ledger-config: parse gets a sourced spec. A fiscal year starts on the
first of a month (IRS Pub. 538); tax_classification is read by whole
words (Treas. Reg. 301.7701-3, Schedule C instructions; "business corp"
no longer reads as an S corp, "corporation or S corporation" is refused);
duplicate or blank members and shared capital accounts are refused; a
negative or non-grammatical receipt threshold is refused; codes trimmed.
tests/spec_config.rs (65 spec-blind tests, 14 properties), fuzz target
fuzz_config_parse (weekly). Mutation: 55 of 55 viable caught (from 25/38).
The receipt policy moves to ledger-config, with one loader
(effective_receipt_policy) and one decimal grammar, so the server and
the viewer enforce and show the same rule (the viewer had its own: only
expense-like debits, a silent $25 default, and no config.json).
ledger-mcp: a module spec (MCP 2025-06-18 tools, JSON-RPC 2.0, the
operating contract). Amounts in are exactly -?digits[.digits]; a number
that is one account's code and another's id (vendors, classes alike) is
refused, not guessed; the threshold is validated at startup. Fixed:
add_line with a bad class journaled the line before refusing;
profit_and_loss_by_class ignored `class`; aging buckets said "0". A wire
in front of rmcp answers malformed JSON with -32700 and invalid requests
with -32600 and their id (rmcp dropped the first, omitted the id).
tests/spec_mcp.rs (26 spec-blind tests: every tool's result against its
own outputSchema, a random-call state machine checking the journal is
untouched by every refusal, amount grammar, previews, the receipt policy).
ledger-gui: money, accounting, and dollars never round (they rounded to
cents, banker's style); export file names avoid Windows device names,
trailing dots and spaces, empty names, and 255-byte overflow; specs on
attention, history, fuzzy search, and axis ticks.
ledger-core: the lifetime profit_and_loss is renamed unclosed_earnings
(docs/testing.md #3).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
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
egui/wgpu app for owners and their accountant: Overview, Cash, Profit,
Transactions (with rendered receipts and journal history), Reports
(statements with interval columns, comparisons, drill-down), Accounts,
Documents, Company, Journal; Ctrl+K palette; back/forward; light/dark.
Follows the journal live (~30 ms from write to screen). --demo opens a
deterministic demo company, also used for screenshot tests.
Engine: ledger-store Snapshot (read-only, incremental, tolerant of a
half-written tail); ledger-core analysis (intervals, balance series,
P&L by interval, cash flows); ledger-config extracted from ledger-mcp
with the full company profile and cash_accounts.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu
swaitsandClaude Opus 5.5