Math signals reach the plot, the signal views and an MDF export

[thebhef]

A math signal was created and edited under the Database panel's
Computed branch and went no further: it could not be dragged, no plot
or signal view could show one, and a save carried none. This finishes
the surface.

The drag payload gains a math provenance slot, so a Computed row drags
like any other signal — carrying the definition's stable id, never its
display name. The plot's side list and a signal view's rows both grow a
math row: the app's standard disclosure, one bus color chip per bus
feeding the series (transitively, through any math operands, resolved
host-side), and "Math - Multiple Busses" when several do. Expanding a
row opens the same in-place editor phase 2 built, on whichever surface
invoked it.

Three things had to be built under that.

The math flag was dropped from the plot's sample_signals and
signal_min_max queries, so a math series dropped on a plot would have
been keyed as a DBC identity nothing decodes and served empty. Both
queries now carry it, and the panel test asserts the points reach the
canvas rather than only the request.

A signal view's math rows are host rows: select_math is
select_file_backed's shape one provenance further — only a manual key
selects one, since a math series has no canonical path for a pattern to
match. Their values come through math_latest, which runs
slice_many's prologue: a math pyramid is session-scoped, so a row has
to drive the fill rather than read what happens to be there. Expansion
made the row pitch variable, using the VariableRowHeights the shared
viewport scaffold already offers the by-id table.

hline and statistic now draw solid. Both are two points spanning the
capture, and ADR 0026's first rule would dash both wings as a hold past
their own data — but a value the user authored is the data, not the plot
inferring. The suppression is in the model, at the one place that
classifies, so the renderer still styles what it is told. ADR 0026
records the exception and its scope: a decoded one-sample series is
still dashed.

Export: MDF carries each math series as an already-decoded channel under
a Computed acquisition group, on the file-backed precedent. The
definition is not written — there is nowhere in the format to say "the
median of these six signals" that a reader would understand, and the
project file keeps it. BLF carries none and now names the computed
signals it drops beside the file-backed ones.

The ADR 0031 harness grows its math case behind --math-on-start: a set
function over a live pattern, an exponential filter, a capture-wide
statistic, and one math-over-math chain, defined over whatever project
the launch opened. A flag rather than a project of its own because
growing examples/ev-zonal would invalidate every reading taken against
it. Defining costs nothing on its own — a math pyramid is built by a
serve — so the flag also puts the series into the open plot areas and
signal views, which is what a person measuring would do by dragging them
there; nothing reaches the project file.

Reviewers should look at select_math and math_latest (a signal
view's poll now drives a fill), at MathFill::constant and the ADR
amendment beside it, and at withPerfMathCase, which writes into live
element configs at launch.

[thebhef]

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• close out math signal, python server client, export dialog #475
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• Math signals reach the plot, the signal views and an MDF export #474 👈 (View in Graphite)
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• main

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