A credential read now routes by what the credential IS: matches a permit
(card/QR credential or a bound plate) -> permit flow; else -> transient exit
flow. Lane resolved once (readerLaneWithAccess); ExitFlow.onRead -> handleAt so
the dispatcher owns lane resolution.
Permit direction is inferred from session state for that car (the read value is
the per-car session key): no open session -> ENTRY (enforce maxConcurrent, sign
vehicle_entry, open); open -> EXIT (sign vehicle_exit, open, close). Fleet
permit = one session per car; anti-passback falls out naturally.
maxConcurrent enforced as a fold over the signed ledger (null = unbound).
Validity window + status + plate-OR-card identity as designed. No ticket/fee;
every use is a signed event carrying permitId. Refusals (revoked / out-of-window
/ at-capacity) are signed anomalies, barrier stays closed.
Verified against stubs: card entry -> inferred exit; fleet cap 2 (F3 rejected
at 2/2, then admitted after F1 exits); plate-bound opens; revoked rejects;
unknown credential falls through to exit reject; verifyChain ok.
julian