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",

crates/ledger-store/src/reconcilable.rs

@@ -55,16 +55,11 @@ pub fn cash_accounts(ledger: &Ledger, configured: &[String]) -> Vec<AccountId> {
         .collect()
 }
 
-/// The card accounts: liabilities whose names contain "card".
+/// The card accounts: liabilities whose names contain "card"
+/// (`ledger_core::parties::card_accounts`, the same rule party money
+/// reads, so the two never disagree on what a card is).
 pub fn card_accounts(ledger: &Ledger) -> Vec<AccountId> {
-    ledger
-        .chart()
-        .all()
-        .filter(|a| {
-            a.account_type == AccountType::Liability && a.name.to_lowercase().contains("card")
-        })
-        .map(|a| a.id)
-        .collect()
+    ledger_core::parties::card_accounts(ledger)
 }
 
 /// The accounts the books reconcile monthly (INVARIANT 1).

crates/ledger-store/src/store.rs

@@ -1238,6 +1238,30 @@ impl Store {
         Ok(())
     }
 
+    /// Name a party the creditor of a liability account the company owes
+    /// it itself on, or stop (`on` false): ledger_core's
+    /// `Ledger::set_party_creditor`. Journaled as `party.creditor_set
+    /// {id, account_id, on}`, after the journal declares the feature it
+    /// needs ([`crate::format::PARTY_CREDITORS`]) the first time, so an
+    /// older wanderbooks stops there and says it is too old instead of
+    /// misreading the books.
+    pub fn set_party_creditor(
+        &mut self,
+        id: ledger_core::PartyId,
+        account: AccountId,
+        on: bool,
+    ) -> Result<(), StoreError> {
+        self.ledger.check_set_party_creditor(id, account, on)?;
+        self.ensure_feature(crate::format::PARTY_CREDITORS)?;
+        let line = self.append_journal(
+            "party.creditor_set",
+            json!({"id": id, "account_id": account, "on": on}),
+        )?;
+        self.ledger.set_party_creditor(id, account, on)?;
+        apply_line_to_sqlite(&self.conn, &line)?;
+        Ok(())
+    }
+
     /// Record or clear a party's W-9 facts. Journaled as `party.w9_set`.
     pub fn set_party_w9(
         &mut self,
@@ -4844,6 +4868,13 @@ pub(crate) fn replay_line_into_ledger(
                 .ok_or_else(|| StoreError::JournalCorrupt("party.role_set on".into()))?;
             ledger.set_party_role(get_u64(p, "id")?, role, on)?;
         }
+        "party.creditor_set" => {
+            let on = p
+                .get("on")
+                .and_then(|v| v.as_bool())
+                .ok_or_else(|| StoreError::JournalCorrupt("party.creditor_set on".into()))?;
+            ledger.set_party_creditor(get_u64(p, "id")?, get_u64(p, "account_id")?, on)?;
+        }
         "party.w9_set" => {
             let facts: Option<ledger_core::W9Facts> = serde_json::from_value(p["facts"].clone())
                 .map_err(|_| StoreError::JournalCorrupt("party.w9_set facts".into()))?;
@@ -5569,8 +5600,8 @@ fn apply_line_rows(conn: &Connection, line: &JournalLine) -> Result<(), StoreErr
             )?;
         }
         "role.assigned" | "party.added" | "party.updated" | "party.role_set" | "party.w9_set"
-        | "party.w4_set" | "party.tin_set" | "entry.party_set" | "entry.parties_set"
-        | "entry.no_party" => {
+        | "party.w4_set" | "party.tin_set" | "party.creditor_set" | "entry.party_set"
+        | "entry.parties_set" | "entry.no_party" => {
             // Control roles and the party directory live in the ledger
             // (rebuilt by replay); the events mirror below keeps the
             // history.