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Cloud Sync Exclusions for Horizon AIOS

If you use Horizon AIOS without git, or alongside a cloud sync service (OneDrive, Google Drive, Dropbox), you need to configure your sync tool to exclude sensitive and large files the same way .gitignore does for git.

Recommendation: Do not place $HORIZON_ROOT inside a synced folder.

The safest approach is to keep your AIOS root outside the OneDrive, Google Drive, or Dropbox folder entirely. Cloud sync + a developer repo is a common source of file corruption, credential leaks, and sync conflicts.

If you must sync AIOS, configure the exclusions below.

Dropbox

Dropbox supports a .dropboxignore file (similar syntax to .gitignore). Place it at the root of your Dropbox-synced directory.

A pre-populated template is at $HORIZON_SYSTEM/templates/dropboxignore.template. Copy it to .dropboxignore at your Dropbox root and adjust as needed:

cp $HORIZON_SYSTEM/templates/dropboxignore.template ~/.dropbox/.dropboxignore
# or wherever your Dropbox root is

Supported since: Dropbox desktop 131.4.4602 (2021). On older clients, use the Dropbox CLI: dropbox.py exclude add <folder>.

OneDrive (Windows)

OneDrive does not support a .onedriveignore file. Options:

Option A — Selective Sync (recommended): 1. Right-click the OneDrive tray icon → Settings → Account → Choose Folders 2. Uncheck any folder you want to exclude from sync

Option B — Attribute-based exclusion (PowerShell): Mark a folder as "offline-only" so OneDrive skips it:

# Exclude a specific folder from OneDrive sync
attrib +U "C:\path\to\folder" /S /D

Note: this marks the folder as a "dehydrated" placeholder. Test on a non-critical folder first.

Option C — Move $HORIZON_ROOT outside the OneDrive folder: The cleanest solution. Example: keep AIOS at C:\devroot (not in C:\Users\<you>\OneDrive\devroot).

Google Drive for Desktop

Google Drive for Desktop does not support an ignore file.

Options: 1. Use the "Sync options" panel in Google Drive for Desktop to select which folders to sync (excludes folders at the root level only). 2. Keep $HORIZON_ROOT outside the Google Drive folder. 3. Use .gdriveignore if you are using the open-source drive CLI tool (not the official Google Drive for Desktop client).

What to Exclude

Regardless of which sync service you use, the following categories must not be synced (they contain secrets or are too large):

  • horizon_system/ai_os_etc/aios_local.conf — machine-local credentials and paths
  • brains/ — all brain session data and any secrets they hold
  • logs/ — log content (scaffold is fine, content is not)
  • handoffs/ — session-local conversation continuity data
  • .gitignore.user — machine-local folder patterns
  • ~/.horizon/ — machine-local AIOS switcher state (registry, active_env.*, wrappers); lives in $HOME, outside the synced AIOS folder, and must never be synced
  • Any file matching patterns in .gitignore (secrets, credentials, ML weights)

See .gitignore for the full list of excluded patterns.