apply_patch rewrites unrelated lines in Python files for single-line edits

[JDNdeveloper]

Description

Using apply_patch to make a one-line docstring change in a Python file can also rewrite unrelated lines in the same file. I consistently see extra formatting changes such as quote normalization (' to ") even when only one line is targeted.

Plugins

None

OpenCode version

1.2.15

Steps to reproduce

1. Create a file named repro.py:

def a():
    """x"""
    return 'y'

2. Apply this patch to repro.py (ask the agent to update "x" to "x updated"):

*** Begin Patch
*** Update File: /absolute/path/to/repro.py
@@
-    """x"""
+    """x updated"""
*** End Patch

3. Inspect repro.py after patch. It becomes:

def a():
    """x updated"""
    return "y"

Note the edit to return "y".

Screenshot and/or share link

No response

Operating System

Windows 11 WSL

Terminal

Windows Terminal

[JDNdeveloper]

Turns out this was just the formatter running, which is expected.