Picking a new "Screen Blank Timeout" in SpoolBuddy Settings → Display
didn't change actual blanking behaviour: whatever value was active when
the kiosk last booted continued to fire. A user who started with the
10m preset and switched to 1m or "Off" still saw the screen blank at 10m.
Cause: blanking is driven by swayidle, started once by spoolbuddy-idle.sh
at labwc autostart with the timeout passed as a command-line argument.
The script fetched blank_timeout from the backend exactly once at startup
and swayidle has no runtime control surface for changing its timeout.
The daemon's display.set_blank_timeout() updated an in-memory variable
that was never reached by swayidle, so UI changes were silently discarded
until the next kiosk restart.
Fix: extend the wake FIFO protocol with a "reload-timeout N" message.
The daemon writes it whenever set_blank_timeout() sees a value that
differs from the current one (the very first call is suppressed because
the watchdog already fetched the same value at its own startup —
signalling there would just thrash swayidle on every cold boot). The
script's FIFO loop is restructured around start_swayidle / stop_swayidle
helpers and a case statement: wake → wlopm --on + arm a re-blank at the
current timeout; reload-timeout N → kill running swayidle, set TIMEOUT=N,
restart swayidle, wlopm --on so the user sees the change took effect
even if the screen was already blanked. The script de-dupes too — a
reload-timeout whose N matches the current value is a no-op. Going from
any positive timeout to 0 ("Off") stops swayidle and doesn't restart
it; going from 0 to a positive value starts a fresh swayidle. Both work
without a kiosk restart.
The script's main loop opens the FIFO read+write (exec 3<>"$WAKE_FIFO")
so bash read never sees EOF when the daemon momentarily disconnects
between writes. A cleanup trap on TERM/INT/HUP stops swayidle, removes
the FIFO, and exits cleanly.
Follow-up to the SpoolBuddy LCD power-off fix. Field-testing on a
Raspberry Pi OS Bookworm kiosk showed the watchdog appearing absent
from `ps ax | grep spool` — actually it had already `exec`'d into
`swayidle`, but with no logging there was no way to confirm that
without manually re-running the script.
- spoolbuddy-idle.sh now redirects stdout+stderr to
~/.cache/spoolbuddy-idle.log and prints WAYLAND_DISPLAY,
XDG_RUNTIME_DIR, PATH, the resolved timeout, and the final
`swayidle` command line on every start.
- Auto-detect WAYLAND_DISPLAY by scanning $XDG_RUNTIME_DIR for a
wayland-* socket (10s retry loop) so the script survives the race
where labwc launches autostart before exporting its env.
- Default XDG_RUNTIME_DIR to /run/user/$(id -u) if unset.
The SpoolBuddy kiosk's "screen blank timeout" setting only painted a
black CSS overlay over the browser window — the HDMI panel's backlight
stayed on indefinitely, wasting power and risking burn-in on
OLED/LED panels.
Move blanking down to the OS layer:
- install.sh now installs swayidle + wlopm + jq and rewrites labwc's
autostart to launch a new spoolbuddy-idle.sh watchdog instead of the
old `wlr-randr --on` keep-alive loop.
- The watchdog sources /opt/bambuddy/spoolbuddy/.env, derives device_id
from the first non-loopback MAC (same algorithm as daemon/config.py),
fetches the configured blank_timeout from the backend once on boot,
and execs `swayidle -w timeout $T 'wlopm --off HDMI-A-1' resume
'wlopm --on HDMI-A-1'`. Touch/keypress wakes via labwc's input event
path. timeout=0 skips swayidle entirely so existing installs that
never picked a timeout keep their current always-on behavior.
- New GET /api/v1/spoolbuddy/devices/{id}/display endpoint returns the
current brightness + blank_timeout. Gated on INVENTORY_UPDATE (same
level the daemon heartbeat key already uses) so existing SpoolBuddy
API keys work without extra permissions.
- SpoolBuddyLayout drops blanked state, the blank timer, activity
listeners, resetActivity, and the CSS overlay. Runtime updates to
the timeout take effect on next kiosk/browser restart; default for
newly-enabled blanking is 300 seconds.
maziggy