Commit Graph
4 Commits
Author SHA1 Message Date
swaitsandClaude Opus 5.5 d0490bf106 test(core): every surviving mutant killed or argued equivalent
check / check (push) Canceled after 0s
Max-testing pass, step 8. The final mutation run left 112 survivors
(89% caught). Three agents triaged them by file, by the playbook's
table: spec the boundary then test it, a law rather than one more
pinned value, assert the real value, never weaken a test. Every expected
value is hand-computed.

- reports.rs (35): 28 killed, chiefly cash flow (inclusive start date,
  each line's sign and label, a loss on disposal moving to investing,
  financing designation), general ledger and members' equity date
  boundaries, and the balanced() checks (a real report nudged by a cent
  must stop balancing). 7 equivalent: four >/>= after an early return on
  zero; two in dead code (removed in this commit); one sign of a zero
  cleaned on output.
- ledger.rs, kernel.rs, journal.rs, money.rs (52, plus one new): 49
  killed, including every replay_* mutant at the core level (ids,
  accumulation, status, vendor tags, out-of-order refusal), FX rates,
  0%/100% deductible boundaries, a dividend sweep with no income, the
  legacy member rounding at close, a bill paid on its own date, a
  liability-account reconciliation, mixed-currency entries (via serde),
  ISO 4217 minor units, Display/Debug. 3 equivalent: zero refused before
  a </<= check; a period whose end is in a closed period refused earlier;
  columns(0).
- schedules, tax, analysis, payouts, assets, form1099 (25): 23 killed
  (schedule length 1-600, recurring end on its start, frequency parsing
  and stepping, cost of goods in tax net, a zero payout, disposal on the
  purchase date, quarter starts, labels); 2 equivalent (zero adds zero;
  days_held is provably >= 1).

Two small production cleanups the triage surfaced: kernel::columns(0)
returned a negative-zero credit that would print "-0" (regression
a_zero_movement_has_no_negative_zero_column, shown to fail before); and
cash_flow computed a book value it never used.

Spec lines added where a boundary wasn't specified (cash flow's
inclusive start and line signs, members' equity start date, payout with
no deposit, disposal on the purchase date, bill paid on its own date).
`just mutants` now runs core and store tests (the store's replay tests),
not the whole workspace, which rebuilt the viewer for every mutant.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
2026-10-13 17:00:45 -06:00
swaitsandClaude Opus 5.5 ad572ae89d docs(spec): every rule traced to an authority; public-domain sources vendored
Stephen asked that specs come from recognized documents, not from
anyone's memory. There is no single US bookkeeping bible; authority is
layered, and this records it:

- docs/spec/sources/: verbatim excerpts (whitespace normalized), each
  with URL, retrieval date, and the SHA-256 of the fetched file, of
  public-domain texts: Pacioli's 1494 treatise in Geijsbeek's 1914
  translation (double entry, the trial balance, one money, write only
  forward, correct by opposite entry, close into capital); IRS Pub. 583,
  538, 946, 15; the 1099-MISC/NEC instructions (2025 and 2026); 26 U.S.C.
  §6041, §6041A, §704; Treas. Reg. §1.263(a)-1(f) and -4(f); Notice
  2015-82; Rev. Proc. 98-25; Form 1065 instructions; 17 U.S.C. §105. The
  excerpts were extracted by matching each passage against the fetched
  file, so none can contain text the source doesn't.
- docs/spec/rules.md: the rule catalog, B-1 to B-22. Each rule says
  AUTHORITY, CONVENTION, or DECISION; cites its sources (FASB's
  Codification and Concepts Statement 8 and OpenStax quoted briefly,
  never copied: copyright and CC BY-NC-SA); and names the code that
  enforces it and the tests and proofs that check it.
- Spec blocks in the code now carry SOURCE: lines into the catalog;
  AGENTS.md makes sourcing rule 0 of the formal-methods bar.

Corrections the sources turned up: the de minimis limit is $500 in the
regulation and $2,500 by Notice 2015-82 (both now cited); 1099
thresholds after 2026 are inflation-indexed, so the engine's flat
$2,000 for 2027+ is an open question (B-19). Unverified ASC paragraphs
(360-10-35-4, 340-10, 230-10-45-10, 606-10-55-37B, 210) are listed in
docs/spec/README.md until someone with a FASB basic-view login reads
them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
2026-10-13 12:18:57 -06:00
swaitsandClaude Opus 5.5 0340f316ee fix(core): due-today is Current; odd cents split by largest remainder
Max-testing pass, step 2: two spec decisions Stephen confirmed
(2026-10-13), each test-first.

Aging (arap::aging_bucket): a document due today was "1-30 days past
due"; it is Current, since past due starts the day after (QuickBooks'
convention). Spec in the doc comment. Boundary examples at every edge
(due today, 1, 30, 31, 60, 61, 90, 91 days) fail on the old code. A
property: the balance lands in exactly one bucket, and time only ages
it.

Member splits (periods::allocate): the last member absorbed every odd
cent, so the same partner always got or lost it. Now largest remainder:
each share rounded toward zero to the cent, leftover cents to the
largest remainders, ties to the earlier member, a loss the negation of
the gain. The core is a new kernel function, kernel::apportion,
allocation-free so Kani proves it (n <= 3): apportion_is_exact (it
succeeds exactly when the shortfall is under a unit per part; then the
parts sum to the whole, each gains 0 or 1 unit, one may take the
sub-unit fraction) and apportion_is_fair (never a unit to a part while
a larger remainder goes without). Kani found an off-by-one in the first
version: a shortfall of n units plus a fraction was accepted. Native
regression apportion_refuses_a_shortfall_of_a_unit_per_part_or_more.
Properties at Decimal (2,000 cases, up to 5 members): conservation,
within a cent of each exact share, fairness, sign symmetry; they fail on
the old rule. Bridge: apportion agrees on i64 and Decimal.

Contract: closes journaled before this change replay exactly. New
member closes journal "rounding": "largest_remainder"; journal lines
without it replay as CloseTo::MembersLastAbsorbs, the old rule
(periods::allocate_last_absorbs, pinned by
closes_journaled_under_the_old_rule_replay_with_it). The members'
equity statement isn't journaled and uses the new rule.

Open gap: Lean proof of apportion's sum law for any n (needs a
permutation lemma on the ranking); Kani covers n <= 3, properties n <= 5.
The Lean closing theorems already hold for any split summing to the
net.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
2026-10-13 12:10:55 -06:00
swaitsandClaude Opus 5.5 3609bf065e feat(core): prove the accounting laws (Kani + Lean); fix three engine gaps
The money arithmetic every invariant rests on now lives in one kernel,
ledger-core/src/kernel.rs: signing a line, totals, net, per-account
movements, reversal, normal balances, trial-balance columns, closing
lines, and the rounding plug for member splits. It is generic over a
checked `Amount` trait. The engine runs it on Decimal (validate,
movements, reverse_entry, account_balance, close_period_to, allocate,
trial_balance): there is one copy of the arithmetic, and it is the one
under proof.

Three layers, docs/verification.md maps every law to its proofs:

- Kani (src/proofs.rs): 17 harnesses prove the kernel at i64 for every
  input up to 4 lines over 3 accounts. An entry is accepted exactly
  when it is two or more positive, in-range lines whose debits equal
  credits; accepted entries net to zero; grouping by account loses
  nothing; a reversal mirrors and cancels its original; trial-balance
  columns balance iff the books net to zero; closing lines zero their
  accounts and a close balances however the net is split; the plug
  makes parts sum to the whole. No panics, no overflow. kani::cover!
  shows the proofs are not vacuous.
- Lean 4 (verify/lean): 24 headline theorems for books of any size. The
  ledger is a state machine (add account, draft, post, reverse, open,
  close), and in every reachable state the books net to zero, the trial
  balance balances (as of any date), and the accounting equation holds.
  Posting only appends ("posted is forever"), closed periods are
  frozen, a close zeroes revenue and expenses and credits exactly the net
  income, and period statements add up. Audit.lean shows standard axioms
  only, no sorry.
- Bridge (tests/kernel_bridge.rs): the Decimal and i64 kernels agree.

What the proofs found (each one missed by every test, fuzzer, and
mutant):

- The engine accepted negative line amounts; only MCP refused them. Now
  NegativeAmountLine: direction is the side's job.
- Summing lines near Decimal::MAX panicked. Lines are now capped at one
  quadrillion and ten decimal places (AmountOutOfRange), which keeps
  every realistic sum exact, and the kernel's sums are checked.
- FX conversion (foreign_amount * fx_rate) could panic the same way; it
  is now a checked multiply.
- Kani itself: 0.68 mis-models symbolic-length copy_from_slice
  (model-checking/kani#4904) and reported a reversal that doesn't net to
  zero. The counterexample, replayed natively, passes, and a 15-line
  standalone crate reproduces the bug. Harnesses avoid bulk copies, and
  a should_panic canary will flag the upstream fix.

`just prove` runs it all (Kani memory- and time-capped, fails on an
unsatisfiable cover or a non-standard Lean axiom). AGENTS.md now makes
formal coverage part of every core change.

Also, docs: GnuCash is *an* oracle, never *the* oracle (Stephen). The
spec is accounting principles, proved. Golden files are recomputed from
principles. External implementations (GnuCash, the old Sheet, QBO/Xero)
are cross-checks whose disagreements get adjudicated, never obeyed.
docs/oracle.md gains "Who is right"; AGENTS, README, architecture,
roadmap, parity, and STATUS are reworded to match.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
2026-10-13 11:12:13 -06:00