Simplify collection of data-layer hierarchy information

[knoepfel]

This PR replaces the complicated end-of-message RAII system with a simpler approach, where a dedicated node is used to collect data-layer hierarchy information.

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
phlex/core/declared_predicate.hpp	50.00%	1 Missing ⚠️
phlex/core/declared_unfold.hpp	95.45%	0 Missing and 1 partial ⚠️

❌ Your project status has failed because the head coverage (75.62%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

@@            Coverage Diff             @@
##             main     #286      +/-   ##
==========================================
+ Coverage   75.28%   75.62%   +0.34%     
==========================================
  Files         126      125       -1     
  Lines        2954     2946       -8     
  Branches      519      519              
==========================================
+ Hits         2224     2228       +4     
+ Misses        505      497       -8     
+ Partials      225      221       -4     

Flag	Coverage Δ
unittests	75.62% <95.65%> (+0.34%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
phlex/core/declared_fold.hpp	94.82% <100.00%> (ø)
phlex/core/declared_provider.hpp	100.00% <100.00%> (ø)
phlex/core/declared_transform.hpp	91.30% <100.00%> (-0.19%)	⬇️
phlex/core/detail/filter_impl.hpp	100.00% <ø> (ø)
phlex/core/filter.cpp	73.91% <100.00%> (-1.09%)	⬇️
phlex/core/framework_graph.cpp	90.90% <100.00%> (+0.58%)	⬆️
phlex/core/framework_graph.hpp	100.00% <ø> (ø)
phlex/core/message.hpp	94.44% <ø> (ø)
phlex/core/message_sender.cpp	56.25% <100.00%> (-11.94%)	⬇️
phlex/core/multiplexer.cpp	79.31% <100.00%> (ø)
... and 2 more

... and 3 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR removes the end-of-message RAII mechanism (and its end_of_message pointer propagation) and replaces hierarchy reporting with a dedicated TBB node that records data-layer information as messages enter the graph.

Changes:

• Simplifies message/predicate_result by removing end_of_message_ptr and updates all affected nodes/tests accordingly.
• Introduces a hierarchy_node_ in framework_graph to record data-cell indices (including those created by unfolds).
• Deletes the end_of_message implementation and removes it from the build/install rules.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/filter_impl.cpp	Updates filter decision-map tests to the new predicate_result shape.
test/allowed_families.cpp	Adjusts an execution-count assertion and relocates a synchronization FIXME.
phlex/core/multiplexer.cpp	Adapts multiplexing to the new message layout (no EOM).
phlex/core/message_sender.hpp	Removes hierarchy/EOM stack dependencies from the sender API.
phlex/core/message_sender.cpp	Stops creating EOM objects and builds simplified messages/flushes.
phlex/core/message.hpp	Removes end_of_message_ptr from message.
phlex/core/fwd.hpp	Drops end_of_message forward decl and pointer alias.
phlex/core/framework_graph.hpp	Removes EOM stack; adds hierarchy_node_; updates sender construction.
phlex/core/framework_graph.cpp	Adds hierarchy_node_ implementation and wires it to source/unfold senders.
phlex/core/filter.cpp	Removes EOM plumbing when forwarding filtered messages downstream.
phlex/core/end_of_message.hpp	Deleted (no longer used).
phlex/core/end_of_message.cpp	Deleted (no longer used).
phlex/core/detail/filter_impl.hpp	Simplifies predicate_result by removing EOM.
phlex/core/declared_unfold.hpp	Removes EOM propagation and updates message construction in unfold paths.
phlex/core/declared_transform.hpp	Removes EOM handling and updates message forwarding.
phlex/core/declared_provider.hpp	Removes EOM handling when producing/forwarding messages.
phlex/core/declared_predicate.hpp	Stops attaching EOM to predicate results.
phlex/core/declared_fold.hpp	Removes EOM forwarding when emitting folded parent stores.
phlex/core/CMakeLists.txt	Removes end_of_message.* from library sources and install set.

[greenc-FNAL]

Review the full CodeQL report for details.

[greenc-FNAL]

I can't claim to fully understand the TBB node operations, but pending my question below, it looks sensible to me.

Replaced ++msg_counter_ increment with safer msg_counter_.fetch_add(1)