core: no entry posts a fraction of a cent; verify compares whole ledgers

CI's run of the store refusal property found a payroll run that posted
$65.27794: the employer tax was passed in unrounded and nothing refused
it, though rules.md B-3 already says a ledger in one money holds no
fractions of its smallest unit. Sums of it then differed in scale
between journal replay and the SQLite read-back.

- Ledger::post_entry refuses any line finer than its currency's ISO 4217
  minor unit (FinerThanMinorUnit), whatever made the line: payroll,
  closes, disposals. add_line refuses it up front. Older journals replay
  as booked through replay_post_entry. Spec tests for the kernel's
  ten-place limit now run on the replay path.
- The property's body is now run_ops, so failing sequences become named
  regression tests (regression_payroll_with_a_fraction_of_a_cent). The
  generator rounds payroll tax to the cent, as callers must.
- Ledger derives PartialEq and gains differs_from; Store::verify compares
  the live ledger with the journal replay in full (drafts, documents,
  schedules, periods, settings), not just balances, and names the parts
  that differ. The property checks the ledger its commands built against
  that replay and against the reopened books.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

docs/testing.md

@@ -15,7 +15,8 @@ the store's journal safety; the other crates come next (gap list).
 | Compatibility contracts | journals written under older rules must open (1) | `ledger-store/tests/store.rs` (`books_written_under_older_rules_still_open`) | `just check` | <1s | every change |
 | Properties | laws over all inputs (2) | `properties.rs`, `spec_*.rs`, `kernel_bridge.rs` | `just check` | seconds | every change |
 | Metamorphic | scaling, reversal, ordering invariance (2) | `spec_reports.rs` | `just check` | seconds | every change |
-| Refusal law (store) | a refused command never reaches the journal (2) | `store.rs` `refused_commands_never_reach_the_journal` | `just check` | ~15s | every change |
+| Refusal law (store) | a refused command never reaches the journal; the books reopen to the same reports (2, 3) | `store.rs` `refused_commands_never_reach_the_journal` | `just check` (`STORE_CASES=5000` deeper) | ~20s | every change |
+| Fault injection (store) | a full disk or a cut-off append leaves whole, openable books (1) | `ledger-store/tests/faults.rs`, `store.rs` (`power_loss_at_any_byte_of_the_last_append_is_recovered`) | `just check` | ~5s | every change |
 | Model-based stateful | the Lean state machine, transcribed (3) | `tests/model.rs` | `just check` | ~3s | every change |
 | Differential: Decimal vs i64 | the kernel at two types (3) | `kernel_bridge.rs` | `just check` | <1s | every change |
 | Differential: GnuCash | another implementation, adjudicated (3) | `tests/oracle_gnucash.rs`, `oracle/gnucash/` | `just oracle` | ~2 min | weekly |
@@ -23,7 +24,7 @@ the store's journal safety; the other crates come next (gap list).
 | Fuzzing | crash, hang, broken books (4) | `fuzz/fuzz_targets/`, corpora in `fuzz/corpus/` | `just fuzz <target> <secs>` | 10 min each | weekly |
 | Miri | undefined behavior in our use of dependencies (4) | the core's unit, bridge, invariant tests | `just miri` | ~2 min | on demand |
 | Golden | `tests/golden/fixture_company.json` (5) | `invariants.rs` | `just check` | <1s | every change |
-| Benchmarks | a budget (6) | `benches/books.rs` | `just bench` | ~1 min | none (no budget yet) |
+| Benchmarks | a baseline (6) | `benches/books.rs` | `just bench` | ~1 min | none (no budget, by decision) |
 | Mutation | can the tests fail? | `ledger-core` | `just mutants` | ~12 min | weekly |
 
 CI: `.github/workflows/check.yml` runs `just check` on every push;
@@ -39,7 +40,10 @@ Layer 1). The van depreciation golden was replaced on 2026-10-13 by a
 hand computation (`van_schedule_is_the_hand_computed_one`) after every
 row was checked against it.
 
-## Benchmarks (baseline 2026-10-13, no budget yet)
+## Benchmarks (baseline 2026-10-13)
+
+No budget, by decision (Stephen, 2026-10-13: the books do little work
+and are fast enough). The numbers are a baseline to spot a regression.
 
 40-account chart, two-line entries across a year, on the development
 laptop:
@@ -83,7 +87,7 @@ say so in their doc comments.
 
 | Technique | Status | Trigger |
 |---|---|---|
-| Fault injection | SKIP for the core (no I/O, clock, or network) | the first I/O or clock in `ledger-core`; the store is next in scope (torn writes, full disk) |
+| Fault injection | SKIP for the core (no I/O, clock, or network); DONE for the store's journal (full disk, cut-off append) | the first I/O or clock in `ledger-core` |
 | Integration | SKIP for the core (no collaborators) | the core gains one; covered at the store and MCP layers |
 | End-to-end | SKIP for the core (a library) | MCP stdio tests cover the journeys |
 | Security properties | SKIP for the core (no roles, no secrets) | the first permission concept, or a secret-bearing field |
@@ -91,4 +95,4 @@ say so in their doc comments.
 | Lean: apportion's sum law for any n | OPEN | Kani covers n <= 3, properties n <= 5; needs a permutation lemma |
 | ASC paragraphs not yet read | OPEN | ASC 360-10-35-4, 340-10, 230-10-45-10, 606-10-55-37B, 210: needs a FASB basic-view login |
 | GnuCash's own close | OPEN | the oracle books closes as ordinary entries; comparing GnuCash's Close Book needs its Scheme API |
-| Store, import, MCP, config, GUI crates | NEXT | in that order, the same playbook |
+| Store: differential replay vs. projection, concurrency (writer + snapshot reader), benchmarks at 10k, mutation | NEXT | then import, MCP, config, GUI, the same playbook |