From d5a06d3cd28463a71ee40415e7bfe31c4f93bcf4 Mon Sep 17 00:00:00 2001
From: Eric Rahm <erahm@google.com>
Date: Mon, 20 Oct 2025 14:41:33 -0700
Subject: [PATCH] fix(core): Preserve significant trailing spaces in gitignore
 patterns (#11536)

---
 .../core/src/utils/gitIgnoreParser.test.ts    | 20 +++++++++++++++++++
 packages/core/src/utils/gitIgnoreParser.ts    |  2 +-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/utils/gitIgnoreParser.test.ts b/packages/core/src/utils/gitIgnoreParser.test.ts
index 95f8dbbe64..580da544fe 100644
--- a/packages/core/src/utils/gitIgnoreParser.test.ts
+++ b/packages/core/src/utils/gitIgnoreParser.test.ts
@@ -250,4 +250,24 @@ src/*.tmp
       expect(parser.isIgnored('bla/!bar')).toBe(true);
     });
   });
+
+  describe('Trailing Spaces', () => {
+    beforeEach(async () => {
+      await setupGitRepo();
+    });
+
+    it('should correctly handle significant trailing spaces', async () => {
+      await createTestFile('.gitignore', 'foo\\ \nbar ');
+      await createTestFile('foo ', 'content');
+      await createTestFile('bar', 'content');
+      await createTestFile('bar ', 'content');
+
+      // 'foo\ ' should match 'foo '
+      expect(parser.isIgnored('foo ')).toBe(true);
+
+      // 'bar ' should be trimmed to 'bar'
+      expect(parser.isIgnored('bar')).toBe(true);
+      expect(parser.isIgnored('bar ')).toBe(false);
+    });
+  });
 });
diff --git a/packages/core/src/utils/gitIgnoreParser.ts b/packages/core/src/utils/gitIgnoreParser.ts
index 762015db8d..199240e69c 100644
--- a/packages/core/src/utils/gitIgnoreParser.ts
+++ b/packages/core/src/utils/gitIgnoreParser.ts
@@ -42,7 +42,7 @@ export class GitIgnoreParser implements GitIgnoreFilter {
 
     return content
       .split('\n')
-      .map((p) => p.trim())
+      .map((p) => p.trimStart())
       .filter((p) => p !== '' && !p.startsWith('#'))
       .map((p) => {
         const isNegative = p.startsWith('!');