Automatic margin curly braces & text on multiple pages

Question

I'm building a command to mark long texts & class them in other part of my document (with help of Malipivo). I managed to do it with collect, multido & mdframed packages. The excellent advantage of mdframed is that you can easily handle four possible cutting of a text on several pages: single, first, middle or second part. This is extraordinary for automatic commands.

So, now, I have a problem I don't solve alone :

1. Following these opportunities, I want to change left lines by curly braces : just old curly braces like in symphonic scores or Diderot's encyclopedia, braces which start from the top of the marked text & coming down… (In truth, I'd use hooks, parens or angle to, like in the Andrew Swann's answer here, and with different levels like in the first Qrrbrbirlbel's answer, but with a more classic brace's style).

Here are two other issues that are less important, but if you find simple solutions… :

2. How to work in mdframed, tikz option (maybe I don't need tikz), with two side pages ? I'm only using the leftmargin, but I'd rather use the outermargin… Exist a twoside-mode man p.9, but I don't understand how to use.
3. With mdframed, I work nether in the real page margin, always in the text width. I'd like to put my lines, mark text, braces & other, outside in the real margin without affecting the text in its width. An idea ?

Here my MWE (For tikz, I use the example 5 of the third document p.5 named : position a specific symbol at line, but maybe I don't need tikz for what I want ?) :

% !TEX encoding = UTF-8 Unicode
% !TEX TS-program = arara
\documentclass{scrbook}
\usepackage{fontspec,collect,multido,lipsum}
\newcounter{extrait}\newcounter{fiche}% for my automatic command
\usepackage[framemethod=tikz,usetwoside]{mdframed}
\usetikzlibrary{calc,arrows}
\tikzset{warningsymbol/.style={rectangle, fill=white, scale=1,    overlay}}
% here begin my automatic command using collect, counter, & mdframed
\newcommand\histoire[2]{\addtocounter{fiche}{1}\definecollection{his\thefiche}
\def\histo{\path let \p1=(P), \p2=(O) in ($(\x2,0)+{0.5}*(-1,\y1)$)}% this is my use of TIKZ (\histo is to simplify later)
\mdfsetup{hidealllines=true, leftline=true, leftmargin=0em,innertopmargin=0em, innerbottommargin=0em, innerrightmargin=1.5em, innerleftmargin=0.5em,% 
firstextra={\histo node[warningsymbol] {\rotatebox[origin=c]{90}{#1 …}};},% 
secondextra={\histo node[warningsymbol] {\rotatebox[origin=c]{90}{… #1}};},% 
middleextra={\histo node[warningsymbol] {\rotatebox[origin=c]{90}{… #1 …}};},% 
singleextra={\histo node[warningsymbol] {\rotatebox[origin=c]{90}{#1}};}} 
\begin{mdframed}
{\begin{collect*}{his\thefiche}{}{}{\minisec{Extrait \addtocounter{extrait}{1}\theextrait : #1}}{}#2\end{collect*}}
\end{mdframed}}% end of my command

\begin{document}
\chapter{Tests}
\histoire{A}{\lipsum[1-3]}\lipsum[4]
\histoire{B}{\lipsum[5-7]}\lipsum[8]
\histoire{C}{\lipsum[9-16]}

\chapter{Restitutions}
\multido{\i=0+1}{\thefiche}{\setcounter{fiche}{1}\addtocounter{fiche}{\i}\includecollection{his\thefiche}}
\end{document}
% arara: xelatex
% arara: xelatex

This is the actual situation (in red, an example what I hope on the page 1, imagine a similar brace, longer, in the second page) :

Answer 1

Here's an option using tcolorbox instead of mdframed; this version takes care of all three requirements:

1. Uses braces.
2. Braces are placed on the outer margin.
3. The box has a width equal to the \textwidth; the braces are in the margin area.

The code:

\documentclass{scrbook}
\usepackage{fontspec,collect,multido,lipsum}
\usepackage{changepage}
\strictpagecheck

\newcounter{extrait}
\newcounter{fiche}
\usepackage[framemethod=tikz,usetwoside]{mdframed}
\usepackage[many]{tcolorbox}
\usetikzlibrary{calc,arrows,decorations.pathreplacing}

\newtcolorbox{tcbdecor}[1]{
  check odd page,
  breakable,
  colback=white,
  boxrule=0pt,
  colframe=white,
  arc=0pt,
  outer arc=0pt,
  top=0pt,
  bottom=0pt,
  enhanced jigsaw,
  oversize,
  overlay={
    \ifoddpage 
      \draw[decoration=brace,decorate,line width=1pt] 
        (frame.north east) -- node[rotate=270,above=4pt] {... #1 ...} (frame.south east);
    \else
      \draw[decoration={brace,mirror},decorate,line width=1pt] 
        (frame.north west) -- node[rotate=90,above=4pt] {... #1 ...} (frame.south west);
    \fi
  },
}

\newcommand\histoire[2]{%
  \addtocounter{fiche}{1}%
  \definecollection{his\thefiche}%
  \begin{tcbdecor}{#1}
  \begin{collect*}%
    {his\thefiche}{}{}%
    {\minisec{Extrait \addtocounter{extrait}{1}\theextrait : #1}}  
   {}
   #2
  \end{collect*}%
  \end{tcbdecor}%
}

\begin{document}

\chapter{Tests}
\histoire{A}{\lipsum[1-3]}\lipsum[4]
\histoire{B}{\lipsum[5-7]}\lipsum[8]
\histoire{C}{\lipsum[9-16]}

\chapter{Restitutions}
\multido{\i=0+1}{\thefiche}{\setcounter{fiche}{1}\addtocounter{fiche}{\i}\includecollection{his\thefiche}}
\end{document}

The result:

A zoomed-in image showing one of the boxes on an odd numbered page:

A zoomed-in image showing one of the boxes on an even numbered page:

If you want brackets instead, simply change the overlay section to

  overlay={
    \ifoddpage 
      \draw[line width=1pt] 
        ([xshift=-5pt]frame.north east) -- (frame.north east) -- node[rotate=270,above=4pt] {... #1 ...} (frame.south east) -- ([xshift=-5pt]frame.south east);
    \else
      \draw[line width=1pt] 
        ([xshift=5pt]frame.north west) -- (frame.north west) -- node[rotate=90,above=4pt] {... #1 ...} (frame.south west) -- ([xshift=5pt]frame.south west);
    \fi
  },

With the above example, one now gets

on an odd numbered page, and

on an even numbered one.