Automatic prefix change to C-a when in ssh or mosh session

.config/tmux-prefix-detect.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+# Auto-set tmux prefix based on connection type.
+# Called from tmux hooks: session-created and client-attached.
+if tmux show-environment SSH_CONNECTION 2>/dev/null | grep -qv '^-' || \
+   tmux show-environment MOSH_SERVER_PID 2>/dev/null | grep -qv '^-'; then
+    tmux set -g prefix C-a
+    tmux bind-key C-a send-prefix
+    tmux unbind-key C-b 2>/dev/null
+    tmux display-message "Prefix: C-a (remote)"
+else
+    tmux set -g prefix C-b
+    tmux bind-key C-b send-prefix
+    tmux unbind-key C-a 2>/dev/null
+    tmux display-message "Prefix: C-b (local)"
+fi