(fix) Proposing a workaround for superfluous indentation on multi-lines

refactor/actions.py

@@ -89,11 +89,11 @@ def apply(self, context: Context, source: str) -> str:
         view = slice(lineno - 1, end_lineno)
         source_lines = lines[view]
 
-        indentation, start_prefix = find_indent(source_lines[0][:col_offset])
-        end_suffix = source_lines[-1][end_col_offset:]
         replacement = split_lines(self._resynthesize(context))
-        replacement.apply_indentation(
-            indentation, start_prefix=start_prefix, end_suffix=end_suffix
+        # Applies the block indentation only if the replacement lines are different from source
+        replacement.apply_source_formatting(
+            source_lines=source_lines,
+            markers=(0, col_offset, end_col_offset),
         )
 
         lines[view] = replacement
@@ -168,12 +168,12 @@ class LazyInsertAfter(_LazyActionMixin[ast.stmt, ast.stmt]):
 
     def apply(self, context: Context, source: str) -> str:
         lines = split_lines(source, encoding=context.file_info.get_encoding())
-        indentation, start_prefix = find_indent(
-            lines[self.node.lineno - 1][: self.node.col_offset]
-        )
 
         replacement = split_lines(context.unparse(self.build()))
-        replacement.apply_indentation(indentation, start_prefix=start_prefix)
+        replacement.apply_source_formatting(
+            source_lines=lines,
+            markers=(self.node.lineno - 1, self.node.col_offset, None),
+        )
 
         original_node_end = cast(int, self.node.end_lineno) - 1
         if lines[original_node_end].endswith(lines._newline_type):

refactor/ast.py

@@ -10,9 +10,10 @@
 from contextlib import contextmanager, nullcontext
 from dataclasses import dataclass
 from functools import cached_property
-from typing import Any, ContextManager, Protocol, SupportsIndex, TypeVar, Union, cast
+from typing import Any, ContextManager, Protocol, SupportsIndex, TypeVar, Union, cast, Tuple
 
 from refactor import common
+from refactor.common import find_indent
 
 DEFAULT_ENCODING = "utf-8"
 
@@ -32,19 +33,33 @@ def join(self) -> str:
         """Return the combined source code."""
         return "".join(map(str, self.lines))
 
-    def apply_indentation(
+    def apply_source_formatting(
         self,
-        indentation: StringType,
+        source_lines: Lines,
         *,
-        start_prefix: AnyStringType = "",
-        end_suffix: AnyStringType = "",
+        markers: Tuple[int, int, int | None] = None,
     ) -> None:
-        """Apply the given indentation, optionally with start and end prefixes
-        to the bound source lines."""
+        """Apply the indentation from source_lines when the first several characters match
 
+        :param source_lines: Original lines in source code
+        :param markers: Indentation and prefix parameters. Tuple of (start line, col_offset, end_suffix | None)
+        """
+
+        indentation, start_prefix = find_indent(source_lines[markers[0]][:markers[1]])
+        end_suffix = "" if markers[2] is None else source_lines[-1][markers[2]:]
+
+        original_line: str | None
         for index, line in enumerate(self.data):
+            if index < len(source_lines):
+                original_line = source_lines[index]
+            else:
+                original_line = None
+
             if index == 0:
                 self.data[index] = indentation + str(start_prefix) + str(line)  # type: ignore
+            # The updated line can have an extra wrapping in brackets
+            elif original_line is not None and original_line.startswith(line[:-1]):
+                self.data[index] = line  # type: ignore
             else:
                 self.data[index] = indentation + line  # type: ignore
 
@@ -77,7 +92,7 @@ def __getitem__(self, index: SupportsIndex | slice) -> SourceSegment:
             # re-implements the direct indexing as slicing (e.g. a[1] is a[1:2], with
             # error handling).
             direct_index = operator.index(index)
-            view = raw_line[direct_index : direct_index + 1].decode(
+            view = raw_line[direct_index: direct_index + 1].decode(
                 encoding=self.encoding
             )
             if not view: