From 25924292fbe3a804507d0acd6d11c2a4fdff4df3 Mon Sep 17 00:00:00 2001
From: lux-liang <249971141+lux-liang@users.noreply.github.com>
Date: Mon, 21 Sep 2026 15:35:37 +0800
Subject: [PATCH] fix(csv-stringify): preserve negative numeric values

---
 packages/csv-stringify/lib/api/index.js           |  7 ++++++-
 .../csv-stringify/test/option.escape_formulas.ts  | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/packages/csv-stringify/lib/api/index.js b/packages/csv-stringify/lib/api/index.js
index 2f5a5abf..a2a04536 100644
--- a/packages/csv-stringify/lib/api/index.js
+++ b/packages/csv-stringify/lib/api/index.js
@@ -228,9 +228,14 @@ const stringifier = function (options, state, info) {
           // Apple Numbers unicode normalization is empirical from testing
           if (escape_formulas) {
             switch (value[0]) {
+              case "-":
+                if (typeof field === "number" || typeof field === "bigint") {
+                  break;
+                }
+                value = `'${value}`;
+                break;
               case "=":
               case "+":
-              case "-":
               case "@":
               case "\t":
               case "\r":
diff --git a/packages/csv-stringify/test/option.escape_formulas.ts b/packages/csv-stringify/test/option.escape_formulas.ts
index 9963c653..eb462adc 100644
--- a/packages/csv-stringify/test/option.escape_formulas.ts
+++ b/packages/csv-stringify/test/option.escape_formulas.ts
@@ -53,6 +53,21 @@ describe("Option `escape_formulas`", function () {
     );
   });
 
+  it("preserves negative numeric values", function (next) {
+    stringify(
+      [[-1.5, -2n, "-3.5"]],
+      {
+        escape_formulas: true,
+        eof: false,
+      },
+      (err, data) => {
+        if (err) return next(err);
+        data.should.eql("-1.5,-2,'-3.5");
+        next();
+      },
+    );
+  });
+
   it("with `quoted` option", function (next) {
     stringify(
       [