improve instant prompt usability, update docs and add an option to the wizard to enable it

internal/wizard.zsh

@@ -1213,6 +1213,50 @@ function ask_empty_line() {
   done
 }
 
+function ask_instant_prompt() {
+  autoload -Uz is-at-least
+  if ! is-at-least 5.4; then
+    instant_prompt=off
+    return
+  fi
+  if (( LINES < 24 )); then
+    local nl=''
+  else
+    local nl=$'\n'
+  fi
+  while true; do
+    clear
+    flowing -c "%BInstant Prompt Mode%b"
+    print -n $nl
+    flowing -c "$(href 'https://github.com/romkatv/powerlevel10k/blob/master/README.md#instant-prompt')"
+    print -P ""
+    flowing +c -i 5 "%B(1)  Off.%b" Disable instant prompt. Choose this if you\'ve tried instant  \
+      prompt and found it incompatible with your zsh configuration files.
+    print -n $nl
+    flowing +c -i 5 "%B(2)  Quiet.%b" Enable instant prompt and %Bdon\'t print warnings%b when    \
+      detecting console output during zsh initialization. Choose this if you\'ve read and         \
+      understood the documentation linked above.
+    print -n $nl
+    flowing +c -i 5 "%B(3)  Verbose.%b"  Enable instant prompt and %Bprint a warning%b when       \
+      detecting console output during zsh initialization. Choose this if you\'ve never tried      \
+      instant prompt, haven\'t seen the warning, or if you are unsure what this all means.
+    print -P ""
+    print -P "(r)  Restart from the beginning."
+    print -P "(q)  Quit and do nothing."
+    print -P ""
+
+    local key=
+    read -k key${(%):-"?%BChoice [123rq]: %b"} || quit -c
+    case $key in
+      q) quit;;
+      r) return 1;;
+      1) instant_prompt=off; break;;
+      2) instant_prompt=quiet; break;;
+      3) instant_prompt=verbose; break;;
+    esac
+  done
+}
+
 function ask_confirm() {
   while true; do
     clear
@@ -1275,10 +1319,11 @@ function ask_zshrc_edit() {
   zshrc_backup=
   zshrc_backup_u=
   zshrc_has_cfg=0
-  zshrc_has_pre=1
-  zshrc_has_post=1
+  zshrc_has_instant_prompt=0
   write_zshrc=0
 
+  [[ $instant_prompt == off ]] && zshrc_has_instant_prompt=1
+
   if [[ -e $__p9k_zshrc ]]; then
     zshrc_content="$(<$__p9k_zshrc)" || quit -c
     local lines=(${(f)zshrc_content})
@@ -1293,12 +1338,9 @@ function ask_zshrc_edit() {
     fi
     local pre='${XDG_CACHE_HOME:-$HOME/.cache}/p10k-instant-prompt-${(%):-%n}.zsh'
     if [[ -n ${(@M)lines:#(#b)[^#]#([^[:IDENT:]]|)source[[:space:]]##($pre|\"$pre\")(|[[:space:]]*|'#'*)} ]]; then
-      zshrc_has_pre=1
+      zshrc_has_instant_prompt=1
     fi
-    if [[ -n ${(@M)lines:#(#b)[^#]#([^[:IDENT:]]|)p10k-instant-prompt-finalize([^[:IDENT:]]*|)} ]]; then
-      zshrc_has_post=1
-    fi
-    (( zshrc_has_cfg && zshrc_has_pre && zshrc_has_post )) && return
+    (( zshrc_has_cfg && zshrc_has_instant_prompt )) && return
   fi
 
   while true; do
@@ -1487,6 +1529,8 @@ function generate_config() {
 
   (( empty_line )) && sub PROMPT_ADD_NEWLINE true || sub PROMPT_ADD_NEWLINE false
 
+  sub INSTANT_PROMPT $instant_prompt
+
   local header=${(%):-"# Generated by Powerlevel10k configuration wizard on %D{%Y-%m-%d at %H:%M %Z}."}$'\n'
   header+="# Based on romkatv/powerlevel10k/config/p10k-$style.zsh"
   if [[ $commands[sum] == ('/bin'|'/usr/bin'|'/usr/local/bin')'/sum' ]]; then
@@ -1525,25 +1569,22 @@ function change_zshrc() {
   {
     print -n >$tmp || return
 
-    if (( !zshrc_has_pre )); then
-      >>$tmp print -r -- "# Enable Powerlevel10k instant prompt. Should stay at the top of ${(%)__p9k_zshrc_u}.
+    if (( !zshrc_has_instant_prompt )); then
+      >>$tmp print -r -- "# Enable Powerlevel10k instant prompt. Should stay close to the top of ${(%)__p9k_zshrc_u}.
+# Initialization code that may require console input (password prompts, [y/n]
+# confirmations, etc.) must go above this block, everything else must go below.
 if [[ -r \"\${XDG_CACHE_HOME:-\$HOME/.cache}/p10k-instant-prompt-\${(%):-%n}.zsh\" ]]; then
   source \"\${XDG_CACHE_HOME:-\$HOME/.cache}/p10k-instant-prompt-\${(%):-%n}.zsh\"
 fi" || return
     fi
     if [[ -n $zshrc_content ]]; then
-      (( zshrc_has_pre )) || print >>$tmp || return
+      (( zshrc_has_instant_prompt )) || print >>$tmp || return
       >>$tmp print -r -- $zshrc_content || return
     fi
     if (( !zshrc_has_cfg )); then
       >>$tmp print -r -- "
 # To customize prompt, run \`p10k configure\` or edit ${(%)__p9k_cfg_path_u}.
 [[ ! -f ${(%)__p9k_cfg_path_u} ]] || source ${(%)__p9k_cfg_path_u}" || return
-    fi
-    if (( !zshrc_has_post )); then
-    >>$tmp print -r -- "
-# Finalize Powerlevel10k instant prompt. Should stay at the bottom of ${(%)__p9k_zshrc_u}.
-(( ! \${+functions[p10k-instant-prompt-finalize]} )) || p10k-instant-prompt-finalize" || return
     fi
     zf_mv -f -- $tmp $__p9k_zshrc || return
   } always {
@@ -1568,8 +1609,8 @@ fi
 source $__p9k_root_dir/internal/icons.zsh || return
 
 while true; do
-  local zshrc_content= zshrc_backup= zshrc_backup_u=
-  local -i zshrc_has_cfg=0 zshrc_has_pre=0 zshrc_has_post=0 write_zshrc=0
+  local instant_prompt=verbose zshrc_content= zshrc_backup= zshrc_backup_u=
+  local -i zshrc_has_cfg=0 zshrc_has_instant_prompt=0 write_zshrc=0
   local POWERLEVEL9K_MODE= style= config_backup= config_backup_u= gap_char=' '
   local left_subsep= right_subsep= left_tail= right_tail= left_head= right_head= show_time=
   local -i num_lines=0 empty_line=0 color=2 left_frame=1 right_frame=1
@@ -1649,6 +1690,7 @@ while true; do
     ask_prefixes       || continue
   fi
   ask_confirm          || continue
+  ask_instant_prompt   || continue
   ask_config_overwrite || continue
   ask_zshrc_edit       || continue
   break