fix(ci): skip unavailable git-wt cache hook

- Skip git-wt cache prewarming when the git-wt helper is absent
- Guard the zsh lazy git-wt hook so runners without the Homebrew package still start
- Keep local git-wt cache generation enabled when the helper exists

Co-authored-by: Codex GPT-5.5 <noreply@openai.com>

Author: lemtoc

.github/scripts/warm-zsh-startup-cache.sh

@@ -57,12 +57,14 @@ while IFS= read -r command_string; do
   warm_cache_eval "$command_string"
 done < <(sed -nE 's/^[[:space:]]*(zsh-defer[[:space:]]+)?cache_eval "([^"]+)".*$/\2/p' "$zshrc")
 
-if [[ -r "$zsh_lazy" ]] && command -v git >/dev/null 2>&1; then
+if [[ -r "$zsh_lazy" ]] && command -v git >/dev/null 2>&1 && command -v git-wt >/dev/null 2>&1; then
   git_wt_cache="$cache_home/sheldon/git-wt.zsh"
   mkdir -p "$(dirname "$git_wt_cache")"
   if [[ ! -s "$git_wt_cache" || "$(readlink "$zshrc")" != "$(cat "${git_wt_cache}.lock" 2>/dev/null)" ]]; then
     echo "warming git-wt zsh cache"
     git wt --init zsh > "$git_wt_cache"
     readlink "$zshrc" > "${git_wt_cache}.lock"
   fi
+elif [[ -r "$zsh_lazy" ]]; then
+  echo "skipping git-wt zsh cache: git-wt is unavailable"
 fi

home/shell/zsh/lazy.zsh

@@ -97,11 +97,13 @@ if (( $+commands[awsctx] )); then
 fi
 
 # git-wt (cache, regenerate when .zshrc symlink target changes)
-git_wt_cache="${XDG_CACHE_HOME:-$HOME/.cache}/sheldon/git-wt.zsh"
-if [[ ! -r "$git_wt_cache" || "$(readlink ~/.zshrc)" != "$(cat "${git_wt_cache}.lock" 2>/dev/null)" ]]; then
-  mkdir -p "${git_wt_cache:h}"
-  git wt --init zsh > "$git_wt_cache"
-  readlink ~/.zshrc > "${git_wt_cache}.lock"
+if (( ${+commands[git-wt]} )); then
+  git_wt_cache="${XDG_CACHE_HOME:-$HOME/.cache}/sheldon/git-wt.zsh"
+  if [[ ! -r "$git_wt_cache" || "$(readlink ~/.zshrc)" != "$(cat "${git_wt_cache}.lock" 2>/dev/null)" ]]; then
+    mkdir -p "${git_wt_cache:h}"
+    git wt --init zsh > "$git_wt_cache"
+    readlink ~/.zshrc > "${git_wt_cache}.lock"
+  fi
+  source "$git_wt_cache"
+  unset git_wt_cache
 fi
-source "$git_wt_cache"
-unset git_wt_cache