cash flow: financing and investing gross; account roles are a setting

From ASC 230 (via Deloitte DART and PwC Viewpoint), replacing two
formerly assumed behaviors:

- Financing and investing are gross (230-10-45-7): per account, cash in
  and cash out are separate lines (contributions apart from
  distributions, borrowing apart from repayment), netted only within
  one entry. Lines come in code order, in before out.
- Investing includes making and collecting loans and buying investments
  (230-10-20, 45-13), not only registered fixed assets:
  CashFlowParams gains investing_accounts.
- The roles are per-company settings: [books] financing_accounts and
  investing_accounts in wanderbooks.toml (beside cash_accounts). The MCP
  tools (cash_flow, export, CPA package) default every list to them and
  share one path; the viewer reads them too, falling back to its name
  guess for debt. A due-to-owners liability listed as financing gives
  PwC 6.9.3.1's constructive treatment of expenses an owner paid.

rules.md B-14 quotes the sources; new tests cite them; docs/testing.md
#8 is resolved.

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

docs/spec/rules.md

@@ -235,9 +235,37 @@ inflows from operating activities: Cash receipts from sales of goods or
 services…". A closing entry is not income or spending (B-11), so period
 statements exclude it.
 
+Investing and financing are gross (ASC 230-10-45-7, via Deloitte DART:
+"information about the gross amounts of cash receipts and cash payments
+during a period is more relevant than information about the net
+amounts"; 45-8 allows netting only where "the turnover is quick, the
+amounts are large, and the maturities are short"). Financing inflows
+include "Proceeds from issuing equity instruments" and "other short- or
+long-term borrowing" (45-14(1), (2)); outflows include "distributions to
+owners" and "Repayments of amounts borrowed" (45-15(1), (2)). Investing
+"include[s] making and collecting loans and acquiring and disposing of
+debt or equity instruments and property, plant, and equipment" (ASC
+230-10-20). Which accounts hold loans made, investments, and debt is a
+fact of each company's chart, so it is a setting: `[books]
+financing_accounts` and `investing_accounts` in wanderbooks.toml (with
+`cash_accounts`), read by the MCP tools and the viewer alike.
+
+Money an owner advances, by paying a company expense personally (a
+"Due to owners" liability), is borrowing: PwC Viewpoint, Financial
+statement presentation 6.9.3.1 (constructive receipts and
+disbursements) presents cash a third party pays on the entity's behalf
+"as though the transaction took place through the bank accounts of the
+reporting entity": a financing inflow and an operating outflow. Listing
+that liability in `financing_accounts` gives exactly that; repaying the
+owner is then a repayment of amounts borrowed. "Judgment is required"
+(PwC), so it is the company's setting, not a fixed rule.
+
 **Enforced:** `profit_and_loss_for_period`, `cash_flow`. **Checked:** Lean
 `statements_add_up`; `prop_period_pnl_partitions`;
-`cash_flow_reconciles_to_change_in_cash`.
+`cash_flow_reconciles_to_change_in_cash`;
+`financing_is_gross_borrowing_apart_from_repayment`,
+`a_loan_the_entity_makes_is_investing_gross`,
+`an_expense_the_owner_paid_is_borrowing_then_operating`.
 
 ## B-15 Depreciation: straight line, salvage never depreciated, partial months by days