refactor(logging): unified logging system with combined logs

- Add log_msg(), log_section(), and strip_ansi() helper functions
- Extend msg_ok, msg_error, msg_warn, msg_info, msg_custom to write to log file
- Log container settings (default and advanced) to log file
- Combine host creation log and container installation log on failure
- Use app-specific log path: /tmp/{app}-{ctid}-{session}.log
- Add timestamps and section headers in log files

misc/build.func

@@ -2764,6 +2764,26 @@ Advanced:
   [[ "$APT_CACHER" == "yes" ]] && echo -e "${INFO}${BOLD}${DGN}APT Cacher: ${BGN}$APT_CACHER_IP${CL}"
   echo -e "${SEARCH}${BOLD}${DGN}Verbose Mode: ${BGN}$VERBOSE${CL}"
   echo -e "${CREATING}${BOLD}${RD}Creating an LXC of ${APP} using the above advanced settings${CL}"
+  
+  # Log settings to file
+  log_section "CONTAINER SETTINGS (ADVANCED) - ${APP}"
+  log_msg "Application: ${APP}"
+  log_msg "PVE Version: ${PVEVERSION} (Kernel: ${KERNEL_VERSION})"
+  log_msg "Operating System: $var_os ($var_version)"
+  log_msg "Container Type: $([ "$CT_TYPE" == "1" ] && echo "Unprivileged" || echo "Privileged")"
+  log_msg "Container ID: $CT_ID"
+  log_msg "Hostname: $HN"
+  log_msg "Disk Size: ${DISK_SIZE} GB"
+  log_msg "CPU Cores: $CORE_COUNT"
+  log_msg "RAM Size: ${RAM_SIZE} MiB"
+  log_msg "Bridge: $BRG"
+  log_msg "IPv4: $NET"
+  log_msg "IPv6: $IPV6_METHOD"
+  log_msg "FUSE Support: ${ENABLE_FUSE:-no}"
+  log_msg "Nesting: $([ "${ENABLE_NESTING:-1}" == "1" ] && echo "Enabled" || echo "Disabled")"
+  log_msg "GPU Passthrough: ${ENABLE_GPU:-no}"
+  log_msg "Verbose Mode: $VERBOSE"
+  log_msg "Session ID: ${SESSION_ID}"
 }
 
 # ==============================================================================
@@ -2871,6 +2891,7 @@ diagnostics_menu() {
 # - Prints summary of default values (ID, OS, type, disk, RAM, CPU, etc.)
 # - Uses icons and formatting for readability
 # - Convert CT_TYPE to description
+# - Also logs settings to log file for debugging
 # ------------------------------------------------------------------------------
 echo_default() {
   CT_TYPE_DESC="Unprivileged"
@@ -2892,6 +2913,20 @@ echo_default() {
   fi
   echo -e "${CREATING}${BOLD}${BL}Creating a ${APP} LXC using the above default settings${CL}"
   echo -e "  "
+  
+  # Log settings to file
+  log_section "CONTAINER SETTINGS - ${APP}"
+  log_msg "Application: ${APP}"
+  log_msg "PVE Version: ${PVEVERSION} (Kernel: ${KERNEL_VERSION})"
+  log_msg "Container ID: ${CT_ID}"
+  log_msg "Operating System: $var_os ($var_version)"
+  log_msg "Container Type: $CT_TYPE_DESC"
+  log_msg "Disk Size: ${DISK_SIZE} GB"
+  log_msg "CPU Cores: ${CORE_COUNT}"
+  log_msg "RAM Size: ${RAM_SIZE} MiB"
+  [[ -n "${var_gpu:-}" && "${var_gpu}" == "yes" ]] && log_msg "GPU Passthrough: Enabled"
+  [[ "$VERBOSE" == "yes" ]] && log_msg "Verbose Mode: Enabled"
+  log_msg "Session ID: ${SESSION_ID}"
 }
 
 # ------------------------------------------------------------------------------
@@ -4043,22 +4078,49 @@ EOF'
     # Copy both logs from container before potential deletion
     local build_log_copied=false
     local install_log_copied=false
+    local combined_log="/tmp/${NSAPP:-lxc}-${CTID}-${SESSION_ID}.log"
 
     if [[ -n "$CTID" && -n "${SESSION_ID:-}" ]]; then
-      # Copy BUILD_LOG (creation log) if it exists
+      # Create combined log with header
+      {
+        echo "================================================================================"
+        echo "COMBINED INSTALLATION LOG - ${APP:-LXC}"
+        echo "Container ID: ${CTID}"
+        echo "Session ID: ${SESSION_ID}"
+        echo "Timestamp: $(date '+%Y-%m-%d %H:%M:%S')"
+        echo "================================================================================"
+        echo ""
+      } > "$combined_log"
+      
+      # Append BUILD_LOG (host-side creation log) if it exists
       if [[ -f "${BUILD_LOG}" ]]; then
-        cp "${BUILD_LOG}" "/tmp/create-lxc-${CTID}-${SESSION_ID}.log" 2>/dev/null && build_log_copied=true
+        {
+          echo "================================================================================"
+          echo "PHASE 1: CONTAINER CREATION (Host)"
+          echo "================================================================================"
+          cat "${BUILD_LOG}"
+          echo ""
+        } >> "$combined_log"
+        build_log_copied=true
       fi
 
-      # Copy INSTALL_LOG from container
-      if pct pull "$CTID" "/root/.install-${SESSION_ID}.log" "/tmp/install-lxc-${CTID}-${SESSION_ID}.log" 2>/dev/null; then
+      # Copy and append INSTALL_LOG from container
+      local temp_install_log="/tmp/.install-temp-${SESSION_ID}.log"
+      if pct pull "$CTID" "/root/.install-${SESSION_ID}.log" "$temp_install_log" 2>/dev/null; then
+        {
+          echo "================================================================================"
+          echo "PHASE 2: APPLICATION INSTALLATION (Container)"
+          echo "================================================================================"
+          cat "$temp_install_log"
+          echo ""
+        } >> "$combined_log"
+        rm -f "$temp_install_log"
         install_log_copied=true
       fi
 
-      # Show available logs
+      # Show combined log location
       echo ""
-      [[ "$build_log_copied" == true ]] && echo -e "${GN}✔${CL} Container creation log: ${BL}/tmp/create-lxc-${CTID}-${SESSION_ID}.log${CL}"
-      [[ "$install_log_copied" == true ]] && echo -e "${GN}✔${CL} Installation log: ${BL}/tmp/install-lxc-${CTID}-${SESSION_ID}.log${CL}"
+      echo -e "${GN}✔${CL} Installation log: ${BL}${combined_log}${CL}"
     fi
 
     # Dev mode: Keep container or open breakpoint shell

misc/core.func

@@ -413,6 +413,69 @@ get_active_logfile() {
 # Legacy compatibility: SILENT_LOGFILE points to active log
 SILENT_LOGFILE="$(get_active_logfile)"
 
+# ------------------------------------------------------------------------------
+# strip_ansi()
+#
+# - Removes ANSI escape sequences from input text
+# - Used to clean colored output for log files
+# - Handles both piped input and arguments
+# ------------------------------------------------------------------------------
+strip_ansi() {
+  if [[ $# -gt 0 ]]; then
+    echo -e "$*" | sed 's/\x1b\[[0-9;]*m//g; s/\x1b\[[0-9;]*[a-zA-Z]//g'
+  else
+    sed 's/\x1b\[[0-9;]*m//g; s/\x1b\[[0-9;]*[a-zA-Z]//g'
+  fi
+}
+
+# ------------------------------------------------------------------------------
+# log_msg()
+#
+# - Writes message to active log file without ANSI codes
+# - Adds timestamp prefix for log correlation
+# - Creates log file if it doesn't exist
+# - Arguments: message text (can include ANSI codes, will be stripped)
+# ------------------------------------------------------------------------------
+log_msg() {
+  local msg="$*"
+  local logfile
+  logfile="$(get_active_logfile)"
+  
+  [[ -z "$msg" ]] && return
+  [[ -z "$logfile" ]] && return
+  
+  # Ensure log directory exists
+  mkdir -p "$(dirname "$logfile")" 2>/dev/null || true
+  
+  # Strip ANSI codes and write with timestamp
+  local clean_msg
+  clean_msg=$(strip_ansi "$msg")
+  echo "[$(date '+%Y-%m-%d %H:%M:%S')] $clean_msg" >>"$logfile"
+}
+
+# ------------------------------------------------------------------------------
+# log_section()
+#
+# - Writes a section header to the log file
+# - Used for separating different phases of installation
+# - Arguments: section name
+# ------------------------------------------------------------------------------
+log_section() {
+  local section="$1"
+  local logfile
+  logfile="$(get_active_logfile)"
+  
+  [[ -z "$logfile" ]] && return
+  mkdir -p "$(dirname "$logfile")" 2>/dev/null || true
+  
+  {
+    echo ""
+    echo "================================================================================"
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $section"
+    echo "================================================================================"
+  } >>"$logfile"
+}
+
 # ------------------------------------------------------------------------------
 # silent()
 #
@@ -555,6 +618,9 @@ msg_info() {
   [[ -n "${MSG_INFO_SHOWN["$msg"]+x}" ]] && return
   MSG_INFO_SHOWN["$msg"]=1
 
+  # Log to file
+  log_msg "[INFO] $msg"
+
   stop_spinner
   SPINNER_MSG="$msg"
 
@@ -598,6 +664,7 @@ msg_ok() {
   stop_spinner
   clear_line
   echo -e "$CM ${GN}${msg}${CL}"
+  log_msg "[OK] $msg"
   unset MSG_INFO_SHOWN["$msg"]
 }
 
@@ -613,6 +680,7 @@ msg_error() {
   stop_spinner
   local msg="$1"
   echo -e "${BFR:-}${CROSS:-✖️} ${RD}${msg}${CL}" >&2
+  log_msg "[ERROR] $msg"
 }
 
 # ------------------------------------------------------------------------------
@@ -627,6 +695,7 @@ msg_warn() {
   stop_spinner
   local msg="$1"
   echo -e "${BFR:-}${INFO:-ℹ️} ${YWB}${msg}${CL}" >&2
+  log_msg "[WARN] $msg"
 }
 
 # ------------------------------------------------------------------------------
@@ -644,6 +713,7 @@ msg_custom() {
   [[ -z "$msg" ]] && return
   stop_spinner
   echo -e "${BFR:-} ${symbol} ${color}${msg}${CL:-\e[0m}"
+  log_msg "$msg"
 }
 
 # ------------------------------------------------------------------------------