An engine-free reference model with exact decimals replays an example's
entries, reversals, close, bills and invoices and computes its
trial_balance, balances, profit_and_loss and entry figures from the
rules' symbolic forms (signed sums, normal sides, A = L + E + (R - X),
net income), and checks that each refusal an example expects is justified
by its rule (debits differ from credits, an amount is not positive, finer
than the minor unit, an entry already reversed, a date inside a closed
period). An example whose figure disagrees fails the specification's
build before any engine is consulted; what the model cannot derive is
reported as skipped, never as passed.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp
bookspec/spec holds the first edition: the model and the five laws
(00-model.md) and one file per area, each B-rule a section with its
status, a MUST/MAY statement, sources pinned either to a vendored source
with a verbatim quotation or to an exact external paragraph, its symbolic
form, its examples and its applicability. B-39, B-40, B-43 and B-45 are
reserved sections (allocated, not yet stated in rules.md); B-44 is stated
in rules.md and now carries its bookspec id and CONVENTION status.
Eight new examples show the laws that had none, each figure worked by
hand: an unbalanced entry is refused (Pacioli ch. 36, Pub. 583), a
negative or zero line is refused, a fraction of a cent is refused (ISO
4217), a child account takes its parent's type, the trial balance and the
accounting equation on one small book (cash 6550.25 = loan 2000 + capital
5000 + (sales 750.50 - rent 1200.25)), a reversal leaves the original
standing and a second reversal is refused, a close sweeps revenue and
expenses into Retained Earnings (3999) and the closed quarter takes no
late entry, and cents add exactly. The refusal vocabulary gains
unbalanced, negative_amount, zero_amount, too_few_lines,
finer_than_minor_unit, parent_type_mismatch, already_reversed and
period_closed; a refused entry may carry a non-positive amount.
The checker's spec.rs fails the build on a rule without its section, a
statement without MUST/SHOULD/MAY, a pin that is not verbatim in its
vendored source, examples that differ from the catalogue, or more than 60
pages.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp
The first edition's five laws (debits equal credits; the accounting
equation; the trial balance balances; net income articulates to equity;
the cash-flow sections sum to the change in cash) are theorems in
bookspec/lean, ported from verify/lean (Basic, Entry, Statements, Closing,
Ledger under namespace Bookspec) and restated by name in Laws.lean, each a
statement about every reachable state of the books. Audit.lean prints
their axioms; the checker's lean.rs test fails on a sorry, a law not
audited, or any axiom beyond propext, Quot.sound and Classical.choice.
Money is Int, the exact count of the smallest unit: every law is a law of
addition, so the model is faithful to exact decimals.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp
The fourth of the paused branches: Ledger::write_off and the bad_debts
control role, invoice.written_off with its evidence filed in the same
store call, books.write_off_invoice, the write-off on the timeline and
in Needs attention, Lean writeOff_within_bounds, rules.md B-41 and the
bookspec examples. Twenty-eight files conflicted with the S4.4, S5 and
S6 merges; resolved as plan 8.0.2 says, keeping both sides' appends with
their seams restored, and: the scope table at 125; S7's law numbered 37;
B-41 placed before B-42; the handbook's step 4 and recovery procedures
folded into the one invoices-and-bills section; S7's wire tests in their
own module with the confirm S4.4's contract needs; S7's copy of the
payment steps dropped (S6 replaced them with Ledger::settle) and its
write-off journaled through S6's journal_auto_lines; in the old-books
fixture S7's hand-written write-off moved to a second invoice, since
S6's hand-written payment settles invoice 1 in full.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp
One payment had to name one document and could take no discount or
processor fee, so paying several invoices from one deposit meant several
entries and the fee had nowhere to go. This adds the kernel's exact
settlement arithmetic (applications total, net deposit), a Ledger::settle
that posts one entry for a customer's or vendor's documents, and the gross
method and gross fee A-8/A-4 chose.
- kernel::settle: sum(cash)+sum(discounts)=applications, sum(cash)-fee=
deposit, None on overflow or a negative deposit. Kani settle_is_exact
plus the Decimal bridge.
- Ledger::settle / settlement_lines: one party and one kind per
settlement, one application per document, each cash+discount within
payment_room; a discount within the terms (discount_max and
discount_by) needs no reason, a larger or later one does; a bill with
an asset line is refused with D-49's remedy; a fee is a customer
payment's only and posts gross.
- Rows are payment lines in application order, then discount lines, the
fee line and the cash line, so a journaled event's line indices are
stable; replay tags exactly the line an event names and leaves an
unmatched line unattached (never refuses).
- receive_payment_with and pay_bill_with become one-application calls.
- Roles: sales_allowances (4100), purchase_discounts (6995) and
payment_processing_fees (6060), constants used on demand but not added
to control_accounts() (existing charts may use those codes for other
things).
- Lean: settle posts through Step.document, so settle_posts_a_document_step
and settle_unattached, no new constructor; both in Audit.lean.
- Core tests: bill_on_terms_with_discount, late_discount_needs_a_reason,
discount_on_an_asset_bill_is_refused_with_the_remedy,
a_fee_posts_gross_to_receivables_and_net_to_the_bank,
a_settlement_names_its_lines_and_refuses_a_document_twice, and
equipment_bill_payment_is_investing_cash in the cash-flow suite.
- Bookspec B-42 is stated, with its id BS-arap-6; the catalogue and index
now record it as CONVENTION.
just check and just prove green.
rules.md B-41 states the write-off: the direct method the owner chose
(A-5), Dr 6990 / Cr 1200 with the receivable tagged, at most what is
owed and at most the least owed from that day on (a partial write-off as
§1.166-3(a) allows), refused on cash-basis books (§1.166-1(e)), its
evidence filed in the same call (§1.166-2(a)); bills are never written
off (ASC 405-20-40-1); and a recovery is not a new movement (D-49): the
same year, reverse the write-off and record the payment; a later year, a
plain entry to a bad-debt-recoveries revenue account, the invoice staying
written off (IRC §111).
bookspec states B-41 for the first time and gives B-38 its example: two
new examples, bad-debt-direct-write-off (two partial write-offs of one
invoice, the balances and the trial balance worked by hand) and
arap-hand-control-posting-refused (a hand line an earlier version wrote
replays, the same line written today is refused). The example schema
gains the dated write_off event, lets a refused entry say so (an entry
posts whole or not at all; older and refused never combine), and its
refusal vocabulary gains untagged_control_line, B-38's control guard.
The registers: docs/architecture.md names the new tool group;
docs/receipt-store.md lists invoice.written_off and what replay does with
it; docs/parity.md records the slice (no row changes status, the floor
stands); docs/testing.md records every test and what P12 must mutate;
docs/verification.md the two Lean theorems and what they cover.
No figure moves: no golden file changed.
`accepted` and `refused` are a command's (and `refused` a period's): the
schema now refuses either on a query that does not take it, as the loader
already did, instead of letting a malformed example reach the runner.
The no-op table walk in the same branch goes with it.
Every rule of `docs/spec/rules.md` now has one bookspec identifier,
`BS-<area>-<n>`: eleven areas (entry, ledger, statement, period, partner,
asset, prepaid, arap, revenue, 1099, format), numbered in B-rule order
within its area. The table is `bookspec/spec/rules-index.md`, and each
stated rule carries its id under its heading in `docs/spec/rules.md`, so
a reader of either can find the other.
rules.md's DECISION status becomes bookspec's CHOICE: the specification
names the options and an engine declares its pick (`Claims::with_choice`),
which is what an example already meant by `status = "CHOICE"`. B-39 to
B-45 are allocated in `plan/served.md` 8.0.3 and not yet stated: they
carry an id and an area and no status, so a later unit fills them in
without moving anyone else's number.
The catalogue names the examples that demonstrate each rule (56 files,
each under at least one rule) and the rule each refusal reason belongs
to. A rule with no example cannot be claimed: a claim needs evidence.
`docs/architecture.md`, `docs/testing.md` (tests and the For-P12
mutation targets) and `docs/parity.md` record the new shape; the
bookspec README points at the checker, the runner and the adapter.
bookspec is a specification first: every rule normative and sourced,
every rule demonstrated by concrete examples, and any accounting engine
checked against them through one interface (D-34). This moves the
examples' schema out of the test that happened to parse them and makes
the interface explicit.
- `bookspec/checker` (its own workspace, inside this repository until
the harness is stable): `Example`, `Setup`, `Event`, `Expect`, `Query`,
`Refusal` and the TOML parser, every structure `deny_unknown_fields`,
with `Example::from_toml` checking the cross-field shape (closed lists,
exact decimal amounts, dates, one event kind, `reverses` counting from
1, the shares summing to 1, commands accepted or refused and not both).
- `Engine` (`load`, `apply`, `query`, `claims`) and `Refusal { rule,
reason }`; the refusal's rule is the bookspec identifier, so a refusal
names the rule it belongs to. `Claims` also carries the option an
engine picks for a CHOICE rule.
- `bookspec/runner` drives any `Engine` through the examples and reports
per rule: pass, fail, not claimed. It compares the answer itself; an
engine is never asked whether it agrees with itself.
- `crates/ledger-core/tests/bookspec.rs` is the wanderbooks adapter over
`Store`: the loader parses through the checker, its own checks are
unchanged, and the new `the_runner_reports_every_claimed_rule_green`
runs all 56 examples through the trait. The IIF appendix is answered
through `ledger_package::export_iif`, the code its own test checks.
- `just check` runs the bookspec workspace's fmt, clippy, rustdoc and
tests too, so an example cannot rot (D-34, Z-17).
The plan's trait has four methods and no path for an example's
`[[changes]]` (a rename, the policy, an asset correction), which post no
entry: `change` is the fifth, required so an engine cannot skip those
examples silently. This is reported to the EM as the one departure.
One money rule holds here too: an answer's figures are exact decimal
strings, never JSON numbers, so no engine can round a cent through a
float.
swaitsandClaude Fable 5.1