import type { ContractShape } from './types.js';
export interface ContractDiff {
    readonly added: readonly string[];
    readonly removed: readonly string[];
    readonly retained: readonly string[];
    /** True when the diff removes a field — consumers reading it break. */
    readonly breaking: boolean;
}
/**
 * Diff a valve contract between two versions. Removing a field breaks any
 * consumer that reads it; adding a field is additive. Field-level — deep
 * schema-change detection within a retained field is a later refinement.
 */
export declare function diffContract(before: ContractShape, after: ContractShape): ContractDiff;
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