chore(run) Note subprocess issue with streaming

Author: tony

src/libvcs/_internal/run.py

@@ -201,6 +201,14 @@ def progress_cb(output: t.AnyStr, timestamp: datetime.datetime) -> None:
             sys.stdout.flush()
 
         callback = progress_cb
+
+    # Note: When git detects that stderr is not a TTY (e.g., when piped),
+    # it outputs progress with newlines instead of carriage returns.
+    # This causes each progress update to appear on a new line.
+    # To get proper single-line progress updates, git would need to be
+    # connected to a pseudo-TTY, which would require significant changes
+    # to how subprocess execution is handled.
+
     while code is None:
         code = proc.poll()
 

tests/_internal/test_run.py

@@ -291,7 +291,8 @@ def test_no_callback_no_streaming(self, tmp_path: pathlib.Path) -> None:
         assert output.strip() == "Normal output"
 
     def test_progress_callback_with_carriage_returns(
-        self, tmp_path: pathlib.Path
+        self,
+        tmp_path: pathlib.Path,
     ) -> None:
         """Test handling of carriage returns in progress output."""
         captured_chunks: list[str] = []