feat(arap)!: documents read their figures from standing lines; control accounts

refuse hand entries (P4b S1, part A)

Plan P4b (D-45), slice S1, the engine half: rules.md B-38.

- ledger-core: every receivables or payables line carries its document
  (Ledger.line_docs: DocRef, Movement, DocTag), written by the document
  commands in the step that posts it, derived on replay from the existing
  document events (the role's account as it stood then; payments by the
  ordinal rule), copied onto a reversal's mirror. Ledger::stands_on;
  doc_state / invoice_state / bill_state (total, paid, outstanding,
  status Open/Partial/Paid/WrittenOff/Void, overdue days) as of any day;
  ar_aging / ap_aging read them, so reversed payments and voids are right.
  The control guard (add_line, add_line_fx, post_entry,
  register_recurring) refuses untagged lines on receivables/payables,
  exempting a reversal's mirror of a legacy line; replay never refuses.
  Bounds (kernel::running_bounds, bounds_kept) on payments and reversals;
  a document reversal never dated before its entry; deposit/payer accounts
  must be cash-like and hold no role. New API: receive_payment_with /
  pay_bill_with (PaymentDetails: instrument, reference), void_document /
  check_void_document, control_check, payments_recorded,
  standing_payments, replay_reverse_entry. Invoice.amount_paid/status
  remain only as derived caches for the MCP layer until part B.
  cashflow bill_splits reads payments from the tags.
- ledger-store: journal feature document_standing (D-39 gated) for a
  payment accepted only because an earlier one was reversed;
  receive_payment_with / pay_bill_with (instrument journaled as
  entry.instrument_set, reference in the description), void_document;
  replay uses replay_reverse_entry; schema 15 drops the projection's
  amount_paid/status. Fixture p4-arap-before + golden figures written by
  the version before S1, adjudicated in arap_standing.rs.
- ledger-gui: party card, cash "coming up" and company owed totals read
  doc_state as of today (late from the derived state).
- Lean Documents.lean (control_agrees and friends); Kani
  bounds_check_matches_definition,
bounds_kept_is_the_definition_on_books_in_bounds;
  rules B-38, B-18/B-23 amended; bookspec `older = true` for legacy hand
  lines; tests that hand-post to 1200/2000 post as replay or renumbered.

Review fixes (both reviews of part A):
- control_role_of guards only an account the role is assigned to or one
  holding its documents' lines (a chart's own 1200 Equipment or card at
  2000 is free until a document posts there); payment accounts check
  other roles by holds_role (type-checked). The MCP tests that failed on
  the guard (oracle_mcp, spec_projects) pass unchanged.
- standing_payments leaves out reversals (sorted, deduped); replayed
  tags match the movement's side; payments_recorded counts every payment
  event (tagged or not, Ledger.payment_events) and refuses overflow.
- The record caches settled (paid + discounted + written off) and owed
  (Invoice/Bill.owed, never serialized): a void never reads as paid.
- assign_role: receivables/payables refuse moving onto an account with
  untagged lines (RoleAccountHasHandLines) and, on their control account
  holding a balance, say DocumentRoleHoldsBalance (no hand entry named);
  B-23 reworded. The reversal-mirror exemption only takes a hand line
  off (even chain depth); putting it back is refused.
- DocStatus Overpaid and Unattached; aging leaves out credit balances;
  ControlCheck.attention lists out-of-bounds and unattached documents.
- stands_on counts a chain in order; indexes (doc_index, doc_accounts,
  order_pos, reversed_by) keep the derived figures linear.
- Viewer reads a post-dated document as of its own date; one state per
  row. bounds_kept's side-crossing documented as intended.
- Tests: ten new spec_documents scenarios, stronger proptests, store
  proptest arap_props (live = replay = snapshot at every date, closed
  months), fuzz ops void/payments with details, a GUI post-dated test;
  Lean Step.assign / Step.release with unattached_zero kept; model
  limits stated in docs/testing.md and B-38.
Review fixes (CPA and engineering lenses): only an assigned role's
account or one holding document lines is a control account (a chart's
own 1200 asset stays free); a role can't move onto untagged lines or off
document lines (Lean Step.assign); a void's cache never reads as paid;
no Decimal sum panics; per-document indexes keep figures linear; a
replayed tag matches its side; the feature gate counts payment events;
a payment's reversal is never listed as standing; an overpaid document
has its own status; the viewer keeps post-dated documents.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

crates/ledger-gui/tests/parties.rs

@@ -2060,3 +2060,49 @@ fn the_journal_says_what_each_1099_record_did() {
         ]
     );
 }
+
+/// A document dated after today is read as of its own date (Books::doc_today):
+/// a post-dated bill still owes its total in the party's open bills (and
+/// in Cash's "Coming up"), and is never late; one dated today or before
+/// reads as of today (review of P4b S1: the viewer dropped post-dated
+/// documents).
+#[test]
+fn a_post_dated_bill_still_shows_what_it_will_owe() {
+    let dir = TempDir::new("post-dated");
+    let data = dir.0.join("books-data");
+    let mut s = Store::create(&data, Currency::USD).unwrap();
+    let bank = s
+        .add_account("1000", "Checking", AccountType::Asset, None, false)
+        .unwrap();
+    let vendor = s.add_vendor("Tobin Harlow Supply").unwrap();
+    let later = s
+        .create_bill(vendor, d(2026, 11, 1), d(2026, 12, 1), doc(45_000))
+        .unwrap();
+    let now = s
+        .create_bill(vendor, d(2026, 9, 1), d(2026, 9, 30), doc(10_000))
+        .unwrap();
+    s.pay_bill(now, d(2026, 9, 10), cents(4_000), bank).unwrap();
+    drop(s);
+    let b = load(&dir.0);
+    let ahead = b
+        .doc_today(ledger_core::DocRef::Bill(later))
+        .unwrap()
+        .expect("read as of its own date");
+    assert_eq!((ahead.outstanding, ahead.overdue_days), (cents(45_000), 0));
+    let late = b
+        .doc_today(ledger_core::DocRef::Bill(now))
+        .unwrap()
+        .unwrap();
+    assert_eq!(late.outstanding, cents(6_000));
+    assert!(late.overdue_days > 0, "{late:?}");
+    let party = b
+        .ledger
+        .party_of_vendor(vendor)
+        .and_then(|p| b.party(p).cloned())
+        .unwrap();
+    assert_eq!(party.open_bills, Some(cents(51_000)));
+    assert_eq!(
+        b.owed_today(ledger_core::DocRef::Bill(later)),
+        Ok(cents(45_000))
+    );
+}

crates/ledger-gui/tests/projects.rs

@@ -67,7 +67,7 @@ fn fixture(tag: &str) -> Fixture {
     let mut s = Store::create(&data_dir, Currency::USD).unwrap();
     let mut add = |code: &str, name: &str, ty| s.add_account(code, name, ty, None, false).unwrap();
     let cash = add("1000", "Cash", AccountType::Asset);
-    let devices = add("1200", "Equipment", AccountType::Asset);
+    let devices = add("1500", "Equipment", AccountType::Asset);
     let revenue = add("4000", "Design Services", AccountType::Revenue);
     let contractors = add("6000", "Contractors", AccountType::Expense);
     let rent = add("6200", "Rent", AccountType::Expense);

crates/ledger-gui/tests/view_model.rs

@@ -82,13 +82,19 @@ fn build(plan: &Plan, tag: &str) -> (TestDir, Source, ledger_core::Ledger) {
         .iter()
         .map(|(c, n, t)| s.add_account(c, n, *t, None, false).unwrap())
         .collect();
-    for &(back, dr, cr, cents) in &plan.entries {
-        let e = s.create_entry(plan.today - Days::new(back), "x").unwrap();
-        let m = Money::new(Decimal::new(cents, 2), Currency::USD);
-        s.add_line(e, ids[dr], Side::Debit, m).unwrap();
-        s.add_line(e, ids[cr], Side::Credit, m).unwrap();
-        s.post_entry(e).unwrap();
-    }
+    // As replay posts them: random lines land on receivables and payables
+    // by hand, as books an earlier version wrote can hold them (the
+    // control guard, rules.md B-38, refuses them as new work), and the
+    // overview must still read them.
+    ledger_core::parties::replaying(|| {
+        for &(back, dr, cr, cents) in &plan.entries {
+            let e = s.create_entry(plan.today - Days::new(back), "x").unwrap();
+            let m = Money::new(Decimal::new(cents, 2), Currency::USD);
+            s.add_line(e, ids[dr], Side::Debit, m).unwrap();
+            s.add_line(e, ids[cr], Side::Credit, m).unwrap();
+            s.post_entry(e).unwrap();
+        }
+    });
     journal_settings(
         &mut s,
         &format!(