Wrong toc small cap heading

Question

In what follows, the toc heading is wrong except for the last page and I cannot find a solution. I've been trying to modify the \tableofcontents as well as the \toc@heading commands without success.

\documentclass[12pt]{book}
\usepackage[left=3.8cm,right=3.8cm,top=10cm,bottom=10cm,letterpaper]{geometry}
\usepackage{kpfonts}        
\DeclareRobustCommand{\capsspacing}[1]{\textsc{\MakeLowercase{#1}}}
\usepackage[linktocpage=true]{hyperref}              
\begin{document}
\tableofcontents
\markboth{\capsspacing{\contentsname}}{\capsspacing{\contentsname}}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\end{document}

The toc heading is supposed to be in small caps for all toc pages.

Answer 1

To get the desired result, you can redefine \tableofcontents as implemented in book.cls to change the marks:

\documentclass[12pt]{book}
\usepackage[left=3.8cm,right=3.8cm,paperheight=10cm,top=2cm,bottom=2cm]{geometry}
\usepackage{kpfonts}  

\DeclareRobustCommand{\capsspacing}[1]{\textsc{\MakeLowercase{#1}}}
\DeclareRobustCommand{\capsspacingb}{\scshape\MakeLowercase}

\usepackage[linktocpage=true]{hyperref}             
\usepackage[titles]{tocloft}

% chapters
\renewcommand{\cftchappresnum}{\normalfont}%
\renewcommand{\cftchapfont}{\capsspacingb}%
\renewcommand{\cftchappagefont}{\normalfont}%      

\makeatletter
\renewcommand\tableofcontents{%
    \if@twocolumn
      \@restonecoltrue\onecolumn
    \else
      \@restonecolfalse
    \fi
    \chapter*{\contentsname
        \@mkboth{%
           \scshape\MakeLowercase{\contentsname}}{\scshape\MakeLowercase{\contentsname}}}%
    \@starttoc{toc}%
    \if@restonecol\twocolumn\fi
    }
\makeatother      


\begin{document}
\tableofcontents
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\end{document}

Using the etoolbox package to patch \tableofcontents, the code simplifies:

\documentclass[12pt]{book}
\usepackage[left=3.8cm,right=3.8cm,paperheight=10cm,top=2cm,bottom=2cm]{geometry}
\usepackage{kpfonts}  
\usepackage{etoolbox}  

\patchcmd{\tableofcontents}{\MakeUppercase\contentsname}{\scshape\MakeLowercase{\contentsname}}{}{}
\patchcmd{\tableofcontents}{\MakeUppercase\contentsname}{\scshape\MakeLowercase{\contentsname}}{}{}

\DeclareRobustCommand{\capsspacing}[1]{\textsc{\MakeLowercase{#1}}}
\DeclareRobustCommand{\capsspacingb}{\scshape\MakeLowercase}

\usepackage[linktocpage=true]{hyperref}             
\usepackage[titles]{tocloft}

% chapters
\renewcommand{\cftchappresnum}{\normalfont}%
\renewcommand{\cftchapfont}{\capsspacingb}%
\renewcommand{\cftchappagefont}{\normalfont}%      

\begin{document}
\tableofcontents

\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\chapter{title}\section{title}\section{title}\section{title}\section{title}\section{title}\section{title}
\end{document}