P3: party totals by what moved the money, once (defects 14, 11, 24)

Each party's part of an entry is signed as its own account would show it,
with a direction and its cash and in-kind amounts; a reversal is its
original negated. Totals on a cash or all basis: for a member, all equals
the members' equity statement and cash the K-1's cash. Money is cash,
cards and the financing accounts, and a liability credit never pays its
own creditor (creditor_of), so accruals and declared distributions count
once. tin_last4 from the TIN or W-9 facts.

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

crates/ledger-store/src/format.rs

@@ -43,6 +43,7 @@ pub const KNOWN_FEATURES: &[&str] = &[
     MEMBERS_CUMULATIVE,
     FEATURE_ACCOUNT_RENAMED,
     FEATURE_REQUIRE_TAX_CATEGORY,
+    PARTY_CREDITORS,
 ];
 
 /// Feature: `period.closed` closes to members with `"rounding":
@@ -70,6 +71,10 @@ pub(crate) fn setting_feature(key: &str) -> Option<&'static str> {
     }
 }
 
+/// The feature `party.creditor_set` lines need: a party named the
+/// creditor of a liability (rules.md B-35, P3 defect 24).
+pub const PARTY_CREDITORS: &str = "party_creditors";
+
 /// The line type that declares the journal format.
 pub const FORMAT_SET: &str = "journal.format_set";
 
@@ -119,6 +124,7 @@ pub const EVENT_TYPES: &[&str] = &[
     "open_item.raised",
     "open_item.resolved",
     "party.added",
+    "party.creditor_set",
     "party.role_set",
     "party.tin_set",
     "party.updated",