The overlay at /overlay/{printer} draws live print data over a
full-screen camera view for OBS, a wall display or any browser source.
It has been tunable since it shipped -- which fields, what size, what
frame rate -- but only through query parameters documented in the wiki,
and temperatures were not among the fields on offer. The request asked
for temperatures first and for the field set to be selectable in the web
UI; this addresses both.
Nozzle, bed and chamber readings join the list. The target is drawn only
while the heater is still climbing, so a settled hotend reads "220°C"
for the rest of the print instead of the noisier "220 / 220°C" -- 219.6
against a target of 220 rounds to the same number, and repeating it says
nothing. Both nozzles appear on a dual-nozzle machine. They are drawn
whether or not a print is running, because a preheating printer is
exactly when they are worth watching, and each reading appears only when
the printer genuinely reports one: chamber temperature stays absent on
P1 and A1 models, which publish a chamber_temper with no sensor behind
it, so the overlay never puts a measurement on screen that does not
exist. Labels reuse the heater chart's strings rather than inventing a
second vocabulary for the same three things.
The feed sends an allow-list rather than the temperatures dict. That
dict doubles as the MQTT client's working memory -- derived heater flags
and private target-set timestamps live alongside the readings -- and an
overlay token is a narrower grant than a login, so it gets exactly what
the overlay draws and does not pick up fields as the dict grows. The
same chamber-sensor gate the full status payload already applies is
applied here. The integration test that asserts the payload's exact key
set, which exists to catch that surface widening silently, is updated
deliberately.
Temperatures are not in the default field set, so an overlay URL already
pasted into a scene renders identically after upgrading.
Settings -> API Keys -> Streaming Overlay now builds the URL: printer,
field checkboxes, size, frame rate, camera toggle, an optional token,
and a copy button. It persists nothing and calls nothing new -- the URL
is the configuration, which keeps a scene reproducible by copy-paste and
lets two displays show different fields off one token. Fields are
emitted in the overlay's own top-to-bottom order rather than click
order, and parameters left at their default are omitted, so the same
selection always produces the same URL. The preview alongside it stays
off until asked for: an always-live iframe would hold a subscriber on
the printer's single camera connection for as long as the settings tab
stayed open.
The preview needed one narrow security-header change. Every SPA route
sent frame-ancestors 'none', which is stricter than the SAMEORIGIN in
X-Frame-Options beside it and refuses even a same-origin frame, so the
preview showed Firefox's "another site has embedded it" page instead of
the overlay. The overlay path now sends 'self', mirroring /gcode-viewer,
which admits a framer only on this origin -- Bambuddy's own UI. Every
other path keeps 'none', and embedding the overlay from another host
still requires TRUSTED_FRAME_ORIGINS.
The /overlay/{id} route renders without a login, but everything it draws is
auth-gated: printer status and name (PRINTERS_READ), one setting (SETTINGS_READ),
and the camera stream (a camera-stream token). A signed-in browser rides its JWT
from local storage; OBS is a fresh browser with no session, so the overlay stayed
blank whenever authentication was enabled. Cloudflare/remote access was never the
cause -- an incognito window fails identically.
Give the overlay a self-contained kiosk-token mode, mirroring the Cam Wall:
- New `overlay` long-lived-token scope, kept separate from `camwall`: the overlay
names the printed file on screen, which a Cam Wall token is trusted never to
expose, so folding it in would silently widen every existing wall token.
- New token-authed GET /printers/{id}/overlay-status returning exactly the fields
the overlay draws and nothing else; added to the auth-middleware allowlist so it
reaches its own RequireOverlayTokenIfAuthEnabled gate.
- StreamOverlayPage reads ?token= and, in that mode, authenticates its status and
camera calls with the token and skips the WebSocket (the 2s poll is the feed).
The logged-in path is unchanged.
- Token-mint UI (Settings > API Keys) offers the scope with a ready-made
/overlay/{id}?token= URL copied once on creation.
Adam Spice