The license server broker pins a single Pulse Pro release, which can be a
prerelease. The update check skips such a pin on the stable channel and
apply refuses it, but the runtime switch check never applied that rule.
A stable install was offered an in-place switch that always failed with
"stable channel cannot install prerelease builds", and Docker installs
were handed digest-pinned commands for the preview Pro image.
The check, the switch check and apply now share one helper,
stableChannelRefusesProPin, so a check can no longer offer what apply
refuses. The switch check reports the new prerelease_only reason with the
pinned version so the Updates card can explain the wait; rc-channel
installs are still offered the prerelease pin.
The API contract adds prerelease_only to the closed reason set for
GET /api/updates/pro-runtime, and the deployment contract records that
the switch check shares the stable-channel guard.
rcourtman
af94620532