fix(pty-proxy): resolve SHELL path in proxied zsh sessions

Author: hangrymuppet

crates/atuin-pty-proxy/src/pty_proxy.rs

@@ -164,12 +164,22 @@ fn render_init(shell: Shell) -> &'static str {
     if [[ -n "${BASH_VERSION:-}" ]]; then
       exec atuin pty-proxy --shell "$BASH"
     elif [[ -n "${ZSH_VERSION:-}" ]]; then
-      # Prefer ZSH_ARGZERO (zsh 5.3+) — it preserves the path zsh was
-      # invoked with — and fall back to PATH lookup otherwise. Login shells
-      # set argv[0] to "-zsh", and ZSH_ARGZERO keeps that leading dash, so
-      # strip it (${var#-}) before passing the path along.
-      _atuin_pty_proxy_zsh="${ZSH_ARGZERO:-$(command -v zsh)}"
-      exec atuin pty-proxy --shell "${_atuin_pty_proxy_zsh#-}"
+      # Resolve zsh to the same executable that launched this init script.
+      # ZSH_ARGZERO preserves argv0, including the leading dash used by login
+      # shells, so normalize it before choosing a shell path.
+      _atuin_pty_proxy_zsh_argv0="${ZSH_ARGZERO:-zsh}"
+      _atuin_pty_proxy_zsh_argv0="${_atuin_pty_proxy_zsh_argv0#-}"
+      if [[ "$_atuin_pty_proxy_zsh_argv0" == */* ]]; then
+        # argv0 already contains a path, so it identifies the spawned zsh.
+        _atuin_pty_proxy_shell="$_atuin_pty_proxy_zsh_argv0"
+      elif [[ -f "${SHELL:-}" ]] && [[ -x "${SHELL:-}" ]] && [[ "${SHELL##*/}" == "$_atuin_pty_proxy_zsh_argv0" ]]; then
+        # Bare argv0: prefer the matching login shell path over PATH lookup.
+        _atuin_pty_proxy_shell="$SHELL"
+      else
+        # Last resort: resolve the bare shell name from PATH.
+        _atuin_pty_proxy_shell="$(command -v "$_atuin_pty_proxy_zsh_argv0")"
+      fi
+      exec atuin pty-proxy --shell "$_atuin_pty_proxy_shell"
     else
       exec atuin pty-proxy
     fi
@@ -252,10 +262,23 @@ mod tests {
     fn init_scripts_forward_shell_path() {
         let posix = render_init(Shell::Bash);
         assert!(posix.contains(r#"exec atuin pty-proxy --shell "$BASH""#));
-        // zsh: capture ZSH_ARGZERO (with PATH fallback), then strip the
-        // leading dash present on login shells before forwarding the path.
-        assert!(posix.contains(r#"_atuin_pty_proxy_zsh="${ZSH_ARGZERO:-$(command -v zsh)}""#));
-        assert!(posix.contains(r#"exec atuin pty-proxy --shell "${_atuin_pty_proxy_zsh#-}""#));
+        // zsh: capture ZSH_ARGZERO, strip the leading dash present on login
+        // shells, and resolve bare shell names to the spawning shell before
+        // forwarding the path.
+        assert!(posix.contains(r#"_atuin_pty_proxy_zsh_argv0="${ZSH_ARGZERO:-zsh}""#));
+        assert!(posix.contains(r#"_atuin_pty_proxy_zsh_argv0="${_atuin_pty_proxy_zsh_argv0#-}""#));
+        assert!(posix.contains(r#"if [[ "$_atuin_pty_proxy_zsh_argv0" == */* ]]; then"#));
+        assert!(posix.contains(r#"_atuin_pty_proxy_shell="$_atuin_pty_proxy_zsh_argv0""#));
+        assert!(posix.contains(
+            r#"elif [[ -f "${SHELL:-}" ]] && [[ -x "${SHELL:-}" ]] && [[ "${SHELL##*/}" == "$_atuin_pty_proxy_zsh_argv0" ]]; then"#
+        ));
+        assert!(posix.contains(r#"_atuin_pty_proxy_shell="$SHELL""#));
+        assert!(
+            posix.contains(
+                r#"_atuin_pty_proxy_shell="$(command -v "$_atuin_pty_proxy_zsh_argv0")""#
+            )
+        );
+        assert!(posix.contains(r#"exec atuin pty-proxy --shell "$_atuin_pty_proxy_shell""#));
 
         let fish = render_init(Shell::Fish);
         assert!(fish.contains("exec atuin pty-proxy --shell (status fish-path)"));