Adds a way to capture the live LVGL screen off the device and rebuild it
as a PNG on the host, so UI changes can be verified remotely without a
camera. A watcher task polls the USB-serial-JTAG RX for a trigger byte and
streams the current screen as raw RGB565 straight to the USB FIFO (framed
by ###SHOT_BEGIN/END### with a CRC); firmware/tools/device_shot.py and the
device-screenshot skill drive it from the host.
Writing straight to the USB FIFO bypasses the primary UART console, which
at 115200 baud would take ~37s per frame. The whole capability is behind
DESKLOCK_DEVMODE (off by default, enable at deploy time with
-DDESKLOCK_DEVMODE=ON) so production spends no internal RAM on the watcher
and nothing extra runs on the render path.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LKPbR6DY2JygHbyLjxm7Uu
jpmschweitzerandClaude Opus 4.8
9521deddc5