Pure pane assembly for the Livebook inspector: folds a compiled Statifier.Machine and a StatifierUI.Trace.Subscriber message list into the render source each pane displays - Mermaid source for the configuration diagram, Markdown for the event log and the datamodel explorer, and a status line from the subscriber's stats/1 snapshot.

No Kino, no process, no session: everything here is testable from a message list, exactly like the pane modules it composes. The Kino shell (StatifierUI.Kino) maps these strings into widgets and owns nothing else.

The active configuration is read from the newest message that stamped one - a trace.macrostep_stable, the quiescent configuration of the last completed macrostep, or a trace.done, the configuration a halted run exited in (docs/wire-format.md). Before either has arrived in view, the caller-supplied initial configuration (typically Statifier.Session.snapshot/1's) is used instead.

A halted chart's final configuration (sui-dc7)

A run that ends by entering a top-level <final> never stabilizes in its last macrostep: quiescence is never reached, so no trace.macrostep_stable is emitted for it and the engine stamps the configuration on trace.done instead. Reading only macrostep_stable therefore left the diagram highlighting the state the chart left, while the datamodel pane showed the assignment that moved it out.

Both stamps are read, and the wire format is what settles that they may be: its trace.done row defines configuration as "the full configuration as it stood at exit, a genuine set, sorted ascending" - the same field, shape, and authority as a macrostep_stable payload. Nothing here re-derives an exit configuration from the exit sets that precede trace.done; that would be re-implementing Appendix D, which this repo does not do (ADR-0002, StatifierUI.EventLog). The two readings stay labelled apart, so a configuration the chart exited in is never presented as one it settled in.

Selecting a past macrostep (sui-3gg)

Every fold function takes a :selection, which is :live (the default, the behaviour above) or {:macrostep, n}. Under a selection the diagram shows the configuration macrostep n settled in, the event log marks that macrostep's entry - shown in the diagram and opens it, and selection_note/2 renders the line that says which point is on screen. That is the whole of the link between the two panes.

Nothing here re-derives a configuration. Every configuration this module can show was stamped by the engine on a trace.macrostep_stable or a trace.done, and a stream reconstructed by catch-up got there through statifier ADR-0034 replay, which re-drives the core in a pure fold rather than rewinding a live session. Time travel is a read of replay output as data (ADR-0002's inherited clause), so selecting a macrostep neither touches the session nor asks the engine for anything new.

A selected macrostep that stamped no configuration of its own - in flight, or its stamp dropped - has none to draw. Rather than draw nothing, the newest configuration at or below it is shown and selection_note/2 says which macrostep it was carried from - a carried configuration is never presented as a measured one.

Linking out to a trace (sui-4w2)

Every fold function also takes :deep_link, the host's APM URL template (ADR-0013). With one configured, the event log's macrostep summaries and selection_note/2 gain an [open trace](...) link for each macrostep whose messages carry the wire format's otel key. Without the option, or on a macrostep carrying no correlation, every pane renders exactly as it did - including the carried-forward wording above, which the link is appended to rather than replacing.