add termux ssh-agent alternative path

dot_config/zsh/dot_zshrc

@@ -102,6 +102,26 @@ if command -v keychain >/dev/null; then
   else
     ssh-add ~/.ssh/id_rsa
   fi
+elif [ -n "$TERMUX_VERSION" ]; then
+  # No keychain/rbw on Termux. Keep a persistent ssh-agent across sessions
+  # (same idea as keychain above) and prompt for the passphrase right here at
+  # shell start instead of waiting for the first `ssh` invocation. To unlock,
+  # long-press the terminal at the "Enter passphrase" prompt below and choose
+  # "Autofill password" to pull it from Bitwarden.
+  termux_ssh_agent_env="$XDG_STATE_HOME/ssh/agent-env"
+  mkdir -p "$(dirname "$termux_ssh_agent_env")"
+  if [ -z "$SSH_AUTH_SOCK" ] && [ -f "$termux_ssh_agent_env" ]; then
+    . "$termux_ssh_agent_env" >/dev/null
+    kill -0 "$SSH_AGENT_PID" 2>/dev/null || unset SSH_AGENT_PID SSH_AUTH_SOCK
+  fi
+  if [ -z "$SSH_AGENT_PID" ]; then
+    ssh-agent -s > "$termux_ssh_agent_env"
+    . "$termux_ssh_agent_env" >/dev/null
+  fi
+  # Only prompts if the agent doesn't already have a key loaded (e.g. from an
+  # earlier session in this same Termux app lifetime).
+  ssh-add -l >/dev/null 2>&1 || ssh-add ~/.ssh/id_rsa
+  unset termux_ssh_agent_env
 fi
 
 # Command not found handler