Smart Home Rule Conflicts: Flapping & Debounce Simulator

Automation Rules

Geofence rule — light ON when phone is home, OFF when away.

Schedule rule — light ON from dusk to dawn, OFF in daylight.

Conflict Priority

GPS & Debounce

Geofence radius 40 m

GPS jitter (noise) 6 m

Hysteresis debounce 1.5 s

Clock speed ×60

Live State

Light state

OFF

Sim time

08:00

Distance to fence

0 m

Flaps / 30s

How it works

Two independent automation rules watch the same device — exactly how HomeKit, SmartThings and IFTTT let unrelated automations target one shared light:

geofence.wants = (distance ≤ radius)   // presence
schedule.wants = isNight(simTime)      // dusk→dawn

When the phone lingers near the fence boundary and GPS noise pushes the reported distance back and forth across it, geofence.wants toggles every tick — this is real GPS multipath jitter, not a bug. Left unresolved, a state machine that reacts instantly produces flapping: the light rewrites itself dozens of times a minute.

Two independent fixes, both used by real automation engines:

Conflict priority — decide in advance which rule's wants value is authoritative when they disagree (geofence-priority, schedule-priority), or let whichever rule fired most recently win ("last-write-wins", the naive and flap-prone default).
Hysteresis debounce — a candidate state must persist for a minimum dwell time τ before it is committed:

if candidate ≠ pending: pending ← candidate, t_pending ← now
if (now − t_pending) ≥ τ and pending ≠ committed:
    committed ← pending   // one real device write, flaps++

Debounce trades responsiveness for stability — a longer τ suppresses jitter-driven flaps but delays a genuine, single crossing by up to τ seconds. Set jitter high and debounce to 0 with "Last-write-wins" to watch flapping run away; then raise τ or switch priority mode to see it settle.

⚡ FLAP

Light ON Light OFF Phone / geofence ring

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