Deterministic repro (emulation-gaps F4): after pinMode(2, INPUT_PULLUP)
with a correctly-wired button-to-GND, all 8 setup()-time digitalReads
and the first two loop() passes returned 0 — the input register only
got its level from the first SPICE solve (~400 ms). That window is what
fired phantom emergency-stop latches and auto-started state machines in
audited sessions (and an unwired INPUT_PULLUP pin on the qemu bridges
never got driven at all: no net in pinNetMap, connector skips it, guest
read 0 forever).
Fix: PinManager.onPullChange fires on pull transitions; AVRSimulator
seeds its port input to the resting level instantly (real silicon does
this in ns), and makePinPullHandler does the same for the qemu-bridge
boards via the shim's setPinState. Sourced nets are still overridden by
the very next solve, so the 'mis-wired button still works' regression
guarded by the June work cannot return.
eb3b04efe3