Command history syncing causes instance duplication failure

[srnyx]

Please confirm the following.

• I checked the existing issues for duplicate problems
• I have tried resolving the issue using the support portal
• I have ensured my Modrinth App installation is up to date

What version of the Modrinth App are you using?

0.19.1

What operating systems are you seeing the problem on?

Windows

Describe the bug

With command history setting syncing on, trying to duplicate an instance causes a file lock on command_history.txt, causing this duplicating failure:

Click to view failure

Context: I am duplicating Event Alerts test 1.21.11

Failure
Code: filesystem_error
Phase: preparing instance
Message: I/O error: The process cannot access the file because it is being used by another process. (os error 32), path: C:\Users\REDACTED\AppData\Roaming\ModrinthApp\profiles\Event Alerts test 1.21.11\command_history.txt

Raw snapshot
{
  "job_id": "b00503a0-1139-41fb-8814-55ad49207381",
  "instance_id": null,
  "kind": "duplicate_instance",
  "status": "failed",
  "target": {
    "type": "new_instance",
    "instance_id": null
  },
  "phase": "rolling_back",
  "progress": null,
  "details": {
    "type": "empty"
  },
  "display": {
    "title": "EU test 26.1.2",
    "icon": "C:\\Users\\REDACTED\\AppData\\Roaming\\ModrinthApp\\caches\\icons\\1c2561d95dcb78614a8fa21803141f0abdb0edee.png"
  },
  "error": {
    "code": "filesystem_error",
    "phase": "preparing_instance",
    "message": "I/O error: The process cannot access the file because it is being used by another process. (os error 32), path: C:\\Users\\REDACTED\\AppData\\Roaming\\ModrinthApp\\profiles\\Event Alerts test 1.21.11\\command_history.txt"
  },
  "rollback_error": null,
  "created": "2026-08-29T18:47:51+00:00",
  "modified": "2026-08-29T18:48:35+00:00",
  "finished": "2026-08-29T18:48:35+00:00"
}

Steps to reproduce

1. Enable command history setting sync
2. Try to duplicate an instance

Expected behavior

No duplication failure when command history setting sync is enabled

Additional context

Full logs: https://paste.srnyx.com/zamahebagi.txt