Builds a modified FlashForge update package that the printer installs by
itself from a USB stick, reusing FlashForge's own updater rather than a
parallel one.
Integration is a single file: /usr/prog/PROGRAM/software/firmwareExe is
replaced with a shell script. Everything funnels through that binary, so
app_startup.sh, rcS and the init chain stay completely stock. The genuine
binary is kept as firmwareExe.stock and remains the default UI.
Key findings from the stock firmware, each enforced by a test:
- components named *.tar.xz are PLAIN tar; the installer runs bare `tar -xvf`
- the .tgz is DES3-encrypted plain tar, not gzip
- nothing in init starts Klipper -- firmwareExe runs start.sh, so replacing
the UI without S70klipper leaves a printer that cannot move
- the installer wipes the software dir before run.sh, so an uninstall package
must ship the genuine firmwareExe rather than back one up
- ssh already works: stock ships dropbear + an enabled S50dropbear, only the
root password is missing
Brick-safety is designed in, not bolted on: a five-rung profile ladder
starting with a probe that changes nothing, a container-based simulation that
actually runs the installer and asserts the printer would still boot, an
uninstall round-trip test, and a SAFE-MODE latch for UI crash loops.
75 checks pass. Not yet run on hardware.
