A map, a data table, a charts rail and a detail drawer behave as one dashboard
without importing each other, and nothing said how. This records the arrangement
that exists on development today; every claim in it was checked against the code
rather than remembered.
One composable provides five keys and every panel injects what it needs, with
null and {} defaults that are load-bearing: a panel rendered outside a shell must
degrade rather than throw, because a thrown setup() removes the subtree with an
empty error and no build failure.
The part worth writing down is that the bus carries two different kinds of
traffic through one generic on/emit pair. Four STATE events belong to
useSelectionBus and are emitted only by it. Seven UI events are passed through
the same bus by panels with no composable behind them. Reading the second kind as
if it were the first is how a maintainer concludes a contract is dead.
That mistake is named in the file because it has already been made twice while
auditing this kit: two panels listen for 'select' and no panel emits it, which
looks like a broken wire until you notice the emitter is the composable at
useSelectionBus.js:202. Grepping components for a bus's traffic cannot see the
bus itself.
It also records that selection is deliberately NOT reactive -- selectionSet is a
plain Set and selectionVersion is the reactive handle -- and that the charts rail
participates in filtering only, so selecting a pin does not highlight its slice.
That last one is the current contract, not an oversight: whether selection should
reach the charts is a product question and it is open.
The components stay in plugin-designs. A library component with one consumer is a
relocation rather than a promotion, and this repo has already had to move such
modules back; they graduate when a second dashboard consumes them.
