AGENTS.md §2 gains the guard this fix wave installed, stated as covering BOTH
an anchored cost's `startDate` and its charges' own dates — checking only the
first is what let the second through — and naming the one place the rule now
lives so a fifth copy does not appear.
Two items for docs/TODO.md, neither of them a defect this branch introduced:
- **Editing a live calendar cost re-grids it.** `updateRecurringCost` refuses
an `anchoring` change on a charged cost but accepts `recurrence` and
`startDate`, which for a calendar cost ARE the grid — so every charge's
stored `occurrenceDate` can be orphaned and the paid bill counts twice.
Reproduced and measured: a 7-day cost with its second slot settled goes from
`expected 4000 / projected 0` to `expected 6000 / projected -2000` when `n`
becomes 5. Silent money wrongness, and the honest fix is a product decision
about what editing a live bill means, so the behaviour is left alone.
- **An anchored cost has no history of expectations.** Recording a charge
erases every earlier month's expectation, so `overdue` collapses to 0 and a
past month's `projected` moves (`remaining` does not). It follows from the
spec, but it sits in tension with §1's "archiving must not retroactively
remove past expected charges" and deserves saying out loud. Measured
figures included.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
