Commit Graph
4 Commits
Author SHA1 Message Date
Lucas WintherandClaude Opus 5 8078057daa test(currency-digits): cover the recurring-cost expected/projected track
The zero-decimals guard drove every money path through rounding except
expectedForMonth and fold.ts's projected balance, added by the recurring
costs feature with the fixture's recurring array still empty. Adds an
unconfirmed, non-base-currency, fixed-split recurring cost so the FX
conversion and the split division both land on a non-whole amount at
zero digits, and extends the fold/month-view/two-decimals assertions to
cover it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-04 07:34:39 +02:00
Lucas Winther a456aadf35 feat(types): recurring costs in the dataset, schema 7
Recurrence is two orthogonal fields, not a list of special cases: a kind
(everyNMonths / everyNDays / everyNWeeks) and an anchoring (calendar /
lastCharge). The phone bill that recharges early when its data cap is hit is
everyNDays(30) anchored to lastCharge — the domain never learns what a data cap
is, because confirming the occurrence early already records the date.

Purchase.source pairs occurrenceDate (identity: which slot this claims) with
Purchase.date (truth: when the money moved). They differ whenever a bill is
paid off schedule, and lastCharge measures from the latter.

RecurringCost.amount is a single mutable Money with no RuleVersion-style
series. Safe only because confirmed purchases hold what was actually paid;
under projection-only it would destroy history.

The 6 -> 7 step writes an empty array and reads nothing. Decimals took 6.
2026-09-03 03:41:48 +02:00
Lucas WintherandClaude Opus 5 8d2b2ca881 feat(money): one decimals setting for the dataset, not one per currency
`Settings.digits` replaces `CurrencyDef.digits`. Every amount rounds to it,
whatever its currency, and `digitsFor` is gone: the sixteen call sites read the
setting, and the domain functions that took a currency table purely to look
digits up take a `digits: number` instead. Schema 6.

The owner asked for this with the cost in front of them, and the cost is real:
a dataset mixing minor units cannot be described any more. Yen at 0 beside
kroner at 2 has no correct global value — 2 gives ¥1234.56, an amount yen
cannot represent; 0 rounds 49.95 DKK to 50 and drifts the carry from the bank.
Nothing in the app warns. docs/specs/2026-09-02-global-decimals-design.md
argues it in full, including what re-adding a per-currency override would take,
and AGENTS.md §1 now says not to reintroduce one without revisiting the
decision.

The 5 -> 6 step takes the MAXIMUM of the per-currency digits, not the base
currency's. A dataset holding a three-decimal currency already has
three-decimal amounts in it, and adopting the base's 2 would truncate the next
edit of one; the maximum can only keep more precision, never less. On every
dataset this app has written all four currencies record 2, so nothing rounds
differently than before.

Changing the setting does not rewrite stored amounts. 49.95 stays 49.95 and
shows as 50; totals recompute at the new precision. Rewriting each Money is a
destructive whole-dataset write, which §1 owes a backup export first, and it is
lossy one way.

Display turned out to be the hole in the plan. src/ui/format.ts pinned
minimumFractionDigits: 2 in a module-level Intl.NumberFormat, so it never read
the dataset at all — equally broken under per-currency digits, where a JPY
rendered "3,333.00", so a pre-existing gap rather than a regression. Shipping a
Settings control that display ignores would look broken at 0 and be lossy at 3,
hiding precision the dataset holds. So format.ts takes digits like roundMoney
does, useMoneyFormat() binds them for the 64 call sites, and postRowCells takes
the formatter as an argument because it is a plain helper, not a component.

currencyDigits.test.ts is rewritten rather than deleted. Driving a dataset at
ZERO decimals through rounding, both FX directions, both split modes, plan
division, the fold and the month view still tells a real implementation from
one assuming 2 — it just cannot prove per-currency flow, because there is none.
It also asserts that raising the setting to 2 changes what the fold produces.

Verified in Chrome, not only in tests: a v5 dataset with digits 2/0/3 written
straight into IndexedDB migrates to a setting of 3, the table loses its
Decimals column, and editing the control persists schema 6 with digits stripped
from each currency and income left at 20000.55. The same month reads 600/206 at
zero decimals and 600.000/205.561 at three, so the figures recompute rather
than merely reformat.

Not verified here: the .ods in a real spreadsheet.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-03 03:12:14 +02:00
Lucas WintherandClaude Opus 5 cdece63c68 feat: user-defined currencies, and amounts that carry their own currency
Two requests. The second is small; the first changed the money layer.

TYPING THE CURRENCY. The purchase total field now reads "30$" as thirty
dollars, "€25,50" as EUR 25.50, "250 kr" as DKK, "1.234,56 usd" as USD
1234.56, and sets the currency selector from what was typed. Entry speed is a
stated product feature and a second control per amount works against it.

The field is type="text", not type="number": a number input silently discards
anything non-numeric, so "30$" would never reach the parser. It keeps its own
text so a half-typed "30." stays as typed and only commits when it parses.

Separator handling is where parseMoneyInput earns its 26 tests. With both "."
and "," present the LAST is the decimal point, which covers "1.234,56" and
"1,234.56" without knowing a locale. With one, it groups thousands if exactly
three digits follow and is a decimal point otherwise — so "1,500" is fifteen
hundred and "1,5" is one and a half. Spaces group thousands only in
three-digit groups, because "30 40" is two amounts typed by mistake and
committing it as 3040 would be worse than rejecting it. An unrecognised
currency returns null rather than falling back: reading "30 GBP" as 30 DKK
would book money at the wrong currency.

USER-DEFINED CURRENCIES. `Currency` was a closed union and decimal places were
a module constant, so "add a currency" was a code change. Both now live in the
dataset: `Dataset.currencies` is the authority on which codes are valid, what
they are called, their symbol, and how many decimals they round to. Settings
grows a table to add, edit and remove them.

That forced the money layer open. `roundMoney` takes a DIGIT COUNT, not a
currency code, and every one of its ~29 call sites resolves digits from the
dataset via `digitsFor`. Making digits a required number rather than an
optional one with a default of 2 is the whole safety argument: every site
became a compile error the type checker enumerated for me, where a default
would have left each one silently correct for DKK/USD/EUR and silently wrong
for the first zero-decimal currency the owner adds.

Because every existing currency uses two decimals, a broken version of this
refactor would still pass all 356 previous tests. src/domain/currencyDigits.test.ts
is the oracle that cannot lie: a JPY-style zero-decimal currency driven through
roundMoney, both FX directions, both split modes, finance-plan division, the
fold, and the month view, asserting no figure has a fractional yen in it.

Guards that come with it, all tested:
- Codes are identity — they key the FX table and every stored Money — so they
  are normalised (" jpy " -> "JPY") and cannot be edited, only added/removed.
- A currency in use cannot be removed, and the refusal names what refers to
  it. The same reasoning as posts being archived rather than deleted: stored
  Money carries the code, and dangling references would make the import
  validator refuse the owner's own exported file. Removing an unused one takes
  its exchange rate with it, leaving no orphan row.
- The import validator now checks the currency table itself — codes, duplicate
  codes, integer decimals 0-4 — and validates every Money against it. That
  boundary check replaces the compile-time safety the closed union provided.
- parseFxResponse takes the accepted codes instead of a global constant, so a
  rate service returning dozens cannot put unreachable rows in the table.

Migration v2 -> v3 seeds the currency table. Behaviour-preserving by
construction: every currency that existed had two decimal places and the
seeded table records two, so not one stored amount can round differently than
it did before. An existing `currencies` field is kept rather than overwritten,
since a hand-edited file could already carry currencies the owner added.

Verified in the browser, not just in tests: JPY added through the real Settings
form with 0 decimals, and the five inputs above typed into the real purchase
field, each setting the right currency.

Two obsolete test helpers went away. plans.test.ts and actions.test.ts used to
monkey-patch the CURRENCY_DIGITS constant to prove the table was consulted;
digits are an argument now, so those tests just ask for zero decimals.
types.test.ts no longer asserts "the supported currencies are exactly DKK,
USD, EUR" — that stopped being a property of the code.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-02 15:52:11 +02:00