export type CriticalPathUnitState = "pending" | "active" | "completed" | "cancelled";
export type CriticalPathExecutor = "luna" | "other";
export type CriticalPathDeadlineObservation = "within_deadline" | "deadline_exceeded" | "unknown";
export type CriticalPathFailureObservation = "not_repeated" | "repeated" | "unknown";
export interface CriticalPathUnitObservation {
    readonly unit_id: string;
    readonly depends_on: readonly string[];
    readonly state: CriticalPathUnitState;
    readonly executor: CriticalPathExecutor;
    /** Caller-owned observation. This module never reads a clock or derives a duration. */
    readonly deadline: CriticalPathDeadlineObservation;
    /** Caller-owned observation. This module never reads or mutates an attempt ledger. */
    readonly failures: CriticalPathFailureObservation;
}
export interface CriticalPathInput {
    readonly units: readonly CriticalPathUnitObservation[];
    readonly active_takeover_count: number;
}
export type CriticalPathRejectionCode = "invalid-input" | "invalid-state" | "duplicate-unit" | "unknown-dependency" | "cycle";
export type CriticalPathRuntimeObligation = "accepted-base" | "same-contract" | "source-stopped" | "exclusive-writer" | "final-validation" | "final-review" | "candidate-cas";
export type CriticalPathTakeoverTrigger = "live_deadline_exceeded" | "live_repeated_failure";
export type CriticalPathResult = {
    readonly status: "rejected";
    readonly code: CriticalPathRejectionCode;
    readonly unit_id: string | null;
} | {
    readonly status: "none";
    readonly reason: "active-takeover" | "no-conservative-blocker";
} | {
    readonly status: "proposed";
    readonly unit_id: string;
    readonly reason: "deadline_exceeded" | "repeated_failure";
    readonly structural_basis: "sole-unfinished-direct-dependency-with-completion-reachability";
    readonly runtime_obligations: readonly CriticalPathRuntimeObligation[];
};
/**
 * Pure, conservative structural decision support. It does not estimate duration: a unit blocks only
 * when it is the sole unfinished direct dependency of a downstream node that can reach the virtual
 * completion sink. The sink depends on every DAG leaf, making the last unfinished leaf observable.
 * Runtime remains responsible for every obligation returned with a proposal.
 */
export declare function proposeCriticalPathTakeover(input: unknown): CriticalPathResult;
/** Preserve the policy reason as a runtime trigger without conflating terminal quality rescue. */
export declare function criticalPathTakeoverTrigger(proposal: Extract<CriticalPathResult, {
    readonly status: "proposed";
}>): CriticalPathTakeoverTrigger;