diff --git a/modules/performance/php-optimizer.sh b/modules/performance/php-optimizer.sh
index 13cd099..7ce4a23 100755
--- a/modules/performance/php-optimizer.sh
+++ b/modules/performance/php-optimizer.sh
@@ -1563,6 +1563,17 @@ optimize_level_1_max_children() {
         echo ""
     fi
 
+    # Calculate server capacity for intelligent three-constraint model
+    local server_capacity_result
+    server_capacity_result=$(calculate_server_capacity "$total_ram_mb")
+    local server_capacity
+    server_capacity=$(echo "$server_capacity_result" | cut -d'|' -f1)
+    local server_memory_per_process
+    server_memory_per_process=$(echo "$server_capacity_result" | cut -d'|' -f3)
+    cecho "  Server PHP-FPM capacity: ${WHITE}${server_capacity}${NC} max_children"
+    cecho "  Using intelligent three-constraint model: Memory + Traffic + Fair Share"
+    echo ""
+
     # Get recommendations
     cecho "${CYAN}Step 2: Calculating optimal settings...${NC}"
     echo ""
@@ -1575,6 +1586,18 @@ optimize_level_1_max_children() {
     local users
     users=$(list_all_users)
 
+    # CRITICAL FIX: Build list of ALL domains on server FIRST
+    # This is needed for accurate traffic percentage calculation
+    all_domains_string=""
+    while IFS= read -r u; do
+        [ -z "$u" ] && continue
+        u_domains=$(get_user_domains "$u")
+        while IFS= read -r d; do
+            [ -z "$d" ] && continue
+            all_domains_string="$all_domains_string$d"$'\n'
+        done <<< "$u_domains"
+    done <<< "$users"
+
     while IFS= read -r username; do
         [ -z "$username" ] && continue
         local user_domains
@@ -1594,16 +1617,21 @@ optimize_level_1_max_children() {
                 current_max="?"
             fi
 
-            # Get recommendations - use profile if available, otherwise use traffic-based
+            # Get recommendations - use profile if available, otherwise use intelligent three-constraint model
             local recommended_max
             if [ "$profiles_exist" = "1" ] && [ -f "/tmp/php-domain-profiles/$domain.profile" ]; then
                 recommended_max=$(get_max_children_recommendation "$domain" "$username")
             else
-                # Fallback to traffic-based (old method)
-                local traffic_rpm
-                traffic_rpm=$(get_domain_peak_concurrent "$domain" 2>/dev/null || echo "0")
-                [ "$traffic_rpm" = "?" ] && traffic_rpm="0"
-                recommended_max=$((traffic_rpm > 5 ? traffic_rpm + 10 : 5))
+                # Use intelligent three-constraint model (same as Level 5)
+                local traffic_pct
+                traffic_pct=$(get_domain_traffic_percentage "$username" "$domain" "$all_domains_string" 2>/dev/null | cut -d'|' -f1)
+                traffic_pct=${traffic_pct:-50}
+
+                # Call intelligent three-constraint function
+                local intel_result
+                intel_result=$(calculate_optimal_php_settings_intelligent "$username" "$total_ram_mb" "$server_capacity" "$traffic_pct" 2>/dev/null || echo "20|dynamic|1|5|ERROR|Failed")
+
+                recommended_max=$(echo "$intel_result" | cut -d'|' -f1)
             fi
 
             recommended_values["$domain"]="$recommended_max"
@@ -1621,6 +1649,46 @@ optimize_level_1_max_children() {
         done <<< "$user_domains"
     done <<< "$users"
 
+    # CRITICAL VALIDATION: Check if combined recommendations exceed safe limits
+    cecho "${CYAN}Step 2b: Validating capacity...${NC}"
+    echo ""
+
+    local total_recommended_max_children=0
+    local avg_memory_per_process=$server_memory_per_process
+    local total_recommended_memory=0
+
+    for domain in "${!recommended_values[@]}"; do
+        local rec_max="${recommended_values[$domain]}"
+        [ -z "$rec_max" ] && continue
+        total_recommended_max_children=$((total_recommended_max_children + rec_max))
+        total_recommended_memory=$((total_recommended_memory + (rec_max * avg_memory_per_process)))
+    done
+
+    # Determine if recommendations are safe
+    local max_safe_php_fpm=$((total_ram_mb * 60 / 100))
+
+    if [ "$total_recommended_memory" -gt "$max_safe_php_fpm" ]; then
+        cecho "${RED}${BOLD}⚠ WARNING: Combined recommendations exceed safe limits!${NC}"
+        cecho "${RED}Recommended total: ${total_recommended_memory}MB (${total_recommended_max_children} max_children combined)${NC}"
+        cecho "${RED}Safe maximum: ${max_safe_php_fpm}MB${NC}"
+        cecho "${YELLOW}Applying safety caps to prevent OOM crashes...${NC}"
+        echo ""
+
+        # Scale down all recommendations proportionally
+        local scale_factor
+        scale_factor=$((max_safe_php_fpm * 100 / total_recommended_memory))
+
+        for domain in "${!recommended_values[@]}"; do
+            local rec_max="${recommended_values[$domain]}"
+            [ -z "$rec_max" ] && continue
+            rec_max=$((rec_max * scale_factor / 100))
+            [ "$rec_max" -lt 5 ] && rec_max=5
+            recommended_values["$domain"]="$rec_max"
+        done
+        cecho "${CYAN}Applied proportional scaling (${scale_factor}%)${NC}"
+        echo ""
+    fi
+
     echo ""
     if [ "$changes_needed" -eq 0 ]; then
         cecho "${GREEN}${BOLD}✓ All domains already optimized - no changes needed${NC}"
@@ -1752,6 +1820,17 @@ optimize_level_2_memory() {
     cecho "  Status: ${WHITE}${status}${NC}"
     echo ""
 
+    # Calculate server capacity for intelligent three-constraint model
+    local server_capacity_result
+    server_capacity_result=$(calculate_server_capacity "$total_ram_mb")
+    local server_capacity
+    server_capacity=$(echo "$server_capacity_result" | cut -d'|' -f1)
+    local server_memory_per_process
+    server_memory_per_process=$(echo "$server_capacity_result" | cut -d'|' -f3)
+    cecho "  Server PHP-FPM capacity: ${WHITE}${server_capacity}${NC} max_children"
+    cecho "  Using intelligent three-constraint model: Memory + Traffic + Fair Share"
+    echo ""
+
     # Check if profiles exist
     local profiles_exist=0
     if [ -d "/tmp/php-domain-profiles" ] && [ "$(ls -1 /tmp/php-domain-profiles/*.profile 2>/dev/null | wc -l)" -gt 0 ]; then
@@ -1762,7 +1841,7 @@ optimize_level_2_memory() {
     else
         cecho "${YELLOW}${BOLD}⚠ No domain profiles found${NC}"
         cecho "${CYAN}For more accurate optimization, run pre-analysis first:${NC}"
-        cecho "  ${WHITE}php-optimizer.sh${NC} → Option 3 (Pre-analyze domains)"
+        cecho "  ${WHITE}php-optimizer.sh${NC} → Option 0 (Pre-analyze domains)"
         echo ""
     fi
 
@@ -1779,6 +1858,18 @@ optimize_level_2_memory() {
     local users
     users=$(list_all_users)
 
+    # CRITICAL FIX: Build list of ALL domains on server FIRST
+    # This is needed for accurate traffic percentage calculation
+    all_domains_string=""
+    while IFS= read -r u; do
+        [ -z "$u" ] && continue
+        u_domains=$(get_user_domains "$u")
+        while IFS= read -r d; do
+            [ -z "$d" ] && continue
+            all_domains_string="$all_domains_string$d"$'\n'
+        done <<< "$u_domains"
+    done <<< "$users"
+
     while IFS= read -r username; do
         [ -z "$username" ] && continue
         local user_domains
@@ -1798,27 +1889,24 @@ optimize_level_2_memory() {
                 current_max="?"
             fi
 
-            # Get recommendations - use profile if available, otherwise use traffic-based
+            # Get recommendations - use profile if available, otherwise use intelligent three-constraint model
             local recommended_max
-            if [ "$profiles_exist" = "1" ] && [ -f "/tmp/php-domain-profiles/$domain.profile" ]; then
-                recommended_max=$(get_max_children_recommendation "$domain" "$username")
-            else
-                # Fallback to traffic-based (old method)
-                local traffic_rpm
-                traffic_rpm=$(get_domain_peak_concurrent "$domain" 2>/dev/null || echo "0")
-                [ "$traffic_rpm" = "?" ] && traffic_rpm="0"
-                recommended_max=$((traffic_rpm > 5 ? traffic_rpm + 10 : 5))
-            fi
-
             local recommended_memory
             if [ "$profiles_exist" = "1" ] && [ -f "/tmp/php-domain-profiles/$domain.profile" ]; then
+                recommended_max=$(get_max_children_recommendation "$domain" "$username")
                 recommended_memory=$(get_memory_limit_recommendation "$domain" "$username")
             else
-                # Fallback to traffic-based (old method)
-                local traffic_rpm
-                traffic_rpm=$(get_domain_peak_concurrent "$domain" 2>/dev/null || echo "0")
-                [ "$traffic_rpm" = "?" ] && traffic_rpm="0"
-                recommended_memory=$(calculate_optimal_memory_limit "$username" "$domain" "$traffic_rpm")
+                # Use intelligent three-constraint model (same as Level 5)
+                local traffic_pct
+                traffic_pct=$(get_domain_traffic_percentage "$username" "$domain" "$all_domains_string" 2>/dev/null | cut -d'|' -f1)
+                traffic_pct=${traffic_pct:-50}
+
+                # Call intelligent three-constraint function
+                local intel_result
+                intel_result=$(calculate_optimal_php_settings_intelligent "$username" "$total_ram_mb" "$server_capacity" "$traffic_pct" 2>/dev/null || echo "20|dynamic|1|5|ERROR|Failed")
+
+                recommended_max=$(echo "$intel_result" | cut -d'|' -f1)
+                recommended_memory=$(calculate_optimal_memory_limit "$username" "$domain" "$recommended_max" 2>/dev/null || echo "128M")
             fi
 
             recommended_max_children["$domain"]="$recommended_max"
@@ -1839,6 +1927,46 @@ optimize_level_2_memory() {
         done <<< "$user_domains"
     done <<< "$users"
 
+    # CRITICAL VALIDATION: Check if combined recommendations exceed safe limits
+    cecho "${CYAN}Step 2b: Validating capacity...${NC}"
+    echo ""
+
+    local total_recommended_max_children=0
+    local avg_memory_per_process=$server_memory_per_process
+    local total_recommended_memory=0
+
+    for domain in "${!recommended_max_children[@]}"; do
+        local rec_max="${recommended_max_children[$domain]}"
+        [ -z "$rec_max" ] && continue
+        total_recommended_max_children=$((total_recommended_max_children + rec_max))
+        total_recommended_memory=$((total_recommended_memory + (rec_max * avg_memory_per_process)))
+    done
+
+    # Determine if recommendations are safe
+    local max_safe_php_fpm=$((total_ram_mb * 60 / 100))
+
+    if [ "$total_recommended_memory" -gt "$max_safe_php_fpm" ]; then
+        cecho "${RED}${BOLD}⚠ WARNING: Combined recommendations exceed safe limits!${NC}"
+        cecho "${RED}Recommended total: ${total_recommended_memory}MB (${total_recommended_max_children} max_children combined)${NC}"
+        cecho "${RED}Safe maximum: ${max_safe_php_fpm}MB${NC}"
+        cecho "${YELLOW}Applying safety caps to prevent OOM crashes...${NC}"
+        echo ""
+
+        # Scale down all recommendations proportionally
+        local scale_factor
+        scale_factor=$((max_safe_php_fpm * 100 / total_recommended_memory))
+
+        for domain in "${!recommended_max_children[@]}"; do
+            local rec_max="${recommended_max_children[$domain]}"
+            [ -z "$rec_max" ] && continue
+            rec_max=$((rec_max * scale_factor / 100))
+            [ "$rec_max" -lt 5 ] && rec_max=5
+            recommended_max_children["$domain"]="$rec_max"
+        done
+        cecho "${CYAN}Applied proportional scaling (${scale_factor}%)${NC}"
+        echo ""
+    fi
+
     echo ""
     if [ "$changes_needed" -eq 0 ]; then
         cecho "${GREEN}${BOLD}✓ All domains already optimized${NC}"
@@ -2006,6 +2134,17 @@ optimize_level_3_advanced() {
     cecho "  Status: ${WHITE}${status}${NC}"
     echo ""
 
+    # Calculate server capacity for intelligent three-constraint model
+    local server_capacity_result
+    server_capacity_result=$(calculate_server_capacity "$total_ram_mb")
+    local server_capacity
+    server_capacity=$(echo "$server_capacity_result" | cut -d'|' -f1)
+    local server_memory_per_process
+    server_memory_per_process=$(echo "$server_capacity_result" | cut -d'|' -f3)
+    cecho "  Server PHP-FPM capacity: ${WHITE}${server_capacity}${NC} max_children"
+    cecho "  Using intelligent three-constraint model: Memory + Traffic + Fair Share"
+    echo ""
+
     # Check if profiles exist
     local profiles_exist=0
     if [ -d "/tmp/php-domain-profiles" ] && [ "$(ls -1 /tmp/php-domain-profiles/*.profile 2>/dev/null | wc -l)" -gt 0 ]; then
@@ -2029,6 +2168,18 @@ optimize_level_3_advanced() {
     local users
     users=$(list_all_users)
 
+    # CRITICAL FIX: Build list of ALL domains on server FIRST
+    # This is needed for accurate traffic percentage calculation
+    all_domains_string=""
+    while IFS= read -r u; do
+        [ -z "$u" ] && continue
+        u_domains=$(get_user_domains "$u")
+        while IFS= read -r d; do
+            [ -z "$d" ] && continue
+            all_domains_string="$all_domains_string$d"$'\n'
+        done <<< "$u_domains"
+    done <<< "$users"
+
     while IFS= read -r username; do
         [ -z "$username" ] && continue
         local user_domains
@@ -2048,14 +2199,18 @@ optimize_level_3_advanced() {
                 recommended_memory_limit["$domain"]=$(get_memory_limit_recommendation "$domain" "$username")
                 recommended_max_requests["$domain"]=$(get_max_requests_recommendation "$domain")
             else
-                # Fallback to traffic-based (old method)
-                local traffic_rpm
-                traffic_rpm=$(get_domain_peak_concurrent "$domain" 2>/dev/null || echo "0")
-                [ "$traffic_rpm" = "?" ] && traffic_rpm="0"
+                # Use intelligent three-constraint model (same as Level 5)
+                local traffic_pct
+                traffic_pct=$(get_domain_traffic_percentage "$username" "$domain" "$all_domains_string" 2>/dev/null | cut -d'|' -f1)
+                traffic_pct=${traffic_pct:-50}
 
-                recommended_max_children["$domain"]=$((traffic_rpm > 5 ? traffic_rpm + 10 : 5))
-                recommended_memory_limit["$domain"]=$(calculate_optimal_memory_limit "$username" "$domain" "$traffic_rpm")
-                recommended_max_requests["$domain"]=$(calculate_optimal_max_requests "$traffic_rpm")
+                # Call intelligent three-constraint function
+                local intel_result
+                intel_result=$(calculate_optimal_php_settings_intelligent "$username" "$total_ram_mb" "$server_capacity" "$traffic_pct" 2>/dev/null || echo "20|dynamic|1|5|ERROR|Failed")
+
+                recommended_max_children["$domain"]=$(echo "$intel_result" | cut -d'|' -f1)
+                recommended_memory_limit["$domain"]=$(calculate_optimal_memory_limit "$username" "$domain" "$recommended_max_children[$domain]" 2>/dev/null || echo "128M")
+                recommended_max_requests["$domain"]=$(calculate_optimal_max_requests "$recommended_max_children[$domain]" 2>/dev/null || echo "0")
             fi
 
             local current_max
@@ -2088,6 +2243,46 @@ optimize_level_3_advanced() {
         done <<< "$user_domains"
     done <<< "$users"
 
+    # CRITICAL VALIDATION: Check if combined recommendations exceed safe limits
+    cecho "${CYAN}Step 2b: Validating capacity...${NC}"
+    echo ""
+
+    local total_recommended_max_children=0
+    local avg_memory_per_process=$server_memory_per_process
+    local total_recommended_memory=0
+
+    for domain in "${!recommended_max_children[@]}"; do
+        local rec_max="${recommended_max_children[$domain]}"
+        [ -z "$rec_max" ] && continue
+        total_recommended_max_children=$((total_recommended_max_children + rec_max))
+        total_recommended_memory=$((total_recommended_memory + (rec_max * avg_memory_per_process)))
+    done
+
+    # Determine if recommendations are safe
+    local max_safe_php_fpm=$((total_ram_mb * 60 / 100))
+
+    if [ "$total_recommended_memory" -gt "$max_safe_php_fpm" ]; then
+        cecho "${RED}${BOLD}⚠ WARNING: Combined recommendations exceed safe limits!${NC}"
+        cecho "${RED}Recommended total: ${total_recommended_memory}MB (${total_recommended_max_children} max_children combined)${NC}"
+        cecho "${RED}Safe maximum: ${max_safe_php_fpm}MB${NC}"
+        cecho "${YELLOW}Applying safety caps to prevent OOM crashes...${NC}"
+        echo ""
+
+        # Scale down all recommendations proportionally
+        local scale_factor
+        scale_factor=$((max_safe_php_fpm * 100 / total_recommended_memory))
+
+        for domain in "${!recommended_max_children[@]}"; do
+            local rec_max="${recommended_max_children[$domain]}"
+            [ -z "$rec_max" ] && continue
+            rec_max=$((rec_max * scale_factor / 100))
+            [ "$rec_max" -lt 5 ] && rec_max=5
+            recommended_max_children["$domain"]="$rec_max"
+        done
+        cecho "${CYAN}Applied proportional scaling (${scale_factor}%)${NC}"
+        echo ""
+    fi
+
     echo ""
     if [ "$changes_needed" -eq 0 ]; then
         cecho "${GREEN}${BOLD}✓ All domains already optimized${NC}"