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/src/pages/cash.rs

@@ -328,7 +328,10 @@ fn coming_up(ui: &mut Ui, b: &Books, shell: &mut Shell<'_>) {
         let Some(inv) = b.ledger.get_invoice(id) else {
             continue;
         };
-        let balance = inv.balance().ok();
+        // As of today, from the lines tagged with it (rules.md B-38): a
+        // reversed payment reopens it, a void closes it.
+        let state = b.doc_today(ledger_core::DocRef::Invoice(id));
+        let balance = crate::books::owed_of(&state);
         if balance.is_some_and(|x| x.is_zero()) {
             continue;
         }
@@ -337,7 +340,7 @@ fn coming_up(ui: &mut Ui, b: &Books, shell: &mut Shell<'_>) {
             .get_customer(inv.customer_id)
             .map(|c| c.name.clone())
             .unwrap_or_default();
-        let late = inv.due_date < b.today;
+        let late = matches!(state, Ok(Some(st)) if st.overdue_days > 0);
         items.push(Upcoming {
             date: inv.due_date,
             label: format!(
@@ -352,7 +355,7 @@ fn coming_up(ui: &mut Ui, b: &Books, shell: &mut Shell<'_>) {
         let Some(bill) = b.ledger.get_bill(id) else {
             continue;
         };
-        let balance = bill.balance().ok();
+        let balance = crate::books::owed_of(&b.doc_today(ledger_core::DocRef::Bill(id)));
         if balance.is_some_and(|x| x.is_zero()) {
             continue;
         }
@@ -645,7 +648,7 @@ mod tests {
         let mut b = Build::new("coming-up");
         let (cash, capital, rent) = (b.cash, b.capital, b.rent);
         let accrued =
-            b.s.add_account("2000", "Accrued", AccountType::Liability, None, false)
+            b.s.add_account("2100", "Accrued", AccountType::Liability, None, false)
                 .unwrap();
         b.post(d(2026, 1, 2), cash, capital, 1_000_000);
         let usd = |c: i64| Money::new(cents(c), Currency::USD);

crates/ledger-gui/src/pages/company.rs

@@ -714,7 +714,11 @@ fn parties(ui: &mut Ui, b: &Books, shell: &mut Shell<'_>) {
                         let owed = (1..b.ledger.next_invoice_id())
                             .filter_map(|i| b.ledger.get_invoice(i))
                             .filter(|i| i.customer_id == c.id)
-                            .try_fold(Decimal::ZERO, |t, i| t.checked_add(i.balance().ok()?));
+                            .try_fold(Decimal::ZERO, |t, i| {
+                                t.checked_add(
+                                    b.owed_today(ledger_core::DocRef::Invoice(i.id)).ok()?,
+                                )
+                            });
                         ui.horizontal_wrapped(|ui| {
                             name(ui, &c.name, b.ledger.party_of_customer(c.id));
                             ui.with_layout(

crates/ledger-gui/src/pages/parties.rs

@@ -1400,13 +1400,15 @@ fn documents_card(ui: &mut Ui, b: &Books, info: &PartyInfo, go: &mut Option<Rout
                     .iter()
                     .filter_map(|i| b.ledger.get_invoice(*i))
                     .map(|i| {
+                        let state = b.doc_today(ledger_core::DocRef::Invoice(i.id));
+                        let owed = crate::books::owed_of(&state);
                         (
                             format!("Invoice {}", i.id),
                             i.date,
                             i.due_date,
-                            i.status,
+                            state,
                             i.total().ok(),
-                            i.balance().ok(),
+                            owed,
                             i.entry_id,
                         )
                     });
@@ -1415,20 +1417,33 @@ fn documents_card(ui: &mut Ui, b: &Books, info: &PartyInfo, go: &mut Option<Rout
                     .iter()
                     .filter_map(|i| b.ledger.get_bill(*i))
                     .map(|i| {
+                        let state = b.doc_today(ledger_core::DocRef::Bill(i.id));
+                        let owed = crate::books::owed_of(&state);
                         (
                             format!("Bill {}", i.id),
                             i.date,
                             i.due_date,
-                            i.status,
+                            state,
                             i.total().ok(),
-                            i.balance().ok(),
+                            owed,
                             i.entry_id,
                         )
                     });
                 let mut docs: Vec<_> = invoices.chain(bills).collect();
                 docs.sort_by(|a, b| b.1.cmp(&a.1).then(a.0.cmp(&b.0)));
-                for (name, date, due, status, total, balance, entry) in docs {
-                    let late = !balance.is_some_and(|x| x.is_zero()) && due < b.today;
+                for (name, date, due, state, total, balance, entry) in docs {
+                    // Late and its status as of today, from the ledger
+                    // lines tagged with it (rules.md B-38; P4b.2 gap 10):
+                    // a reversed payment makes it owed again, a void
+                    // never late.
+                    let late = matches!(state, Ok(Some(st)) if st.overdue_days > 0);
+                    let status = match state {
+                        // Read as of its own date (Books::doc_today).
+                        Ok(Some(_)) if date > b.today => "Dated ahead",
+                        Ok(Some(st)) => st.status.label(),
+                        Ok(None) => "Unknown",
+                        Err(_) => "Can't compute",
+                    };
                     let resp = row(
                         ui,
                         w,
@@ -1441,7 +1456,7 @@ fn documents_card(ui: &mut Ui, b: &Books, info: &PartyInfo, go: &mut Option<Rout
                                 false,
                                 if late { p.warning } else { p.text },
                             ),
-                            (fmt::words(&format!("{status:?}")), 90.0, false, p.muted),
+                            (status.to_string(), 90.0, false, p.muted),
                             (fmt::money_or(total), amt, true, p.text),
                             (fmt::money_or(balance), amt, true, p.text),
                         ],