The SDK could contribute a theme through `THEMES_AREA` but never select one,
and `useTheme().setTheme` needs a component to hang the hook on. A plugin that
repaints on an event — a gateway coming up, a socket message — had nowhere to
call, so shipping one meant patching the app and re-patching it after every
upgrade.
`requestTheme(name)` writes to the same one-shot channel the backend `/skin`
sync already uses, so the ThemeProvider drains it through `setTheme` and an
imperative switch normalizes and persists per profile exactly like a manual
pick — one policy, one owner.
An unresolvable name is refused rather than coerced. `setTheme` falls back to
the default skin, which is right for a person picking off a list and wrong for
code reacting to an event: a gateway naming a theme the user never installed
would silently reset an appearance the caller never meant to touch. The
returned boolean doubles as the availability check.
Brooklyn Nicholson
2e1e3cc91d