/** Formats the widget's content drawer can render. */
export declare const WIDGET_DISPLAY_FORMATS: readonly ["text", "markdown", "code", "html"];
/**
 * Parse a user-supplied JSON string into a userVariables object. Returns an
 * empty object on null/undefined/empty input, and on parse failure logs a
 * warning and returns an empty object — never throws.
 */
export declare function parseUserVariablesAttribute(raw: string | null | undefined): Record<string, unknown>;
/**
 * Merge widget self-advertisement (display_content capability + opened_at
 * timestamp) into a userVariables object. User-supplied keys win on shallow
 * conflict; capability and metadata sub-objects are deep-merged one level so
 * callers can add their own keys without losing the widget's signal.
 *
 * The shape matches what `Sigmond2Agent._caller_has_display` looks for:
 *   - `capabilities.display_content` (signal #1)
 *   - `metadata.widget.opened_at`    (signal #2)
 */
export declare function withWidgetCapabilities(base: Record<string, unknown>, now?: () => string): Record<string, unknown>;
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