Max-testing pass, rank 3. tests/model.rs transcribes the Lean ledger
state machine (verify/lean/Wanderbooks/Ledger.lean) into the plainest
Rust with the same observable behavior: lists of accounts, drafts,
posted entries, and periods. Random command sequences (add account,
draft, add line, a balanced pair of lines, post, reverse, create period,
close), weighted toward commands that interact, run against both; after
every command the engine and the model must make the same accept/refuse
decision and agree on the posted log line for line, the chart, drafts,
periods, ids, and every account's balance. 2,048 sequences of up to 60
commands; about 3s.
Honest about its first version: it agreed vacuously. Counting accepted
commands (MODEL_STATS=1) showed zero posts and zero reversals: random
lines never balance. A balanced-pair command fixed it (now ~150 posts,
~100 reversals, ~200 closes per 512 sequences). Shown to have teeth:
letting the model reverse an entry twice fails in 0.03s.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX
swaitsandClaude Opus 5.5
8a9a2485cf