hey zbench              # Run + display with threshold indicators (auto-compares if baseline exists)
hey zbench-save         # Run + save as baseline + append history
hey zbench-compare      # Run + explicit diff against baseline
hey zbench-check        # Exit non-zero if over threshold (for git bisect)
hey zbench-baseline     # Show saved baseline (no run)
hey zbench-history      # Show TSV history

git bisect start
git bisect bad HEAD
git bisect good <known-good-commit>
git bisect run hey zbench-check

benchmarks/zsh-bench/
├── <Host>.json              # Current baseline per host
└── history/
    └── <Host>.tsv           # Append-only history (timestamp, git_rev, metrics)
packages/zsh-bench.nix       # Nix package (romkatv/zsh-bench with internal/ helpers)
bin/hey.d/zbench.just         # Hey recipes
bin/zbench-report             # Python — parse, compare, format results

# 1. Establish baseline on a clean build
hey zbench-save

# 2. Make zsh config changes
vim config/zsh/.zshrc
hey rebuild

# 3. Check for regressions
hey zbench                    # Shows comparison vs baseline

# 4. If satisfied, update baseline
hey zbench-save

zsh -c '
zmodload zsh/datetime
export XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-$HOME/.config}"
export XDG_CACHE_HOME="${XDG_CACHE_HOME:-$HOME/.cache}"
export ZDOTDIR="${ZDOTDIR:-$XDG_CONFIG_HOME/zsh}"
export ZSH_CACHE="${ZSH_CACHE:-$XDG_CACHE_HOME/zsh}"
function _source { [[ -f "$1" ]] && source "$1"; }
function _cache {
  local cache_dir="$XDG_CACHE_HOME/zsh"; local cache_file="$cache_dir/$1.zsh"
  if [[ ! -f "$cache_file" ]] || [[ "$commands[$1]" -nt "$cache_file" ]]; then
    mkdir -p "$cache_dir"; "$@" > "$cache_file"; fi
  source "$cache_file"
}

t0=$EPOCHREALTIME
source $ZDOTDIR/.zshenv 2>/dev/null; t1=$EPOCHREALTIME
source $ZDOTDIR/config.zsh; t2=$EPOCHREALTIME
# ... add phases matching your .zshrc ...
source $ZDOTDIR/completion.zsh 2>/dev/null; t3=$EPOCHREALTIME
_source $ZDOTDIR/extra.zshrc; t4=$EPOCHREALTIME

printf "zshenv:     %4.0fms\n" $(( (t1-t0)*1000 ))
printf "config:     %4.0fms\n" $(( (t2-t1)*1000 ))
printf "completion: %4.0fms\n" $(( (t3-t2)*1000 ))
printf "extra:      %4.0fms\n" $(( (t4-t3)*1000 ))
printf "TOTAL:      %4.0fms\n" $(( (t4-t0)*1000 ))
'

function _cache {
  local cache_dir="$XDG_CACHE_HOME/zsh"
  local cache_file="$cache_dir/$1.zsh"
  if [[ ! -f "$cache_file" ]] || [[ "$commands[$1]" -nt "$cache_file" ]]; then
    mkdir -p "$cache_dir"
    "$@" > "$cache_file"
  fi
  source "$cache_file"
}

# Usage:
_cache zoxide init zsh        # instead of eval "$(zoxide init zsh)"
_cache direnv hook zsh        # instead of eval "$(direnv hook zsh)"
_cache entire completion zsh  # instead of source <(entire completion zsh)