Function gainDefaultOf

The gain a control behind this capability COMES UP AT — the value a fresh strip starts on, the value a surface's reset lands on, and the default OPTIONS publishes — with the provenance that says how the desk knows it. undefined where the travel cannot hold it.

ONE resolver for both source classes, because "does a preamp own this gain" is the same question the travel, the ownership and the refusal all turn on: a preamp resolves against its own declared travel, a preamp-less channel against DESK_GAIN_RANGE, which is whose gain it is (channelCapabilityOf already reads it that way).

overrideDb is the operator's /console/defaults value. It is compared to the declaration rather than trusted blindly: that row always carries a number, so consulting it unconditionally would stamp every untouched desk operator and the word would stop meaning anything. An override EQUAL to the declaration is not an override. An override that DIFFERS moves the value the desk offers and publishes operator — it never rewrites the hardware fact, which is still what answers the moment the override is cleared.

Derived on every read and stored nowhere: a re-patch from a Roland box to a browser changes the answer with nothing to invalidate, the same rule gainRange obeys.