diff --git a/tools/file_tools.py b/tools/file_tools.py
index d34c59f4..b192c226 100644
--- a/tools/file_tools.py
+++ b/tools/file_tools.py
@@ -5,6 +5,7 @@ import errno
 import json
 import logging
 import os
+import re
 import threading
 from typing import Optional
 from tools.file_operations import ShellFileOperations
@@ -12,6 +13,18 @@ from agent.redact import redact_sensitive_text
 
 logger = logging.getLogger(__name__)
 
+# Regex to match ANSI escape sequences (CSI codes, OSC codes, simple escapes).
+# Models occasionally copy these from terminal output into file content.
+_ANSI_ESCAPE_RE = re.compile(r"\x1b\[[0-9;]*[A-Za-z]|\x1b\][^\x07]*\x07|\x1b[()][A-B012]|\x1b[=>]")
+
+
+def _strip_ansi(text: str) -> str:
+    """Remove ANSI escape sequences from text destined for file writes."""
+    if not text or "\x1b" not in text:
+        return text
+    return _ANSI_ESCAPE_RE.sub("", text)
+
+
 _EXPECTED_WRITE_ERRNOS = {errno.EACCES, errno.EPERM, errno.EROFS}
 
 
@@ -288,6 +301,7 @@ def notify_other_tool_call(task_id: str = "default"):
 def write_file_tool(path: str, content: str, task_id: str = "default") -> str:
     """Write content to a file."""
     try:
+        content = _strip_ansi(content)
         file_ops = _get_file_ops(task_id)
         result = file_ops.write_file(path, content)
         return json.dumps(result.to_dict(), ensure_ascii=False)
@@ -311,10 +325,13 @@ def patch_tool(mode: str = "replace", path: str = None, old_string: str = None,
                 return json.dumps({"error": "path required"})
             if old_string is None or new_string is None:
                 return json.dumps({"error": "old_string and new_string required"})
+            old_string = _strip_ansi(old_string)
+            new_string = _strip_ansi(new_string)
             result = file_ops.patch_replace(path, old_string, new_string, replace_all)
         elif mode == "patch":
             if not patch:
                 return json.dumps({"error": "patch content required"})
+            patch = _strip_ansi(patch)
             result = file_ops.patch_v4a(patch)
         else:
             return json.dumps({"error": f"Unknown mode: {mode}"})