merge: P4b S7, bad debts (branch S7, 4b4fecb9)

The fourth of the paused branches: Ledger::write_off and the bad_debts
control role, invoice.written_off with its evidence filed in the same
store call, books.write_off_invoice, the write-off on the timeline and
in Needs attention, Lean writeOff_within_bounds, rules.md B-41 and the
bookspec examples. Twenty-eight files conflicted with the S4.4, S5 and
S6 merges; resolved as plan 8.0.2 says, keeping both sides' appends with
their seams restored, and: the scope table at 125; S7's law numbered 37;
B-41 placed before B-42; the handbook's step 4 and recovery procedures
folded into the one invoices-and-bills section; S7's wire tests in their
own module with the confirm S4.4's contract needs; S7's copy of the
payment steps dropped (S6 replaced them with Ledger::settle) and its
write-off journaled through S6's journal_auto_lines; in the old-books
fixture S7's hand-written write-off moved to a second invoice, since
S6's hand-written payment settles invoice 1 in full.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

docs/parity.md

@@ -163,3 +163,13 @@ posted gross (A-4), and the bills-due list with the agings' detail,
 tie-out and exports. The pre-S6 fixture's figures still hold (no figure
 moves), and every new write needs the journal feature `documents_v2`,
 which the owner's books declare at their next upgrade (D-52).
+## P4b S7: bad debts (write-offs), 2026-10-27
+
+A/R gained the direct write-off the owner chose (A-5; plan 8.2 S7): an
+invoice that will not be collected comes off 1200 with Dr 6990 Bad Debt
+Expense, its receivable line tagged `WriteOff` so the receipt's figures
+stay derived, and its evidence of worthlessness filed in the same call
+(rules.md B-41; IRC §166, §111; Treas. Reg. §1.166-1(e), (f), -2(a),
+-3(a)). A same-year recovery is the reversal D-49 records, not a new
+movement; bills are never written off. No row above changed status (the
+A/R and A/P rows already say `done`), so the floor stands (10 done).