diff --git a/.bin/test-tmux.sh b/.bin/test-tmux.sh
index 9ebccff..62457b6 100755
--- a/.bin/test-tmux.sh
+++ b/.bin/test-tmux.sh
@@ -1,8 +1,30 @@
-#!/bin/bash
+#!/usr/bin/env bash
+set -euo pipefail
 
-XDG_CONFIG_HOME="$PWD/.config" \
-  XDG_DATA_HOME="$PWD/.local/share" \
-  XDG_STATE_HOME="$PWD/.state" \
-  XDG_CACHE_HOME="$PWD/.cache" \
-  TMUX="" \
-  tmux new-session -s dev -n editor 'nvim'
+PWD="$(pwd -P)"
+
+if [ "$(basename "$PWD")" != "workspaces" ]; then
+  echo "Error: this script must be run from a directory named 'workspaces', not '$(basename "$(pwd -P)")'" >&2
+  exit 1
+fi
+
+# Override PWD and HOME for this invocation
+export PWD=$PWD
+export HOME=$PWD
+export TMUX=""
+
+# Optionally adjust XDG_CONFIG_HOME if you use that
+# export XDG_CONFIG_HOME="$HOME/.config"
+
+# Start (or attach to) your dev session
+SESSION="dev"
+
+# If the session doesn't exist, create it
+if ! tmux has-session -t "$SESSION" 2>/dev/null; then
+  tmux new-session -d -s "$SESSION" -n editor 'HOME='"$HOME"' XDG_STATE_HOME='"$HOME/.state"' /usr/bin/fish'
+fi
+
+tmux send-keys -t $SESSION:editor 'fisher install jorgebucaran/fisher pure-fish/pure patrickf1/fzf.fish jorgebucaran/autopair.fish gazorby/fish-abbreviation-tips jethrokuan/z' Enter
+
+# Attach to it
+exec tmux attach -t "$SESSION"