Simple Codex login shell wrapper: prompts go to Codex, !commands go to Bash

codex-login-shell

#!/usr/bin/env bash

set -uo pipefail

CODEX_BIN="${CODEX_BIN:-/home/sid/.nvm/versions/node/v22.12.0/bin/codex}"
BASH_BIN="${BASH_BIN:-${SHELL:-/bin/bash}}"
CODEX_SANDBOX="${CODEX_SANDBOX:-danger-full-access}"
CODEX_OUTPUT_MODE="${CODEX_OUTPUT_MODE:-quiet}"
CODEX_NAME="${CODEX_NAME:-hal9000}"
CODEX_BASE_PROMPT="${CODEX_BASE_PROMPT:-\\[\\e[32m\\]\\w\\[\\e[0m\\] \\[\\e[36m\\]\\$\\[\\e[0m\\] }"

if [[ ! -x "$CODEX_BIN" ]]; then
  printf 'error: codex binary not found or not executable: %s\n' "$CODEX_BIN" >&2
  exit 1
fi

if [[ ! -x "$BASH_BIN" ]]; then
  printf 'error: bash binary not found or not executable: %s\n' "$BASH_BIN" >&2
  exit 1
fi

_interrupted=0

handle_sigint() {
  _interrupted=1
  printf '\n'
}

trim_leading_spaces() {
  local value="$1"
  value="${value#"${value%%[![:space:]]*}"}"
  printf '%s' "$value"
}

expand_ps1() {
  local prompt_source="$CODEX_BASE_PROMPT"
  local host short_host cwd dollar_char rl_start rl_end

  host="$(hostname 2>/dev/null || printf 'host')"
  short_host="${host%%.*}"
  cwd="${PWD/#${HOME:-}/\~}"
  rl_start=$'\001'
  rl_end=$'\002'

  if [[ ${EUID:-$(id -u)} -eq 0 ]]; then
    dollar_char="#"
  else
    dollar_char="$"
  fi

  prompt_source="${prompt_source//\\u/${USER:-user}}"
  prompt_source="${prompt_source//\\h/$short_host}"
  prompt_source="${prompt_source//\\H/$host}"
  prompt_source="${prompt_source//\\w/$cwd}"
  prompt_source="${prompt_source//\\W/${PWD##*/}}"
  prompt_source="${prompt_source//\\\$/$dollar_char}"
  prompt_source="${prompt_source//\\n/$'\n'}"
  prompt_source="${prompt_source//\\r/$'\r'}"
  prompt_source="${prompt_source//\\a/$'\a'}"
  prompt_source="${prompt_source//\\e/$'\e'}"
  prompt_source="${prompt_source//\\[/$rl_start}"
  prompt_source="${prompt_source//\\]/$rl_end}"

  printf '%s @ %s' "$CODEX_NAME" "$prompt_source"
}

run_bash_builtin() {
  local command="$1"
  local trimmed

  trimmed="$(trim_leading_spaces "$command")"

  if [[ "$trimmed" == cd || "$trimmed" == cd\ * ]]; then
    local target="${trimmed#cd}"
    target="$(trim_leading_spaces "$target")"
    if [[ -z "$target" ]]; then
      target="${HOME:-/}"
    fi

    if ! builtin cd -- "$target"; then
      return 1
    fi
    return 0
  fi

  if [[ "$trimmed" == pwd ]]; then
    pwd
    return 0
  fi

  "$BASH_BIN" -lc "$command"
}

run_codex_exec() {
  local prompt="$1"

  if [[ "$CODEX_OUTPUT_MODE" == "quiet" ]] && command -v jq >/dev/null 2>&1; then
    "$CODEX_BIN" exec \
      --json \
      --skip-git-repo-check \
      --sandbox "$CODEX_SANDBOX" \
      -C "$PWD" \
      "$prompt" | jq -r '
        select(.type == "item.completed" and .item.type == "agent_message")
        | .item.text
      '
    return
  fi

  "$CODEX_BIN" exec \
    --skip-git-repo-check \
    --sandbox "$CODEX_SANDBOX" \
    -C "$PWD" \
    "$prompt"
}

main() {
  local line bang_command prompt

  trap handle_sigint INT

  while true; do
    _interrupted=0

    prompt="$(expand_ps1)"

    if ! IFS= read -r -e -p "$prompt" line; then
      printf '\n'
      break
    fi

    if (( _interrupted )); then
      continue
    fi

    if [[ -z "${line//[[:space:]]/}" ]]; then
      continue
    fi

    case "$line" in
      exit|logout)
        break
        ;;
      \!*)
        bang_command="${line:1}"
        if [[ -z "${bang_command//[[:space:]]/}" ]]; then
          continue
        fi
        run_bash_builtin "$bang_command"
        ;;
      *)
        run_codex_exec "$line"
        ;;
    esac
  done
}

main "$@"