Every device control was offered to every display. A browser tab was shown
"Reboot device", a Tizen TV was shown screen power, a player with no
framebuffer read was shown a live view that stayed black. They all looked
like working buttons and did nothing — the "reports success and changes
nothing" shape that keeps costing people days.
Players now declare what they can do at registration, because only the
player knows at runtime: an Android panel gains real screenshots when
accessibility is switched on and loses Tier-2 when device owner is revoked.
The dashboard hides what is not supported rather than disabling it, and the
Info tab lists the capability set so a missing control is explainable.
The declaration is three-state and the middle state is load bearing: NULL
means "has never told us anything" and falls back to a per-platform
baseline, because several hundred displays in the field will not update
before this deploys and blanking their controls would be a far worse bug.
An empty array means "I genuinely can do nothing" and is honoured.
Hiding a button is not enforcement, so unsupported commands are also
refused server-side — the socket is reachable directly and a stale tab
still renders the old controls. Group sends report skipped devices
separately from sent ones; counting an unreachable member as "sent" is how
an operator walks away believing the whole group rebooted.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uaeo9MvzKoyXuN6ZsbhtkL
Foundation for platform-native parity. The dashboard offered every control to
every display — a browser tab cannot reboot its host, a Tizen TV has no
device-owner concept, a BrightSign has no per-window brightness — so those
buttons did nothing, silently, and read as bugs. "UI that reports success and
changes nothing" is a recurring shape here; this ends it by letting the frontend
hide what a display cannot do.
The player DECLARES its capabilities at registration rather than the server
inferring them from a table, because only the player knows at runtime: an Android
device gains real screenshots when accessibility is switched on and loses Tier-2
commands when it is not device owner.
The trap this had to avoid is the opposite failure. Several hundred displays are
in the field declaring nothing, and none will update before the next dashboard
deploy — treating absence as "supports nothing" would strip the UI for the entire
fleet at once. So an ABSENT declaration falls back to a per-platform baseline,
while an EMPTY one is honoured as a player genuinely saying it can do nothing.
Those two cases are trivial to conflate and the difference is a dark dashboard.
Baselines carry only what has always worked on that platform. Anything
conditional — screenshots needing accessibility, kiosk needing device owner,
native sync needing one L2 network — is omitted, so a legacy display shows those
controls only once it declares them. A control that appears late beats one that
lies now.
Capability names are stable strings because they are persisted per device and
sent over the wire; renaming one silently disables a control on every display
still reporting the old name. An unknown name from a NEWER player is dropped
rather than invalidating the whole declaration.
1094 pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uaeo9MvzKoyXuN6ZsbhtkL
