Enhance backtunnel-share with improved desktop integration, port collision checks, and pre-flight validations

completions/backtunnel.bash

@@ -32,6 +32,20 @@ _backtunnel_complete() {
     return 0
   fi
 
+  # backtunnel-share: after positionals, propose flags incl. invite
+  if [[ ${COMP_WORDS[0]} == backtunnel-share && ${COMP_CWORD} -ge 5 ]]; then
+    local opts="-p --tunnel-port -l --local-ssh-port -i --invite --invite-mount --invite-file --qr -h --help"
+    mapfile -t COMPREPLY < <(compgen -W "${opts}" -- "${cur}")
+    return 0
+  fi
+
+  # backtunnel-access: after positionals, propose its flags
+  if [[ ${COMP_WORDS[0]} == backtunnel-access && ${COMP_CWORD} -ge 3 ]]; then
+    local opts="-p --port -m --mount-point -h --help"
+    mapfile -t COMPREPLY < <(compgen -W "${opts}" -- "${cur}")
+    return 0
+  fi
+
   COMPREPLY=()
 }