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accounted/lib/money.ts
T
Jakob Wennberg ec27228a8e style: remove em/en dashes repo-wide, add CLAUDE.md rule against them (#890)
Em dashes (—) and en dashes (–) had spread across comments, docs, tests,
and a few UI strings, reading as AI-generated boilerplate rather than
house style. Replaced each with punctuation matching its context: colon
for explanatory clauses, comma for asides, plain hyphen for numeric/legal
ranges (e.g. "21-23§"), "to"/"till" for date ranges, parentheses for
paired-dash asides. messages/en.json and messages/sv.json were fixed by
hand together to keep sv/en in sync.

Left untouched where the dash is the functional subject rather than
decorative punctuation: date-range-parser.ts's separator regex,
charset-repair.ts's CP1252 byte-mapping table (and its test), the SIE
encoding mojibake docs, generic-csv.ts's minus-sign normalizer, the
agent system-prompt files that already instruct against em dashes, and
a golden iXBRL test fixture compared byte-for-byte.

Also fixes two bugs surfaced along the way: an off-by-one in
ApiKeysPanel's scope-label split (a leftover from an earlier partial
pass), and a charset-repair test that had lost the literal en-dash it
exists to verify.

Regenerated the agent atom seed migration (skills:generate) since 27
SKILL.md files changed. Added a CLAUDE.md rule against em/en dashes,
with an explicit carve-out for the functional-dash cases above.

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
2026-07-04 15:58:06 +02:00

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/**
* Canonical money primitives for Accounted.
*
* Swedish öresavrundning was abolished in 2010, but our journal entries still
* store amounts in hundredths of SEK. Floating-point arithmetic accumulates
* IEEE 754 drift, so all monetary calculations must funnel through `roundOre()`
* before being compared, summed across rows, or persisted as
* journal_entry_lines.
*
* Per CLAUDE.md accounting guard rail #9: never use `.toFixed()` for money, and
* never hand-roll `Math.round(x * 100) / 100`: that naive form is subtly wrong
* (see `roundOre` below). Import these helpers instead.
*
* This module is the single source of truth. `lib/bokslut/rounding.ts`
* re-exports `roundOre`/`ORE_TOLERANCE` from here for back-compat; new code
* should import from `@/lib/money`.
*/
/**
* Round a SEK amount to the nearest öre (two decimal places).
*
* Naive `Math.round(x * 100) / 100` fails on exact-half values like 1.005
* because IEEE-754 stores 1.005 as 1.00499999…, so multiplying by 100 yields
* 100.49999… and Math.round drops it to 100 instead of 101.
*
* The Number.EPSILON nudge bridges the IEEE gap for double-precision values
* near unit magnitude: large enough to push 100.49999… across the half-integer
* boundary, small enough to leave well-formed decimals (1.234, 1.235, etc.)
* untouched. Zero is special-cased so negative-zero inputs preserve their sign
* through the round trip.
*/
export function roundOre(n: number): number {
if (n === 0) return n
return Math.round((n + Number.EPSILON) * 100) / 100
}
/**
* Tolerance for comparing two öre-rounded amounts.
*
* Half an öre is the strictest meaningful threshold: any difference larger than
* this represents a real one-öre discrepancy, not float drift. Use for
* invariant assertions on closing entries, IB/UB continuity per-account, and
* balance-sheet equality checks.
*/
export const ORE_TOLERANCE = 0.005
/**
* Maximum |bank payment invoice remaining| (in SEK) that is treated as
* öresavrundning: booked to BAS 3740 (Öres- och kronutjämning) so the invoice
* settles fully: rather than left as a genuine partial payment.
*
* Swedish whole-krona settlements (Bankgiro, Swish, kort) pay an öre-bearing
* invoice total rounded to the nearest krona, so the residual is always strictly
* under 1 krona. A real shortfall is ≥ 1 krona, so this band can never hide one.
*
* NOTE: deliberately looser than `ORE_TOLERANCE` (0,005). That constant is
* float-equalisation; this is an accounting policy band. Keep them distinct:
* never reuse `ORE_TOLERANCE` for settlement rounding.
*/
export const ORE_ROUNDING_SETTLEMENT_MAX = 1.0
/**
* True when two amounts are equal to the öre (within `ORE_TOLERANCE`). Prefer
* this over `a === b` for money: direct equality on floats fails on drift.
*/
export function equalOre(a: number, b: number): boolean {
return Math.abs(a - b) <= ORE_TOLERANCE
}
/**
* True when `n` is zero to the öre. Useful for "fully settled / balances"
* checks where accumulated float drift would defeat `n === 0`.
*/
export function isZeroOre(n: number): boolean {
return Math.abs(n) <= ORE_TOLERANCE
}
/**
* Sum a list of SEK amounts with a single öre-round applied to the total.
*
* Rounding once at the end (rather than per addend) matches how a verifikat is
* totalled and avoids compounding half-öre rounding across many lines.
*/
export function sumOre(values: readonly number[]): number {
return roundOre(values.reduce((acc, v) => acc + v, 0))
}