Strange distancing when starting with a bulleted enviroment.

[Sk1nk]

I noticed that the spacing is of if I start a (centered) exercise with an itemize or enumerate enviroment.

Minimal working example:

\documentclass[%
a4paper,            
]{memoir}

\usepackage{cmbright}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\usepackage[clear-aux]{xsim}
\xsimsetup{
    load-style=layouts,
    exercise/template=centered,
    solution/print = false, 
    exercise/name = Aufgabe,
    blank/filled-style=\textcolor{Red}{#1},
    blank/line-minimum-length = 1cm,
    blank/scale = 1.5,
}       

\begin{document}
\begin{exercise}
Normal  distance between header and text!
\end{exercise}

\begin{exercise}
\begin{enumerate}
    \item Greater distance between header and text!
\end{enumerate}
\end{exercise}

\end{document}

produces

[muzimuzhi]

With the default setting exercise/template=default, exercise title is typeset by \subsection*{<title>}, which takes care of vertical spacing between following list (like enumerate) automatically, through \@afterheading.

With exercise/template=centered, the same exercise title is now typeset manually, by \hfil\textbf{<title>}...\hfil\par\noindent. This time the vertical space \topsep inserted by a list environment (between it and the previous text) is not ignored automatically any more.

Implementations of exercise templates default and centered

https://github.com/cgnieder/xsim/blob/06e3dba43b96ed493968ddd54add9fc8a1d9a264/code/xsim.sty#L5509-L5533 https://github.com/cgnieder/xsim/blob/06e3dba43b96ed493968ddd54add9fc8a1d9a264/code/xsim.style.layouts.code.tex#L95-L115

Adding back \@afterheading (manually or by patching the centered template) solves the problem, partially. Note with exercise/template=centered, if exercise property points is given for an exercise starting with a list environment, the value of points will be typeset in its own paragraph, as a marginal note. You may need to manually adjust the vertical spacing.

\documentclass{article}
\usepackage{lipsum}

% to show distances between baseline heights
\usepackage{lineno}
\renewcommand{\thelinenumber}{\arabic{linenumber}\rlap{\rule{.4pt}{11pt}}}
\linenumbers

%\usepackage{cmbright}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\usepackage[clear-aux]{xsim}
\xsimsetup{
    load-style=layouts,
    exercise/template=centered,
}

\makeatletter
% cheat `xsim` as if `centered` template is undefined
\ExpandArgs{cc}\relax {cs_undefine:N} {l__xsim_template_begin_centered_setup_tl}
\ExpandArgs{cc}\relax {cs_undefine:N} {l__xsim_template_end_centered_setup_tl}

\DeclareExerciseEnvironmentTemplate{centered}
  {%
    \par\vspace{\baselineskip}
    \Needspace*{2\baselineskip}
    \noindent
    \hfil\textbf{\XSIMmixedcase{\GetExerciseName}~\GetExerciseProperty{counter}}%
    \GetExercisePropertyT{subtitle}{ \textit{#1}}\hfil
    \par\noindent\@afterheading % <<< changed
    \IfInsideSolutionF{%
      \GetExercisePropertyT{points}{%
          \marginpar{%
            \printgoal{\PropertyValue}%
            \GetExercisePropertyT{bonus-points}{+\printgoal{\PropertyValue}}%
            \,\IfExerciseGoalSingularTF{points}
                {\XSIMtranslate{point}}
                {\XSIMtranslate{points}}%
          }%
      }%
    }%
  }
  {}
\makeatother

\begin{document}
\begin{exercise}[subtitle={no points + plain text}]
  Normal distance between header and text!
\end{exercise}

\begin{exercise}[subtitle={no points + list}]
  \begin{enumerate}
    \item Greater distance between header and text!
  \end{enumerate}
\end{exercise}

\begin{exercise}[points=2, subtitle={points + plain text}]
  Normal distance between header and text!
\end{exercise}

\begin{exercise}[points=3, subtitle={points + list}]
  \begin{enumerate}
    \item Greater distance between header and text!
  \end{enumerate}
\end{exercise}

\begin{exercise}[points=4, subtitle={points + list + manual adjustment}]
  \vspace{-\baselineskip}
  \begin{enumerate}
    \item Greater distance between header and text!
  \end{enumerate}
\end{exercise}

\section*{Emulation}
\subsection*{EnvironmentTemplate=default}
\lipsum[2][1]

\subsection*{EnvironmentTemplate=default}
\begin{enumerate}
  \item \lipsum[2][1]
\end{enumerate}

\hfil\textbf{EnvironmentTemplate=centered}\hfil \par
\lipsum[2][1]

\hfil\textbf{EnvironmentTemplate=centered}\hfil \par
\begin{enumerate}
  \item \lipsum[2][1]
\end{enumerate}

\hfil\textbf{EnvironmentTemplate=centered, patched}\hfil \par
\UseName{@afterheading}%
\begin{enumerate}
  \item \lipsum[2][1]
\end{enumerate}
\end{document}