/**
 * AvatarFallbackElement implements "fallback first" loading pattern:
 * 1. Fallback SVG is rendered immediately as <img> src
 * 2. Real avatar URL is test-loaded in background using new Image()
 * 3. On success, swaps to real image; on failure, fallback stays visible
 *
 * This approach prevents flicker by never showing a broken image state.
 * Inspired by OpenProject's Angular PrincipalRendererService.
 *
 * Note: We read attributes directly via getAttribute() instead of using @attr
 * due to a Catalyst bug where @attr accessors aren't properly initialized
 * when elements have pre-existing attribute values.
 */
export declare class AvatarFallbackElement extends HTMLElement {
    private img;
    private testImage;
    connectedCallback(): void;
    disconnectedCallback(): void;
    /**
     * Test-loads the real avatar URL in background.
     * On success, swaps the visible img to the real URL.
     * On failure, does nothing - fallback stays visible.
     */
    private testLoadImage;
    private applyColor;
    private valueHash;
    private updateSvgColor;
}