feat: add an Extra Usage Daily Budget widget - #672

What

A new Extra Usage Daily Budget widget shows how much of the monthly extra usage limit can be spent per day for the rest of the month: what's left of the limit divided by the days left, today included. With $376.55 left of a $500 limit on Monday 5 October 2026, it shows Daily Budget: $13.95 (27 days left), or $18.83 with weekdays only (20 weekdays left).

Why

With a monthly limit, the number that matters during the day is how much you can still spend per day without running out before the limit resets. The existing widgets give the pieces (spent, left, percent) but not the pace. It's especially useful on usage-based Enterprise plans, where the monthly limit is the only limit.

How

• Days left: today through the last day of the month. Monthly limits reset at 00:00 UTC on the 1st (per Anthropic's Spend Limits docs), so days are UTC days: in US Central time the day, and the month, roll over at 7pm.
• Weekdays only: a w keybind in the line editor toggles counting weekdays only (Saturday and Sunday in UTC are skipped). The editor row shows (weekdays) when it's on. Today always counts, even a weekend day, so working on a weekend still shows a budget and nothing ever divides by zero.
• Edge cases: once the limit is used up it shows $0.00. Without a monthly limit it shows nothing, like Extra Usage Remaining. With extra usage off it shows n/a. The disabled and no-data hide options, raw value mode, the reported currency and the cost number format all work like the other Extra Usage widgets.
• Data: the extra usage state, limit and amount spent, all from the fetch the other Extra Usage widgets already make. The day counting is a small pure helper (countBudgetDaysLeft) that takes the time as a parameter.
• Preview: a fixed sample ($194.70, the Remaining sample over 20 days), so the preview doesn't change with the date.

Demo

Rendered from a fake usage cache (no login, no API call) on Monday 5 October 2026: $123.45 spent of a $500 limit. The third widget counts every day left ($376.55 ÷ 27), the fourth weekdays only (÷ 20).

Powerline

Plain

Toggling weekdays only with w in the line editor:

Powerline

Plain

Testing

• Day counting, against hand-checked calendars: all days and weekdays only on a Monday, a weekend day with weekdays only, the last day of the month, the first instant of a new month in UTC, and a US Central Friday night that is already Saturday in UTC.
• Widget tests with the clock fixed: the budget for all days and weekdays only, $0.00 past the limit, the reported currency, no limit, n/a and its hidden state, errors and no-data, the fixed preview, and the w toggle (keybind label, editor modifier, metadata). A prefetch test checks the widget fetches exactly the extra usage state, limit and spend.
• On today's main (with docs: explain an empty status line in one folder (workspace trust) #606 and feat(git-is-fork): render forks as an editable glyph #617 merged in locally): bun test gives 2798 pass, 0 fail (Bun 1.4.2), and bun run lint passes.
• Under Node (Vitest): the new and touched test files pass, 56 of 56.
• Built CLI under Bun 1.4.2 and Node 26.10.0 with a fake usage cache: all runtimes give identical output in plain and Powerline modes; it differs from main only by the new widgets. The TUI opens and exits cleanly under both.