/**
 * Which bus the daemon hands its engine, and whether exec mediation arms (DES-TEAMING-002 T0) —
 * one pure decision, so every branch is testable without booting a daemon.
 *
 * The rule: an UNAVAILABLE bus dominates every branch. Whichever file the engine would get — the
 * crew bus for an engine with the one-connection rule, or (an engine without it, under
 * `--engine-exec`) the pre-T0 exec bus — if crew's boot probe could not open it, the engine is
 * handed NO bus, exec mediation stays off, and the reason rides `/health.warnings`. Otherwise the
 * engine gets that file, and exec mediation arms exactly when `--engine-exec` asked for it.
 */
export interface BusUnavailable {
    dbPath: string;
    reason: string;
    /** Which failure (see `core/bus-notice.ts`): crew's probe could not open the file, or the engine
     *  could not arm its bus bridge on it. */
    kind: 'probe_open' | 'bridge_not_armed';
}
export interface EngineBusInput {
    /** The linked engine carries the one-connection rule (`Core.busConnectionStats`). */
    engineRule: boolean;
    /** `--engine-exec` / `WICKED_BUS_EXEC` asked for exec mediation. */
    engineExec: boolean;
    /** The crew bus (`resolveCrewBus`) and its boot probe (`undefined` = it opened). */
    busDbPath: string;
    busUnavailable: BusUnavailable | undefined;
    /** The pre-T0 exec bus an engine without the rule gets under `--engine-exec`, and its probe. */
    preRuleExecBusDbPath: string;
    preRuleExecUnavailable: BusUnavailable | undefined;
}
export type EngineBusHandoff = {
    busDbPath: string;
    engineExec: boolean;
} | {
    busUnavailable: BusUnavailable;
    engineExec: false;
} | {
    engineExec: false;
};
export declare function engineBusHandoff(input: EngineBusInput): EngineBusHandoff;
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