User report: clicked Pi 3 board → nothing visible happens. Three
defects, all on the same path:
1. The kernel cmdline carried over from the original pre-OSS-split
code: `quiet init=/bin/sh`. Result: kernel boot messages
suppressed, then dropped straight to bare /bin/sh with no PS1 so
the user sees an empty serial. Removed both. The kernel cmdline
is now just `console=ttyAMA0 root=/dev/mmcblk0p2 rootwait rw
dwc_otg.lpm_enable=0`, which lets systemd start a real
serial-getty@ttyAMA0.service.
2. Pi OS Trixie armhf since Bookworm ships without a default user
(no more pi/raspberry). With cmdline #1 fixed, the user would
land at a login prompt and be stuck. Fix: pre-bake a systemd
drop-in at /etc/systemd/system/serial-getty@ttyAMA0.service.d/
autologin.conf that uses `agetty --autologin root` so the serial
console drops to a root shell on first prompt. The browser
canvas IS the authentication boundary; the SD image is mounted
RO via a qcow2 overlay so per-session edits don't persist.
Edit happens in velxio-prod/scripts/configure-pi3-autologin.sh
(to follow in a separate commit).
3. Architectural: the original cache-hit probe was size-only.
Today's SD image rebake produced a file with identical byte count
but different SHA256 — the cache served stale content for every
request even after a manifest bump. Fix: write a sidecar
`<file>.sha256` after every successful materialise and trust it
on subsequent probes. Manifest SHA bumps invalidate the cache
regardless of size. Two regression tests guard this:
- test_provider_sidecar_invalidates_on_sha_mismatch
- test_provider_missing_sidecar_treats_file_as_invalid
Manifest bumped to version "2026-04-21+autologin" for the SD image
(kernel + DTB unchanged, still 2026-04-21).
b9d39c0bd7