/**
 * Get a Range from the current selection that can see into shadow DOM.
 * Tries `shadowRoot.getSelection` (older Chrome), then `document.getSelection`
 * with a containment check, then `getComposedRanges` (Safari 17+, Chrome 130+)
 * as a fallback when `getRangeAt` can't cross the shadow boundary.
 */
export declare function getShadowRange(shadowRoot: ShadowRoot | null): Range | null;
/**
 * Whether the rich-input caret is at a valid trigger boundary (collapsed, after a
 * newly typed character). Returns true when the character *before* that typed
 * character is start-of-input, space, newline, NBSP, or an element badge — so
 * call from `input` once the trigger key is in the DOM and selection sits after it.
 */
export declare function isAtWordBoundary(shadowRoot: ShadowRoot | null): boolean;
/**
 * Get the bounding position of the caret for overlay anchoring.
 * Returns the position at the trigger character (one char before the caret).
 */
export declare function getCaretRect(shadowRoot: ShadowRoot | null, richInputElement: HTMLElement | null): {
    x: number;
    y: number;
} | null;
/**
 * Extract the trigger search string from the rich input DOM.
 * Scans backwards from the caret in the current text node to find text
 * typed after the trigger character.
 */
export declare function extractTriggerSearchString(shadowRoot: ShadowRoot | null, triggerKey: string): string | null;
/**
 * Focus the rich input and place the caret right after the badge's
 * trailing space node. Uses `setBaseAndExtent` for Safari shadow-DOM
 * compatibility, with `addRange` as a fallback.
 */
export declare function placeCursorAfterBadge(input: HTMLElement, badgeId: string): void;
/**
 * Remove the trigger character and search string from a contenteditable.
 * First tries selection-based removal, then falls back to a text-node scan.
 */
export declare function removeTriggerText(shadowRoot: ShadowRoot | null, richInputElement: HTMLElement, triggerKey: string, searchString: string): void;