swaits
4e71cf6320
A bad debt is deducted on evidence it is worthless (Treas. Reg.
§1.166-2), so the store will not journal one without it:
Store::write_off_invoice takes the evidence as bytes to file or as an
attachment already filed, and files it in the same call — a
receipt.attached on the write-off's entry and an attachment.linked to
the invoice (rules.md B-41). With no evidence it refuses, journaling
nothing.
The entry (Dr 6990 Bad Debt Expense / Cr 1200) and its evidence are
journaled after the engine's whole check and after the feature gate: the
new event type invoice.written_off needs documents_v2, so an older
version stops at the declaration rather than reading a written-off
invoice as still owed (B-27, D-52). Its payload is the invoice, the
entry, the day, the amount and the reason; replay tags the receivable
line WriteOff, and the projection keeps no written-off figure — it is
the tagged lines' sum (B-38).
`meta::invoice_written_off_of` reads and writes the payload; the replay
fuzzer draws the type.
8.0.6: (1) `books_written_under_older_rules_still_open` hand-writes the
new event and its entry through JournalWriter and still opens, with the
figures tailing; (2) a new fixture old-books/p4_s7_before was written by
main 4cad2cfc (the version before this unit) through the old-books-writer
harness — a numbered invoice with terms and snapshots, a partial payment,
a voided invoice and a paid bill — with its expected.json; this version
opens it and reports the same figures, the viewer included; (3) the
cut-over entry is in format_upgrade.rs's books_p2_served_cut_over_whole;
(4) documents_v2_is_its_own_feature is green and the event gate's arms
pass; (5) no figure moves: no golden changed (the previous version's
expected.json is the comparison); (6) merge does not need the owner's
go-ahead; the live books refuse the new write until he gives it.
Tests: write_off_waits_for_documents_v2, write_off_replays_and_projects,
write_off_without_evidence_is_refused; arap_props.rs gains WriteOff.
wanderbooks
Canonical double-entry bookkeeping, rebuilt from scratch. The engine is verified against oracles, parity is tracked automatically, and the primary interface is AI-first: you talk to an agent, the agent drives the books through MCP. Self-hosted, no rent.
What it is
ledger-core— the semantics engine. Exact decimal money, five account types, balanced journal entries, immutable posted log with reversing entries, trial balance, P&L, balance sheet, the statement of cash flows (direct method, with the reconciliation and noncash schedules), fixed-asset register with straight-line depreciation.ledger-store— durable storage. The source of truth is an append-only, hash-chained JSONL journal; SQLite is a disposable projection rebuilt from it; receipts live in a content-addressed blob store. Drafts are durable, corrupt projections self-heal.ledger-mcp— the AI-first interface. 118 MCP tools, served by the books server (wanderbooks server) on the data root's local sockets and reached through the agents' bridge (wanderbooks mcp --book ID): draft → preview → post workflow, server-side receipt policy (>$25), anti-splitting detection, asset management, digest for human review, plus read-only resources for dashboards.ledger-import— QuickBooks interop. Import bank/credit-card CSVs and chart-of-accounts CSVs; export IIF journal entries (for QuickBooks Desktop) and XLSX reports.ledger-config— the company settings in a books dir'swanderbooks.toml.ledger-gui— the viewer: a read-only, live window on the books for owners and their accountant (egui). Answers first (cash, runway, profit, what needs attention), then every number drills down to its lines, its entry, the rendered receipt, and the journal history. Follows the journal live: a change the agent makes appears in milliseconds.--demoopens a realistic demo company.
Verification
This is the storytold way applied to accounting: agents verify against oracles, never ship what they haven't demonstrated.
- 190+ workspace tests: invariant tests encoding accounting law, golden-file report snapshots, property tests (proptest), end-to-end MCP tests through a real books server.
- Formal proofs of the accounting laws (
just prove,docs/verification.md). Kani model-checks the engine's arithmetic kernel exhaustively within bounds. Lean 4 proves that, after any sequence of commands, the trial balance balances, the accounting equation holds, posted entries are forever, closed periods stay frozen, and a close moves exactly the net income to equity. The first pass found three engine bugs that every test, fuzzer, and mutant had missed: negative amounts accepted, and two crashes on oversized amounts. It also caught a soundness bug in the model checker itself. - Mutation testing via cargo-mutants; fuzzing via cargo-fuzz (11.5M+ executions, zero crashes).
- GnuCash is a behavioral cross-check, never the authority and never a code source (clean room, MIT OR Apache-2.0). Accounting principles, proved, are the spec. Where any other program disagrees, we work out from principles who is right.
Status
Parity is 12 of 12 against the spreadsheet workflow it replaces
(docs/capability-parity.md). The parallel-run plan
(docs/parallel-run.md) is written; the Google Sheet stays the system of
record until a clean month and explicit cutover approval.
See plan/STATUS.md for where things stand and
plan/roadmap.md for where it's going.
Quickstart
cargo test # whole suite
cargo run -p ledger-gui -- --demo # the viewer, on a demo company
New books, one command (installs Rust and wanderbooks if needed, makes the
books' private folder, starts books called acme and lets Claude Code reach
them; nothing needs sudo):
curl -fsSL https://wanderbooks.ai/install.sh | sh -s -- acme
Already installed, three commands: wanderbooks setup, wanderbooks books create acme, wanderbooks connect claude --book acme (or connect codex).
Then talk to the agent; wanderbooks gui acme shows the books, and its
Books menu backs them up, restores, starts new books and closes them.
Developing
Every tool the recipes use (Rust, just, Kani, Lean, cargo-mutants,
cargo-fuzz, Node for deploys) is pinned in mise.toml:
mise install
just # lists the recipes: check, build, prove, demo, ...
Layout
crates/ledger-core/ # engine: money, accounts, journal, ledger, reports
crates/ledger-store/ # journal + SQLite projection + blob store
crates/ledger-mcp/ # MCP server: 118 tools, resources, handbook, receipt policy
crates/ledger-import/ # QBO CSV import, IIF/XLSX export
crates/ledger-config/ # wanderbooks.toml company settings
crates/ledger-cli/ # `wanderbooks`: the one executable (every mode)
crates/ledger-host/ # the host, the agents' bridge, the owner's commands
crates/ledger-package/ # The CPA package and the 1099 worksheet (server and viewer)
crates/ledger-gui/ # the viewer: read-only, live (egui)
docs/ # requirements, architecture, oracle, parity, glossary
plan/ # STATUS.md, roadmap.md
AGENTS.md # operating manual for agents working here
License
MIT OR Apache-2.0. See LICENSE-MIT and LICENSE-APACHE.