The Cashino KP-300H printed entry tickets as raster garbage (solid black
bars / banding) while the Rongta printed the same byte stream fine. Root
cause: the barcode overflowed the print line, not data corruption.
A 13-digit Code128 at module width 3 is ~534 dots. The KP-300H prints 72mm
(512 usable dots at 203 dpi), so the symbol overran the line and the firmware
rendered the overflow as raster noise. The Rongta runs 80mm (576 dots) and had
just enough room — which is why only the Cashino failed. Confirmed on hardware:
plain text printed clean, the barcode was the trigger, and an 11-digit code at
width 3 (~468 dots) both fits and scans the full value at the exit reader.
- Ticket IDs reduced 13 → 11 digits (10 random + Luhn). Length is driven by
guess-resistance (10^10 space, ~1-in-10^7 to hit a live OPEN ticket even with
thousands parked — the booth-operator threat model), not volume.
- validateTicketCode is now length-agnostic (\d{10,14} + Luhn) so legacy
13-digit tickets still in circulation keep validating; the id stays opaque.
Also: sendRaw now closes the print socket GRACEFULLY (end()+FIN, wait for
close) instead of write-then-destroy, which could RST mid-stream and truncate a
job. A separate latent bug found while diagnosing, fixed here.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
julian
bbf61c48df