/** Long enough for an ordinary working session, short enough that a copied
 *  preview URL dies on its own. The guard shell refreshes itself shortly
 *  before this elapses so a long-lived pane never silently breaks. */
export declare const PREVIEW_CONTENT_CAPABILITY_TTL_MS: number;
/** Characters a capability may use inside a URL path segment. */
export declare const PREVIEW_CONTENT_CAPABILITY_PATTERN: RegExp;
export interface PreviewContentCapabilityClaims {
    version: 1;
    purpose: 'preview-content';
    sessionId: string;
    userId: string;
    authSessionId: string;
    capabilityId: string;
    issuedAt: number;
    expiresAt: number;
}
export interface PreviewContentCapabilityIdentity {
    userId: string;
    authSessionId: string;
    /** Authentication expiry of the minting identity; the capability never
     *  outlives the session that created it. */
    expiresAt: number;
}
export type PreviewContentCapabilityVerification = {
    ok: true;
    claims: PreviewContentCapabilityClaims;
} | {
    ok: false;
    reason: 'missing' | 'malformed' | 'invalid' | 'expired' | 'session_mismatch';
};
/**
 * Mint the capability for one session. Returns null (never a fallback token)
 * for out-of-shape identities or an already-expired authentication, so the
 * caller fails closed instead of serving an unauthenticated content path.
 */
export declare function mintPreviewContentCapability(secret: string, sessionId: string, identity: PreviewContentCapabilityIdentity, now?: number): {
    token: string;
    expiresAt: number;
} | null;
export declare function verifyPreviewContentCapability(secret: string, token: string | undefined, expectedSessionId: string, now?: number): PreviewContentCapabilityVerification;
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