refactor(mcp): the party_id, document_id and cash_account aliases are removed (P5)

Agent reason: one name for one thing. S4 and S6 kept the old spellings "until
P5" so an agent that learned them did not break; P5 removes them, so the
schema an agent reads has one parameter for each fact and a call cannot name
the same thing twice with different answers.

books.create_invoice takes customer and books.create_bill vendor (a record's
id, its party's id or its name; required), no party_id.
books.receive_payment and books.pay_bill take invoice or bill and
deposit_to or paid_from, no document_id or cash_account; a payment names its
document and its account or is refused saying which to pass. A number that is
one record's id and another's name is still refused, never guessed (INVARIANT
6).

The over-the-wire tests that used the old spellings now use the new
(document_id becomes invoice or bill, cash_account becomes deposit_to or
paid_from, party_id becomes customer or vendor given as the id's text); the
one test that named the alias, party_id_alias_still_works, is now
a_customer_by_id_and_by_name_is_one_record and checks the same two spellings
of a customer, by id and by name, name one record.

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

crates/ledger-cli/tests/spec_projects.rs

@@ -1231,7 +1231,7 @@ fn invoice_and_bill_lines_count_toward_their_projects() {
     );
     let inv = m.ok(
         "books.create_invoice",
-        json!({"party_id": cedar, "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
+        json!({"customer": (cedar).to_string(), "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
             {"description": "Design", "amount": "3000.00", "class": "Zeta site"},
             {"description": "Hosting", "amount": "200.00", "class": harbor.to_string()},
             {"description": "Rush fee", "amount": "100.00"},
@@ -1264,7 +1264,7 @@ fn invoice_and_bill_lines_count_toward_their_projects() {
     );
     let bill = m.ok(
         "books.create_bill",
-        json!({"party_id": dana_vendor, "date": "2026-03-09", "due_date": "2026-04-08",
+        json!({"vendor": (dana_vendor).to_string(), "date": "2026-03-09", "due_date": "2026-04-08",
                "vendor_ref": "DANA-77",
                "lines": [
             {"description": "Illustration", "amount": "1200.00", "account": "6000", "class": "Zeta site"},
@@ -1284,11 +1284,11 @@ fn invoice_and_bill_lines_count_toward_their_projects() {
     // Payments are balance-sheet only: no project.
     let got = m.ok(
         "books.receive_payment",
-        json!({"confirmed": true, "document_id": inv["id"], "date": "2026-03-20", "amount": "3800.00", "cash_account": "1000"}),
+        json!({"confirmed": true, "invoice": inv["id"], "date": "2026-03-20", "amount": "3800.00", "deposit_to": "1000"}),
     );
     let paid = m.ok(
         "books.pay_bill",
-        json!({"confirmed": true, "document_id": bill["id"], "date": "2026-03-30", "amount": "1250.00", "cash_account": "1000"}),
+        json!({"confirmed": true, "bill": bill["id"], "date": "2026-03-30", "amount": "1250.00", "paid_from": "1000"}),
     );
     for e in [&got["entry_id"], &paid["entry_id"]] {
         let e = e.as_u64().unwrap();
@@ -1356,7 +1356,7 @@ fn a_document_naming_an_unknown_project_is_refused_whole() {
     for (tool, party) in [("books.create_invoice", &cedar), ("books.create_bill", &v)] {
         let why = m.refuse(
             tool,
-            json!({"party_id": party, "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
+            json!({"customer": (party).to_string(), "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
                 {"description": "a", "amount": "10.00", "class": "Zeta site"},
                 {"description": "b", "amount": "10.00", "class": "Nowhere"},
             ]}),
@@ -1379,7 +1379,7 @@ fn a_document_for_a_finished_project_says_so() {
     let cedar = m.ok("books.add_customer", json!({"name": "Cedar"}))["id"].clone();
     let out = m.ok(
         "books.create_invoice",
-        json!({"party_id": cedar, "date": "2026-10-05", "due_date": "2026-11-04", "lines": [
+        json!({"customer": (cedar).to_string(), "date": "2026-10-05", "due_date": "2026-11-04", "lines": [
             {"description": "Final", "amount": "10.00", "class": "Harbor"},
             {"description": "Again", "amount": "10.00", "class": "harbor"},
             {"description": "Old", "amount": "10.00", "class": "Dock"},
@@ -1424,7 +1424,7 @@ fn an_invoice_for_an_on_spec_project_asks_about_an_agreement() {
     let v = m.ok("books.add_vendor", json!({"name": "Dana"}))["id"].clone();
     let out = m.ok(
         "books.create_invoice",
-        json!({"party_id": cedar, "date": "2026-10-05", "due_date": "2026-11-04", "lines": [
+        json!({"customer": (cedar).to_string(), "date": "2026-10-05", "due_date": "2026-11-04", "lines": [
             {"description": "Build", "amount": "10.00", "class": "Kestrel"},
             {"description": "More", "amount": "5.00", "class": "kestrel"},
             {"description": "Site", "amount": "7.00", "class": "Zeta"},
@@ -1450,7 +1450,7 @@ fn an_invoice_for_an_on_spec_project_asks_about_an_agreement() {
     );
     let bill = m.ok(
         "books.create_bill",
-        json!({"party_id": v, "date": "2026-10-05", "due_date": "2026-11-04",
+        json!({"vendor": (v).to_string(), "date": "2026-10-05", "due_date": "2026-11-04",
                "vendor_ref": "V-512",
                "lines": [
             {"description": "Icons", "amount": "10.00", "account": "6000", "class": "Kestrel"},
@@ -1475,7 +1475,7 @@ fn books_without_the_feature_refuse_a_tagged_document() {
     for (tool, party) in [("books.create_invoice", &cedar), ("books.create_bill", &v)] {
         let why = m.refuse(
             tool,
-            json!({"party_id": party, "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
+            json!({"customer": (party).to_string(), "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
                 {"description": "a", "amount": "10.00", "class": "Zeta site"},
             ]}),
         );
@@ -1487,7 +1487,7 @@ fn books_without_the_feature_refuse_a_tagged_document() {
     assert_eq!(m.journal(), head, "nothing journaled");
     m.ok(
         "books.create_invoice",
-        json!({"party_id": cedar, "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
+        json!({"customer": (cedar).to_string(), "date": "2026-03-02", "due_date": "2026-04-01", "lines": [
             {"description": "a", "amount": "10.00"},
         ], "confirmed": true}),
     );