% \iffalse
%<*internal>
\ifx\documentclass\undefined
\input docstrip.tex
\keepsilent
\askforoverwritefalse
%% New single-organiser session interface: to generate those files
%% instead, change 'false' to 'true' in the conditional below.
\iffalse
\generate{
  \file{confschedule.sty}{\from{\jobname.dtx}{package,new-session}}
  \nopreamble\nopostamble
  \file{process-submissions.lua}{\from{\jobname.dtx}{lua}}
  \file{talk-template.tex}{\from{\jobname.dtx}{talk-template}}
  \file{session-template.tex}{\from{\jobname.dtx}{session-template,new-session}}
}
\else
\generate{
  \file{confschedule.sty}{\from{\jobname.dtx}{package,old-session}}
  \nopreamble\nopostamble
  \file{process-submissions.lua}{\from{\jobname.dtx}{lua}}
  \file{talk-template.tex}{\from{\jobname.dtx}{talk-template}}
  \file{session-template.tex}{\from{\jobname.dtx}{session-template,old-session}}
}
\fi
\endbatchfile
\fi
\documentclass[full]{l3doc}
\begin{document}
  \DocInput{\jobname.dtx}
\end{document}
%</internal>
% \fi
%
% \title{\pkg{confschedule}\\Conference Schedule and Proceedings Management}
% \author{}
% \date{2025/05/16 v1.0}
% \maketitle
%
% \begin{abstract}
% \pkg{confschedule} manages the full pipeline for conference proceedings:
% submission files are ingested by a \LuaTeX{} module
% (\texttt{process-submissions.lua}) that populates a database of sessions,
% talks, and participants; the package then typesets schedule grids, session
% and abstract listings, and a participant index from that database.
% All session types, colours, and formatting hooks are user-configurable.
% \end{abstract}
%
% \tableofcontents
%
% ^^A ------------------------------------------------------------------
% \section{Usage Example}
% ^^A ------------------------------------------------------------------
%
% The following minimal example shows the complete workflow.
%
% \subsection{Session submission files}
%
% Each session corresponds to a subdirectory whose name is the session id.
% The directory contains any number of \texttt{.tex} files, each holding
% exactly one environment (\texttt{session} or \texttt{talk}).
% Files are processed in sorted (alphabetical) order.
% Files whose name begins with digits are assigned a talk index; gaps
% in the numeric sequence cause \cs{missingTalk} to be emitted automatically.
% Files without a leading digit (e.g.\ \texttt{session.tex}) are processed
% but do not consume a talk index slot.
% Any content outside the environments in a file is silently ignored.
%
% A typical session directory looks like this:
%
% \begin{verbatim}
% sessions/
%   contrib-1/
%     session.tex     <- session metadata and description
%     01.tex          <- first talk
%     02.tex          <- second talk
%     04.tex          <- fourth talk (03.tex absent: \missingTalk{3} emitted)
% \end{verbatim}
%
% \paragraph{Session file (\texttt{session.tex})}
% Contains one \texttt{session} environment.  The body is the session
% abstract or description; it is re-typeset verbatim by \cs{renderSessions}.
%
% \begin{verbatim}
% \begin{session}
%   {Numerical Optimisation}     % session title
%   {Jane Smith}                 % chair (first organiser)
%   {MIT}                        % organiser affiliation
%   {j.smith@mit.edu}            % organiser email
%   {}{}{}                       % second organiser (leave blank to omit)
% This session covers recent advances in first-order methods for
% large-scale convex and non-convex problems.
% \end{session}
% \end{verbatim}
%
% \paragraph{Talk file (\texttt{01.tex})}
% Contains one \texttt{talk} environment.  The body is the abstract;
% it is re-typeset verbatim by \cs{renderTalks}.
%
% \begin{verbatim}
% \begin{talk}
%   {A Fast Gradient Method}     % title
%   {Alice Brown}                % speaker
%   {Stanford University}        % affiliation
%   {a.brown@stanford.edu}       % email
%   {C.~White}                   % coauthors (empty if none)
%   {}                           % special note (empty if none)
% We present a gradient method achieving optimal complexity for
% smooth strongly-convex objectives.
% \end{talk}
% \end{verbatim}
%
% \paragraph{Cancelled talk (\texttt{02.tex})}
% Use \cs{cancelTalk} in the optional hook argument.
%
% \begin{verbatim}
% \begin{talk}
%   {Convergence Rates}
%   {Bob Green}{Cambridge}{b.green@cam.ac.uk}{}{}
%   [\cancelTalk]
% This abstract will not be rendered and the talk will appear
% with strikethrough in the schedule.
% \end{talk}
% \end{verbatim}
%
% \subsection{Main document}
%
% \begin{verbatim}
% \documentclass{book}
% \usepackage{confschedule}
%
% % Register session types with display label and background colour.
% \defineSessionType{contrib}{Contributed Talk}{blue!15}
% \defineSessionType{invited}{Invited Talk}{green!20}
% \defineSessionType{plenary}{Plenary}{orange!30}
%
% % Redefine schedule colours if desired (before or after \usepackage).
% \colorlet{clrScheduleOdd}{blue!5}
%
% \begin{document}
%
% % Ingest all session directories under sessions/.
% % Must run under LuaLaTeX; use \directlua or a Lua file loaded at startup.
% \setDefaultSessionType{contrib}
% \directlua{
%   local proc = require("process-submissions")
%   proc.process_root("sessions")
% }
%
% % Assign locations, and override colour/label for individual sessions.
% % All three keys are optional; values with commas need braces.
% \setSessionsData{plenary-1}{location={Auditorium}}
% \setSessionsData{contrib-1, contrib-2}{
%   location = {Room~A},
%   color    = {yellow!25},
%   label    = {Special~Session}
% }
%
% % A single standalone talk (e.g.\ a plenary with its own .tex file):
% \addSessionTalk[plenary]{plenary-1}{Prof.\ Keynote}{plenary.tex}
%
% \chapter{Programme}
%
% \begin{schedule}{2}{Monday Morning}
%   \scheduleEvent{gray!20}{09:00}{Registration and Coffee}
%   \scheduleSessionTalk{10:00}{plenary-1}        % full-width row, talk 1
%   \scheduleEvent{gray!20}{11:00}{Coffee Break}
%   \scheduleSessions{11:30}                      % concurrent sessions
%     {Talk 1, Talk 2, Talk 3}                    % per-row time labels
%     {contrib-1, contrib-2}                      % session ids (columns)
% \end{schedule}
%
% \chapter{Session Descriptions}
% \renderSessions{contrib,invited}
%
% \chapter{Abstracts}
% \renderTalks*{contrib,invited}   % starred: include chair line per talk
%
% \chapter{Participants}
% \printParticipants
%
% \end{document}
% \end{verbatim}
%
% ^^A ------------------------------------------------------------------
% \section{User Interface}
% ^^A ------------------------------------------------------------------
%
% \subsection{Session types and configuration}
%
% \begin{function}{\defineSessionType}
%   \begin{syntax}
%     \cs{defineSessionType} \marg{key} \marg{label} \marg{colour}
%   \end{syntax}
%   Registers a session type.
%   \meta{key} is the internal identifier used in all other commands.
%   \meta{label} is the display string shown in schedule cells.
%   \meta{colour} is any \pkg{xcolor} colour expression used as the
%   cell background.
%   The colour and label are copied into each session's own property
%   record when the session is opened (via the Lua processor or
%   \cs{openSession}), so \cs{defineSessionType} must be called before
%   sessions are loaded.  Individual sessions may override these values
%   afterwards with \cs{setSessionsData}.
% \end{function}
%
% \begin{function}{\setDefaultSessionType}
%   \begin{syntax}
%     \cs{setDefaultSessionType} \marg{key}
%   \end{syntax}
%   Sets the type stamped onto sessions opened subsequently.
%   The initial default is \texttt{UNKNOWN}.
%   Must be called before \cs{openSession}; changing the type while a
%   session is open has no effect on that session.
% \end{function}
%
% \begin{function}{\setSessionsData}
%   \begin{syntax}
%     \cs{setSessionsData} \marg{id, id, \ldots} \marg{key=value, \ldots}
%   \end{syntax}
%   Sets one or more properties on each session in the comma-list.
%   All three keys are optional; omit any that should remain unchanged.
%   \begin{center}\small
%   \begin{tabular}{ll}
%   \hline
%   Key & Aliases \\
%   \hline
%   \texttt{location} & \texttt{loc} \\
%   \texttt{color}    & \texttt{colour}, \texttt{clr} \\
%   \texttt{label}    & \texttt{lbl} \\
%   \hline
%   \end{tabular}
%   \end{center}
%   Values containing commas must be wrapped in braces,
%   e.g.\ \texttt{location=\{Room~A,~Level~2\}}.
%   Issues a warning for each unknown session id.
%   Must be called after session files have been loaded.
%   Unknown keys are an error.
% \end{function}
%
% \begin{function}{\sessionLocation,\sessionSlot,\talkSlot}
%   \begin{syntax}
%     \cs{sessionLocation} \marg{id}
%     \cs{sessionSlot} \marg{id}
%     \cs{talkSlot} \marg{id@n}
%   \end{syntax}
%   Query commands that expand to the stored location, schedule slot
%   label, or talk slot label respectively.
%   Error if the id is unknown or has not been scheduled.
% \end{function}
%
% \begin{function}{\sessionCount,\talkCount,\participantCount}
%   \begin{syntax}
%     \cs{sessionCount} \marg{type, type, \ldots}
%     \cs{talkCount} \marg{type, type, \ldots}
%     \cs{participantCount}
%   \end{syntax}
%   Typeset the count of scheduled sessions or non-cancelled scheduled
%   talks whose type appears in the comma-list, or the number of
%   participants in the database who have not been removed via
%   \cs{removeParticipant}.
%   All three are valid anywhere after the submission files have been
%   processed.
% \end{function}
%
% \begin{function}{\setInputFilepath}
%   \begin{syntax}
%     \cs{setInputFilepath} \marg{path}
%   \end{syntax}
%   Records the path of the file about to be \cs{input}.
%   Called automatically by the Lua processor before each file;
%   not normally needed in document files.
% \end{function}
%
% \subsection{Session and talk lifecycle}
%
% \begin{function}{\openSession,\closeSession}
%   \begin{syntax}
%     \cs{openSession} \marg{id} \marg{path}
%     \cs{closeSession}
%   \end{syntax}
%   Open and close a session accumulator.
%   Called automatically by the Lua processor; use directly only
%   if driving the pipeline from \TeX{} rather than Lua.
% \end{function}
%
% \begin{environment}{session}
%   \begin{syntax}
%     \cs{begin}\{session\}
%       \marg{title} \marg{chair} \marg{org1-name} \marg{org1-affil} \marg{org1-email}
%       \marg{org2-name} \marg{org2-affil} \marg{org2-email}
%       \oarg{extra-setup}
%     \meta{body}
%     \cs{end}\{session\}
%   \end{syntax}
%   Declares the session metadata.
%   Omit the second organiser by passing three empty braces.
%   \meta{extra-setup} (optional argument) is executed in the session
%   context, e.g.\ \cs{addSessionOrganizer}.
%   The \meta{body} is the session abstract or description.
%   It is re-typeset verbatim by \cs{renderSessions} and may contain
%   arbitrary prose.  Leave it empty if no description is provided.
% \end{environment}
%
% \begin{environment}{talk}
%   \begin{syntax}
%     \cs{begin}\{talk\}
%       \marg{title} \marg{speaker} \marg{affil} \marg{email}
%       \marg{coauthors} \marg{special-note}
%       \oarg{hook}
%     \meta{abstract}
%     \cs{end}\{talk\}
%   \end{syntax}
%   Declares one talk and its abstract.
%   \meta{hook} is executed after all fields are stored but before
%   the talk is committed; use it for \cs{cancelTalk}.
%   The \meta{abstract} is the talk abstract.
%   It is re-typeset verbatim by \cs{renderTalks}.
% \end{environment}
%
% \begin{environment}{extrainfo}
%   Content inside this environment is silently discarded.
%   Useful in submission files for author-side notes or metadata
%   that should not appear in the proceedings.
% \end{environment}
%
% \begin{function}{\addSessionOrganizer}
%   \begin{syntax}
%     \cs{addSessionOrganizer} \marg{name} \marg{affil} \marg{email}
%   \end{syntax}
%   Adds an organiser to the current session (beyond the two in the
%   \texttt{session} environment).
% \end{function}
%
% \begin{function}{\setSessionChair}
%   \begin{syntax}
%     \cs{setSessionChair} \marg{name}
%   \end{syntax}
%   Overrides the chair of the current session.
% \end{function}
%
% \begin{function}{\addSessionTalk}
%   \begin{syntax}
%     \cs{addSessionTalk} \oarg{type} \marg{id} \marg{chair} \marg{filepath}
%   \end{syntax}
%   Convenience wrapper that opens a one-talk session of the given
%   \meta{type} (default \texttt{plenary}), inputs \meta{filepath},
%   then closes the session.
% \end{function}
%
% \begin{function}{\cancelTalk}
%   Marks the enclosing talk as cancelled.
%   Call inside the optional \meta{hook} argument of the \texttt{talk}
%   environment.
%   Cancelled talks appear with \cs{cancelledTalkFormat} in the
%   schedule and session listing, and are omitted from \cs{renderTalks}.
%   The speaker remains a participant; use \cs{removeParticipant} to
%   suppress them from the printed participant list.
% \end{function}
%
% \begin{function}{\cancelledTalkFormat}
%   \begin{syntax}
%     \cs{cancelledTalkFormat} \marg{text}
%   \end{syntax}
%   Applied to cancelled speaker/title text in the schedule and session
%   listing.  Default: \cs{sout}\marg{text} (strikethrough via
%   \pkg{ulem}).  Override with \cs{renewcommand}.
% \end{function}
%
% \begin{function}{\missingTalk}
%   \begin{syntax}
%     \cs{missingTalk} \marg{index}
%   \end{syntax}
%   Inserts a blank talk placeholder for \meta{index}.
%   Emitted automatically by the Lua processor when a numbered file
%   is absent from a session directory.
% \end{function}
%
% \subsection{Participant management}
%
% \begin{function}{\addParticipant}
%   \begin{syntax}
%     \cs{addParticipant} \marg{name} \marg{email} \marg{affil}
%   \end{syntax}
%   Registers a participant who is not a speaker or organiser.
%   Appears in \cs{printParticipants} with empty session/talk lists.
% \end{function}
%
% \begin{function}{\removeParticipant}
%   \begin{syntax}
%     \cs{removeParticipant} \marg{email}
%   \end{syntax}
%   Marks a participant as removed, identified by their \meta{email}
%   address.  Removed participants are silently skipped by
%   \cs{printParticipants} but remain in the database, so their names
%   still appear correctly in session and talk listings.
%   Issues a warning if the address is not found in the database.
%   No-op for a blank address.
% \end{function}
%
% \subsection{Schedule construction}
%
% All schedule commands are valid only inside the \texttt{schedule}
% environment.
%
% \begin{environment}{schedule}
%   \begin{syntax}
%     \cs{begin}\{schedule\} \marg{num-cols} \marg{heading}
%     \meta{body}
%     \cs{end}\{schedule\}
%   \end{syntax}
%   Typesets a \pkg{tabularx} schedule grid with \meta{num-cols}
%   session columns and a header row showing \meta{heading}.
%   The \meta{body} contains \cs{scheduleSessionTalk},
%   \cs{scheduleSessions}, and \cs{scheduleEvent} calls.
% \end{environment}
%
% \begin{function}{\scheduleSessionTalk}
%   \begin{syntax}
%     \cs{scheduleSessionTalk} \oarg{n} \marg{slot} \marg{id}
%   \end{syntax}
%   Adds a full-width row for the \meta{n}-th talk (default~1) of
%   session \meta{id} at time \meta{slot}.
%   Shows location, type label, speaker, title (with page reference),
%   and chair.
%   Cancelled talks appear with strikethrough and no page reference.
% \end{function}
%
% \begin{function}{\scheduleSessions}
%   \begin{syntax}
%     \cs{scheduleSessions} \marg{slot-title}
%       \marg{row-label, row-label, \ldots}
%       \marg{id, id, \ldots}
%   \end{syntax}
%   Adds a concurrent-session block.
%   \meta{row-labels} (comma-list) are used as time labels for each
%   talk row; \meta{ids} (comma-list) name the session columns.
%   The header row uses per-column type colours; talk rows alternate
%   \texttt{clrScheduleOdd}/\texttt{clrScheduleEven}.
%   First placement of any session or talk wins; duplicates are
%   silently ignored.
% \end{function}
%
% \begin{function}{\scheduleEvent}
%   \begin{syntax}
%     \cs{scheduleEvent} \marg{colour} \marg{slot} \marg{content}
%   \end{syntax}
%   Adds a full-width coloured row for a non-talk event such as a
%   coffee break, meal, or ceremony.
% \end{function}
%
% \subsection{Output}
%
% \begin{function}{\renderSessions}
%   \begin{syntax}
%     \cs{renderSessions} \marg{type, type, \ldots}
%   \end{syntax}
%   Outputs in schedule order all sessions whose type is in the
%   comma-list.  Each session entry contains: a coloured slot/location
%   bar, a \cs{subsection*} title with a \cs{label}, the organiser
%   list with affiliations and email addresses, the session description
%   body (re-input from the submission file), and a talk list with
%   fill-to-right page references.
% \end{function}
%
% \begin{function}{\renderTalks}
%   \begin{syntax}
%     \cs{renderTalks}  \marg{type, type, \ldots}
%     \cs{renderTalks}* \marg{type, type, \ldots}
%   \end{syntax}
%   Renders talk abstracts in schedule order, filtered by type.
%   Each entry contains: a coloured slot/location bar, an optional
%   session title back-reference, an optional chair line (starred form
%   only), a \cs{subsection*} title with \cs{label}, speaker name,
%   affiliation, email, coauthors, and the abstract body.
%   Cancelled talks are silently skipped.
% \end{function}
%
% \begin{function}{\printParticipants}
%   \begin{syntax}
%     \cs{printParticipants} \oarg{min}
%     \cs{printParticipants}* \oarg{min}
%   \end{syntax}
%   Typesets an alphabetically sorted two-column list of participants.
%   Each entry shows name, affiliation, email, and page references to
%   their sessions and talks.
%   The optional \meta{min} argument (default~0) suppresses participants
%   with fewer than \meta{min} combined session and talk engagements.
%   The starred form additionally prints each participant's scheduled
%   slots below the page references, one per line.  Each slot line
%   shows a role label (\enquote{Organizer:} or \enquote{Speaker:}),
%   the session title in quotes, an inline page reference, and the
%   slot string; for example:
%   \begin{quote}
%     \textit{Speaker:} ``Numerical Optimisation'', p.\,3,
%     Monday Morning, 10:00
%   \end{quote}
%   Issues a warning for any slot that cannot be resolved.
%   Removed participants are always omitted.
% \end{function}
%
% \subsection{Page references}
%
% \begin{function}{\blockPageref,\fillPageref}
%   \begin{syntax}
%     \cs{blockPageref} \marg{label}
%     \cs{fillPageref} \marg{label}
%   \end{syntax}
%   Both expand to \enquote{p.\,\meta{N}}.
%   \cs{blockPageref} is inline; \cs{fillPageref} adds a
%   \cs{hfill} so the reference floats to the right margin.
% \end{function}
%
% \subsection{Colour customisation}
%
% The following colours are defined by the package with
% \cs{@ifundefined} guards, so they may be pre-defined in the
% document class or redefined with \cs{definecolor}/\cs{colorlet}
% after \cs{usepackage}:
%
% \begin{center}\small
% \begin{tabular}{lll}
% \hline
% Name & Default & Used in \\
% \hline
% \texttt{clrScheduleEmpty} & gray 0.85 &
%   time cell in \cs{scheduleSessions} header \\
% \texttt{clrScheduleOdd}   & gray 0.93 &
%   odd talk rows in \cs{scheduleSessions} \\
% \texttt{clrScheduleEven}  & white &
%   even talk rows in \cs{scheduleSessions} \\
% \hline
% \end{tabular}
% \end{center}
%
% Session type colours are set per type via \cs{defineSessionType};
% each cell uses \cs{cellcolor} for the type colour and
% \cs{rowcolor} for the alternating row colour.
%
% ^^A ------------------------------------------------------------------
% \section{Lua Submission Processor}
% ^^A ------------------------------------------------------------------
%
% \texttt{process-submissions.lua} is a LuaLaTeX module that scans a
% directory tree and drives the \TeX{} pipeline.  Each session occupies
% a subdirectory; each file in that directory contains exactly one
% \texttt{session} or \texttt{talk} environment.  Content outside an
% environment in a file is ignored.  Load the module with
% \cs{directlua} or from a Lua startup file:
%
% \begin{verbatim}
% local proc = require("process-submissions")
%
% -- Process all session subdirectories under "sessions/":
% proc.process_root("sessions")
%
% -- Or process a single session directory directly:
% proc.process("sessions/contrib-1")
% \end{verbatim}
%
% \begin{function}[label=lua-process-root]{process\_root}
%   \begin{syntax}
%     proc.process\_root(\meta{dir})
%   \end{syntax}
%   Iterates over every immediate subdirectory of \meta{dir}
%   (skipping hidden entries).  For each subdirectory it emits
%   \cs{openSession}\marg{name}\marg{path}, calls
%   \texttt{process}, then emits \cs{closeSession}.
%   The subdirectory name becomes the session id.
% \end{function}
%
% \begin{function}[label=lua-process]{process}
%   \begin{syntax}
%     proc.process(\meta{dir})
%   \end{syntax}
%   Collects all \texttt{.tex} files in \meta{dir}, sorts them
%   alphabetically, then inputs each in turn via \cs{setInputFilepath}
%   and \cs{input}.  Each file is expected to contain exactly one
%   \texttt{session} or \texttt{talk} environment; content outside
%   any environment is ignored.
%   Files whose name begins with digits have the leading number
%   extracted as the talk index (\cs{currentTalkIndex}); gaps in the
%   sequence trigger automatic \cs{missingTalk} calls.
%   Files without a leading digit are input normally but do not
%   advance the talk index counter.
% \end{function}
%
% \StopEventually{}
%
% ^^A ------------------------------------------------------------------
% \section{Implementation}
% ^^A ------------------------------------------------------------------
%
% \subsection{Package file (\texttt{confschedule.sty})}
%
% \subsubsection{Package infrastructure}
%
% Required packages and default colour definitions.
% \pkg{xcolor} must receive the \texttt{table} option before being
% loaded to avoid option-clash warnings; \cs{PassOptionsToPackage}
% ensures this even if \pkg{xcolor} was loaded earlier.
% The three \texttt{clrSchedule*} colours use \cs{@ifundefined}
% guards so that pre-defined values are respected.
%
% \iffalse
%<*package>
% \fi
%    \begin{macrocode}
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{confschedule}
  [2025/05/16 v1.0 Conference schedule and proceedings management]

\PassOptionsToPackage{table}{xcolor}
\RequirePackage{expl3}
\RequirePackage{xparse}
\RequirePackage{xcolor}
\RequirePackage{tabularx}
\RequirePackage{multicol}
\RequirePackage[normalem]{ulem}

\@ifundefined{color@clrScheduleEmpty}
  { \definecolor{clrScheduleEmpty}{gray}{0.85} }{}
\@ifundefined{color@clrScheduleOdd}
  { \definecolor{clrScheduleOdd}{gray}{0.93} }{}
\@ifundefined{color@clrScheduleEven}
  { \colorlet{clrScheduleEven}{white} }{}
%    \end{macrocode}
%
% \subsubsection{Declarations}
%
% All expl3 code runs inside \cs{ExplSyntaxOn}.
% The three \cs{def}s give safe defaults for the values that the Lua
% processor overwrites before each \cs{input}. The \cs{nolinkurl}
% fallback covers documents that load neither \pkg{url} nor
% \pkg{hyperref}.
%
%    \begin{macrocode}
\ExplSyntaxOn

\def\currentSessionType{UNKNOWN}
\def\currentFilepath{}
\def\currentTalkIndex{}

\cs_if_exist:NF \nolinkurl
  { \cs_new:Npn \nolinkurl #1 { \texttt{#1} } }

% --- Core session/talk storage ---
\prop_new:N \g_sessions_prop
\prop_new:N \g_session_prop
\prop_new:N \l_sched_talk_prop
\prop_new:N \l_sched_session_prop
\seq_new:N  \g_session_organizers_seq
\seq_new:N  \g_session_talks_seq
\seq_new:N  \g_orphan_talks_seq
\tl_new:N   \g_current_session_id_tl

% --- Schedule state ---
\seq_new:N  \g_schedule_sessions_seq
\seq_new:N  \g_schedule_talk_order_seq
\prop_new:N \g_talk_titles_prop
\prop_new:N \g_sched_session_slots_prop
\prop_new:N \g_sched_talk_slots_prop
\prop_new:N \g_session_type_colors_prop
\prop_new:N \g_session_type_labels_prop

% --- Schedule table row-building state ---
\tl_new:N   \l_sched_header_tl
\tl_new:N   \l_sched_numcols_tl
\seq_new:N  \l_sched_rows_out_seq
\tl_new:N   \l_sched_row_out_tl
\bool_new:N \l_sched_row_odd_bool
\int_new:N  \l_sched_talk_idx_int
\clist_new:N \l_sched_ids_clist
\clist_new:N \l_sched_labels_clist
\prop_new:N \l_sched_record_prop

% --- Named temporaries for resolved schedule values ---
\tl_new:N   \l_sched_color_tl
\tl_new:N   \l_sched_type_label_tl
\tl_new:N   \l_sched_session_id_tl
\tl_new:N   \l_sched_talks_tl
\tl_new:N   \l_sched_title_tl
\tl_new:N   \l_sched_speaker_tl
\tl_new:N   \l_sched_chair_tl
\tl_new:N   \l_sched_location_tl

% --- Participant database ---
\prop_new:N \g_participant_info_prop
\prop_new:N \g_participant_sessions_prop
\prop_new:N \g_participant_talks_prop
\prop_new:N \l_sched_participant_prop

% --- Scratch registers (single context, no nesting) ---
\tl_new:N   \l_sched_tmpa_tl
\tl_new:N   \l_sched_tmpb_tl
\tl_new:N   \l_sched_tmpc_tl
\bool_new:N \l_sched_tmpa_bool
\seq_new:N  \l_sched_tmpa_seq
\int_new:N  \l_sched_tmpa_int

% --- Cancelled-talk formatting registers ---
\tl_new:N   \l_sched_fmt_speaker_tl
\tl_new:N   \l_sched_fmt_title_tl

% --- Context flags ---
% \g_sched_in_talk_hook_bool: true only while the optional hook argument of
% the talk environment is being executed; guards \cancelTalk.
\bool_new:N \g_sched_in_talk_hook_bool

% --- Participant key and transient display-name map ---
% \g_participant_display_prop is built immediately before sorting in
% \sched_print_participants:.  It must be a flat prop because \seq_sort:Nn
% comparators must be purely expandable, and \prop_item:Nn only gives
% expandable single-level lookup.
\tl_new:N   \l_sched_participant_key_tl
\prop_new:N \g_participant_display_prop
\seq_new:N  \l_sched_sorted_participants_seq

% --- Render mode flag ---
\bool_new:N \g_sched_render_body_bool
%    \end{macrocode}
%
% \subsubsection{Messages}
%
%    \begin{macrocode}
\msg_new:nnn { session } { no-open-session }
  { \session_end:~called~but~no~session~is~currently~open. }

\msg_new:nnn { session } { participant-not-found }
  { Participant~key~'#1'~not~found~in~the~database. \\
    The~name~has~been~left~as~the~raw~key. }

\msg_new:nnn { schedule } { unknown-session }
  { Unknown~session~'#1'. \\
    Check~the~ID~and~that~\openSession{#1}~was~
    processed~before~\begin{document}. }

\msg_new:nnn { schedule } { render-missing-session }
  { Session~'#1'~is~in~the~schedule~but~not~found~in~the~database. }

\msg_new:nnn { schedule } { unknown-location }
  { No~location~set~for~session~'#1'. \\
    Use~\setSessionsData{#1}{location={room}}~after~loading~sessions. }

\msg_new:nnn { schedule } { session-not-scheduled }
  { Session~'#1'~has~not~been~placed~in~any~schedule. }

\msg_new:nnn { schedule } { talk-not-scheduled }
  { Talk~'#1'~not~found~in~the~schedule. }

\msg_new:nnn { schedule } { no-sessions-of-type }
  { No~sessions~of~type(s)~'#1'~found~in~the~schedule. \\
    Check~that~the~type~key(s)~match~those~passed~to~\defineSessionType. }

\msg_new:nnn { schedule } { session-not-found-for-assign }
  { Session~'#1'~not~found~in~the~database. \\
    Ensure~sessions~are~loaded~before~calling~\setSessionsData. }

\msg_new:nnn { schedule } { unknown-session-data-key }
  { Unknown~key~'#1'~passed~to~\setSessionsData. \\
    Valid~keys:~location~(loc),~color~(colour,~clr),~label~(lbl). }

\msg_new:nnn { session } { empty-participant-name }
  { A~talk,~organiser,~or~\addParticipant~entry~supplied~an~empty~name.~
    The~entry~has~been~ignored. }

\msg_new:nnn { session } { cancel-outside-hook }
  { \cancelTalk~may~only~appear~in~the~optional~hook~argument~of~
    the~talk~environment~(before~the~abstract~body). }

\msg_new:nnn { session } { organizer-outside-session }
  { \addSessionOrganizer~may~only~appear~while~a~session~is~open,~
    i.e.~inside~the~session~environment's~optional~setup~argument. }

\msg_new:nnn { session } { chair-outside-session }
  { \setSessionChair~may~only~appear~while~a~session~is~open,~
    i.e.~inside~the~session~environment's~optional~setup~argument. }

\msg_new:nnn { session } { missing-talk-outside-session }
  { \missingTalk~may~only~appear~inside~a~session~context.~
    It~is~normally~called~automatically~by~the~Lua~processor. }

\msg_new:nnn { schedule } { slot-not-found }
  { No~scheduled~slot~found~for~'#1'. \\
    Check~that~\renderSessions~or~\renderTalks~has~been~called~
    and~that~the~item~was~placed~in~a~schedule. }
%    \end{macrocode}
%
% \subsubsection{Cancellation commands}
%
% \begin{macro}{\cancelTalk}
% Writes the \texttt{cancelled} field into \cs{l\_sched\_talk\_prop}
% while it is live (called from the talk hook argument, inside
% \cs{talk\_store:nnnnnnnn}).
% \end{macro}
%
% \begin{macro}{\removeParticipant}
% Sets a \texttt{removed} flag on the participant record so that
% \cs{printParticipants} silently skips them.  The participant remains
% in the database, so their page references in session and talk listings
% are unaffected.  Issues a warning if the key is not found.
% \end{macro}
%
% \begin{macro}{\cancelledTalkFormat}
% User-overridable strikethrough hook; default uses \cs{sout}.
% \end{macro}
%
%    \begin{macrocode}
\NewDocumentCommand{\cancelTalk}{}
{
  \bool_if:NF \g_sched_in_talk_hook_bool
    { \msg_error:nn { session } { cancel-outside-hook } }
  \prop_put:Nnn \l_sched_talk_prop { cancelled } { true }
}

\NewDocumentCommand{\removeParticipant}{m}
{
  \tl_if_blank:nF {#1}
  {
    \tl_set:Ne \l_sched_tmpa_tl { \sched_key_normalize:n {#1} }
    \prop_get:NVN \g_participant_info_prop \l_sched_tmpa_tl \l_sched_participant_prop
    \tl_if_eq:NNT \l_sched_participant_prop \q_no_value
      { \msg_warning:nnV { session } { participant-not-found } \l_sched_tmpa_tl }
    \tl_if_eq:NNF \l_sched_participant_prop \q_no_value
    {
      \prop_put:Nnn \l_sched_participant_prop { removed } { true }
      \prop_gput:NVV \g_participant_info_prop \l_sched_tmpa_tl \l_sched_participant_prop
    }
  }
}

\NewDocumentCommand{\cancelledTalkFormat}{m}{\sout{#1}}
%    \end{macrocode}
%
% \subsubsection{General helpers}
%
% \cs{prop\_get\_ne:NnN} is like \cs{prop\_get:NnN} but stores an
% empty token list (not \cs{q\_no\_value}) on a miss, avoiding
% repetitive sentinel checks at call sites.
%
% \cs{sched\_session\_color:NNN} resolves a session prop to its
% background colour and display label, falling back to \texttt{white}
% and the raw type key when the type has not been registered.
%
%    \begin{macrocode}
\cs_generate_variant:Nn \prop_if_in:NnTF { NV }
\cs_generate_variant:Nn \str_compare:nNnTF { eNe }
\cs_generate_variant:Nn \str_casefold:n { e }
\cs_generate_variant:Nn \str_lowercase:n { e }

\cs_new_protected:Npn \prop_get_ne:NnN #1 #2 #3
{
  \prop_get:NnN #1 {#2} #3
  \tl_if_eq:NNT #3 \q_no_value { \tl_clear:N #3 }
}
\cs_generate_variant:Nn \prop_get_ne:NnN { NVN }

% Normalize a participant key: strip leading/trailing spaces and lowercase.
% Expandable so it may be used inside e-type arguments.
\cs_new:Npn \sched_key_normalize:n #1
  { \str_lowercase:e { \tl_trim_spaces:n {#1} } }
\cs_generate_variant:Nn \sched_key_normalize:n { e, V }

% Look up the original name string for a participant key.
% Leading and trailing spaces are stripped from the key before the lookup.
% Falls back to the trimmed key itself when the participant is absent from the database.
\cs_new_protected:Npn \sched_participant_name:nN #1 #2
{
  \tl_set:Ne \l_sched_tmpa_tl { \sched_key_normalize:n {#1} }
  \prop_get_ne:NVN \g_participant_info_prop \l_sched_tmpa_tl \l_sched_participant_prop
  \tl_if_empty:NTF \l_sched_participant_prop
    {
      \msg_warning:nnn { session } { participant-not-found } {#1}
      \tl_set_eq:NN #2 \l_sched_tmpa_tl
    }
    {
      \prop_get_ne:NnN \l_sched_participant_prop { name } #2
      \tl_if_empty:NT #2 { \tl_set_eq:NN #2 \l_sched_tmpa_tl }
    }
}
\cs_generate_variant:Nn \sched_participant_name:nN { eN }

\cs_new_protected:Npn \sched_colored_subsection:nnn #1 #2 #3
{
  \subsection*{%
    {\normalfont\small
    \colorbox{#1}%
      { \parbox{\dimexpr\hsize - 2\fboxsep\relax}{\hfill#2} }}%
    \newline
    #3%
  }%
}
\cs_generate_variant:Nn \sched_colored_subsection:nnn { Vnn }

% \cs{sched\_colored\_subsection:nnn} typesets a \cs{subsection*} whose title
% argument begins with a full-width coloured slot/location bar (built from
% arguments~|#1| and~|#2|) followed by a \cs{newline} and the actual title
% text~|#3|.  Embedding both in a single \cs{subsection*} call prevents any
% page break or extra vertical space between the bar and the title.
%
% fields that were written into the session prop at creation time (by
% \cs{sched\_session\_copy\_type\_defaults:} called from \cs{openSession}
% and \cs{setDefaultSessionType}).  Falls back to \texttt{white} and the
% raw type key so that sessions with an unregistered type still render.
\cs_new_protected:Npn \sched_session_color:NNN #1 #2 #3
{
  \prop_get_ne:NnN #1 { color } #2
  \tl_if_empty:NT #2 { \tl_set:Nn #2 { white } }
  \prop_get_ne:NnN #1 { label } #3
  \tl_if_empty:NT #3
  {
    \prop_get_ne:NnN #1 { type } #3
    \tl_if_empty:NT #3 { \tl_set:Nn #3 { UNKNOWN } }
  }
}

\prg_new_protected_conditional:Npnn \sched_type_matches:nn #1#2 { T, F, TF }
{
  \clist_if_in:nnTF {#2} {#1}
    { \prg_return_true: }
    { \prg_return_false: }
}
\cs_generate_variant:Nn \sched_type_matches:nnTF { Vn }
\cs_generate_variant:Nn \sched_type_matches:nnT  { Vn  }
%    \end{macrocode}
%
% \subsubsection{Schedule helpers}
%
% \cs{sched\_get\_session:nNTF} retrieves a session prop by id,
% issuing an error and taking the false branch when the id is unknown.
%
% \cs{sched\_record\_talk:nnn} appends a talk record to the global
% schedule order sequence; first placement wins and duplicates are
% silently ignored.
%
% \cs{sched\_maybe\_cancel:NnN} is the single site for the
% cancelled/normal formatting decision.  It stores \meta{content}
% in \meta{output-tl} as-is, or wrapped in \cs{cancelledTalkFormat},
% depending on the cancelled flag tl.
%
%    \begin{macrocode}
\prg_new_protected_conditional:Npnn \sched_get_session:nN #1 #2 { T, F, TF }
{
  \prop_get:NnN \g_sessions_prop {#1} #2
  \tl_if_eq:NNTF #2 \q_no_value
    { \msg_error:nnn { schedule } { unknown-session } {#1}
      \prg_return_false: }
    { \prg_return_true: }
}

\cs_new_protected:Npn \sched_get_nth_talk:NnN #1 #2 #3
{
  \prop_clear:N #3
  \seq_map_indexed_inline:Nn #1
  {
    \int_compare:nNnT { ##1 } = { #2 }
      { \tl_set:Nn #3 { ##2 } \seq_map_break: }
  }
}
\cs_generate_variant:Nn \sched_get_nth_talk:NnN { NVN }

\cs_new_protected:Npn \sched_record_talk:nnn #1 #2 #3
{
  \prop_if_in:NnF \g_sched_talk_slots_prop {#1@#2}
  {
    \prop_gput:Nnn \g_sched_talk_slots_prop {#1@#2} {#3}
    \prop_clear:N \l_sched_record_prop
    \prop_put:Nnn \l_sched_record_prop { session } {#1}
    \prop_put:Nnn \l_sched_record_prop { index   } {#2}
    \prop_put:Nnn \l_sched_record_prop { slot    } {#3}
    \seq_gput_right:NV \g_schedule_talk_order_seq \l_sched_record_prop
  }
}
\cs_generate_variant:Nn \sched_record_talk:nnn { nne, nee }

\cs_new_protected:Npn \sched_maybe_cancel:NnN #1 #2 #3
{
  \tl_if_empty:NTF #1
    { \tl_set:Nn #3 {#2} }
    { \tl_set:Nn #3 { \cancelledTalkFormat{#2} } }
}
\cs_generate_variant:Nn \sched_maybe_cancel:NnN { NeN }
%    \end{macrocode}
%
% \subsubsection{Participant database}
%
% Participant names are normalised to a canonical key of the form
% \enquote{Lastname,~Firstname} by \cs{participant\_name\_to\_key:nN},
% which accepts both \enquote{First Last} (space-separated, last word
% is the last name) and \enquote{Last, First} (comma-separated) input.
% Tildes in space-form names are treated as spaces.
%
% \cs{participant\_ensure:nnn} is idempotent: on a repeat encounter
% it back-fills blank email or affiliation but does not overwrite
% existing data.
%
%    \begin{macrocode}
\cs_new_protected:Npn \sched_append_to_prop_clist:Nnn #1 #2 #3
{
  \prop_get_ne:NnN #1 {#2} \l_sched_tmpa_tl
  \tl_if_empty:NTF \l_sched_tmpa_tl
    { \tl_set:Nn  \l_sched_tmpa_tl {#3} }
    { \tl_put_right:Nn \l_sched_tmpa_tl { ,#3 } }
  \prop_gput:NnV #1 {#2} \l_sched_tmpa_tl
}
\cs_generate_variant:Nn \sched_append_to_prop_clist:Nnn { NnV, NVn, NVV }

% Like \sched_append_to_prop_clist:Nnn but silently skips if the value is
% already present, preventing double-counting when render commands are called
% more than once with overlapping type lists.
\cs_new_protected:Npn \sched_append_unique_to_prop_clist:Nnn #1 #2 #3
{
  \prop_get_ne:NnN #1 {#2} \l_sched_tmpa_tl
  \tl_if_empty:NTF \l_sched_tmpa_tl
    { \prop_gput:Nnn #1 {#2} {#3} }
    {
      \clist_if_in:NnF \l_sched_tmpa_tl {#3}
      {
        \tl_put_right:Nn \l_sched_tmpa_tl { ,#3 }
        \prop_gput:NnV #1 {#2} \l_sched_tmpa_tl
      }
    }
}
\cs_generate_variant:Nn \sched_append_unique_to_prop_clist:Nnn { NnV, NVn, NVV }

\cs_new_protected:Npn \participant_split_name:nNN #1 #2 #3
{
  \tl_if_in:nnTF {#1} {,}
  {
    \seq_set_split:Nnn \l_sched_tmpa_seq {,} {#1}
    \tl_set:Ne #2 { \seq_item:Nn \l_sched_tmpa_seq {1} }
    \tl_trim_spaces:N #2
    \tl_set:Ne #3 { \seq_item:Nn \l_sched_tmpa_seq {2} }
    \tl_trim_spaces:N #3
  }
  {
    \tl_set:Nn \l_sched_tmpb_tl {#1}
    \regex_replace_all:nnN { \~ } { \x{20} } \l_sched_tmpb_tl
    \seq_set_split:NnV \l_sched_tmpa_seq { ~ } \l_sched_tmpb_tl
    \seq_remove_all:Nn \l_sched_tmpa_seq {}
    \tl_set:Ne #2 { \seq_item:Nn \l_sched_tmpa_seq { -1 } }
    \tl_clear:N #3
    \seq_map_indexed_inline:Nn \l_sched_tmpa_seq
    {
      \int_compare:nNnT {##1} < { \seq_count:N \l_sched_tmpa_seq }
      {
        \tl_if_empty:NTF #3
          { \tl_set:Nn  #3 {##2} }
          { \tl_put_right:Nn #3 { ~##2 } }
      }
    }
  }
}

\cs_new_protected:Npn \participant_name_to_key:nN #1 #2
{
  \participant_split_name:nNN {#1} \l_sched_tmpb_tl \l_sched_tmpc_tl
  \tl_if_empty:NTF \l_sched_tmpc_tl
    { \tl_set_eq:NN #2 \l_sched_tmpb_tl }
    { \tl_set:Ne #2
        { \tl_use:N \l_sched_tmpb_tl ,~ \tl_use:N \l_sched_tmpc_tl } }
}

\cs_new_protected:Npn \participant_ensure:nnn #1 #2 #3
{
  \tl_if_blank:nF {#1}
  {
    \participant_name_to_key:nN {#1} \l_sched_tmpa_tl
    \tl_if_blank:nTF {#2}
      { \tl_set_eq:NN \l_sched_participant_key_tl \l_sched_tmpa_tl }
      { \tl_set:Ne    \l_sched_participant_key_tl { \sched_key_normalize:n {#2} } }
    \prop_if_in:NVTF \g_participant_info_prop \l_sched_participant_key_tl
    {
      \prop_get:NVN \g_participant_info_prop \l_sched_participant_key_tl \l_sched_participant_prop
      \prop_get_ne:NnN \l_sched_participant_prop { email } \l_sched_tmpb_tl
      \tl_if_empty:NT \l_sched_tmpb_tl
        { \prop_put:Nnn \l_sched_participant_prop { email } {#2} }
      \prop_get_ne:NnN \l_sched_participant_prop { affil } \l_sched_tmpb_tl
      \tl_if_empty:NT \l_sched_tmpb_tl
        { \prop_put:Nnn \l_sched_participant_prop { affil } {#3} }
      \prop_gput:NVV \g_participant_info_prop \l_sched_participant_key_tl \l_sched_participant_prop
    }
    {
      % New participant: a single prop_gput registers the key implicitly
      \prop_clear:N \l_sched_participant_prop
      \prop_put:Nnn \l_sched_participant_prop { name    } {#1}
      \prop_put:NnV \l_sched_participant_prop { display } \l_sched_tmpa_tl
      \prop_put:Nnn \l_sched_participant_prop { email   } {#2}
      \prop_put:Nnn \l_sched_participant_prop { affil   } {#3}
      \prop_gput:NVV \g_participant_info_prop \l_sched_participant_key_tl \l_sched_participant_prop
    }
  }
}

%    \end{macrocode}
%
% \subsubsection{Talk and session storage}
%
% \cs{talk\_store:nnnnnnnn} builds \cs{l\_sched\_talk\_prop},
% executes the hook argument~|#8| (where \cs{cancelTalk} may write
% the \texttt{cancelled} field), registers the speaker in the
% participant database via \cs{participant\_ensure:nnn} and stores
% their key in the \texttt{speakerkey} field of the talk prop
% (rather than duplicating the speaker's data), then pushes the prop
% to the appropriate accumulator sequence.
%
% \cs{session\_end:} finalises the current session accumulator and
% stores it in the global sessions database under its id.
%
%    \begin{macrocode}
\cs_new_protected:Npn \talk_store:nnnnnnnn #1#2#3#4#5#6#7#8
{
  \prop_clear:N \l_sched_talk_prop
  \prop_put:Nnn \l_sched_talk_prop { title     } {#1}
  \prop_put:Nnn \l_sched_talk_prop { coauthors } {#5}
  \prop_put:Nnn \l_sched_talk_prop { special   } {#6}
  \tl_set:Ne    \l_sched_tmpa_tl   { \currentFilepath }
  \prop_put:NnV \l_sched_talk_prop { filepath  } \l_sched_tmpa_tl
  \bool_gset_true:N  \g_sched_in_talk_hook_bool
  #8
  \bool_gset_false:N \g_sched_in_talk_hook_bool
  \tl_if_empty:NF \g_current_session_id_tl
  {
    \participant_ensure:nnn {#2} {#4} {#3}
    \prop_put:NnV \l_sched_talk_prop { speakerkey } \l_sched_participant_key_tl
    \tl_set:Ne \l_sched_tmpa_tl
      { \g_current_session_id_tl @ \int_eval:n { \seq_count:N \g_session_talks_seq + 1 } }
    \prop_gput:NVn \g_talk_titles_prop \l_sched_tmpa_tl {#1}
  }
  \tl_if_empty:NTF \g_current_session_id_tl
    { \seq_gput_right:NV \g_orphan_talks_seq  \l_sched_talk_prop }
    { \seq_gput_right:NV \g_session_talks_seq \l_sched_talk_prop }
}

\cs_new_protected:Npn \session_end:
{
  \tl_if_empty:NTF \g_current_session_id_tl
    { \msg_warning:nn { session } { no-open-session } }
    {
      \prop_gput:NnV \g_session_prop { talks      } \g_session_talks_seq
      \prop_gput:NnV \g_session_prop { organizers } \g_session_organizers_seq
      \prop_gput:NVV \g_sessions_prop \g_current_session_id_tl \g_session_prop
      \tl_gclear:N   \g_current_session_id_tl
    }
}

\cs_new_protected:Npn \session_add_organizer:nnn #1#2#3
{
  \participant_ensure:nnn {#1} {#3} {#2}
  % \l_sched_participant_key_tl now holds the key; append it to the accumulator.
  \seq_gput_right:NV \g_session_organizers_seq \l_sched_participant_key_tl
}
% \cs{sched\_session\_copy\_type\_defaults:} copies the colour and label
% registered for the current session's type into \cs{g\_session\_prop}.
% Called from \cs{openSession} and \cs{setDefaultSessionType} so that the
% session prop always carries its own resolved colour and label.
% If the type has not been registered the fields are left blank and
% \cs{sched\_session\_color:NNN} will fall back to safe defaults at render
% time.
\cs_new_protected:Npn \sched_session_copy_type_defaults:
{
  \prop_get_ne:NnN \g_session_prop { type } \l_sched_tmpa_tl
  \prop_get_ne:NVN \g_session_type_colors_prop \l_sched_tmpa_tl \l_sched_tmpb_tl
  \tl_if_empty:NF \l_sched_tmpb_tl
    { \prop_gput:NnV \g_session_prop { color } \l_sched_tmpb_tl }
  \prop_get_ne:NVN \g_session_type_labels_prop \l_sched_tmpa_tl \l_sched_tmpb_tl
  \tl_if_empty:NF \l_sched_tmpb_tl
    { \prop_gput:NnV \g_session_prop { label } \l_sched_tmpb_tl }
}

%    \end{macrocode}
%
% \subsubsection{User-facing commands}
%
% \begin{macro}{\defineSessionType,\setDefaultSessionType}
% \begin{macro}{\setSessionsData}
% \begin{macro}{\setInputFilepath}
% \begin{macro}{\openSession,\closeSession}
% \begin{macro}{session,talk,extrainfo}
% \begin{macro}{\addSessionOrganizer,\setSessionChair,\addSessionTalk}
% \begin{macro}{\addParticipant}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
%
%    \begin{macrocode}
\NewDocumentCommand{\defineSessionType}{mmm}
{
  \prop_gput:Nnn \g_session_type_labels_prop {#1} {#2}
  \prop_gput:Nnn \g_session_type_colors_prop {#1} {#3}
}

\NewDocumentCommand{\setDefaultSessionType}{m}
{
  \def\currentSessionType{#1}
}

\NewDocumentCommand{\setInputFilepath}{m}
  { \def\currentFilepath{#1} }

% Key family for \setSessionsData: canonical keys plus aliases.
% The handlers write into \l_sched_session_prop, which \setSessionsData
% reads back from \g_sessions_prop before calling \keys_set:nn and
% writes back afterwards.
\keys_define:nn { confschedule / session-data }
{
  location .code:n = { \prop_put:Nnn \l_sched_session_prop { location } {#1} } ,
  loc      .meta:n = { location = {#1} } ,
  color    .code:n = { \prop_put:Nnn \l_sched_session_prop { color    } {#1} } ,
  colour   .meta:n = { color = {#1} } ,
  clr      .meta:n = { color = {#1} } ,
  label    .code:n = { \prop_put:Nnn \l_sched_session_prop { label    } {#1} } ,
  lbl      .meta:n = { label = {#1} } ,
  unknown  .code:n =
    { \msg_error:nnV { schedule } { unknown-session-data-key } \l_keys_key_tl } ,
}

\NewDocumentCommand{\setSessionsData}{mm}
{
  \clist_map_inline:nn {#1}
  {
    \prop_get:NnN \g_sessions_prop {##1} \l_sched_session_prop
    \tl_if_eq:NNT \l_sched_session_prop \q_no_value
      { \msg_warning:nnn { schedule } { session-not-found-for-assign } {##1} }
    \tl_if_eq:NNF \l_sched_session_prop \q_no_value
    {
      \keys_set:nn { confschedule / session-data } {#2}
      \prop_gput:NnV \g_sessions_prop {##1} \l_sched_session_prop
    }
  }
}

\NewDocumentCommand{\openSession}{mm}
{
  \tl_if_empty:NF \g_current_session_id_tl { \session_end: }
  \tl_gset:Nn  \g_current_session_id_tl {#1}
  \seq_gclear:N \g_session_organizers_seq
  \seq_gclear:N \g_session_talks_seq
  \prop_gclear:N \g_session_prop
  \prop_gput:NnV \g_session_prop { type  } \currentSessionType
  \sched_session_copy_type_defaults:
}

\NewDocumentCommand{\closeSession}{} { \session_end: }

\NewDocumentEnvironment{talk}{mmmmmmO{}+b}
  {}
  {
    \bool_if:NTF \g_sched_render_body_bool
      { #8 }
      { \talk_store:nnnnnnnn {#1}{#2}{#3}{#4}{#5}{#6}{}{#7} }
  }

%<*new-session>
\NewDocumentEnvironment{session}{m m m m O{} +b}
{
  \bool_if:NTF \g_sched_render_body_bool
  { #6 }
  {
    \prop_gput:Nnn \g_session_prop { title } {#1}
    \tl_set:Ne    \l_sched_tmpa_tl { \currentFilepath }
    \prop_gput:NnV \g_session_prop { filepath } \l_sched_tmpa_tl
    \session_add_organizer:nnn {#2}{#3}{#4}
    \prop_gput:NnV \g_session_prop { chair } \l_sched_participant_key_tl
    #5
  }
}
{}
%</new-session>
%<*old-session>
\NewDocumentEnvironment{session}{m m m m m m m O{} +b}
{
  \bool_if:NTF \g_sched_render_body_bool
  { #9 }
  {
    \prop_gput:Nnn \g_session_prop { title } {#1}
    \tl_set:Ne    \l_sched_tmpa_tl { \currentFilepath }
    \prop_gput:NnV \g_session_prop { filepath } \l_sched_tmpa_tl
    \session_add_organizer:nnn {#2}{#3}{#4}
    \prop_gput:NnV \g_session_prop { chair } \l_sched_participant_key_tl
    \tl_if_blank:nF {#6} { \session_add_organizer:nnn {#5}{#6}{#7} }
    #8
  }
}
{}
%</old-session>

\NewDocumentEnvironment{extrainfo}{+b} {}{}

\NewDocumentCommand{\addSessionOrganizer}{mmm}
{
  \tl_if_empty:NTF \g_current_session_id_tl
    { \msg_error:nn { session } { organizer-outside-session } }
    { \session_add_organizer:nnn {#1}{#2}{#3} }
}

\NewDocumentCommand{\setSessionChair}{m}
{
  \tl_if_empty:NTF \g_current_session_id_tl
    { \msg_error:nn { session } { chair-outside-session } }
    { \prop_gput:Nne \g_session_prop { chair } { \sched_key_normalize:n {#1} } }
}

%<*new-session>
\NewDocumentCommand{\addSessionTalk}{O{plenary}mmm}
{
  \setDefaultSessionType{#1}
  \setInputFilepath{#4}
  \openSession{#2}{}
  \begin{session}{}{}{}{}[\setSessionChair{#3}]
  \end{session}
  \input{#4}
  \closeSession
}
%</new-session>
%<*old-session>
\NewDocumentCommand{\addSessionTalk}{O{plenary}mmm}
{
  \setDefaultSessionType{#1}
  \setInputFilepath{#4}
  \openSession{#2}{}
  \begin{session}{}{}{}{}{}{}{}[\setSessionChair{#3}]
  \end{session}
  \input{#4}
  \closeSession
}
%</old-session>

\NewDocumentCommand{\addParticipant}{mmm}
{
  \tl_if_blank:nTF {#1}
    { \msg_warning:nnn { session } { empty-participant-name } {} }
    { \participant_ensure:nnn {#1} {#2} {#3} }
}
%    \end{macrocode}
%
% \subsubsection{Schedule table construction}
%
% \cs{sched\_session\_talk:nnn} builds one full-width table row.
% All token-list content is deferred into \cs{l\_sched\_rows\_out\_seq}
% via \cs{seq\_put\_right:Ne} so that variable values are captured at
% construction time, not at typeset time.
% \cs{sched\_maybe\_cancel:NeN} applies the formatting decision; the
% inline \cs{tl\_if\_empty:NT} eagerly resolves whether to emit a
% page reference during the \texttt{e}-expansion.
%
%    \begin{macrocode}
\cs_new_protected:Npn \sched_session_talk:nnn #1 #2 #3
{
  \sched_get_session:nNTF {#2} \l_sched_session_prop
  {
    \sched_session_color:NNN \l_sched_session_prop \l_sched_color_tl \l_sched_type_label_tl
    \prop_get_ne:NnN \l_sched_session_prop { talks } \l_sched_talks_tl
    \sched_get_nth_talk:NnN \l_sched_talks_tl { #3 } \l_sched_talk_prop
    \prop_get_ne:NnN \l_sched_talk_prop { title } \l_sched_title_tl
    \prop_if_in:NnF \g_sched_session_slots_prop {#2}
      { \prop_gput:Nne \g_sched_session_slots_prop {#2} { \l_sched_header_tl,~#1 } }
    \prop_get_ne:NnN \l_sched_session_prop { location } \l_sched_location_tl
    \tl_if_empty:NTF \l_sched_title_tl
    {
      \seq_put_right:Ne \l_sched_rows_out_seq
      {
        \exp_not:N\rowcolor{\l_sched_color_tl} #1
        & \exp_not:N\multicolumn{\l_sched_numcols_tl}{F}{} \\ \exp_not:N\hline
      }
    }
    {
      \prop_get_ne:NnN \l_sched_talk_prop    { speakerkey } \l_sched_tmpa_tl
      \sched_participant_name:eN
        { \tl_use:N \l_sched_tmpa_tl } \l_sched_speaker_tl
      \sched_participant_name:eN
        { \prop_item:Nn \l_sched_session_prop { chair } } \l_sched_chair_tl
      \sched_record_talk:nne {#2} {#3} { \l_sched_header_tl,~#1 }
      \prop_get_ne:NnN \l_sched_talk_prop { cancelled } \l_sched_tmpa_tl
      \sched_maybe_cancel:NeN \l_sched_tmpa_tl
        { \exp_not:N\textbf{\exp_not:N\textit{ \exp_not:V \l_sched_speaker_tl }} }
        \l_sched_fmt_speaker_tl
      \sched_maybe_cancel:NeN \l_sched_tmpa_tl
        { \exp_not:N\textbf{ \exp_not:V \l_sched_title_tl } }
        \l_sched_fmt_title_tl
      \seq_put_right:Ne \l_sched_rows_out_seq
      {
        \exp_not:N\rowcolor{\l_sched_color_tl} #1
        & \exp_not:N\multicolumn{\l_sched_numcols_tl}{F}
        {
          \exp_not:V \l_sched_location_tl \exp_not:N\par
          \exp_not:N\textbf{ \exp_not:V \l_sched_type_label_tl }~(#2)
          \exp_not:N\vspace{1mm}\exp_not:N\par
          \exp_not:V \l_sched_fmt_speaker_tl \qquad
          ``\exp_not:V \l_sched_fmt_title_tl''
          \tl_if_empty:NT \l_sched_tmpa_tl
          { \exp_not:N\quad \exp_not:N\blockPageref{talk:#2@#3} }
          \exp_not:N\vspace{1mm}\exp_not:N\par
          \qquad Chair:~\exp_not:N\textit{ \exp_not:V \l_sched_chair_tl }
        } \\ \exp_not:N\hline
      }
    }
  }
  {
    \seq_put_right:Ne \l_sched_rows_out_seq
    {
      \exp_not:N\rowcolor{white} #1
      & \exp_not:N\multicolumn{\l_sched_numcols_tl}{F}{} \\ \exp_not:N\hline
    }
  }
}

\NewDocumentCommand{\scheduleSessionTalk}{O{1}mm}
{
  \seq_if_in:NnF \g_schedule_sessions_seq {#3}
    { \seq_gput_right:Nn \g_schedule_sessions_seq {#3} }
  \sched_session_talk:nnn {#2} {#3} {#1}
}

\cs_new_protected:Npn \sched_conc_sessions:nnn #1 #2 #3
{
  \clist_set:Nn \l_sched_ids_clist    {#3}
  \clist_set:Nn \l_sched_labels_clist {#2}

  \tl_set:Nn \l_sched_row_out_tl { \cellcolor{clrScheduleEmpty} #1 }

  \clist_map_inline:Nn \l_sched_ids_clist
  {
    \sched_get_session:nNTF {##1} \l_sched_session_prop
    {
      \sched_session_color:NNN \l_sched_session_prop \l_sched_color_tl \l_sched_type_label_tl
      \prop_if_in:NnF \g_sched_session_slots_prop {##1}
        { \prop_gput:Nne \g_sched_session_slots_prop {##1} { \l_sched_header_tl,~#1 } }
      \prop_get_ne:NnN \l_sched_session_prop { location } \l_sched_location_tl
      \prop_get_ne:NnN \l_sched_session_prop { title } \l_sched_title_tl
      \sched_participant_name:eN
        { \prop_item:Nn \l_sched_session_prop { chair } } \l_sched_chair_tl
      \tl_put_right:Ne \l_sched_row_out_tl
      {
        & \exp_not:N\cellcolor{\l_sched_color_tl}
        \exp_not:V \l_sched_location_tl \exp_not:N\par
        \exp_not:N\textbf{ \exp_not:V \l_sched_type_label_tl }~(##1) \exp_not:N\par
        \tl_if_empty:NF \l_sched_title_tl
        {\exp_not:V \l_sched_title_tl
          \quad \exp_not:N\blockPageref{session:##1} \exp_not:N\par}
        Chair:~\exp_not:N\textit{ \exp_not:V \l_sched_chair_tl }
      }
    }
    { \tl_put_right:Nn \l_sched_row_out_tl { & } }
  }
  \tl_put_right:Nn \l_sched_row_out_tl { \\ \hline }
  \seq_put_right:NV \l_sched_rows_out_seq \l_sched_row_out_tl

  \int_zero:N \l_sched_talk_idx_int
  \bool_set_true:N \l_sched_row_odd_bool

  \clist_map_inline:Nn \l_sched_labels_clist
  {
    \int_incr:N \l_sched_talk_idx_int
    \bool_if:NTF \l_sched_row_odd_bool
      { \tl_set:Nn \l_sched_row_out_tl { \rowcolor{clrScheduleOdd}  ##1 }
        \bool_set_false:N \l_sched_row_odd_bool }
      { \tl_set:Nn \l_sched_row_out_tl { \rowcolor{clrScheduleEven} ##1 }
        \bool_set_true:N  \l_sched_row_odd_bool }

    \clist_map_inline:Nn \l_sched_ids_clist
    {
      \sched_get_session:nNTF {####1} \l_sched_session_prop
      {
        \prop_get_ne:NnN \l_sched_session_prop { talks } \l_sched_talks_tl
        \sched_get_nth_talk:NVN \l_sched_talks_tl \l_sched_talk_idx_int \l_sched_talk_prop
        \prop_get_ne:NnN \l_sched_talk_prop { title } \l_sched_title_tl
        \tl_if_empty:NTF \l_sched_title_tl
          { \tl_put_right:Nn \l_sched_row_out_tl { & } }
          {
            \prop_get_ne:NnN \l_sched_talk_prop { speakerkey } \l_sched_tmpa_tl
            \sched_participant_name:eN
              { \tl_use:N \l_sched_tmpa_tl } \l_sched_speaker_tl
            \prop_get_ne:NnN \l_sched_talk_prop { cancelled } \l_sched_tmpa_tl
            \sched_record_talk:nee {####1}
              { \int_use:N \l_sched_talk_idx_int }
              { \l_sched_header_tl,~##1 }
            \sched_maybe_cancel:NeN \l_sched_tmpa_tl
              { \exp_not:N\textit{ \exp_not:V \l_sched_speaker_tl } }
              \l_sched_fmt_speaker_tl
            \sched_maybe_cancel:NeN \l_sched_tmpa_tl
              { \exp_not:V \l_sched_title_tl }
              \l_sched_fmt_title_tl
            \tl_put_right:Ne \l_sched_row_out_tl
            {
              &
              \exp_not:V \l_sched_fmt_speaker_tl \exp_not:N\par
              \exp_not:V \l_sched_fmt_title_tl
              \tl_if_empty:NT \l_sched_tmpa_tl
                { \exp_not:N\quad \exp_not:N\blockPageref
                  {talk:####1@\int_use:N \l_sched_talk_idx_int} }
            }
          }
      }
      { \tl_put_right:Nn \l_sched_row_out_tl { & } }
    }
    \tl_put_right:Nn \l_sched_row_out_tl { \\ \hline }
    \seq_put_right:NV \l_sched_rows_out_seq \l_sched_row_out_tl
  }
}
\cs_generate_variant:Nn \sched_conc_sessions:nnn { eee }

\NewDocumentCommand{\scheduleSessions}{mmm}
{
  \clist_map_inline:nn {#3}
  {
    \seq_if_in:NnF \g_schedule_sessions_seq {##1}
      { \seq_gput_right:Nn \g_schedule_sessions_seq {##1} }
  }
  \sched_conc_sessions:eee {#1} {#2} {#3}
}

\NewDocumentCommand{\scheduleEvent}{mmm}{
  \seq_put_right:Ne \l_sched_rows_out_seq
    { \exp_not:N\rowcolor{#1} #2
      & \exp_not:N\multicolumn{\l_sched_numcols_tl}{F}{#3} \\ }
}

\NewDocumentEnvironment{schedule}{mm+b}
{
  \tl_set:Nn \l_sched_header_tl  {#2}
  \tl_set:Nn \l_sched_numcols_tl {#1}
  \seq_clear:N \l_sched_rows_out_seq
  \arrayrulecolor{white}
  #3
  \small
  \begin{tabularx}{\linewidth}{l*{\l_sched_numcols_tl}{|H}}
    & \multicolumn{#1}{F}{\cellcolor{white}\large\textbf{#2}} \\
    \seq_use:Nn \l_sched_rows_out_seq {}
  \end{tabularx}
}{}
%    \end{macrocode}
%
% \subsubsection{Query commands}
%
% The location and slot queries use \cs{l\_sched\_tmpa\_tl} for the
% result and issue an error on a miss.  The three counting commands
% use \cs{l\_sched\_tmpa\_int} as a local accumulator; \cs{talkCount}
% additionally retrieves each talk prop to check the \texttt{cancelled}
% field, skipping cancelled talks.
%
%    \begin{macrocode}
\NewDocumentCommand{\sessionLocation}{m}
{
  \sched_get_session:nNTF {#1} \l_sched_session_prop
  {
    \prop_get_ne:NnN \l_sched_session_prop { location } \l_sched_tmpa_tl
    \tl_if_empty:NTF \l_sched_tmpa_tl
      { \msg_error:nnn { schedule } { unknown-location } {#1} }
      { \tl_use:N \l_sched_tmpa_tl }
  }
  { }
}

\NewDocumentCommand{\sessionSlot}{m}
{
  \prop_get:NnN \g_sched_session_slots_prop {#1} \l_sched_tmpa_tl
  \tl_if_eq:NNT \l_sched_tmpa_tl \q_no_value
    { \msg_error:nnn { schedule } { session-not-scheduled } {#1} }
  \tl_use:N \l_sched_tmpa_tl
}

\NewDocumentCommand{\talkSlot}{m}
{
  \prop_get:NnN \g_sched_talk_slots_prop {#1} \l_sched_tmpa_tl
  \tl_if_eq:NNT \l_sched_tmpa_tl \q_no_value
    { \msg_error:nnn { schedule } { talk-not-scheduled } {#1} }
  \tl_use:N \l_sched_tmpa_tl
}

% \sessionCount{types}: count scheduled sessions matching type filter.
\cs_new_protected:Npn \sched_count_sessions:n #1
{
  \int_zero:N \l_sched_tmpa_int
  \seq_map_inline:Nn \g_schedule_sessions_seq
  {
    \sched_get_session:nNT {##1} \l_sched_session_prop
    {
      \prop_get_ne:NnN \l_sched_session_prop { type } \l_sched_tmpb_tl
      \sched_type_matches:VnT \l_sched_tmpb_tl {#1}
        { \int_incr:N \l_sched_tmpa_int }
    }
  }
  \int_use:N \l_sched_tmpa_int
}

% \talkCount{types}: count scheduled non-cancelled talks matching type filter.
\cs_new_protected:Npn \sched_count_talks:n #1
{
  \int_zero:N \l_sched_tmpa_int
  \seq_map_inline:Nn \g_schedule_talk_order_seq
  {
    \tl_set:Nn \l_sched_record_prop {##1}
    \prop_get_ne:NnN \l_sched_record_prop { session } \l_sched_session_id_tl
    \prop_get:NVN \g_sessions_prop \l_sched_session_id_tl \l_sched_session_prop
    \tl_if_eq:NNF \l_sched_session_prop \q_no_value
    {
      \prop_get_ne:NnN \l_sched_session_prop { type } \l_sched_tmpb_tl
      \sched_type_matches:VnT \l_sched_tmpb_tl {#1}
      {
        \prop_get_ne:NnN \l_sched_record_prop { index } \l_sched_tmpa_tl
        \prop_get_ne:NnN \l_sched_session_prop { talks } \l_sched_talks_tl
        \sched_get_nth_talk:NVN \l_sched_talks_tl \l_sched_tmpa_tl \l_sched_talk_prop
        \prop_get_ne:NnN \l_sched_talk_prop { cancelled } \l_sched_tmpc_tl
        \tl_if_empty:NT \l_sched_tmpc_tl
          { \int_incr:N \l_sched_tmpa_int }
      }
    }
  }
  \int_use:N \l_sched_tmpa_int
}

% \participantCount: count participants not marked as removed.
\cs_new_protected:Npn \sched_count_participants:
{
  \int_zero:N \l_sched_tmpa_int
  \prop_map_inline:Nn \g_participant_info_prop
  {
    \tl_set:Nn \l_sched_participant_prop {##2}
    \prop_get_ne:NnN \l_sched_participant_prop { removed } \l_sched_tmpb_tl
    \tl_if_empty:NT \l_sched_tmpb_tl
      { \int_incr:N \l_sched_tmpa_int }
  }
  \int_use:N \l_sched_tmpa_int
}

\NewDocumentCommand{\sessionCount}{m} { \sched_count_sessions:n {#1} }
\NewDocumentCommand{\talkCount}{m}    { \sched_count_talks:n {#1} }
\NewDocumentCommand{\participantCount}{} { \sched_count_participants: }
%    \end{macrocode}
%
% \subsubsection{Output commands}
%
% \cs{sched\_output\_session\_listing:Nn} renders one session:
% coloured slot bar and \cs{subsection*} title (combined via
% \cs{sched\_colored\_subsection:nnn}), organiser list,
% session description body (re-input with render mode active), and
% talk list.  Cancelled talks appear with strikethrough and no page
% reference.
%
% \cs{sched\_render\_talks:Nn} iterates \cs{g\_schedule\_talk\_order\_seq}
% in schedule order, filters by type, and renders each non-cancelled
% talk.  Argument~|#1| is a bool controlling whether the chair line
% is included (true for starred \cs{renderTalks}).
%
%    \begin{macrocode}
\cs_new_protected:Npn \sched_output_session_listing:Nn #1 #2
{
  \sched_session_color:NNN #1 \l_sched_color_tl \l_sched_type_label_tl

  \prop_get_ne:NnN \g_sched_session_slots_prop {#2} \l_sched_title_tl
  \prop_get_ne:NnN #1 { location } \l_sched_location_tl
  \sched_colored_subsection:Vnn \l_sched_color_tl
    {
      \tl_use:N \l_sched_title_tl
      \tl_if_empty:NF \l_sched_location_tl
        { ,\enskip \tl_use:N \l_sched_location_tl }
    }
    { \prop_item:Nn #1 { title } }
  \label{session:#2}

  \noindent\textbf{Organizers:}\par\medskip
  \prop_get_ne:NnN #1 { organizers } \l_sched_tmpa_tl
  \seq_map_inline:Nn \l_sched_tmpa_tl
  {
    % ##1 is a participant key; look up all display data from the participant DB.
    \prop_get:NnN \g_participant_info_prop {##1} \l_sched_participant_prop
    \tl_if_eq:NNT \l_sched_participant_prop \q_no_value
      { \msg_warning:nnn { session } { participant-not-found } {##1} }
    \tl_if_eq:NNF \l_sched_participant_prop \q_no_value
    {
      \prop_get_ne:NnN \l_sched_participant_prop { name  } \l_sched_tmpb_tl
      \noindent\textit{ \tl_use:N \l_sched_tmpb_tl }\par
      \prop_get_ne:NnN \l_sched_participant_prop { affil } \l_sched_tmpb_tl
      \tl_if_empty:NF \l_sched_tmpb_tl { \noindent \tl_use:N \l_sched_tmpb_tl \par }
      \prop_get_ne:NnN \l_sched_participant_prop { email } \l_sched_tmpb_tl
      \tl_if_empty:NF \l_sched_tmpb_tl
        { \noindent{\ttfamily \tl_use:N \l_sched_tmpb_tl}\par }
      \sched_append_unique_to_prop_clist:Nnn
        \g_participant_sessions_prop {##1} {#2}
    }
    \smallskip
  }
  \medskip

  \prop_get_ne:NnN #1 { filepath } \l_sched_tmpa_tl
  \tl_if_empty:NF \l_sched_tmpa_tl
  {
    \noindent\textbf{Session~Description:}\par
    \bool_gset_true:N  \g_sched_render_body_bool
    \filename@parse{\l_sched_tmpa_tl}
    \begingroup\edef\x{\noexpand\graphicspath{{\filename@area}}}\expandafter\endgroup\x
    \file_input:V \l_sched_tmpa_tl
    \bool_gset_false:N \g_sched_render_body_bool
    \medskip
  }

  \prop_get_ne:NnN #1 { talks } \l_sched_tmpa_tl
  \seq_map_indexed_inline:Nn \l_sched_tmpa_tl
  {
    \tl_set:Nn \l_sched_talk_prop {##2}
    \prop_get_ne:NnN \l_sched_talk_prop { cancelled } \l_sched_tmpb_tl
    \prop_get_ne:NnN \l_sched_talk_prop { speakerkey } \l_sched_tmpa_tl
    \sched_participant_name:eN { \tl_use:N \l_sched_tmpa_tl } \l_sched_tmpa_tl
    \tl_if_empty:NTF \l_sched_tmpb_tl
    {
      \noindent\textit{ \tl_use:N \l_sched_tmpa_tl },~
      ~``\prop_item:Nn \l_sched_talk_prop { title }''
      \fillPageref{talk:#2@##1}\par
    }
    {
      \noindent\cancelledTalkFormat{
        \textit{ \tl_use:N \l_sched_tmpa_tl },~
        ``\prop_item:Nn \l_sched_talk_prop { title }''
      }\par
    }
    \smallskip
  }
  \bigskip
}

\cs_new_protected:Npn \sched_list_sessions_by_type:n #1
{
  \bool_set_false:N \l_sched_tmpa_bool
  \seq_map_inline:Nn \g_schedule_sessions_seq
  {
    \sched_get_session:nNT {##1} \l_sched_session_prop
    {
      \prop_get_ne:NnN \l_sched_session_prop { type } \l_sched_tmpb_tl
      \sched_type_matches:VnT \l_sched_tmpb_tl {#1}
      {
        \bool_set_true:N \l_sched_tmpa_bool
        \sched_output_session_listing:Nn \l_sched_session_prop {##1}
      }
    }
  }
  \bool_if:NF \l_sched_tmpa_bool
  { \msg_warning:nnn { schedule } { no-sessions-of-type } {#1} }
}

\NewDocumentCommand{\renderSessions}{m}
  { \sched_list_sessions_by_type:n {#1} }

\cs_new_protected:Npn \sched_render_talks:Nn #1 #2
{
  \seq_map_inline:Nn \g_schedule_talk_order_seq
  {
    \tl_set:Nn \l_sched_record_prop {##1}
    \prop_get_ne:NnN \l_sched_record_prop { session } \l_sched_session_id_tl
    \prop_get:NVN \g_sessions_prop \l_sched_session_id_tl \l_sched_session_prop
    \tl_if_eq:NNT \l_sched_session_prop \q_no_value
      { \msg_warning:nnV { schedule } { render-missing-session } \l_sched_session_id_tl }
    \tl_if_eq:NNF \l_sched_session_prop \q_no_value
    {
      \prop_get_ne:NnN \l_sched_session_prop { type } \l_sched_tmpc_tl
      \sched_type_matches:VnT \l_sched_tmpc_tl {#2}
      {
        \prop_get_ne:NnN \l_sched_record_prop { slot    } \l_sched_tmpb_tl
        \sched_session_color:NNN \l_sched_session_prop \l_sched_color_tl \l_sched_type_label_tl
        \prop_get_ne:NnN \l_sched_session_prop { talks } \l_sched_talks_tl

        \prop_get_ne:NnN \l_sched_record_prop { index   } \l_sched_tmpa_tl
        \sched_get_nth_talk:NVN \l_sched_talks_tl \l_sched_tmpa_tl \l_sched_talk_prop
        \prop_get_ne:NnN \l_sched_talk_prop { title } \l_sched_title_tl

        \tl_if_empty:NF \l_sched_title_tl
        {
          \prop_get_ne:NnN \l_sched_talk_prop { cancelled } \l_sched_tmpc_tl
          \tl_if_empty:NT \l_sched_tmpc_tl
          {
          \prop_get_ne:NnN \l_sched_session_prop { location } \l_sched_location_tl
          \sched_colored_subsection:Vnn \l_sched_color_tl
          {
            \tl_use:N \l_sched_tmpb_tl
            \tl_if_empty:NF \l_sched_location_tl
            { ,\enskip \tl_use:N \l_sched_location_tl }
          }
          { \tl_use:N \l_sched_title_tl }
          \label{talk:\tl_use:N \l_sched_session_id_tl @\tl_use:N \l_sched_tmpa_tl}

          % Use the stored speaker key directly for participant tracking.
          \prop_get_ne:NnN \l_sched_talk_prop { speakerkey } \l_sched_participant_key_tl
          \tl_if_empty:NF \l_sched_participant_key_tl
          {
            \tl_set:Ne \l_sched_tmpc_tl
              { \tl_use:N \l_sched_session_id_tl @ \tl_use:N \l_sched_tmpa_tl }
            \sched_append_unique_to_prop_clist:NVV
              \g_participant_talks_prop \l_sched_participant_key_tl \l_sched_tmpc_tl
          }

          \prop_get_ne:NnN \l_sched_session_prop { title } \l_sched_tmpc_tl
          \tl_if_empty:NF \l_sched_tmpc_tl
          {
            \noindent\textit{Session:~\tl_use:N \l_sched_tmpc_tl}
            \quad \fillPageref{session:\tl_use:N \l_sched_session_id_tl}
            \par
          }

          \bool_if:NT #1
          {
            \sched_participant_name:eN
              { \prop_item:Nn \l_sched_session_prop { chair } } \l_sched_chair_tl
            \tl_if_empty:NF \l_sched_chair_tl
              { \noindent\textit{Chair:~\tl_use:N \l_sched_chair_tl}\par }
          }

          % Look up all speaker display data from the participant database.
          \prop_get:NVN \g_participant_info_prop \l_sched_participant_key_tl
            \l_sched_participant_prop
          \tl_if_eq:NNT \l_sched_participant_prop \q_no_value
            { \msg_warning:nnV { session } { participant-not-found }
                \l_sched_participant_key_tl }
          \tl_if_eq:NNF \l_sched_participant_prop \q_no_value
          {
          \prop_get_ne:NnN \l_sched_participant_prop { name  } \l_sched_speaker_tl
          \prop_get_ne:NnN \l_sched_participant_prop { affil } \l_sched_tmpa_tl
          \prop_get_ne:NnN \l_sched_participant_prop { email } \l_sched_tmpb_tl
          \prop_get_ne:NnN \l_sched_talk_prop { coauthors    } \l_sched_tmpc_tl
          \noindent \tl_use:N \l_sched_speaker_tl \par
          \tl_if_empty:NF \l_sched_tmpa_tl
          { \noindent \tl_use:N \l_sched_tmpa_tl \par }
          \tl_if_empty:NF \l_sched_tmpb_tl
          { \noindent\nolinkurl{ \tl_use:N \l_sched_tmpb_tl } \par }
          \tl_if_empty:NF \l_sched_tmpc_tl
          { \noindent\textit{Coauthor(s):~\tl_use:N \l_sched_tmpc_tl} \par }
          }

          \medskip
          \prop_get_ne:NnN \l_sched_talk_prop { filepath } \l_sched_title_tl
          \bool_gset_true:N  \g_sched_render_body_bool
          \filename@parse{\l_sched_title_tl}
          \begingroup\edef\x{\noexpand\graphicspath{{\filename@area}}}\expandafter\endgroup\x
          \file_input:V \l_sched_title_tl
          \bool_gset_false:N \g_sched_render_body_bool
          \bigskip
          }
        }
      }
    }
  }
}

\NewDocumentCommand{\renderTalks}{s m}
{
  \IfBooleanTF {#1}
    { \sched_render_talks:Nn \c_true_bool  {#2} }
    { \sched_render_talks:Nn \c_false_bool {#2} }
}

% \cs{sched\_build\_sorted\_participant\_list:} populates
% \cs{g\_participant\_display\_prop} and
% \cs{l\_sched\_sorted\_participants\_seq} from the participant
% database, skipping removed entries and sorting case-insensitively
% by display name.  Called by both \cs{sched\_print\_participants:}
% and \cs{sched\_print\_participant\_slots:n}.
\cs_new_protected:Npn \sched_build_sorted_participant_list:
{
  \prop_gclear:N \g_participant_display_prop
  \seq_clear:N   \l_sched_sorted_participants_seq
  \prop_map_inline:Nn \g_participant_info_prop
  {
    \tl_set:Nn \l_sched_participant_prop {##2}
    \prop_get_ne:NnN \l_sched_participant_prop { removed } \l_sched_tmpb_tl
    \tl_if_empty:NT \l_sched_tmpb_tl
    {
      \prop_get_ne:NnN \l_sched_participant_prop { display } \l_sched_tmpa_tl
      \prop_gput:NnV \g_participant_display_prop {##1} \l_sched_tmpa_tl
      \seq_put_right:Nn \l_sched_sorted_participants_seq {##1}
    }
  }
  \seq_sort:Nn \l_sched_sorted_participants_seq
  {
    \str_compare:eNeTF
      { \str_casefold:e { \prop_item:Nn \g_participant_display_prop {##1} } }
      >
      { \str_casefold:e { \prop_item:Nn \g_participant_display_prop {##2} } }
      { \sort_return_swapped: }
      { \sort_return_same: }
  }
}

% \cs{sched\_print\_participants:Nn} is the single implementation behind
% \cs{printParticipants}.  Argument~|#1| is a bool: true adds slot strings
% below the page references (starred form).  Argument~|#2| is the minimum
% engagement count; participants below the threshold are silently skipped.
% In the starred form, each slot line shows the session title in quotes,
% an inline page reference, and the slot string.
% Session lines are labelled ``Organizer:'' and talk lines ``Speaker:''.
% A warning is issued for any item whose slot cannot be resolved.
\cs_new_protected:Npn \sched_print_participants:Nn #1 #2
{
  \sched_build_sorted_participant_list:
  \begin{multicols}{2}
  \seq_map_inline:Nn \l_sched_sorted_participants_seq
  {
    % Fetch engagement lists and test against the minimum threshold.
    \prop_get_ne:NnN \g_participant_sessions_prop {##1} \l_sched_tmpb_tl
    \prop_get_ne:NnN \g_participant_talks_prop    {##1} \l_sched_tmpc_tl
    \int_zero:N \l_sched_tmpa_int
    \tl_if_empty:NF \l_sched_tmpb_tl
      { \int_add:Nn \l_sched_tmpa_int { \exp_args:NV \clist_count:n \l_sched_tmpb_tl } }
    \tl_if_empty:NF \l_sched_tmpc_tl
      { \int_add:Nn \l_sched_tmpa_int { \exp_args:NV \clist_count:n \l_sched_tmpc_tl } }
    \int_compare:nT { \l_sched_tmpa_int >= #2 }
    {
      \prop_get:NnN \g_participant_info_prop {##1} \l_sched_participant_prop
      \noindent\begin{minipage}{\linewidth}
      \prop_get_ne:NnN \l_sched_participant_prop { display } \l_sched_tmpa_tl
      \noindent\textbf{ \tl_use:N \l_sched_tmpa_tl }\par
      \prop_get_ne:NnN \l_sched_participant_prop { affil } \l_sched_tmpa_tl
      \tl_if_empty:NF \l_sched_tmpa_tl
        { \noindent \tl_use:N \l_sched_tmpa_tl \par }
      \prop_get_ne:NnN \l_sched_participant_prop { email } \l_sched_tmpa_tl
      \tl_if_empty:NF \l_sched_tmpa_tl
        { \noindent\nolinkurl{ \tl_use:N \l_sched_tmpa_tl } \par }
      % Page references (always shown).
      \exp_args:NV \clist_map_inline:nn \l_sched_tmpb_tl
        { \blockPageref{session:####1}~ }
      \exp_args:NV \clist_map_inline:nn \l_sched_tmpc_tl
        { \blockPageref{talk:####1}~ }
      % Slot strings with title and inline page ref (starred form only).
      \bool_if:NT #1
      {
        \par
        % Organiser sessions: \l_sched_tmpb_tl is captured so free to reuse.
        \exp_args:NV \clist_map_inline:nn \l_sched_tmpb_tl
        {
          \prop_get_ne:NnN \g_sched_session_slots_prop {####1} \l_sched_tmpa_tl
          \tl_if_empty:NTF \l_sched_tmpa_tl
            { \msg_warning:nnn { schedule } { slot-not-found } {####1} }
            {
              \tl_clear:N \l_sched_tmpb_tl
              \sched_get_session:nNT {####1} \l_sched_session_prop
                { \prop_get_ne:NnN \l_sched_session_prop { title } \l_sched_tmpb_tl }
              \noindent\textit{Organizer:}~
              \tl_if_empty:NF \l_sched_tmpb_tl { ``\tl_use:N \l_sched_tmpb_tl'',~ }
              \blockPageref{session:####1},~\tl_use:N \l_sched_tmpa_tl\par
            }
        }
        % Speaker talks: split key on @ to get session id, look up title.
        % \l_sched_tmpc_tl is captured so free to reuse for the title.
        \exp_args:NV \clist_map_inline:nn \l_sched_tmpc_tl
        {
          \prop_get_ne:NnN \g_sched_talk_slots_prop {####1} \l_sched_tmpa_tl
          \tl_if_empty:NTF \l_sched_tmpa_tl
            { \msg_warning:nnn { schedule } { slot-not-found } {####1} }
            {
              \seq_set_split:Nnn \l_sched_tmpa_seq { @ } {####1}
              \tl_set:Ne \l_sched_tmpb_tl { \seq_item:Nn \l_sched_tmpa_seq {1} }
              \tl_clear:N \l_sched_tmpc_tl
              \prop_get:NVN \g_sessions_prop \l_sched_tmpb_tl \l_sched_session_prop
              \tl_if_eq:NNF \l_sched_session_prop \q_no_value
                { \prop_get_ne:NnN \l_sched_session_prop { title } \l_sched_tmpc_tl }
              \noindent\textit{Speaker:}~
              \tl_if_empty:NF \l_sched_tmpc_tl { ``\tl_use:N \l_sched_tmpc_tl'',~ }
              \blockPageref{talk:####1},~\tl_use:N \l_sched_tmpa_tl\par
            }
        }
      }
      \end{minipage}\par\bigskip
    }
  }
  \end{multicols}
}

\NewDocumentCommand{\printParticipants}{s O{0}}
{
  \IfBooleanTF {#1}
    { \sched_print_participants:Nn \c_true_bool  {#2} }
    { \sched_print_participants:Nn \c_false_bool {#2} }
}

\NewDocumentCommand{\missingTalk}{m}
{
  \tl_if_empty:NTF \g_current_session_id_tl
    { \msg_error:nn { session } { missing-talk-outside-session } }
    {
      \begin{talk}{}{}{}{}{}{}
        EMPTY TALK
      \end{talk}
    }
}

\NewDocumentCommand{\blockPageref}{m} {\ifcsname r@#1\endcsname
    p.\nobreakspace{}\pageref{#1}
  \fi}
\NewDocumentCommand{\fillPageref}{m}
{\ifcsname r@#1\endcsname
    ~\unskip\penalty0\hspace*{\fill}\mbox{p.\nobreakspace{}\pageref{#1}}
  \fi}
%    \end{macrocode}
%
% \subsubsection{Column types}
%
% Column~|F| must be defined inside \cs{ExplSyntaxOn} because its
% width formula references \cs{l\_sched\_numcols\_tl}, an expl3
% variable whose name uses underscores as letters.
%
%    \begin{macrocode}
\newcolumntype{Y}{>{\centering\arraybackslash}X}
\newcolumntype{H}{>{\raggedright\arraybackslash}X}
\newcolumntype{F}
  {>{\hsize=\dimexpr
      \l_sched_numcols_tl\hsize
      + \tabcolsep  * (2 * (\l_sched_numcols_tl - 1))
      + \arrayrulewidth * (\l_sched_numcols_tl - 1)
    \relax}H}

\ExplSyntaxOff
%    \end{macrocode}
% \iffalse
%</package>
% \fi
%
% \subsection{Lua submission processor (\texttt{process-submissions.lua})}
%
% The module is a standard Lua table returned with |return M|.
% It requires |lfs| (LuaFileSystem, bundled with \LuaTeX{}).
%
% |M.process| iterates all sorted \texttt{.tex} files in a session
% directory and inputs each one.  Each file is expected to contain
% exactly one environment; content outside an environment is silently
% ignored by \TeX{}.  Files with leading digits are tracked as talk
% slots: gaps trigger \cs{missingTalk}; files without leading digits
% (typically the session description file) are input but do not
% advance the slot counter.
%
% |M.process\_root| iterates immediate subdirectories (skipping hidden
% entries), bracketing each with \cs{openSession}/\cs{closeSession}
% and delegating file processing to |M.process|.
%
% \iffalse
%<*lua>
% \fi
%    \begin{macrocode}
local M = {}

local lfs = require("lfs")

local function list_tex(dir)
    local t = {}
    for f in lfs.dir(dir) do
        if f:match("%.tex$") then
            t[#t+1] = f
        end
    end
    table.sort(t)
    return t
end

function M.process(dir)
    local files = list_tex(dir)
    local expected = 1

    for _, f in ipairs(files) do
        local idx = f:match("^(%d+)")
        if idx then
            idx = tonumber(idx)
            while expected < idx do
                tex.print("\\missingTalk{" .. expected .. "}")
                expected = expected + 1
            end
            tex.print("\\def\\currentTalkIndex{" .. idx .. "}")
            expected = idx + 1
        else
            tex.print("\\def\\currentTalkIndex{}")
        end

        tex.print("\\setInputFilepath{" .. dir .. "/" .. f .. "}")
        tex.print("\\input{" .. dir .. "/" .. f .. "}")
    end
end

function M.process_root(dir)
    for d in lfs.dir(dir) do
        if d:sub(1,1) ~= "." then
            local full_path = dir .. "/" .. d
            local attr = lfs.attributes(full_path)

            if attr and attr.mode == "directory" then
                tex.print("\\openSession{" .. d .. "}{" .. full_path .. "}")
                M.process(full_path)
                tex.print("\\closeSession")
            end
        end
    end
end

return M
%    \end{macrocode}
% \iffalse
%</lua>
% \fi
%
% \subsection{Submission templates}
%
% Two standalone template files are generated for submitters.
% Each compiles independently (no \pkg{confschedule} required) and
% renders a preview that approximates the final programme output.
%
% \iffalse
%<*talk-template>
%% ===========================================================================
%% TALK SUBMISSION TEMPLATE
%%
%% INSTRUCTIONS
%% ------------
%% 1. Fill in your details in the six mandatory braced arguments below.
%% 2. Compile with pdflatex (or lualatex) to preview your submission.
%% 3. Submit this .tex file to the organisers -- not the PDF.
%%
%% ARGUMENT GUIDE
%% --------------
%%  {1} Title of the talk
%%  {2} Speaker full name, e.g. "Alice Brown" or "Brown, Alice"
%%  {3} Affiliation / institution
%%  {4} Email address
%%  {5} Co-authors, comma-separated (leave {} empty if none)
%%  {6} Special note, e.g. acknowledgement of funding (leave {} empty if none)
%%
%% REFERENCES
%% ----------
%% If your abstract cites prior work, list references in plain text at the
%% end of the abstract body.  Do NOT use \bibliography, \bibliographystyle,
%% BibTeX, or biblatex.  Use the following format (AMS-style):
%%
%%  [1] A.~B. Author and C.~D. Coauthor, ``Title of paper,''
%%      \textit{Journal Name} \textbf{vol} (year), no.~N, pp.~ZZ--ZZ.
%%  [2] E.~F. Author, \textit{Title of Book}, Publisher, City, year.
%%  [3] G.~H. Author, ``Chapter title,'' in \textit{Book Title}
%%      (I.~J. Editor, ed.), Publisher, City, year, pp.~ZZ--ZZ.
%%
%% EXAMPLE
%% -------
%%  \begin{talk}
%%    {A Fast Gradient Method}
%%    {Alice Brown}
%%    {Stanford University}
%%    {a.brown@stanford.edu}
%%    {C.~White, J.~Green}
%%    {}
%%  We present a gradient method achieving optimal complexity...
%%  \end{talk}
%%
%% WARNING: Any package inclusions or definitions outside the document
%% environment will be ignored.
%%
%% ===========================================================================
\documentclass{article}
\usepackage{geometry}
\geometry{a4paper, margin=2.5cm}
\usepackage{amsmath,amssymb}
\usepackage{tabularx,graphicx,url,xcolor,rotating,multicol,epsfig,colortbl}
\usepackage{xparse,comment}
\definecolor{slotbar}{gray}{0.75}

%% ---------------------------------------------------------------------------
%% Preview rendering -- approximates how the talk appears in the programme.
%% Do not modify this block.
%% ---------------------------------------------------------------------------
\NewDocumentEnvironment{talk}{m m m m m m O{} +b}
{%
  \par\bigskip
  \noindent\colorbox{slotbar}{\parbox{\dimexpr\linewidth-2\fboxsep}%
    {\strut\textit{Preview -- slot and location assigned by organisers}}}
  \par\medskip
    \noindent\textbf{\large #1}\par\smallskip
    \noindent\textit{#2}\par
    \ifblank{#3}{}{\noindent #3\par}%
    \ifblank{#4}{}{\noindent\texttt{#4}\par}%
    \ifblank{#5}{}{\noindent\textit{Co-authors: #5}\par}%
    \ifblank{#6}{}{\noindent\textit{Note: #6}\par}%
    \medskip
    #8%
  \par\bigskip\noindent\rule{\linewidth}{0.4pt}
}{}

%% ---------------------------------------------------------------------------
%% Your submission -- fill in between the braces.
%% ---------------------------------------------------------------------------
\begin{document}

\begin{talk}
  {Title of your talk}                % {1} title
  {Your Full Name}                    % {2} speaker
  {Your Institution}                  % {3} affiliation
  {your.email@example.com}           % {4} email
  {}                                  % {5} co-authors  (empty if none)
  {}                                  % {6} special note (empty if none)
Your abstract text goes here.
This may span multiple paragraphs.

Second paragraph of the abstract.

%% References (if any) -- plain text, no BibTeX/biblatex:
%% [1] A.~B. Author, ``Title,'' \textit{Journal} \textbf{vol} (year), pp.~ZZ--ZZ.
\end{talk}

\end{document}
%</talk-template>
%<*session-template&old-session>
%% ===========================================================================
%% SESSION SUBMISSION TEMPLATE
%%
%% INSTRUCTIONS
%% ------------
%% 1. Fill in your details in the mandatory braced arguments below.
%% 2. Compile with pdflatex (or lualatex) to preview your submission.
%% 3. Submit this .tex file to the organisers -- not the PDF.
%%
%% ARGUMENT GUIDE
%% --------------
%%  {1} Session title
%%  {2} Chair / first organiser full name
%%  {3} First organiser affiliation
%%  {4} First organiser email
%%  {5} Second organiser full name  (leave {} empty to omit)
%%  {6} Second organiser affiliation (leave {} empty to omit)
%%  {7} Second organiser email       (leave {} empty to omit)
%%
%% OPTIONAL SETUP CODE (in square brackets, after the 7 braced arguments)
%%  [\addSessionOrganizer{Name}{Affiliation}{email}]
%%  Use this to add a third (or further) organiser.
%%  Multiple calls may be chained:
%%    [\addSessionOrganizer{...}{...}{...}
%%     \addSessionOrganizer{...}{...}{...}]
%%
%% REFERENCES
%% ----------
%% If the session description cites prior work, list references in plain
%% text at the end of the description body.  Do NOT use \bibliography,
%% \bibliographystyle, BibTeX, or biblatex.  Use the following format
%% (AMS-style):
%%
%%  [1] A.~B. Author and C.~D. Coauthor, ``Title of paper,''
%%      \textit{Journal Name} \textbf{vol} (year), no.~N, pp.~ZZ--ZZ.
%%  [2] E.~F. Author, \textit{Title of Book}, Publisher, City, year.
%%  [3] G.~H. Author, ``Chapter title,'' in \textit{Book Title}
%%      (I.~J. Editor, ed.), Publisher, City, year, pp.~ZZ--ZZ.
%%
%% EXAMPLE
%% -------
%%  \begin{session}
%%    {Numerical Optimisation}
%%    {Jane Smith}
%%    {MIT}
%%    {j.smith@mit.edu}
%%    {}{}{}
%%  This session covers recent advances in first-order methods...
%%  \end{session}
%%
%% WARNING: Any package inclusions or definitions outside the document
%% environment will be ignored.
%% ===========================================================================
\documentclass{article}
\usepackage{geometry}
\geometry{a4paper, margin=2.5cm}
\usepackage{amsmath,amssymb}
\usepackage{tabularx,graphicx,url,xcolor,rotating,multicol,epsfig,colortbl}
\usepackage{xparse,comment}
\definecolor{slotbar}{gray}{0.75}

%% ---------------------------------------------------------------------------
%% Preview rendering -- approximates how the session appears in the programme.
%% Do not modify this block.
%% ---------------------------------------------------------------------------
\def\organiserlist{}

\NewDocumentCommand{\addSessionOrganizer}{m m m}{%
  \expandafter\def\expandafter\organiserlist\expandafter{%
    \organiserlist
    \noindent\textit{#1}\par
    \ifblank{#2}{}{\noindent #2\par}%
    \ifblank{#3}{}{\noindent\texttt{#3}\par}%
    \smallskip
  }%
}

\NewDocumentEnvironment{session}{m m m m m m m O{} +b}
{%
  \def\organiserlist{}%
  \addSessionOrganizer{#2}{#3}{#4}%
  \ifblank{#6}{}{\addSessionOrganizer{#5}{#6}{#7}}%
  #8%
  \par\bigskip
  \noindent\colorbox{slotbar}{\parbox{\dimexpr\linewidth-2\fboxsep}%
    {\strut\textit{Preview -- slot and location assigned by organisers}}}
  \par\medskip
  \noindent\textbf{\large #1}\par\medskip
  \noindent\textbf{Organizers:}\par\smallskip
  \organiserlist
  \medskip
  \noindent\textbf{Session Description:}\par\medskip
  #9%
  \par\bigskip\noindent\rule{\linewidth}{0.4pt}
}{}

%% ---------------------------------------------------------------------------
%% Your submission -- fill in between the braces.
%% ---------------------------------------------------------------------------
\begin{document}

\begin{session}
  {Session Title}                     % {1} session title
  {Organizer Full Name}               % {2} chair / first organiser
  {Organizer Institution}             % {3} first organiser affiliation
  {organizer@example.com}            % {4} first organiser email
  {}                                  % {5} second organiser name (empty to omit)
  {}                                  % {6} second organiser affiliation
  {}                                  % {7} second organiser email
  % Optional: [\addSessionOrganizer{Name}{Institution}{email}]
Session description or abstract goes here.
This may span multiple paragraphs.

Second paragraph.

%% NOTE: If you have a list of speakers, add it inside a comment block. The
%% final list will be generated with the programme.
\begin{comment}
  This is the list of speakers:
  1. Speaker one
  2. Speaker two
\end{comment}

%% References (if any) -- plain text, no BibTeX/biblatex:
%% [1] A.~B. Author, ``Title,'' \textit{Journal} \textbf{vol} (year), pp.~ZZ--ZZ.
\end{session}

\end{document}
%</session-template&old-session>
%<*session-template&new-session>
%% ===========================================================================
%% SESSION SUBMISSION TEMPLATE
%%
%% INSTRUCTIONS
%% ------------
%% 1. Fill in your details in the mandatory braced arguments below.
%% 2. Compile with pdflatex (or lualatex) to preview your submission.
%% 3. Submit this .tex file to the organisers -- not the PDF.
%%
%% ARGUMENT GUIDE
%% --------------
%%  {1} Session title
%%  {2} Organiser full name
%%  {3} Organiser affiliation
%%  {4} Organiser email
%%
%% OPTIONAL SETUP CODE (in square brackets, after the 4 braced arguments)
%%  [\addSessionOrganizer{Name}{Affiliation}{email}]
%%  Use this to add a second (or further) organiser.
%%  Multiple calls may be chained:
%%    [\addSessionOrganizer{...}{...}{...}
%%     \addSessionOrganizer{...}{...}{...}]
%%
%% REFERENCES
%% ----------
%% If the session description cites prior work, list references in plain
%% text at the end of the description body.  Do NOT use \bibliography,
%% \bibliographystyle, BibTeX, or biblatex.  Use the following format
%% (AMS-style):
%%
%%  [1] A.~B. Author and C.~D. Coauthor, ``Title of paper,''
%%      \textit{Journal Name} \textbf{vol} (year), no.~N, pp.~ZZ--ZZ.
%%  [2] E.~F. Author, \textit{Title of Book}, Publisher, City, year.
%%  [3] G.~H. Author, ``Chapter title,'' in \textit{Book Title}
%%      (I.~J. Editor, ed.), Publisher, City, year, pp.~ZZ--ZZ.
%%
%% EXAMPLE
%% -------
%%  \begin{session}
%%    {Numerical Optimisation}
%%    {Jane Smith}
%%    {MIT}
%%    {j.smith@mit.edu}
%%    [\addSessionOrganizer{Bob Jones}{Cambridge}{b.jones@cam.ac.uk}]
%%  This session covers recent advances in first-order methods...
%%  \end{session}
%%
%% WARNING: Any package inclusions or definitions outside the document
%% environment will be ignored.
%% ===========================================================================
\documentclass{article}
\usepackage{geometry}
\geometry{a4paper, margin=2.5cm}
\usepackage{amsmath,amssymb}
\usepackage{tabularx,graphicx,url,xcolor,rotating,multicol,epsfig,colortbl}
\usepackage{xparse,comment}
\definecolor{slotbar}{gray}{0.75}

%% ---------------------------------------------------------------------------
%% Preview rendering -- approximates how the session appears in the programme.
%% Do not modify this block.
%% ---------------------------------------------------------------------------
\def\organiserlist{}

\NewDocumentCommand{\addSessionOrganizer}{m m m}{%
  \expandafter\def\expandafter\organiserlist\expandafter{%
    \organiserlist
    \noindent\textit{#1}\par
    \ifblank{#2}{}{\noindent #2\par}%
    \ifblank{#3}{}{\noindent\texttt{#3}\par}%
    \smallskip
  }%
}

\NewDocumentEnvironment{session}{m m m m O{} +b}
{%
  \def\organiserlist{}%
  \addSessionOrganizer{#2}{#3}{#4}%
  #5%
  \par\bigskip
  \noindent\colorbox{slotbar}{\parbox{\dimexpr\linewidth-2\fboxsep}%
    {\strut\textit{Preview -- slot and location assigned by organisers}}}
  \par\medskip
  \noindent\textbf{\large #1}\par\medskip
  \noindent\textbf{Organizers:}\par\smallskip
  \organiserlist
  \medskip
  \noindent\textbf{Session Description:}\par\medskip
  #6%
  \par\bigskip\noindent\rule{\linewidth}{0.4pt}
}{}

%% ---------------------------------------------------------------------------
%% Your submission -- fill in between the braces.
%% ---------------------------------------------------------------------------
\begin{document}

\begin{session}
  {Session Title}                     % {1} session title
  {Organizer Full Name}               % {2} chair / organiser
  {Organizer Institution}             % {3} affiliation
  {organizer@example.com}            % {4} email
  % Optional: [\addSessionOrganizer{Name}{Institution}{email}]
Session description or abstract goes here.
This may span multiple paragraphs.

Second paragraph.

%% NOTE: If you have a list of speakers, add it inside a comment block. The
%% final list will be generated with the programme.
\begin{comment}
  This is the list of speakers:
  1. Speaker one
  2. Speaker two
\end{comment}

%% References (if any) -- plain text, no BibTeX/biblatex:
%% [1] A.~B. Author, ``Title,'' \textit{Journal} \textbf{vol} (year), pp.~ZZ--ZZ.
\end{session}

\end{document}
%</session-template&new-session>
% \fi
%
% \Finale
%
% \endinput
% Local Variables:
% mode: doctex
% TeX-master: t
% End: