/** Diagnostic codes emitted while registering or resolving viewers. */
export type ViewerRegistryDiagnosticCode = 'default-not-found' | 'deprecated-details-normalized' | 'explicit-not-found' | 'matcher-error';
/** Structured diagnostic event from viewer registration or resolution. */
export interface ViewerRegistryDiagnostic {
    code: ViewerRegistryDiagnosticCode;
    error?: unknown;
    identity?: string;
    message: string;
    viewerId?: string;
}
/** Registered viewer entry with optional aliases and a payload matcher. */
export interface ViewerRegistryEntry<TPayload, TViewer> {
    aliases?: readonly string[];
    id: string;
    matches: (payload: TPayload) => boolean;
    viewer: TViewer;
}
/** Error codes raised when registering a viewer fails. */
export type ViewerRegistryRegistrationErrorCode = 'duplicate-alias' | 'duplicate-id' | 'invalid-identity';
/** Error thrown when a viewer cannot be registered in the registry. */
export declare class ViewerRegistryRegistrationError extends Error {
    readonly code: ViewerRegistryRegistrationErrorCode;
    readonly identity?: string;
    constructor(code: ViewerRegistryRegistrationErrorCode, message: string, identity?: string);
}
/** Result of matching a payload against registered viewers. */
export interface ViewerRegistryMatchResult<TPayload, TViewer> {
    diagnostics: ViewerRegistryDiagnostic[];
    matches: ViewerRegistryEntry<TPayload, TViewer>[];
}
/** How a resolved viewer was selected from the registry. */
export type ViewerRegistrySelectionSource = 'default' | 'explicit' | 'fallback' | 'none' | 'ordered';
/** Options controlling how {@link ViewerRegistry} resolves a viewer for a payload. */
export interface ViewerRegistryResolveOptions<TPayload, TViewer> {
    allowExplicitMismatch?: boolean;
    defaultId?: string;
    explicitId?: string;
    fallback?: TViewer;
    payload: TPayload;
}
/** Result of resolving a single viewer for a payload, including source and diagnostics. */
export interface ViewerRegistryResolveResult<TPayload, TViewer> extends ViewerRegistryMatchResult<TPayload, TViewer> {
    entry?: ViewerRegistryEntry<TPayload, TViewer>;
    source: ViewerRegistrySelectionSource;
    viewer?: TViewer;
}
/** Construction options for {@link ViewerRegistry}. */
export interface ViewerRegistryOptions {
    onDiagnostic?: (diagnostic: ViewerRegistryDiagnostic) => void;
}
/** Registry that matches payloads to registered viewers by id, alias, or matcher. */
export declare class ViewerRegistry<TPayload, TViewer> {
    private readonly entries;
    private readonly identities;
    private readonly onDiagnostic?;
    constructor({ onDiagnostic }?: ViewerRegistryOptions);
    get(identity: string): ViewerRegistryEntry<TPayload, TViewer> | undefined;
    list(): ViewerRegistryEntry<TPayload, TViewer>[];
    match(payload: TPayload): ViewerRegistryMatchResult<TPayload, TViewer>;
    register(entry: ViewerRegistryEntry<TPayload, TViewer>): this;
    resolve({ allowExplicitMismatch, defaultId, explicitId, fallback, payload, }: ViewerRegistryResolveOptions<TPayload, TViewer>): ViewerRegistryResolveResult<TPayload, TViewer>;
    private reportMissing;
}
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