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.
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.