Edit tool strips all leading whitespace from matched lines (space-indented Python files) #24549

Description

The Edit tool strips ALL leading whitespace from lines in the oldString/newString match, flattening them to column 0. The diff output shows correct indentation, but the actual file on disk has zero indentation on the edited lines. This makes the tool unusable for any edit inside indented blocks (functions, classes, if/try/for blocks, etc.).

Reproduction

1. Have a Python file with space-indented code inside a try block:

        assert cs.temp_storage_path is not None
        # Updates storage_path to point to the new file

2. Use Edit tool with oldString/newString that includes the 8-space indentation:

oldString: "        assert cs.temp_storage_path is not None\n        # Updates storage_path to point to the new file"
newString: "        assert cs.temp_storage_path is not None\n        assert cs.content_hash is not None\n        # Updates storage_path to point to the new file"

3. Tool reports "Edit applied successfully"
4. File on disk has zero indentation:

assert cs.temp_storage_path is not None
assert cs.content_hash is not None
# Updates storage_path to point to the new file

5. This breaks Python syntax (try block without except)

Verification

• cat -An confirms the edited lines have 0 leading spaces instead of 8
• git diff shows the lines lost their indentation
• python3 -c "import ast; ast.parse(open('file').read())" confirms syntax error
• Reverting with git checkout -- restores valid file
• The same bug occurs across multiple edit attempts and across OpenCode restarts
• A worker sub-agent (different model) had the exact same issue, confirming it's the tool, not the model

Affected versions

• 1.14.25
• 1.14.26

OS

Linux

Related issues

• Edit tool messes with indentation (but this is not shown in the diff) #14612 (tab→double-tab, different mechanism)
• Edit Tool Not Applying Whitespace-Only Changes #20876 (whitespace-only edits silently ignored, different mechanism)
• This bug is more severe: it corrupts file structure for ANY edit inside indented blocks