\DocumentMetadata{}
\input regression-test.tex
\documentclass{ltx-talk}
\usepackage{ltxtalk-theme}

\ExplSyntaxOn
\tl_new:N \g_lttheme_test_rows_tl

\RegisterLTXTalkTheme { test-recipe }
  {
    \ltxtalksetup { }
    \setltxtalkcolors { primary = { model=HTML, value=204060 } }
    % A layout that carries setup code.  The code records the header row
    % count in effect when it ran, so the test can see whether a per-call
    % override reached it.
    \DeclareLTXTalkLayout { test-branded }
      { header = true, header-height = 1.4cm, header-rows = 2 }
      [
        \defineltxtalkslot { tl-nav } { header } { custom } { role = navigation }
        \setltxtalkslotcontent { tl-nav } { nav }
        \positionltxtalkslot { tl-nav } { left } { 0.2cm } { 4cm } { 0.5cm }
        \tl_gset:Nx \g_lttheme_test_rows_tl { \int_use:N \l__ltxtalk_header_rows_int }
      ]
    \UseLTXTalkLayout { test-branded }
  }
\RegisterLTXTalkTheme { test-recipe-empty } { \ltxtalksetup { } }
\ExplSyntaxOff

\useltxtalktheme{test-recipe}

\begin{document}
\begin{frame}{First}
  Body one.
\end{frame}

% Per-call override: header-rows becomes 3; both the layout keys and the
% setup code must see it.
\UseLTXTalkLayout{test-branded}[header-rows = 3]

\begin{frame}{Second}
  Body two.
\end{frame}

\START
\ExplSyntaxOn

% 1. The layout's setup code ran on \UseLTXTalkLayout.
\IfInstanceExistsTF { lttheme-slot } { tl-nav }
  { \TYPE { slot-declared:passed } } { \TYPE { slot-declared:FAILED } }

% 2. Idempotency: the layout ran twice (theme + explicit override call),
%    the slot is in the header order exactly once.
\int_compare:nNnTF { \seq_count:N \g__ltxtalk_header_slots_seq } = { 1 }
  { \TYPE { idempotent:passed } }
  { \TYPE { idempotent:FAILED= \seq_count:N \g__ltxtalk_header_slots_seq } }

% 3. The per-call override reached the layout keys ...
\int_compare:nNnTF { \l__ltxtalk_header_rows_int } = { 3 }
  { \TYPE { override-key:passed } } { \TYPE { override-key:FAILED } }
% ... and the setup code, which ran after the override was applied.
\str_if_eq:eeTF { \g_lttheme_test_rows_tl } { 3 }
  { \TYPE { override-code:passed } } { \TYPE { override-code:FAILED } }

% 4. A theme switch drops the previous theme's declared layouts.
\useltxtalktheme { test-recipe-empty }
\prop_if_in:NnTF \g__ltxtalk_layouts_prop { test-branded }
  { \TYPE { layout-cleared:FAILED } } { \TYPE { layout-cleared:passed } }

\ExplSyntaxOff
\END
\end{document}