Function createExecBootstrapShell

packages/ai-sandbox/src/shell.ts:210–288

(
  handle: SandboxHandle,
  opts: BootstrapShellOptions = {},
)

 * marker lines) so the NEXT command inherits any directory change or exports.
 */
export function createExecBootstrapShell(
  handle: SandboxHandle,
  opts: BootstrapShellOptions = {},
): BootstrapShell {
  let cwd = opts.cwd ?? '/'
  let env: Record<string, string> = {}
  let counter = 0

  async function run(
    command: string,
  ): Promise<{ exitCode: number; stdout: string }> {
    const id = counter
    counter += 1
    const sentinel = `__BSSH_${id}__`

    // Run the command, then emit its exit code, cwd and exported env behind
    // marker lines so we can recover state even when the command itself fails
    // (no `set -e`). Capturing `$?` immediately after the command keeps the
    // reported exit code the command's own, not the trailing introspection's.
    const script = [
      command,
      `__bssh_rc=$?`,
      `printf '\\n%s %s\\n' '${sentinel}' "$__bssh_rc"`,
      `printf '%s\\n' '${sentinel}_CWD'`,
      `pwd`,
      `printf '%s\\n' '${sentinel}_ENV'`,
      `export -p`,
    ].join('\n')

    const res = await handle.process.exec(script, { cwd, env })

    const cmdOut: Array<string> = []
    const cwdLines: Array<string> = []
    const envLines: Array<string> = []
    let exitCode = res.exitCode
    let phase: 'cmd' | 'await-cwd' | 'cwd' | 'env' = 'cmd'

    for (const line of res.stdout.split('\n')) {
      if (phase === 'cmd') {
        if (line.startsWith(`${sentinel} `)) {
          const parsed = parseInt(line.slice(sentinel.length + 1).trim(), 10)
          exitCode = Number.isFinite(parsed) ? parsed : res.exitCode
          phase = 'await-cwd'
          continue
        }
        cmdOut.push(line)
      } else if (phase === 'await-cwd') {
        if (line === `${sentinel}_CWD`) phase = 'cwd'
      } else if (phase === 'cwd') {
        if (line === `${sentinel}_ENV`) phase = 'env'
        else cwdLines.push(line)
      } else {
        envLines.push(line)
      }
    }

    // `pwd` prints a single line; the last non-empty one is the new cwd.
    const newCwd = cwdLines