/**
 * Shared, dependency-free protocol for server- and client-managed document
 * head elements. Keeping normalization and identity here prevents hydration
 * from making different decisions than the SSR collector.
 */
export declare const HEAD_PROVENANCE_ATTRIBUTE = "data-vf-head";
export declare const HEAD_LEGACY_MANAGED_ATTRIBUTE = "data-veryfront-managed";
export declare const HEAD_CONTENT_HASH_ATTRIBUTE = "data-vf-hash";
export declare const HEAD_REACT_MANAGED_ATTRIBUTE = "data-vf-react-head";
export declare const HEAD_REACT_OWNER_ATTRIBUTE = "data-vf-react-head-owner";
export declare const HEAD_ROUTE_MANAGED_ATTRIBUTE = "data-vf-route-head";
export declare const HEAD_SERVER_COMMIT_ATTRIBUTE = "data-vf-server-head-commit";
export declare const HEAD_SHELL_PROVENANCE_ATTRIBUTE = "data-vf-shell-head";
export declare const HEAD_SSR_PAYLOAD_ATTRIBUTE = "data-vf-ssr-head";
export declare const HEAD_MANAGER_RETIRE_SYMBOL: unique symbol;
/** Request-level limits shared by SSR collection and client route handoff. */
export declare const MAX_MANAGED_HEAD_ENTRIES = 128;
export declare const MAX_MANAGED_HEAD_BYTES: number;
export declare const MAX_MANAGED_HEAD_PAYLOAD_BYTES: number;
export type ManagedHeadContentMode = "text" | "html";
export type ManagedHeadAttribute = readonly [name: string, value: string];
export interface ManagedHeadDescriptor {
    readonly tagName: string;
    readonly attributes: readonly ManagedHeadAttribute[];
    readonly content?: string;
    readonly contentMode: ManagedHeadContentMode;
    readonly signature: string;
    readonly singletonKey?: string;
    /**
     * Every stable identity alias for a script. Both `id` and `src` matter:
     * scripts intersecting on either alias represent the same executable slot.
     */
    readonly scriptKeys: readonly string[];
}
export interface ManagedHeadTransportEntry {
    readonly tagName: string;
    readonly attributes: readonly (readonly [string, string])[];
    readonly content?: string;
}
export declare const BOOLEAN_HEAD_ATTRIBUTES: Set<string>;
export declare function isHeadFrameworkAttribute(name: string): boolean;
export declare function isSingletonHeadMetaKey(key: string | undefined): boolean;
export declare function isSingletonHeadLinkRel(rel: string | undefined): boolean;
export declare function headMetaSingletonKeyFromRecord(meta: Readonly<Record<string, string | undefined>>): string | undefined;
export declare function headLinkSingletonKeyFromRecord(link: Readonly<Record<string, string | undefined>>): string | undefined;
export declare function normalizeManagedHeadString(value: string): string;
export declare function readManagedHeadContent(props: Readonly<Record<string, unknown>>): {
    content?: string;
    isRawHTML: boolean;
} | null;
export declare function normalizeManagedHeadAttributes(tagName: string, props: Readonly<Record<string, unknown>>, ambientNonce?: string): readonly ManagedHeadAttribute[] | null;
export declare function descriptorFromHeadProps(rawTagName: string, props: Readonly<Record<string, unknown>>, ambientNonce?: string): ManagedHeadDescriptor | null;
/**
 * Normalizes a collector/frontmatter head record through the same bounded
 * protocol used for React props. `contentProperty` identifies inline
 * script/style text and is never emitted as an HTML attribute.
 */
export declare function descriptorFromManagedHeadRecord(rawTagName: string, record: Readonly<Record<string, unknown>>, options?: {
    readonly contentProperty?: string;
    readonly ambientNonce?: string;
}): ManagedHeadDescriptor | null;
export declare function scriptIdentityKeysFromRecord(script: Readonly<Record<string, string | undefined>>): readonly string[];
export declare function headScriptKeysIntersect(left: readonly string[], right: readonly string[]): boolean;
/**
 * Page/layout aggregation contract shared with the SSR collector.
 * Singletons are last-wins in the first slot, repeatables preserve order, and
 * executable scripts are first-wins when any stable identity alias intersects.
 */
export declare function aggregateManagedHeadDescriptors(descriptors: readonly ManagedHeadDescriptor[]): ManagedHeadDescriptor[];
export declare function managedHeadDescriptorBytes(descriptor: ManagedHeadDescriptor): number;
export declare function assertManagedHeadDescriptorBudget(descriptors: readonly ManagedHeadDescriptor[]): void;
export declare function managedHeadDescriptorToTransportEntry(descriptor: ManagedHeadDescriptor): ManagedHeadTransportEntry;
export declare function descriptorFromManagedHeadTransportEntry(entry: unknown, ambientNonce?: string): ManagedHeadDescriptor;
export declare function serializeManagedHeadPayload(descriptors: readonly ManagedHeadDescriptor[]): string;
export interface ManagedHeadPayloadInspection {
    readonly descriptors: ManagedHeadDescriptor[];
    readonly entryCount: number;
    readonly descriptorBytes: number;
    readonly payloadBytes: number;
}
export declare function inspectManagedHeadPayload(payload: string, ambientNonce?: string): ManagedHeadPayloadInspection;
export declare function deserializeManagedHeadPayload(payload: string, ambientNonce?: string): ManagedHeadDescriptor[];
export declare function escapeManagedHeadRawText(content: string, tagName: string): string;
export declare function managedHeadContentHash(content: string): string;
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