From b2144b3c76658e5cbe247ed86baebe8fc6b5f4f6 Mon Sep 17 00:00:00 2001
From: Charan Rathore <180254320+charan-rathore@users.noreply.github.com>
Date: Tue, 6 Oct 2026 02:11:39 +0530
Subject: [PATCH] fix: accept a byte order mark before the transaction CSV
 header

Signed-off-by: Charan Rathore <180254320+charan-rathore@users.noreply.github.com>
---
 apps/server/src/engine/finance.ts |  2 ++
 tests/finance.test.ts             | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/apps/server/src/engine/finance.ts b/apps/server/src/engine/finance.ts
index b42d1fac3..f7704ee7c 100644
--- a/apps/server/src/engine/finance.ts
+++ b/apps/server/src/engine/finance.ts
@@ -3,6 +3,8 @@ import { z } from "zod";
 /** CSV amounts use positive expenses and negative income. No currency conversion is inferred. */
 export function analyzeSpending(csv: string) {
   if (csv.length > 500000) throw new Error("Import at most 500 KB of transaction CSV");
+  // Excel and many bank exports start a UTF-8 CSV with a byte order mark. It is not part of the first header.
+  if (csv.charCodeAt(0) === 0xfeff) csv = csv.slice(1);
   const rows: string[][] = [];
   let row: string[] = [],
     cell = "",
diff --git a/tests/finance.test.ts b/tests/finance.test.ts
index 94ae732d8..e26e1214e 100644
--- a/tests/finance.test.ts
+++ b/tests/finance.test.ts
@@ -30,3 +30,14 @@ test("transaction imports preserve valid quoted fields at CSV boundaries", () =>
     assert.equal(report.transactions[1].category, "Uncategorized");
   }
 });
+
+test("transaction imports accept a UTF-8 byte order mark before the header", () => {
+  for (const header of [
+    "date,description,amount,category",
+    '"date","description","amount","category"',
+  ]) {
+    const report = analyzeSpending(`\uFEFF${header}\n2026-09-01,Coffee,10.10,Food`);
+    assert.equal(report.count, 1);
+    assert.equal(report.spending, 10.1);
+  }
+});