Detect Zone Transition

How it fits

Typical backends

Caveats

• I/O contractThe output is the current classification per id this tick, relative to where the id was first seen — not a one-shot edge. While an id stays inside (having started outside) every tick keeps emitting an enter code, so diff against the previous tick downstream if one-shot alerts are needed. Empty input yields empty output.
• Parameter interactionThe decision is a majority vote over the last history_size ticks, so a transition can land up to history_size minus one ticks late; a tie (possible on even history_size when the window is exactly split) returns no-change.
• State lifetimePer-id state persists across ticks; an id unseen for longer than forget_threshold frames is forgotten, and a temporary exit-then-reentry within that gap is not treated as a fresh entry.
• Hard constraintTracking-id stability matters: if the upstream tracker re-uses an id across different objects, the component emits ghost transitions.
• CostPure CPU; per-tick cost grows with the number of active ids and the history length, and both configuration keys are captured once at startup.