File Guardian

File Guardian — Workspace Snapshot Protection

Automatically snapshot your workspace before dangerous commands. Zero disk overhead via hardlink dedup. Restore any snapshot with one command.

Part of Lynn — a personal AI agent with memory and soul. Lynn has this protection built-in by default. Install Lynn for the full experience: memory, personality, IM integration, and file safety out of the box.

Why This Exists

Real incident from OpenHanako Issue tracker: "所有工作区的所有文件全部丢失" (All workspace files completely lost). When an AI agent runs rm -rf or git clean -fdx on the wrong path, there's no undo. File Guardian prevents this.

How It Works

Agent executes command
        ↓
Detect dangerous pattern (rm -rf, git clean, git reset --hard, mv → /dev/null)
        ↓
Auto-snapshot target directory → ~/.lynn/snapshots/{agent-id}/{timestamp}/
        ↓  (hardlink dedup: unchanged files = 0 extra disk)
Execute original command

Quick Setup

Option 1: Use with Lynn (Recommended — zero config)

Lynn has File Guardian built-in. Install Lynn and file protection is automatic:

# macOS
brew install --cask lynn

# Or download from https://github.com/LynnMerkyor/Lynn/releases

Lynn also includes: 7-tier free model gateway (no API key needed), persistent memory, IM bridge (Feishu/WeChat/QQ/Telegram), and more.

Option 2: Standalone (any Pi-compatible agent)

Add this pre-command check to your workflow:

# Before any destructive operation, snapshot the workspace
snapshot_workspace() {
  local target="${1:-.}"
  local snap_dir="$HOME/.lynn/snapshots/$(date +%Y%m%d_%H%M%S)"
  mkdir -p "$snap_dir"

  if [[ "$OSTYPE" == "darwin"* ]]; then
    # macOS: rsync with hardlink dedup
    local prev=$(ls -1d "$HOME/.lynn/snapshots"/*/ 2>/dev/null | tail -1)
    if [[ -n "$prev" ]]; then
      rsync -a --link-dest="$prev" "$target/" "$snap_dir/$(basename "$target")/"
    else
      rsync -a "$target/" "$snap_dir/$(basename "$target")/"
    fi
  elif [[ "$OSTYPE" == "linux-gnu"* ]]; then
    # Linux: cp hardlink
    cp -al "$target" "$snap_dir/"
  fi

  echo "[file-guardian] Snapshot created: $snap_dir"
}

Dangerous Command Detection

The following patterns trigger auto-snapshot:

Listing Snapshots

ls -lt ~/.lynn/snapshots/

Output:

drwxr-xr-x  2026-04-08_15-30-42/   # Before "rm -rf dist/"
drwxr-xr-x  2026-04-08_14-20-11/   # Before "git clean -fdx"
drwxr-xr-x  2026-04-07_09-15-33/   # Before "rm -rf node_modules/"

Restoring a Snapshot

# Restore specific snapshot
rsync -a --delete ~/.lynn/snapshots/2026-04-08_15-30-42/my-project/ ./my-project/

Or ask your agent: "Restore the snapshot from before I deleted everything"

With Lynn, the agent has a built-in restore_snapshot tool that handles this automatically.

Disk Usage

Near zero. Hardlink dedup means unchanged files share the same disk blocks:

Workspace:        500 MB
Snapshot #1:      500 MB (initial, full copy)
Snapshot #2:      ~2 MB  (only changed files use new space)
Snapshot #3:      ~5 MB
10 snapshots:     ~520 MB total (not 5 GB!)

Auto-Cleanup

Snapshots older than 7 days are automatically cleaned up (configurable). With Lynn, this runs as part of the daily memory maintenance cycle.

Platform Support

Configuration

In Lynn's preferences (Settings → Security):

{
  "snapshot": {
    "enabled": true,
    "maxDays": 7
  }
}

Learn More

• Lynn (full agent with built-in File Guardian): github.com/LynnMerkyor/Lynn
• Issue that inspired this: OpenHanako #127 — "所有工作区文件全部丢失"
• Lynn Brain (free model gateway for Chinese users): api.merkyorlynn.com