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Author SHA1 Message Date
ScreenTinker 684e60fc55 Offline media on every player, and a revision so the cache can still be updated
Two halves of the same problem. A screen has to keep playing when the link is
gone, and it must not keep playing the wrong thing once the link is back.

CACHING FOR OFFLINE, on the players that could not:

- Tizen cached nothing but the playlist, so a panel came back from a reboot
  knowing exactly what to show and fetched every frame of it from a server that
  was not there. tizen/js/media-cache.js caches the media itself to wgt-private
  (the store Tizen documents as surviving reboots), resumable via Range and
  If-Range, with the transfer async so a stalled chunk cannot freeze the player.
  offline.cache moves from "absent" to a runtime claim: a build with no writable
  private storage still says nothing.

- The web player's worker stored only what a single fetch() happened to
  complete, which on a marginal link is nothing at all — a 200MB asset never
  finishes in one go and every retry starts from zero. It now accumulates in
  resumable chunks, driven by the player's playlist rather than by playback, so
  the prefetch is not competing with the video that is currently on screen for
  the same scarce bandwidth. BrightSign inherits this.

STILL UPDATING, which caching quietly breaks:

PUT /api/content/:id/replace changes an asset's bytes under a stable id. Every
cache keys on that id, so before this the new bytes could not reach a panel that
already held the old ones — not until the next refresh, but never. Content now
carries a revision, stamped onto each item at send time like widget revs, and
every player keys its cache on it. The same send-time refresh fixes a second
bug: a replace writes a new randomly-named file and unlinks the old one, so the
filepath in a published snapshot pointed at a deleted file and web panels 404'd
on the item until somebody republished the playlist. The route now also pushes
to affected devices, which it never did.

Bytes are kept only where they can be built upon: no validator means no safe
resume, so the partial is discarded and the attempt backs off as the failure it
is rather than re-fetching the same prefix forever.

Server needed no new transfer support — res.sendFile already does Range,
If-Range and 416. The Tizen cache and the service worker are both driven in Node
against fakes, because neither can be exercised without hardware and "the chunks
assemble correctly" is not something to discover from a panel showing a corrupt
video.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uaeo9MvzKoyXuN6ZsbhtkL
2026-08-05 15:27:36 -05:00
ScreenTinker 8fd6eb75d5 BrightSign: cache content for offline, and let the package update itself
Two gaps that both end the same way — a panel nobody can fix without a van.

OFFLINE. Content bytes were never persistently cached. The service worker
skipped /uploads/content/ and leaned on the browser's HTTP cache, which is
reasonable on a desktop and is not a documented-persistent store here:
BrightSign guarantees survival across reboots for IndexedDB, localStorage and
SQLite, and their own answer for offline video is to cache the bytes explicitly.
A panel could come back from a power cut with its playlist intact — that lives in
localStorage — and no media to play it with.

The reason content was skipped is real, and player-cache-policy.js is what makes
intercepting it safe. Seeking video issues range requests, and naive caching is
worse than none: storing a 206 as the whole file means every later full request
gets a fragment, and answering a range request with a 200 makes some media stacks
fail outright. So only complete 200s are stored, and ranges are served by slicing
the stored body into a correct 206. The content cache survives shell
re-versioning, or every deploy would re-download the playlist over a link that may
be exactly what is broken.

SELF-UPDATE. The package can replace autorun.brs, so a truncated file is a dark
panel with no app underneath. The safety is the ordering: download to .part,
verify sha256 AND size, then delete the .done marker, rename, reboot. Marker
first is not stylistic — leaving it makes the next boot skip the archive and the
update silently never happens. A failed extract parks the zip as .bad instead of
retrying every boot, which would be a loop indistinguishable from a hardware
fault. sha256 because that is what roMessageDigest can compute; a checksum the
player cannot verify is an unverifiable package.

The decision lives on the server and is unit-tested, and the host only executes
it — re-implementing the version comparison in BrightScript would put the
prerelease trap somewhere untestable. That trap is honoured directly: a player on
1.9.29-rc1 is running something semver-OLDER than 1.9.29, so an opted-in player
HOLDS a prerelease of its own core rather than being pulled off the build it was
given to test. Narrowly — a newer core still lands, so opting in never means
never updating again.

Both loop conditions are closed by construction. The manifest and the download
come from one buffer hashed once, so a checksum cannot describe bytes we are not
serving. And the version is stamped into autorun.brs at build time by both
builders, so the script reports the version it actually is — otherwise the player
applies the update, still reports the old version, and is offered the same
package forever.

Failure always degrades to "keep running the old version": an unreachable
manifest, a missing checksum, a failed verification, a full attempt counter and
an unbuildable package all resolve to skip.

998 tests pass (was 954).
2026-08-05 10:09:00 -05:00