feat(mcp): books.documents and books.document (P4b S2, read tools)

books.documents lists invoices or bills, due date first, with what each
still owes and its status, all derived from its ledger lines that stand
(B-38): status open (default), overdue, paid, void, written_off,
overpaid or all; party and due_by narrow it (what to pay this week).
books.document shows one (ref invoice:N or bill:N) as of a day: lines
with projects, total, paid, discounted, written off, outstanding,
status, days overdue, and its timeline of every tagged ledger line, each
saying whether its entry still stands. The over-the-wire test
documents_list_and_timeline_over_the_wire covers a reversed payment;
the happy-path journey covers both output schemas.

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

crates/ledger-cli/tests/spec_mcp.rs

@@ -891,6 +891,11 @@ fn happy_path(name: &str) -> Mcp {
         json!({"kind": "invoice", "id": dup, "date": "2026-02-02", "reason": "entered twice"}),
     );
     m.ok("books.control_check", json!({"as_of": "2026-06-30"}));
+    m.ok(
+        "books.documents",
+        json!({"kind": "invoices", "status": "all"}),
+    );
+    m.ok("books.document", json!({"ref": format!("invoice:{inv}")}));
 
     // Fixed assets.
     let registered = m.ok(
@@ -2617,3 +2622,120 @@ fn documents_void_and_tie_out_over_the_wire() {
         "{verified}"
     );
 }
+
+/// P4b S2 over the real server: books.documents lists what is owed, due
+/// date first, and books.document shows one with its timeline; a
+/// reversed payment shows twice (the payment, which no longer stands,
+/// and its reversal, which does: the two net to nothing), and the invoice
+/// owes its whole total again.
+#[test]
+fn documents_list_and_timeline_over_the_wire() {
+    let dir = test_dir("p4b_s2");
+    let toml = books_toml(&dir, "600.00", "");
+    let mut m = Mcp::start(&dir, &toml);
+    m.accounts(BASE_CHART);
+    let customer = m.ok("books.add_customer", json!({"name": "Client"}))["id"]
+        .as_u64()
+        .unwrap();
+    let invoice = |m: &mut Mcp, date: &str, due: &str, amount: &str| {
+        m.ok(
+            "books.create_invoice",
+            json!({"party_id": customer, "date": date, "due_date": due,
+                   "lines": [{"description": "Consulting", "amount": amount}]}),
+        )["id"]
+            .as_u64()
+            .unwrap()
+    };
+    let late = invoice(&mut m, "2026-02-01", "2026-03-01", "500.00");
+    let later = invoice(&mut m, "2026-02-05", "2026-04-30", "80.00");
+    let pay = m.ok(
+        "books.receive_payment",
+        json!({"document_id": late, "date": "2026-02-10", "amount": "200.00", "cash_account": "1000"}),
+    )["entry_id"]
+        .as_u64()
+        .unwrap();
+    m.ok(
+        "books.reverse_entry",
+        json!({"entry_id": pay, "date": "2026-02-12", "description": "the transfer bounced", "confirmed": true}),
+    );
+
+    let open = m.ok(
+        "books.documents",
+        json!({"kind": "invoices", "as_of": "2026-03-15"}),
+    );
+    let refs: Vec<&str> = open["documents"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|d| d["ref"].as_str().unwrap())
+        .collect();
+    assert_eq!(
+        refs,
+        [format!("invoice:{late}"), format!("invoice:{later}")],
+        "{open}"
+    );
+    assert_eq!(open["outstanding_total"], "580.00", "{open}");
+    assert_eq!(open["documents"][0]["overdue_days"], 14, "{open}");
+    let overdue = m.ok(
+        "books.documents",
+        json!({"kind": "invoices", "status": "overdue", "as_of": "2026-03-15"}),
+    );
+    assert_eq!(
+        overdue["documents"].as_array().unwrap().len(),
+        1,
+        "{overdue}"
+    );
+    let due_soon = m.ok(
+        "books.documents",
+        json!({"kind": "invoices", "due_by": "2026-03-31", "as_of": "2026-03-15"}),
+    );
+    assert_eq!(
+        due_soon["documents"].as_array().unwrap().len(),
+        1,
+        "{due_soon}"
+    );
+    assert_eq!(
+        m.ok("books.documents", json!({"kind": "bills"}))["documents"],
+        json!([])
+    );
+
+    let one = m.ok(
+        "books.document",
+        json!({"ref": format!("invoice:{late}"), "as_of": "2026-03-15"}),
+    );
+    assert_eq!(one["outstanding"], "500.00", "{one}");
+    assert_eq!(one["paid"], "0.00", "{one}");
+    assert_eq!(one["status"], "open", "{one}");
+    let moves: Vec<(String, bool, bool)> = one["timeline"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|e| {
+            (
+                e["kind"].as_str().unwrap().to_string(),
+                e["reversal"].as_bool().unwrap(),
+                e["stands"].as_bool().unwrap(),
+            )
+        })
+        .collect();
+    assert_eq!(
+        moves,
+        [
+            ("origin".to_string(), false, true),
+            ("payment".to_string(), false, false),
+            ("payment".to_string(), true, true),
+        ],
+        "{one}"
+    );
+    assert!(
+        m.tool("books.document", json!({"ref": "invoice"}))
+            .refused()
+    );
+    assert!(
+        m.tool(
+            "books.documents",
+            json!({"kind": "invoices", "status": "late"})
+        )
+        .refused()
+    );
+}