FA-67692 / Elevator dispatch scheduling / Member archive

Emergency power sequential return: selection fallback · case 02

The selected car is unavailable or not the first returned car.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

On emergency power in-service cars (not oos) return to the lobby one at a time: occupied cars (load > 0) first, then by lower floor, then id. Each return takes floor*per_floor_s + door_s; starts are cumulative. Afterwards the preselected car runs if it is in service, otherwise the first car of the return order (None if no car).

Why this case matters

Lift group controllers make these decisions many times per minute; a wrong answer strands passengers, wastes trips or overrides a safety rule.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: occupied car first	`{"done_s": 32, "order": ["P2", "P1"], "selected": null, "starts": {"P1": 23, "P2": 0}}`	`{"done_s": 32, "order": ["P2", "P1"], "selected": "P2", "starts": {"P1": 23, "P2": 0}}`	Failed

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