From 25cf2cf052d8e2439dd583c98d55bada41a45a70 Mon Sep 17 00:00:00 2001
From: guoyunfeng <jdjioe5@gmail.com>
Date: Sun, 25 Oct 2026 03:33:50 +0800
Subject: [PATCH] fix(csv-parser): strip leading UTF-8 BOM before parsing batch
 CSVs (closes #1031)

---
 __tests__/lib/csv-parser.test.ts | 15 +++++++++++++++
 lib/csv-parser.ts                |  1 +
 2 files changed, 16 insertions(+)

diff --git a/__tests__/lib/csv-parser.test.ts b/__tests__/lib/csv-parser.test.ts
index 7be0405..5d1971a 100644
--- a/__tests__/lib/csv-parser.test.ts
+++ b/__tests__/lib/csv-parser.test.ts
@@ -151,6 +151,20 @@ describe("parseCsvBatch", () => {
     });
   });
 
+  describe("UTF-8 BOM handling", () => {
+    it("parses CSV with a leading UTF-8 BOM identically to one without", () => {
+      const csvWithoutBom = `${HEADER}\n${makeRow()}`;
+      const csvWithBom = `\uFEFF${csvWithoutBom}`;
+      const resultWithout = parseCsvBatch(csvWithoutBom);
+      const resultWith = parseCsvBatch(csvWithBom);
+
+      expect(resultWith.errors).toHaveLength(0);
+      expect(resultWith.rows).toHaveLength(1);
+      expect(resultWith.rows[0].recipient).toBe("GABC");
+      expect(resultWith).toEqual(resultWithout);
+    });
+  });
+
   describe("quoted fields", () => {
     it("handles quoted values containing commas", () => {
       const csv = [HEADER, '"GABC,rest",1000,1000,2000'].join("\n");
@@ -228,4 +242,5 @@ describe("parseDuration", () => {
     expect(parseDuration("1.5d")).toBeNull();
     expect(parseDuration("-5d")).toBeNull();
   });
+
 });
diff --git a/lib/csv-parser.ts b/lib/csv-parser.ts
index 731439f..746b585 100644
--- a/lib/csv-parser.ts
+++ b/lib/csv-parser.ts
@@ -106,6 +106,7 @@ export function parseCsvBatch(
   customColumnMapping?: Record<string, number>,
 ): CsvParseResult {
   const lines = csvText
+    .replace(/^\uFEFF/, "")
     .replace(/\r\n/g, "\n")
     .split("\n")
     .map((line) => line.trim())