diff --git a/apps/cloudpanel.sh b/apps/cloudpanel.sh
index b08575c..c439869 100755
--- a/apps/cloudpanel.sh
+++ b/apps/cloudpanel.sh
@@ -219,7 +219,8 @@ install_cloudpanel() {
         echo -e "${YELLOW}CloudPanel is already installed!${NC}"
         return 0
     fi
-    
+
+    require_disk_space 2048 || return 1
     check_requirements || return 1
     echo ""
     
diff --git a/apps/coolify.sh b/apps/coolify.sh
index 21902b0..ef31432 100755
--- a/apps/coolify.sh
+++ b/apps/coolify.sh
@@ -66,7 +66,8 @@ install_coolify() {
         echo -e "${YELLOW}Coolify is already installed!${NC}"
         return 0
     fi
-    
+
+    require_disk_space 3072 || return 1
     check_requirements || return 1
     echo ""
     
diff --git a/apps/proxmox.sh b/apps/proxmox.sh
index 02b8304..6155d1f 100755
--- a/apps/proxmox.sh
+++ b/apps/proxmox.sh
@@ -242,16 +242,18 @@ clear_cache() {
 
 update_proxmox() {
     echo -e "${WHITE}${BOLD}UPDATE PROXMOX VE${NC}\n"
-    
+
     check_proxmox || return 1
-    
+
+    require_disk_space 1024 || return 1
+
     # Configure non-interactive mode
     export DEBIAN_FRONTEND=noninteractive
     export NEEDRESTART_MODE=a
     export NEEDRESTART_SUSPEND=1
-    
+
     local start_time=$(date +%s)
-    
+
     run_spinner "Updating package lists..." "apt update"
     
     echo ""
diff --git a/apps/pterodactyl.sh b/apps/pterodactyl.sh
index 0b4367f..c4f8ab2 100755
--- a/apps/pterodactyl.sh
+++ b/apps/pterodactyl.sh
@@ -211,7 +211,9 @@ install_pterodactyl() {
         echo -e "${YELLOW}Pterodactyl is already installed!${NC}"
         return 0
     fi
-    
+
+    require_disk_space 3072 || return 1
+
     echo "[1/10] Installing dependencies..."
     install_dependencies && install_composer
     echo ""
diff --git a/apps/uptime-kuma.sh b/apps/uptime-kuma.sh
index a6840f8..6f64aab 100755
--- a/apps/uptime-kuma.sh
+++ b/apps/uptime-kuma.sh
@@ -93,7 +93,9 @@ install_uptime_kuma() {
         echo -e "${YELLOW}Uptime Kuma is already installed!${NC}"
         return 0
     fi
-    
+
+    require_disk_space 1024 || return 1
+
     echo "[1/4] Installing dependencies..."
     install_dependencies
     echo ""
diff --git a/lib/common.sh b/lib/common.sh
index fa8c974..8fa6d9c 100644
--- a/lib/common.sh
+++ b/lib/common.sh
@@ -171,6 +171,42 @@ require_debian_ubuntu() {
     fi
 }
 
+# Verify enough free disk space before doing apt installs or writing config.
+# Fails early with a clear message so we don't get half-installed packages or
+# files truncated mid-write when the disk is full.
+#
+# Usage:
+#   require_disk_space                       # 500MB on /var (apt cache + lists)
+#   require_disk_space 1024                  # 1024MB on /var
+#   require_disk_space 1024 /var /opt        # 1024MB on each listed path
+#
+# Duplicate filesystems (e.g. /var on the same fs as /) are checked once.
+require_disk_space() {
+    local min_mb=${1:-500}
+    shift 2>/dev/null || true
+    local paths=("$@")
+    [ ${#paths[@]} -eq 0 ] && paths=(/var)
+
+    local path avail fs seen=" " rc=0
+    for path in "${paths[@]}"; do
+        fs=$(df -P "$path" 2>/dev/null | awk 'NR==2 {print $1}')
+        if [ -z "$fs" ]; then
+            err "Cannot read disk usage for ${path}"
+            rc=1
+            continue
+        fi
+        [[ "$seen" == *" $fs "* ]] && continue
+        seen="$seen$fs "
+
+        avail=$(df -Pm "$path" 2>/dev/null | awk 'NR==2 {print $4}')
+        if [ "${avail:-0}" -lt "$min_mb" ]; then
+            err "Not enough disk space on ${path} (${fs}): ${avail}MB free, ${min_mb}MB required."
+            rc=1
+        fi
+    done
+    return $rc
+}
+
 # Re-exec the current script via sudo if not already root. Preserves env and
 # arguments. Call near the top of a sub-script:
 #   require_root "$0" "$@"
diff --git a/tools/harden.sh b/tools/harden.sh
index fda5d1c..0cbb333 100755
--- a/tools/harden.sh
+++ b/tools/harden.sh
@@ -56,6 +56,7 @@ done
 # ═══════════════════════════════════════════════════════════════════════════
 
 require_debian_ubuntu || exit 1
+require_disk_space 500 || exit 1
 
 # Read the effective Port from sshd_config + any drop-in under sshd_config.d/
 sshd_effective_port() {
diff --git a/tools/server-benchmark.sh b/tools/server-benchmark.sh
index 00450e3..4932faf 100755
--- a/tools/server-benchmark.sh
+++ b/tools/server-benchmark.sh
@@ -38,7 +38,9 @@ install_dependencies() {
     if ! command -v sysbench &> /dev/null; then
         echo -e "${YELLOW}[!] sysbench not found, installing...${NC}"
         echo ""
-        
+
+        require_disk_space 300 || return 1
+
         if command -v apt-get &> /dev/null; then
             run_spinner "Updating package list..." "apt-get update -qq"
             run_spinner "Installing sysbench..." "DEBIAN_FRONTEND=noninteractive apt-get install -y -qq sysbench"
diff --git a/tools/update-server.sh b/tools/update-server.sh
index 25bf53b..bf105fd 100755
--- a/tools/update-server.sh
+++ b/tools/update-server.sh
@@ -62,6 +62,8 @@ if ! command -v apt-get >/dev/null 2>&1; then
     exit 1
 fi
 
+require_disk_space 1024 || exit 1
+
 UPGRADE_CMD="upgrade"
 UPGRADE_LABEL="Upgrade installed packages"
 if [ $DO_FULL_UPGRADE -eq 1 ]; then