\documentclass{article}

\usepackage{agda}

\begin{document}

No indentation should be inserted before \AgdaKeyword{postulate} or
the last occurrence of \AgdaPrimitiveType{Set}, and the last
occurrence of \AgdaPrimitiveType{Set} should be aligned with the
penultimate occurrence of \AgdaPrimitiveType{Set}:
\begin{code}
  postulate
    A  : Set
    B  : Set →
         Set
\end{code}

\end{document}
