Disassembly confirmed the bench theory: the no-ACK wait loop at $D9E0
self-clocks in byte times (each tick transmits an IDLE keep-alive and
re-enters on its TX-complete interrupt), so raising the baud silently
shrank the ACK grace from ~5.2ms to ~1.6ms - under USB turnaround,
hence the v1 retry storm. --widen-ackwait (requires --baud31250) sets
the limit to 40 ticks (~12.8ms at 31250). v2 image: 25 bytes changed,
sha256 420d4cfc...; re-disasm diff vs v1 is exactly the CMPA operand.
v1/classic hashes reproduce unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
