Validated live against the ESP32 alarm-keypad project. Three fixes over
the initial implementation:
- Active-row model: the write-pin callback only fires on OUTPUT-latch
changes (after the first pass re-driving the row LOW is a no-change
write), and dir alone misses the first pass. A matrix scan drives one
row at a time with the latch LOW, so 'the row that most recently went
active (dir=OUTPUT, or latch write LOW)' IS the scanned row.
- Idempotent install: the canvas effect re-attaches on every boards[]
mutation (each serial line); reinstalling wiped the pressed-key set
mid-scan. Same wiring now keeps the existing state dict.
- Gap-free listeners: the keypad's button-press listeners were attached
on a 300ms setTimeout per effect run, opening a listener-less window
on every re-run in which a press was lost entirely. Attach
synchronously and drop the sendSensorDetach cleanup (detach+reattach
on unrelated re-renders is exactly the wipe the idempotent install
guards against).
2a4d19e9c2