O(1) ETS cache of rendered palette-card previews, keyed by the template a card would drop.

Why a cache at all

The first render of a component costs 0.5–1.4 seconds — that is its module being compiled — and every later one costs about 2 ms. Without this, moving back along a row of cards would pay the first price again each time the pointer returned, because nothing else remembers the answer.

Keyed on the TEMPLATE rather than the component name, because two cards for the same component with different presets are two different previews, and the template is the thing that actually differs. The site rides in the key too: the same component draws differently under two sites' stylesheets.

Why it is a plain table and not a GenServer

The reads are the hot path and there is nothing to serialise: a preview is a pure function of its key, so two processes racing to compute the same one write identical bytes. CompileFailureState is the precedent.

What bounds it

A single install ships on the order of a hundred components, each a few kilobytes rendered, so a full cache is measured in hundreds of kilobytes — small enough to keep for the life of the node. It is dropped wholesale when a site recompiles, because that is when a preview can become a lie.