From f255ac3e6c6283812287139273cd09345c8f82e0 Mon Sep 17 00:00:00 2001
From: Rutger Broekhoff
Date: Thu, 8 Jan 2026 02:48:35 +0100
Subject: What a day

---
 lib/ledger.ml | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/ledger.ml b/lib/ledger.ml
index 3e1d177..54a030e 100644
--- a/lib/ledger.ml
+++ b/lib/ledger.ml
@@ -524,6 +524,15 @@ module World = struct
     let%map pre_bal, post_bal = mres in
     (pre_bal, post_bal, world')
 
+  let get_bal aid (world : t) : (Commodity_id.t * Money.Diff.t) option =
+    let open Option.Let_syntax in
+    let%map cb, _world' =
+      Account_hierarchy.alter aid
+        (fun _acc_type acc_comm acc_bal -> ((acc_comm, acc_bal), acc_bal))
+        world
+    in
+    cb
+
   let apply_tx (tx : Tx.t) world : t option =
     Map.fold_option tx.entries ~init:world
       ~f:(fun ~key:aid ~(data : Tx.entry) world ->
@@ -536,6 +545,11 @@ module World = struct
         | Some bal_ass ->
             if Money.Diff.(bal_ass = new_bal) then Some world else None)
 
+  let apply_ba (ba : bal_assert) world : t option =
+    let open Option.Let_syntax in
+    let%bind _comm, bal = get_bal ba.account world in
+    if not Money.Diff.(bal = ba.bal) then None else Some world
+
   let apply : item -> t -> t option = function
     | Tx_item tx -> apply_tx tx
     | Bal_assert_item ba -> apply_ba ba
-- 
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