pgfkey and macro parameter pass the same test differently

Question

In the next MWE, the test provided on a macro parameter gives the expected answer (it finds if the parameter begins with a (), but the same test fails on or ignores the pgfkey it has to test.

This is a minimal example, it is to finish my answer to this question : How to define at tikz style option to draw a dimension line between to specific points

    \documentclass{article}
\usepackage{xparse,tikz}
\usetikzlibrary{calc}
\usepackage{ifluatex}

\makeatletter

\ifluatex
\RequirePackage{pdftexcmds}
\let\pdfstrcmp\pdf@strcmp
\let\pdffilemoddate\pdf@filemoddate
\fi

\tikzset{%
    Cote/.style={to path={\pgfextra{
        \pgfinterruptpath
               \draw[>=latex,|<->|] let
    \p1=($(\tikztostart)!2mm!90:(\tikztotarget)$),
    \p2=($(\tikztotarget)!2mm!-90:(\tikztostart)$)
    in(\p1) -- (\p2) node[pos=.5,sloped,above]{%
    \expandafter\Cote\expandafter{\@aspect} -- 
    \expandafter\CoteBis{$\pi$}\expandafter<\@aspect>};
        \endpgfinterruptpath
        }(\tikztostart) -- (\tikztotarget) \tikztonodes}}
}

\pgfkeys{tikz/Cote/.cd,
    aspect/.store in=\@aspect,
    aspect=o,
} 
\makeatletter

\NewDocumentCommand{\Cote}{m}{%
    \ifnum\pdfstrcmp{\unexpanded\expandafter{\@car#1\@nil}}{(}=\z@
        true
    \else
        false
    \fi
    }

\NewDocumentCommand{\CoteBis}{md<>
    }{%
    #1
    \ifnum\pdfstrcmp{\unexpanded\expandafter{\@car#2\@nil}}{(}=\z@
        true
    \else
        false
    \fi
    }

\makeatother

\begin{document}

\verb+\Cote+ : \Cote{(F)} -- \Cote{F} : The test gives the expected answers

\verb+\Codetis+ : \CoteBis{$\pi$}<(F)> -- \CoteBis{$\pi$}<F> : The test gives the expected answers

\bigskip

In the \verb+\Cote+ macro, the test gives the expected answers

In the \verb+\CoteBis+ macro, the test gives unexpected answers

\bigskip

\begin{tikzpicture}
\path[Cote/aspect=F] (0,0) to[Cote] (5,0) ;
\path[Cote/aspect=(F)] (0,1) to[Cote] (5,1) ;
\end{tikzpicture}
\end{document}

Answer 1

Two issues:

• \CoteBis is never called in the TikZ style Cote. I assume the second \Cote should be \CoteBis.

• \expandafter only jumps over one token, not a group of tokens. Thus, the line

  \expandafter\Cote{$\pi$}\expandafter<\@aspect>
  

  needs much more calls of \expandafter (and probably \CoteBis instead of \Cote):

  \expandafter\CoteBis\expandafter{%
    \expandafter$\expandafter\pi\expandafter$\expandafter}%
    \expandafter<\@aspect>
  

The result: