Enumerate Environment with Item Numbers in Left Margin and Item Textwidth = Page Textwidth

Question

MWE---

\documentclass[12pt]{book}
\usepackage{enumitem,lipsum} 
\begin{document}
\thispagestyle{empty}
\lipsum[3]
\begin{enumerate}[wide,labelwidth=6pt,labelindent=-15pt]
\item \lipsum[13]
\item \lipsum[13]
\item[10] \lipsum[13]
\item[100] \lipsum[13]
\end{enumerate}
\end{document}

which produces the output

I would like to construct an enumerate environment in which the text of each item spans the normal textwidth, and the item numbers lie entirely in the left-hand margin.

I have tried to manually construct such---which, as you can see, works fine for item numbers 1-9, after which, there is an indentation in the text.

How may I accomplish this so that all items numbers 1-999 lie entirely in the left-hand margin of the page, while the text of each item spans the page textwidth?

Answer 1

For explanations see enumitem section 3.2 Horizontal spacing of labels, I can't do any better. (hmm)

\documentclass{article}
\usepackage{enumitem,lipsum}
\begin{document}
\thispagestyle{empty}
\def\sometext{\lipsum[1][1-2]}
\sometext

\begin{enumerate}[align=left, listparindent=\parindent,
                  leftmargin=0pt, labelsep=0pt, itemindent=0pt,
                  labelwidth= 3em]
\item \sometext
\item \sometext
\item[10.] \sometext
\item[100.] \sometext
\end{enumerate}

\sometext

%% \clearpage

%% \sometext

\begin{enumerate}[align=right, listparindent=\parindent,
                  leftmargin=0pt, labelsep=1em, itemindent=0pt,
                  labelwidth= 3em]
\item \sometext
\item \sometext
\item[10.] \sometext
\item[100.] \sometext
\end{enumerate}

\sometext

\end{document}