fix(cli): address review feedback on omz generate plugin

- Turn %placeholders% into private markers when a template is read and
  strip the marker from every value, so text inserted from user input
  (e.g. -d '%name%') is never rescanned as a placeholder.
- When --enable is used for a name already in $plugins (a custom
  override of an enabled built-in), report it and reload instead of
  failing in _omz::plugin::enable.
- Make the completion note accurate whether or not a _<cmd> file was
  generated.
- Test the write-phase cleanup with a template set missing a later
  template, and test that placeholder-looking values come out literally.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

lib/cli.zsh

@@ -429,7 +429,13 @@ function _omz::generate::plugin {
   # Last thing we do: in an interactive shell this restarts zsh
   if (( enable )); then
     print
-    _omz::plugin::enable "$name"
+    if (( ${plugins[(Ie)$name]} )); then
+      # Already enabled (e.g. a custom override of a built-in): just reload
+      _omz::log info "'$name' is already in your plugins list."
+      [[ ! -o interactive ]] || _omz::reload
+    else
+      _omz::plugin::enable "$name"
+    fi
   fi
 }
 
@@ -516,31 +522,39 @@ function _omz::generate::plugin::ask {
   REPLY="${${REPLY##[[:space:]]#}%%[[:space:]]#}"
 }
 
-# Print a template file, or explain which one is missing
+# Print a template file with its %placeholders% turned into private markers,
+# or explain which one is missing
 function _omz::generate::plugin::template {
   if [[ ! -f "$templates/$1" ]]; then
     _omz::log error "missing template '${templates/#$HOME/\~}/$1'." "omz::generate::plugin"
     return 1
   fi
-  print -r -- "$(<"$templates/$1")"
+
+  local content="$(<"$templates/$1")" token m=$'\x1f'
+  for token in completion cache name command description compgen; do
+    content="${content//\%${token}\%/${m}${token}${m}}"
+  done
+  print -r -- "$content"
 }
 
-# Fill in the %placeholders% of a template and write it to a file. Values come
+# Fill in the placeholders of a template and write it to a file. Values come
 # from the caller: $name, $cmd, $description, $compgen, $block and $cache.
-# Substitution is done with parameter expansion rather than sed so that the
-# values are always taken literally.
+#
+# Placeholders are matched as the markers that ::template produced, and the
+# marker character is stripped from every value, so a value that happens to
+# look like a placeholder (e.g. -d '%name%') is written out literally.
 function _omz::generate::plugin::render {
   setopt localoptions extendedglob
-  local content
+  local content m=$'\x1f'
   content="$(_omz::generate::plugin::template "$1")" || return 1
 
-  # Blocks go first: they contain placeholders of their own
-  content="${content//'%completion%'/$block}"
-  content="${content//'%cache%'/$cache}"
-  content="${content//'%name%'/$name}"
-  content="${content//'%command%'/$cmd}"
-  content="${content//'%description%'/$description}"
-  content="${content//'%compgen%'/$compgen}"
+  # Blocks go first: they are templates too and carry markers of their own
+  content="${content//${m}completion${m}/$block}"
+  content="${content//${m}cache${m}/$cache}"
+  content="${content//${m}name${m}/${name//$m/}}"
+  content="${content//${m}command${m}/${cmd//$m/}}"
+  content="${content//${m}description${m}/${description//$m/}}"
+  content="${content//${m}compgen${m}/${compgen//$m/}}"
   # Drop blank lines left behind by an empty placeholder at the end
   content="${content%%$'\n'##}"
 

lib/tests/generate-plugin.test.zsh

@@ -75,6 +75,12 @@ else
   pass "foo has no unfilled placeholders"
 fi
 
+## Values that look like placeholders are written literally
+
+omz generate plugin lit -d '%compgen% and %name% stay' -c lit --yes >/dev/null 2>&1
+assert_contains "$ZSH_CUSTOM/plugins/lit/README.md" '%compgen% and %name% stay'
+assert_contains "$ZSH_CUSTOM/plugins/lit/lit.plugin.zsh" '%compgen% and %name% stay'
+
 ## A plugin with no command
 
 if omz generate plugin bar --yes >/dev/null 2>&1; then
@@ -151,6 +157,25 @@ else
 fi
 [[ -e "$ZSH_CUSTOM/plugins/quux" ]] && fail "quux was created by a failed run"
 
+## A failure after the first file is written removes everything it created
+
+broken="$(mktemp -d)"
+mkdir -p "$broken/templates/generators/plugin" "$broken/plugins"
+cp "$ZSH/templates/generators/plugin/plugin.zsh-template" \
+   "$ZSH/templates/generators/plugin/completion-note.zsh-template" "$broken/templates/generators/plugin/"
+# README.md-template is missing, so the plugin file is written and then the README fails
+if ( ZSH="$broken"; omz generate plugin partial -c partial --yes >/dev/null 2>&1 ); then
+  fail "succeeded with a missing README template"
+else
+  pass "fails when a later template is missing"
+fi
+if [[ -e "$ZSH_CUSTOM/plugins/partial" ]]; then
+  fail "partial plugin directory was left behind: $(ls "$ZSH_CUSTOM/plugins/partial")"
+else
+  pass "cleans up the partial plugin directory"
+fi
+command rm -rf "$broken"
+
 ## The prompt helper
 
 _omz::generate::plugin::ask "Q" "dflt" 2>/dev/null < <(print '')

templates/generators/plugin/completion-note.zsh-template

@@ -3,5 +3,4 @@
 #
 # Oh My Zsh adds this directory to $fpath, so a file named `_%command%` next to
 # this one is picked up automatically as the completion for %command%.
-# There is nothing to do here.
 #