Is your host phone-ready?

Run this on your host

Copy the script and run it on the machine you connect to, your Mac or server, not the phone. It prints an OK, WARN, or FAIL for each thing TermHub needs, and only reads your settings; nothing is uploaded or changed.

#!/usr/bin/env bash
# TermHub host check, runs entirely on your machine. Nothing is uploaded.
# Review it, then run on your host:   bash host-check.sh
set -u
ok(){   echo "  OK    $1  $2"; }
warn(){ echo "  WARN  $1  $2"; }
fail(){ echo "  FAIL  $1  $2"; }

echo "TermHub host check"
os=$(uname -s)

# SSHD, can TermHub reach an SSH server here at all?
if [ "$os" = Darwin ]; then
  systemsetup -getremotelogin 2>/dev/null | grep -qi on \
    && ok   "SSHD " "Remote Login is on" \
    || warn "SSHD " "turn on Remote Login (System Settings > General > Sharing)"
else
  pgrep -x sshd >/dev/null 2>&1 \
    && ok "SSHD " "sshd is running" || warn "SSHD " "sshd not detected"
fi

# SHELL, your login shell
ok "SHELL" "login shell is ${SHELL##*/}"

# tmux / herdr, installed AND visible to a non-login SSH (how TermHub attaches)
for m in tmux herdr; do
  here=$(command -v "$m" 2>/dev/null)
  seen=$("$SHELL" -c "command -v $m" 2>/dev/null)
  if [ -n "$here" ] && [ -n "$seen" ]; then
    ok   "$m " "visible to SSH  ($here)"
  elif [ -n "$here" ]; then
    fail "$m " "installed at $here but a non-login SSH cannot see it, PATH trap"
  else
    warn "$m " "not installed"
  fi
done

# SLEEP, will the Mac stay reachable while you are away?
if [ "$os" = Darwin ]; then
  pmset -g 2>/dev/null | grep -qiE 'SleepDisabled +1| sleep +0' \
    && ok   "SLEEP" "the Mac is set to stay awake" \
    || warn "SLEEP" "the Mac may sleep and drop connections"
fi

echo "Done, any FAIL or WARN is explained on the page you copied this from."

Paste it into your host's terminal, or save it as host-check.sh and run bash host-check.sh.

What each line means

• SSHD An SSH server is running, so TermHub can connect at all. On a Mac that's Remote Login (System Settings › General › Sharing).
• SHELL Your login shell, it tells you which startup file matters for the PATH trap below.
• tmux / herdr Installed and visible to a non-login SSH. A FAIL here is the one that bites people.
• SLEEP The Mac won't fall asleep and drop your session while you're away.

The multiplexer your phone can't see

On Apple-Silicon Homebrew hosts, /opt/homebrew/bin is often added from ~/.zprofile, which a non-login SSH never reads, so a healthy Herdr or tmux comes back as a FAIL. Fix it by adding Homebrew's path to your shell's non-login startup so every SSH session can find it:

# add to ~/.zshenv
export PATH="/opt/homebrew/bin:$PATH"

Keeping the host awake

A phone terminal can't wake a sleeping Mac. For a machine that should stay reachable, especially an overnight agent, set Energy Saver so it doesn't sleep, or run caffeinate while it matters.