Function formatRandomPortUnavailableError

browse/src/server.ts:829–847

(attempts: FailedPortAttempt[])

}

function formatRandomPortUnavailableError(attempts: FailedPortAttempt[]): Error {
  const blockingAttempts = attempts.filter((attempt) => !isOccupiedPort(attempt.result));

  if (blockingAttempts.length > 0) {
    const last = blockingAttempts[blockingAttempts.length - 1];
    return new Error(
      `[browse] Cannot bind localhost ports after ${attempts.length} attempts in range ` +
      `${RANDOM_PORT_MIN}-${RANDOM_PORT_MAX}. Last error: ${formatPortFailureDetail(last)}. ` +
      `This usually means the current sandbox or OS permissions are blocking localhost port binding, ` +
      `not that every sampled port is occupied. Allow localhost binding, set BROWSE_PORT to an approved ` +
      `port, or run browse from an unrestricted terminal.`
    );
  }

  return new Error(
    `[browse] No available port after ${RANDOM_PORT_RETRIES} attempts in range ` +
    `${RANDOM_PORT_MIN}-${RANDOM_PORT_MAX}; every sampled port was already in use`
  );
}

// Test if a port is available by binding and immediately releasing.
// Uses net.createServer instead of Bun.serve to avoid a race condition