The 2.9" tri-colour ESP32 alert badge rendered the red ALERT pill as white:
the red plane (0x26) was received but landed out of bounds and was dropped.
GxEPD2_3C writes the 0x24 (black) plane then the 0x26 (red) plane WITHOUT
re-seeking the RAM address counter between them — it relies on the SSD168x
counter wrapping back to the window start after the last byte of the window.
Our decoder advanced Y past the window end instead of wrapping, so every
0x26 byte hit y >= rows and was discarded (red_ram stayed all-init).
Mirror the hardware: when the X cursor wraps at the end of a row, advance Y
with a wrap at the active window boundary (yrange), honouring the data-entry
Y direction. Applied identically to the worker slave, the browser decoder,
and the Python golden reference so the three stay in lockstep. No regression
on the mono panels (their counter is re-seeked per plane, so the wrap is a
no-op for them); verified the tri-colour pill now renders red and the 2.9"
weather / 2.13" clock / 1.54" hello panels are unchanged.