Claude Code Session Data Loss: Backup Script for Windows & Mac

Multiple users on r/ClaudeAI report that Claude Code silently loses session data — the session title remains in the sidebar, but clicking it reveals an empty transcript. No warning, no error, no recovery. This appears to happen during context compression, unexpected exits, or storage-layer issues.

The Backup Solution

A community-written script backs up all Claude Code data (sessions, projects, plans, drafts, memory) from ~/.claude to a separate folder, runs daily via Task Scheduler (Windows) or launchd (Mac), and retains 7 days of rolling backups.

Windows (PowerShell + Task Scheduler)

Create the backup folder:

mkdir C:\Users\%USERNAME%\ClaudeBackups

Save the following as backup-claude-sessions.ps1 in that folder:

$ErrorActionPreference = "Stop"
$source = "$env:USERPROFILE\.claude"
$backupRoot = "$env:USERPROFILE\ClaudeBackups"
$logFile = Join-Path $backupRoot "backup.log"
$keepDays = 7
$timestamp = Get-Date -Format "yyyy-MM-dd_HHmmss"
$backupDir = Join-Path $backupRoot $timestamp
$dirs = @("sessions", "projects", "plans", "drafts", "memory")

function Write-Log($msg) {
    $line = "$(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - $msg"
    Add-Content -Path $logFile -Value $line -Encoding utf8
}
try {
    Write-Log "=== Backup started ==="
    New-Item -ItemType Directory -Path $backupDir -Force | Out-Null
    foreach ($d in $dirs) {
        $src = Join-Path $source $d
        if (Test-Path $src) {
            $dst = Join-Path $backupDir $d
            Copy-Item -Path $src -Destination $dst -Recurse -Force
            $count = (Get-ChildItem $dst -Recurse -File -ErrorAction SilentlyContinue | Measure-Object).Count
            Write-Log " Copied $d ($count files)"
        } else {
            Write-Log " Skipped $d (not found)"
        }
    }
    $size = (Get-ChildItem $backupDir -Recurse -File | Measure-Object -Property Length -Sum).Sum
    Write-Log " Total backup size: $([math]::Round($size/1MB, 2)) MB"
    $cutoff = (Get-Date).AddDays(-$keepDays)
    Get-ChildItem $backupRoot -Directory | Where-Object { $.Name -match '^\d{4}-\d{2}-\d{2}\d{6}$' -and $.CreationTime -lt $cutoff } | ForEach-Object {
        Remove-Item $.FullName -Recurse -Force -Confirm:$false
        Write-Log " Rotated old backup: $($.Name)"
    }
    Write-Log "=== Backup completed successfully ==="
} catch {
    Write-Log "!!! BACKUP FAILED: $"
    exit 1
}

Create install-schedule.ps1 and run as Administrator once:

$action = New-ScheduledTaskAction     -Execute "powershell.exe"
    -Argument "-ExecutionPolicy Bypass -WindowStyle Hidden -File "$env:USERPROFILE\ClaudeBackups\backup-claude-sessions.ps1""
$trigger = New-ScheduledTaskTrigger -Daily -At 8:00AM
$settings = New-ScheduledTaskSettingsSet     -AllowStartIfOnBatteries
    -DontStopIfGoingOnBatteries     -StartWhenAvailable Register-ScheduledTask
    -TaskName "ClaudeSessionsBackup"     -Action $action
    -Trigger $trigger     -Settings $settings
    -Description "Daily backup of Claude Code sessions" `
    -RunLevel Limited
Write-Host "Done! Runs daily at 8:00 AM." -ForegroundColor Green

Run the installer:

powershell -ExecutionPolicy Bypass -File "C:\Users%USERNAME%\ClaudeBackups\install-schedule.ps1"

Mac (launchd + shell script)

Create the backup folder:

mkdir -p /ClaudeBackups

Save as /ClaudeBackups/backup-claude-sessions.sh:

#!/bin/bash
set -euo pipefail
SOURCE="$HOME/.claude"
BACKUP_ROOT="$HOME/ClaudeBackups"
LOG_FILE="$BACKUP_ROOT/backup.log"
KEEP_DAYS=7
TIMESTAMP=$(date +"%Y-%m-%d_%H%M%S")
BACKUP_DIR="$BACKUP_ROOT/$TIMESTAMP"
DIRS=("sessions" "projects" "plans" "drafts" "memory")
log() { echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" >> "$LOG_FILE"; }
log "=== Backup started ==="
mkdir -p "$BACKUP_DIR"
for d in "${DIRS[@]}"; do
    src="$SOURCE/$d"
    if [ -d "$src" ]; then
        cp -R "$src" "$BACKUP_DIR/$d"
        count=$(find "$BACKUP_DIR/$d" -type f | wc -l | tr -d ' ')
        log " Copied $d ($count files)"
    else
        log " Skipped $d (not found)"
    fi
done
size=$(du -sb "$BACKUP_DIR" | cut -f1)
log " Total backup size: $(echo "scale=2; $size/1048576" | bc) MB"
find "$BACKUP_ROOT" -maxdepth 1 -type d -name "????-??-??_??????" -mtime +$KEEP_DAYS -exec rm -rf {} + -exec log " Rotated old backup: {}" ;
log "=== Backup completed successfully ==="

Make executable and schedule via launchd (see original post for plist setup).

The script runs completely independently of Claude Code, so even if Claude crashes or loses data, backups are preserved. It logs each run to backup.log for verification.