Root cause of "whiteboard stuck on old content, no errors anywhere":
the Node sidecar had crashed at some point and, since it was just a
bare backgrounded process with nothing supervising it, stayed dead
permanently. Every refresh since then hit connection-refused, which
get_or_refresh_whiteboard treats as a soft failure and falls back to
the last successfully cached image -- so it looked exactly like a
caching bug from the outside, silently, forever, with no error visible
anywhere except a crash trace that had already scrolled out of the log
buffer.
Wrap it in a restart loop instead of a bare `&` so a future crash (a
still-unknown third jsdom/Excalidraw edge case, most likely) is a
few-second hiccup instead of a silent permanent outage.
New third mode alongside photos/calendar: fetches a .whiteboard file
over plain WebDAV (Basic auth -- generic, not Nextcloud-specific) and
renders it via a small Node.js sidecar using Excalidraw's own real
export code (@excalidraw/utils + @resvg/resvg-js, no headless browser),
since a .whiteboard file turns out to be Excalidraw scene JSON, not an
image. The sidecar runs as a second process inside this same container
(Dockerfile installs Node, start.sh backgrounds it before exec'ing
uvicorn) rather than a separate docker-compose service -- lightweight,
stateless, reachable only at 127.0.0.1 from the Python process, nothing
worth independently scaling.
The rendered PNG is treated exactly like a photo from there on --
composed/quantized through the existing image_pipeline (letterboxed,
never cropped) rather than a second parallel rendering pipeline.
WebDAV credentials support the common "it's actually the same Nextcloud
account as my CalDAV" case (an explicit opt-in checkbox, not silently
inferred) while still working with any WebDAV server generically.
Frame-level source (URL + owning account) follows the same owner-
controls-their-own-data permission split as calendar sources and the
week view's task list: only the account owner can point a frame at it,
anyone linked can clear it.
Honest limitation: this environment has no Node.js/npm, so
render-service/ is written carefully against each library's documented
API (verified via the npm registry, including transitive dependency
licenses after the CalDAV/AGPL surprise earlier this session) but has
never actually been executed. First real docker build is the first
true test -- see render-service/README.md.
tfaour