swaitsandClaude Opus 5.5
c6faeeb827
The engine only had life-of-ledger P&L and balance sheet totals, so every export labeled with a date range or as-of date (PDF, XLSX, CPA package) printed all-time numbers under that label. Core now has: - profit_and_loss_for_period(start, end, class?) and balance_sheet_as_of(as_of), each with a line per account (StatementLine: code, name, normal-side amount) and exact totals. - Ledger::closing_entry_ids(). Period statements exclude closing entries. A close (Dr revenue / Cr expense / net to Retained Earnings, dated at period end) moves earnings; it doesn't earn or spend. Counting it made a closed period's P&L read as break-even, and made the cash flow show zero net income plus a fake "owner contribution" to Retained Earnings. The as-of balance sheet keeps closing entries: after a close the earnings belong in Retained Earnings, not current earnings. Tests: tests/statements.rs, a two-month fixture with every expected number computed by hand (Jan NI 1,700; Feb 880; balance sheets on four dates; a closed January still reporting 1,700 and a cash flow with one financing line). Mutation-checked: dropping the closing exclusion fails it (0 vs 1,700). Properties: period P&Ls partition a year at any split, and a range's net income equals the change in current earnings across it, with A = L + E on both dates. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu
119 lines
6.5 KiB
Markdown
119 lines
6.5 KiB
Markdown
# Requirements — accounting semantics (Phase 1)
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Numbered requirements for the engine. `R-N` is current scope; `R-FUTURE-N`
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is explicitly out of scope for now but designed for. Agents: if code and a
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requirement conflict, the requirement wins.
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## Core double-entry
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- **R-1 — Balanced entries.** Every journal entry has at least two lines and
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total debits exactly equal total credits (`Decimal` equality, no epsilon).
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Unbalanced entries are rejected at post time with the offending totals.
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- **R-2 — Exact arithmetic.** All money is `Decimal`. No binary floats in any
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money path. No silent rounding: amounts are exact end to end. (Presentation
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rounding, when the UI arrives, is half-up to the currency's minor unit and
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is a display concern only.)
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- **R-3 — Immutability.** Posted entries cannot be edited or deleted. The only
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correction mechanism is a reversing entry (same lines, sides flipped)
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linked via `reversal_of`. Draft → Posted is one-way.
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- **R-4 — Chart of accounts.** Five closed types (Asset, Liability, Equity,
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Revenue, Expense) with fixed normal sides (debit-normal: Asset, Expense;
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credit-normal: Liability, Equity, Revenue). Codes are unique and non-empty.
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Accounts may have parents (hierarchy). Placeholder (header) accounts
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organize the chart and reject postings.
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- **R-5 — Single currency per ledger (day one).** Every account and every
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journal line uses the ledger's base currency. Anything else is rejected,
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not converted. Multi-currency with translation is R-FUTURE-1.
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- **R-6 — Line hygiene.** Zero-amount lines are rejected, not ignored.
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Unknown accounts are rejected. Single-line entries are rejected.
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## Reports
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- **R-7 — Trial balance.** Every non-zero, non-placeholder account appears
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with its debit or credit balance, sorted by code. Total debits must equal
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total credits (the `balanced()` check).
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- **R-8 — Balance sheet.** Assets, liabilities, equity grouped by account
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type. The accounting equation holds exactly: assets = liabilities + equity.
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Current earnings (revenue minus expenses not yet closed to retained
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earnings) are folded into equity so the equation holds on a live book.
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`balance_sheet_as_of` gives the statement as of any date, a line per
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account, counting every entry dated on or before it (closing entries
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included: after a close the earnings sit in retained earnings).
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- **R-9 — Profit and loss.** Revenue and expenses with net income.
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`profit_and_loss_for_period` scopes it to a date range (optionally one
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class), a line per account, and **excludes closing entries**: a close moves
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earnings into retained earnings and must not make a closed period read as
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break-even. The cash flow statement excludes closing entries for the same
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reason. Period P&Ls partition: split a range anywhere and the halves sum
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to the whole, and a range's net income equals the change in current
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earnings across it (property-tested).
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- **R-10 — Canonical snapshots.** `reports::snapshot()` renders the three
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core reports as deterministic JSON (decimal strings, sorted lines, fixed
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keys). Two engines fed the same books must produce identical output. This
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is the oracle interchange format.
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## Auditability
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- **R-11 — Append-only log.** Posted entries are kept in posting order. The
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log plus the chart fully determine every report.
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- **R-12 — Command surface.** All mutations go through `Ledger` methods.
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There is no second way to change the books.
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## Receipt policy (MCP phase)
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- **R-13a — Receipt corrections.** Posted entries are immutable (R-3); their
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evidence is not frozen but is append-only. A receipt is replaced by
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attaching the new one and unlinking the old with a reason; unwanted
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receipts and documents are withdrawn with a reason. Unlinking may never
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leave an entry the policy (R-13) requires a receipt for with none. Every
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step is a journal event; no blob is deleted.
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- **R-13 — Receipt enforcement.** The MCP layer (not the engine — the engine
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stays policy-free) enforces a configurable receipt policy: postings at or
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above a threshold (`require_receipts_above`, default `"25.00"` in base
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currency) must have at least one attached receipt, with per-account
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overrides. `post_entry` with `confirmed: true` refuses with a typed
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`receipt_required` error otherwise. The draft preview always includes the
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receipt checklist (`attached: [...]`, `required_but_missing: bool`), so the
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human sees it before confirming. Full spec: `docs/mcp-interface.md`.
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## Explicitly future work
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- **R-FUTURE-6 — Budgets and scheduled transactions.** (Budgets explicitly
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declined as bloat; scheduled transactions remain future.)
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## Promoted from future (done)
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- **R-? — Cash flow statement** (indirect method). Was R-FUTURE-3.
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`ledger-core::reports::cash_flow` + `books.cash_flow`.
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- **R-? — QuickBooks-compatible import/export.** Was R-FUTURE-4.
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`ledger-import` crate: CSV bank/chart import, IIF and XLSX export.
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- **R-? — Multi-currency (foreign-currency lines).** Was R-FUTURE-1.
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`JournalLine` carries optional foreign currency/amount; `amount` is the
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base-currency equivalent. `Ledger::add_line_fx`, `Ledger::set_fx_rate`.
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Reports work in base currency. (Full per-account currencies and translation
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remain future.)
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- **R-? — Periods and close.** Was R-FUTURE-2.
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`ledger-core::periods`: `create_period`, `close_period` (posts closing
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entry to `3999` Retained Earnings), closed periods reject new entries.
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- **R-? — A/R and A/P workflows.** Was R-FUTURE-5.
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`ledger-core::arap`: customers, vendors, invoices, bills, payments,
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AR/AP aging. MCP tools for the full workflow.
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- **R-? — Bank reconciliation.** Cleared flags on posted lines,
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`reconciliation_report` with uncleared-line detail.
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- **R-? — Payroll (accounting only).** `ledger-core::payroll`:
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`run_payroll` posts one balanced entry (Dr 6100 gross, Dr 6110 employer
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FICA, Cr 2110–2150 payables, Cr cash net); `remit_payroll_taxes` clears
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the payables. No tax tables — the caller supplies every number.
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- **R-? — Tracking classes (divisional P&L).** `ledger-core::classes`:
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`JournalLine.class_id`, `add_class`, `set_line_class` (drafts only),
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`profit_and_loss_filtered`, `profit_and_loss_by_class`. Shared costs are
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split explicitly across lines at entry time.
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- **R-? — CPA handoff package.** `books.export_cpa_package`: zip with
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trial-balance XLSX, general-ledger XLSX (every posted line), P&L and
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balance-sheet PDFs (printpdf, MIT).
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## Non-goals (all phases of the engine)
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The engine never does I/O, networking, wall-clock time sourcing, or UI. It is
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a pure domain library: data in, validated books out.
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