chore(sync): merge upstream startup optimizations

tests/installers.sh

@@ -216,6 +216,26 @@ HOME="$pyenv_env_home" XDG_CONFIG_HOME="$pyenv_env_xdg" \
     zsh -lc '[[ "$(command -v python3)" == "$HOME/.pyenv/shims/python3" ]]' ||
     fail "pyenv Python is not restored in login zsh after the system profile"
 
+# Interactive initialization runs once while repeated sourcing restores PATH.
+mkdir -p "$pyenv_env_home/.pyenv/bin"
+cat >"$pyenv_env_home/.pyenv/bin/pyenv" <<'PYENV'
+#!/bin/sh
+printf '%s\n' "$*" >> "$PYENV_ROOT/init-calls"
+printf '%s\n' 'pyenv() { command pyenv "$@"; }'
+PYENV
+chmod +x "$pyenv_env_home/.pyenv/bin/pyenv"
+HOME="$pyenv_env_home" PYENV_ROOT="$pyenv_env_home/.pyenv" PATH=/usr/bin:/bin \
+    zsh -dfic '
+        source "$1"
+        (( $+functions[pyenv] )) || exit 1
+        path=(/usr/bin /bin)
+        source "$1"
+        [[ $(command -v python3) == "$PYENV_ROOT/shims/python3" ]]
+    ' zsh "$ROOT/zsh/pyenv.zsh" ||
+    fail "interactive pyenv initialization did not preserve its function and Python PATH"
+printf '%s\n' 'init - --no-rehash zsh' | cmp -s - "$pyenv_env_home/.pyenv/init-calls" ||
+    fail "pyenv initialization must run once without a startup rehash"
+
 # A later easyzsh migration still restores pyenv; the old pyenv-only hook is replaced.
 pyenv_login_hook='[[ -f "${XDG_CONFIG_HOME:-$HOME/.config}/zsh/pyenv.zsh" ]] && . "${XDG_CONFIG_HOME:-$HOME/.config}/zsh/pyenv.zsh"'
 printf '%s\n' "$pyenv_login_hook" > "$pyenv_env_home/.zprofile"