The schema required all nine properties, but the current API accepts and
round-trips sparse objects — settings_device_test.go stores
{"fontSize":"xxlarge"} and reads it back — and the web client has always
merged whatever it gets over DEFAULT_SUBTITLE_APPEARANCE. Requiring the full
object would have made the cutover migration quarantine preferences users
really set, or block on them.
Every property is now optional and a stored value is documented as a sparse
override merged over the definition's complete default. An empty object is
still rejected: an override that overrides nothing is the same state as no
override, which the contract represents as unset.
Cross-scope resolution is deliberately unchanged. A device override still
replaces the profile's object rather than merging into it, because a device
override means "draw subtitles this way on this screen", not "amend the
profile" — and that is what the server does today.
Reported by Codex review on #479.
Quick
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