import { type DiffLine } from "./workflow-yaml-diff.js";
/** Return value of {@link useWorkflowVersionDiff}. */
export interface UseWorkflowVersionDiffReturn {
    /** Array of diff lines, or `null` while loading / on error / when disabled. */
    readonly diff: readonly DiffLine[] | null;
    /** `true` while both versions are being fetched and diffed. */
    readonly isLoading: boolean;
    /** Error from the fetch or diff computation, or `null` when healthy. */
    readonly error: Error | null;
}
/**
 * Data hook that computes a unified YAML diff between two workflow versions.
 *
 * Fetches both version entries via `stigmer.workflow.getVersion()` in
 * parallel, extracts their `validatedYaml` fields, and runs
 * {@link computeUnifiedDiff} to produce a line-by-line diff result.
 *
 * **Graceful degradation**: If the backend returns UNIMPLEMENTED for
 * either fetch, the hook resolves to `null` without raising an error.
 *
 * Pass `null` for any parameter to disable fetching (stable no-op).
 *
 * @example
 * ```tsx
 * const { diff, isLoading } = useWorkflowVersionDiff(workflowId, hashA, hashB);
 *
 * if (diff) {
 *   return <DiffViewer lines={diff} />;
 * }
 * ```
 */
export declare function useWorkflowVersionDiff(workflowId: string | null, hashA: string | null, hashB: string | null): UseWorkflowVersionDiffReturn;
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