From 7601583928edf20653383b261828b6c8257d2d59 Mon Sep 17 00:00:00 2001
From: m3ta-chiron <m3ta-chiron@agentmail.to>
Date: Mon, 31 Aug 2026 09:56:13 +0200
Subject: [PATCH] fix(shell): exec into nushell by parent process, not env
 marker

The exported M3_SHELL_TO_NU marker leaked into programs started from
nu (zellij, zed, herdr), keeping their spawned terminals in bash.
Decide via /proc/$PPID/comm instead: interactive bash whose parent is
neither nu nor bash execs into nu; a deliberate 'bash' started from
nu/bash stays bash. Non-interactive bash (ssh command exec, Mosh app
bootstrap, see 765ae15) is still covered by the $- == *i* check.
---
 hosts/common/default.nix | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/hosts/common/default.nix b/hosts/common/default.nix
index 956daa9..d7c6e64 100644
--- a/hosts/common/default.nix
+++ b/hosts/common/default.nix
@@ -80,9 +80,17 @@
   programs.bash = {
     enable = true;
     interactiveShellInit = ''
-      if [[ $- == *i* ]] && [[ -z "''${M3_SHELL_TO_NU:-}" ]]; then
-        export M3_SHELL_TO_NU=1
-        exec ${pkgs.nushell}/bin/nu --login
+      # Interactive bash -> nushell, unless started deliberately from
+      # nu/bash (parent check — an exported env marker would leak into
+      # zellij/zed/herdr children). Non-interactive bash (ssh command
+      # exec, Mosh app bootstrap) stays bash.
+      if [[ $- == *i* ]]; then
+        parent=""
+        [[ -r /proc/$PPID/comm ]] && IFS= read -r parent < /proc/$PPID/comm
+        if [[ "$parent" != "nu" && "$parent" != "bash" ]]; then
+          exec ${pkgs.nushell}/bin/nu --login
+        fi
+        unset parent
       fi
     '';
   };