[Bug] Edit tool false positive "File has been unexpectedly modified" detection

Bug Description
Edit tool repeatedly fails with "File has been unexpectedly modified" even when file hasn't changed. Verified via certutil -hashfile and Get-Item LastWriteTime - file timestamp was hours old, no actual modification occurred.

Repro:

1. Read file (succeeds)
2. Edit file in same response (fails with "unexpectedly modified")
3. Re-read and retry (still fails)
4. File timestamp confirms no actual modification

Observations:

• Affects some files but not others in same session
• Agent subprocesses (Task tool) can sometimes edit when main conversation cannot
• Closing VS Code doesn't fix it
• Restarting VS Code doesn't fix it
• Issue persists across multiple read/edit cycles

Environment: Windows, VS Code extension + CLI, Claude Code latest

Environment Info

• Platform: win32
• Terminal: vscode
• Version: 2.0.69
• Feedback ID: 48f41c22-0974-48cb-8cc5-82f3798ff9b5

Errors

[{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n    at async bwH (B:/~BUN/root/claude.exe:3861:3683)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:9283)\n    at async TBA (B:/~BUN/root/claude.exe:3861:141)\n    at async Z_I (B:/~BUN/root/claude.exe:3861:9079)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-14T17:27:48.336Z"},{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n    at async bwH (B:/~BUN/root/claude.exe:3861:3683)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:9283)\n    at async TBA (B:/~BUN/root/claude.exe:3861:141)\n    at async Z_I (B:/~BUN/root/claude.exe:3861:9079)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-14T17:27:48.336Z"},{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n    at async bwH (B:/~BUN/root/claude.exe:3861:3683)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:9283)\n    at async TBA (B:/~BUN/root/claude.exe:3861:141)\n    at async Z_I (B:/~BUN/root/claude.exe:3861:9079)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-14T17:27:48.336Z"},{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n    at async bwH (B:/~BUN/root/claude.exe:3861:3683)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:9283)\n    at async TBA (B:/~BUN/root/claude.exe:3861:141)\n    at async Z_I (B:/~BUN/root/claude.exe:3861:9079)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-14T17:27:48.337Z"},{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n    at async bwH (B:/~BUN/root/claude.exe:3861:3683)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:9283)\n    at async TBA (B:/~BUN/root/claude.exe:3861:141)\n    at async Z_I (B:/~BUN/root/claude.exe:3861:9079)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-14T17:27:48.337Z"},{"error":"Error: Error parsing line in C:\\Users\\Lex\\.claude\\projects\\D--Dev-deleteme-test\\6b92645a-1dd4-45ba-a7b3-b7a2311cd87e.jsonl: SyntaxError: JSON Parse error: Invalid escape character D\n    at <anonymous> (B:/~BUN/root/claude.exe:77:84)\n    at map (native:1:11)\n    at AR (B:/~BUN/root/claude.exe:77:29)\n    at async <anonymous> (B:/~BUN/root/claude.exe:3861:3838)\n

Note: Error logs were truncated.