From bfaad12cac828cd098294c7d7980a6bef614f3f1 Mon Sep 17 00:00:00 2001
From: muravvv <50175509+muravvv@users.noreply.github.com>
Date: Sun, 1 Jun 2025 14:56:23 +0300
Subject: [PATCH] add missing encoding conversion for diff contents

---
 aider/repo.py            | 16 ++++++++++++----
 tests/basic/test_repo.py | 22 ++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/aider/repo.py b/aider/repo.py
index 83d9e202a..bd4937303 100644
--- a/aider/repo.py
+++ b/aider/repo.py
@@ -391,14 +391,20 @@ class GitRepo:
         try:
             if current_branch_has_commits:
                 args = ["HEAD", "--"] + list(fnames)
-                diffs += self.repo.git.diff(*args)
+                diffs += self.repo.git.diff(*args, stdout_as_string=False).decode(
+                    self.io.encoding, "replace"
+                )
                 return diffs
 
             wd_args = ["--"] + list(fnames)
             index_args = ["--cached"] + wd_args
 
-            diffs += self.repo.git.diff(*index_args)
-            diffs += self.repo.git.diff(*wd_args)
+            diffs += self.repo.git.diff(*index_args, stdout_as_string=False).decode(
+                self.io.encoding, "replace"
+            )
+            diffs += self.repo.git.diff(*wd_args, stdout_as_string=False).decode(
+                self.io.encoding, "replace"
+            )
 
             return diffs
         except ANY_GIT_ERROR as err:
@@ -412,7 +418,9 @@ class GitRepo:
             args += ["--color=never"]
 
         args += [from_commit, to_commit]
-        diffs = self.repo.git.diff(*args)
+        diffs = self.repo.git.diff(*args, stdout_as_string=False).decode(
+            self.io.encoding, "replace"
+        )
 
         return diffs
 
diff --git a/tests/basic/test_repo.py b/tests/basic/test_repo.py
index 0f1e7ed0e..5c366f87f 100644
--- a/tests/basic/test_repo.py
+++ b/tests/basic/test_repo.py
@@ -59,6 +59,28 @@ class TestRepo(unittest.TestCase):
             self.assertIn("index", diffs)
             self.assertIn("workingdir", diffs)
 
+    def test_diffs_with_single_byte_encoding(self):
+        with GitTemporaryDirectory():
+            encoding = "cp1251"
+
+            repo = git.Repo()
+
+            fname = Path("foo.txt")
+            fname.write_text("index\n", encoding=encoding)
+            repo.git.add(str(fname))
+
+            # Make a change with non-ASCII symbols in the working dir
+            fname.write_text("АБВ\n", encoding=encoding)
+
+            git_repo = GitRepo(InputOutput(encoding=encoding), None, ".")
+            diffs = git_repo.get_diffs()
+
+            # check that all diff output can be converted to utf-8 for sending to model
+            diffs.encode("utf-8")
+
+            self.assertIn("index", diffs)
+            self.assertIn("АБВ", diffs)
+
     def test_diffs_detached_head(self):
         with GitTemporaryDirectory():
             repo = git.Repo()