Make the /display kiosk survive losing its infrastructure, then surrender
authority cleanly when it returns. The Phase 5A renderer is unchanged: this
builds on its two permanent scene layers, explicit Cache Storage, IndexedDB,
Service Worker, timing anchors, and structured errors.
While connected the server is authoritative. While disconnected the display
becomes a deterministic local continuation of the last authoritative state
it persisted, and the moment the server speaks again the local cursor is
abandoned rather than reconciled or reported back.
A small client evaluator resolves offline playback from the persisted
manifest and clock anchor. Catch-up is arithmetic rather than iterative:
whole rotations are skipped between eligibility boundaries, so a month
offline resolves in milliseconds. Mixed durations, wraparound, [start, end)
schedules, and expirations are evaluated locally, and a null expiration
stays permanent. Mode off keeps the hidden cursor advancing, pause holds
its slide and remainder, static holds until the cached metadata says the
asset genuinely expired, and an activation queued for an unknown playlist
holds the last good frame instead of continuing into a playlist that is
being replaced. Contract tests run this evaluator and the real Phase 3B
engine over identical scenarios and assert the same slide, start, and
deadline, so the client tracks the server without refactoring it.
Cold start restores signage from the Service Worker shell, IndexedDB, and
Cache Storage with the entire stack down, keeping the same persistent
display identity.
Validated display error codes now become Home Assistant incidents through
the Phase 4 machinery, keyed per display and condition so a persisting
error reports once and recovers once. Arbitrary browser text stays
telemetry.
Corrects the deployment assumption: the kiosk runs on a separate machine,
so production requires a trusted HTTPS origin and localhost is development
only. Verifying on a real trusted certificate exposed two production bugs
that localhost had hidden — behind a reverse proxy an outage arrives as a
502 rather than a refused connection, and an unbounded shell fetch left a
restarting kiosk blank for the proxy's whole connect timeout. The worker
now treats a gateway error as an outage and bounds that wait.
Verified with 200/200 backend, 20 client unit, and 30 Playwright tests on
a trusted HTTPS origin with no browser security flags weakened.
Co-Authored-By: Claude Opus 5 <[email protected]>
Build the real /display Chromium signage client as a React route on the
existing single-page build. The server remains authoritative; the display
only consumes the verified Phase 3B snapshot and reports telemetry.
The renderer owns two permanent scene layers that are never recreated. A
transition prepares the hidden layer, decodes the incoming image on the
element that will actually be composited, then raises that layer above the
current one at opacity 0 and fades it in while the outgoing layer stays
fully opaque underneath. This removes the v1 defect where two simultaneous
fades let the black root through the composite. Every asynchronous load
and transition carries a generation token, so work finishing after
authoritative state moved on is discarded rather than shown.
A true 16:9 slide fills the frame with no backdrop or shadow; anything
else is contained, centred, and uncropped over a blurred, solid, or black
background with a subtle shadow. Blur uses the global setting and is
overscanned; boolean darkening applies to the background only. Static
targets use the same renderer with the snapshot's global presentation
defaults, and mode off is a topmost gate while the renderer keeps
tracking underneath.
Slide bytes live in an explicit Cache Storage cache with reference
counted object URLs and conservative pruning, never in ordinary HTTP
caching. A new manifest is staged before promotion, so one unfetchable
asset marks only itself unavailable instead of rejecting a playlist. A
small IndexedDB store with explicit version handling holds the persistent
client ID, last known good manifest, timing anchor, and last structured
error, and discards malformed records on read. A narrow service worker
caches only the /display app shell, network-first for navigations, and
explicitly bypasses media, API, and socket traffic.
The display sends a real display:heartbeat every 12 seconds with its
actual state, and reports structured errors as bounded JSON that the
server's existing string validation already accepts; /api/displays parses
them back into an object, so no migration was required.
Verified against an isolated stack through Nginx with 20 Playwright
Chromium tests plus 9 client unit tests, and 187/187 backend tests.
Co-Authored-By: Claude Opus 5 <[email protected]>
