swaitsandClaude Fable 5.1
1fbc1383cb
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
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. 122 MCP tools (2026-10-28), 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.
- About 2,950 tests across the two workspaces (2026-10-29): 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, a local run (paused for development until the P12 max-testing pass, D-33; not a CI job, D-59); fuzzing via cargo-fuzz (11.5M+ executions, zero crashes), weekly in CI.
- 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 replaced
(docs/capability-parity.md); the books cut over on 2026-10-20 and the
Sheet is frozen as of 2026-10-11. The remaining work, its order and its
hand-off are plan/served.md section 8.0; the destination is one
installed app for Mac, Windows and Linux (P11), then the hosted service
the plan describes and does not build. Today the agent path runs on
Linux: tokens live in the OS keyring (the Secret Service on Linux, the
login Keychain on macOS, the Credential Manager on Windows; the last two
are written and compiled by the CI matrix, P11a step 0, and not yet
proven on a machine of ours); the rest of the host is Unix-only, so
Windows is WSL2 only until its sockets and data root are ported.
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
(Linux today. On macOS the same line installs and sets up, and the viewer runs; connecting an agent uses the login Keychain, new with P11a step 0 and proven only by the CI matrix so far. On Windows run it inside WSL2.)
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: 129 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 shared read-only view: the CPA package, the invoice PDF, Needs attention
crates/ledger-vault/ # the TIN vault (XChaCha20-Poly1305 under the book's key)
crates/ledger-gui/ # the viewer: read-only, live (egui)
verify/lean/ # the accounting laws as Lean theorems (`just prove`)
bookspec/ # the formal accounting specification: checker, runner, examples (P13)
fuzz/, oracle/ # fuzz targets; the GnuCash differential (`just oracle`)
deploy/ # the self-host recipe and system unit (P9a)
site/ # wanderbooks.ai and install.sh
docs/ # requirements, architecture, oracle, parity, testing, verification, spec, glossary
plan/ # served.md (the plan), STATUS.md, roadmap.md, HANDOFF.md, gui.md
AGENTS.md # operating manual for agents working here
License
MIT OR Apache-2.0. See LICENSE-MIT and LICENSE-APACHE.