park-lab re-added to resources.toml for the reproduction box: copied from park-2 then
corrected — the copy carried park-2's review outbox (collector URL, booth-2 id, booth-2's
token), which would have fed the training pool under a booth's identity; removed, the
outbox is off on the bench. Pinned to the booth's stage-2d9bb15, comments say what the
lab is for.
Wiki, printer-usb-transport: the failing printer identified (USB 1fc9:2016 "POS-80", NXP
controller, no brand in the descriptor); attached to WSL via usbipd and cover-cycled — no
disconnect, no re-enumeration, so the stale /dev/usb bind-mount hypothesis is falsified
for this unit; the next discriminator is the monitor's offline detail text on park-buzi
(EBUSY / open timeout / EIO). WSL caveat: Microsoft's kernel lacks CONFIG_USB_PRINTER.
fleet-deployment-komodo: park-lab row updated. Log: both entries of the day.
Claude-Session: https://claude.ai/code/session_01FWncR69HgGPuei1dLrW3cU
Printer investigation (park-buzi): cover-open on the USB thermal
printer wedges its status offline/faulty, surviving a full reboot,
recoverable only via `docker restart server`. Traced sendRawUsb/
probeUsb end-to-end — no persistent handle in the app layer, so the
leading theory is the container's /dev/usb directory bind-mount
retaining a stale view across the printer's physical re-enumeration.
Not yet confirmed on hardware; documented with repro/confirmation
commands and ranked candidate fixes.
Also registers a new lab bench box, "art-docker-station", as a Komodo
Stack (dev tier, same shape as park-lab, its own isolated secret refs).
Claude-Session: https://claude.ai/code/session_01FWncR69HgGPuei1dLrW3cU
The kernel numbers usblp nodes by plug/boot order (park-buzi's printer
is lp1); the wizard hardcoded lp0 in labels/default and the admin had to
shell in and `ls /dev/usb`. Now:
- GET /api/setup/usb-printers enumerates /dev/usb/lpN (visible via the
compose bind-mount) and enriches each with the printer's self-reported
make/model from sysfs ieee1284_id (readable through Docker's ro /sys).
- The wizard's devicePath becomes a SELECT of printers actually present
("/dev/usb/lp1 — Xprinter XP-K200L"): a fresh form preselects the
first real device; a saved-but-unplugged path stays selectable,
flagged "saved — not present now"; zero found falls back to free text
+ a check-the-cable hint.
- Transport option label no longer hardcodes lp0.
Wiki: printer-usb-transport marked HARDWARE-VERIFIED (lab 2026-07-07:
full slip + feed + cut over USB — parity with TCP).
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
The chunked-write fix (81bc2e3) still truncated on hardware: the lab
test slip stopped mid-sentence with no feed and no cut (text hidden
until the feed button). Verified against drivers/usb/class/usblp.c:
- write() returns at URB SUBMISSION, not completion;
- only ONE write URB is in flight (the next write EAGAINs until it
completes);
- usblp_release() — our close() — KILLS in-flight URBs.
The printer drains bulk data at PRINT speed (tiny internal buffer on
these clones), so closing right after the last accepted write cancels
the still-transferring tail — exactly where the feed + GS V cut bytes
live. Kernel-accepted ≠ printer-received.
Fix: the one-URB rule makes acceptance of write N a completion
certificate for write N−1. writeAllUsb now writes the payload's FINAL
BYTE alone — its acceptance proves everything before it is physically
in the printer — then drains 300 ms for that single packet before the
caller closes. New test pins the final-byte-alone chunking; wiki
printer-usb-transport.md carries the kernel-level account.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
Field bug (ICS XP-K200L over USB): text printed, barcode + cut missing;
same bytes over TCP fine. sendRawUsb did ONE write() on an O_NONBLOCK
usblp fd and never checked bytesWritten — the kernel accepts only what
fits the printer's ~8 KB USB buffer and returns a short write, so the
tail of any job bigger than one buffer (the barcode mid-payload, the cut
at the end) was silently discarded. The regular-file test stand-in can't
short-write, which is why tests never caught it.
writeAllUsb now pushes 4 KB chunks until every byte is accepted,
continues after partial writes, retries EAGAIN/zero-byte with a short
pause, and fails at the deadline with an (N/M bytes) diagnostic. Driven
by fake-handle tests (short writes, EAGAIN interleave, wedged-printer
timeout, non-EAGAIN passthrough).
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
New concepts/printer-usb-transport.md (the seam, usblp char device,
reachability-only status, threat model). open-questions #14: confirm the
on-site printer is USB and bake the usblp + udev write-access rule into the
appliance image (provisioning, not app code; unverified on hardware). Updated
rongta-printer.md (USB transport note), index.md, log.md.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
julian