PLN asked for the rendering to show where things REST, not only what just moved,
and asked that the wire not pay any cost twice.

Written down before any of it is built, because the interesting part is not the
drawing: state has exactly one legitimate owner. The surface has no readback and
in relative mode sends deltas, so the driver's integrated value is not a cache
of something else — it is the only copy. A viewer cannot derive it, and at boot
there is nothing on the wire at all.

The design: level and edge as two channels, state as last-value-wins in one
small atomically-replaced file with a seq counter so an unchanged frame parses
and paints nothing, and dirty-cell repaint so the layer costs nothing at rest.
Explicitly NOT built: a fan-out daemon for the duplicate aseqdump subscriptions,
which buys microseconds at the price of a process and a failure mode.

Two findings worth the doc on their own. Zero on a DJF is the CENTRE detent, so
the readout wants three zones with the detent drawn, not a 0-127 bar. And the
Pulsar-style feed needs no new producer: ~/.cache/parvagues/eval-events.jsonl is
already being written, one line per ctrl+enter with the orbits it touched, and
the driver already reads it.