v0.3.0 does exactly that. It was a post-mortem tool — it read your AI coding bill and explained why it looked wrong. Now it's also a pre-flight tool: it shows per-account quota headroom before you dispatch the next task, and tells you which account can survive it. pip install blackbox-bill Zero dependencies — Python 3.9+ stdlib only. No network, no API keys; everything runs on files you already have. GitHub https://github.com/hahahahahahahahah6/blackbox-bill , MIT. Billing exports never carry quota limits — no vendor puts remaining quota in a CSV — so you declare them once in a small JSON file. blackbox-bill subtracts your observed usage from your declared caps, per account, per quota pool: blackbox-bill headroom --csv export.csv --limits-file limits.json account 'cursor-pro' plan cursor:pro, 3 bill row s pool consumed limit remaining remaining status api-key $0.00 unlimited unlimited ???????????????????? n/a UNLIMITED cursor-models $30.00 $500.00 $470.00 - 94.0% OK other-models $120.00 $125.00 $5.00 ------------------- 4.0% LOW Pools get flagged OK / LOW under 25% left / EXHAUSTED / UNLIMITED . limits.json looks like this — caps in USD, null for unlimited, and an optional match spec to partition bill rows across accounts by a CSV column value: { "accounts": {"name": "cursor-pro", "plan": "cursor:pro", "limits": {"cursor-models": 500.0, "other-models": 125.0, "api-key": null}}, {"name": "shared-api-key", "plan": "api-only", "limits": {"api-key": 200.0}, "match": {"column": "account", "value": "shared-api-key"}} } No CSV yet this cycle? Run it limits-only — the dashboard shows your declared caps and you re-run with the export later. Planning a long agent run? Add --task-in/--task-out and blackbox-bill re-prices the task under each account's plan rate card the same illustrative cards the plan-switch what-if simulator uses and recommends the account with headroom for it: blackbox-bill headroom --csv export.csv --limits-file limits.json \ --task-in 1000000 --task-out 250000 --task-pool other-models 'cursor-pro' est $10.00 DOES NOT FIT remaining $-5.00 'shared-api-key' cannot price: no declared limit for pool 'other-models' WARNING: no account has headroom for this task under the declared limits. Top up, switch plan, or shrink the task before you dispatch — not after you're stuck mid task. Or, when an account does fit: RECOMMEND: dispatch on 'acct-b' — it has headroom for this task. Bring your own numbers with --rates-file and the estimates become real. v0.1–v0.2 were post-mortem: the bill arrived, the tool reconstructed why it looks wrong "why your 'Other Models' pool drained first", silent model swaps, unattended $40-while-you-slept burn . v0.3 is pre-flight: remaining quota per account, and which account survives the next dispatch, before you commit. The positioning doesn't change — it's still the same read-only billing-attribution ledger. No enforcement, no budget lines, no blocking. Use the statusline to watch the burn; use blackbox-bill to audit it — now also before you light the fuse. limits.json . If your plan cap changes and you don't update the file, the dashboard is wrong in the way you'd expect — keep the numbers conservative. --rates-file with your own. The repo is hahahahahahahahah6/blackbox-bill https://github.com/hahahahahahahahah6/blackbox-bill MIT . If you've ever been rate-limited mid-task with a quota sitting untouched on another account, this one's for you.