/**
 * Pure helpers for SAFELY editing a GTM tag's parameters.
 *
 * GTM's `tags.update` is a FULL replace (PUT) — any field omitted from the request
 * body is cleared. So a naive "send only the new parameter" update WIPES a GA4 event
 * tag's eventName / measurementId / measurementIdOverride / eventSettingsTable. These
 * helpers do the read-modify-write merge that keeps the rest of the tag intact.
 *
 * No runtime googleapis import — types only (erased at build).
 */
import type { tagmanager_v2 } from 'googleapis';
type Param = tagmanager_v2.Schema$Parameter;
type Tag = tagmanager_v2.Schema$Tag;
/** Merge `provided` parameters onto `existing` BY KEY: a provided param with the same
 *  key replaces the existing one; new keys are added; existing keys not provided are
 *  kept. Keyless params (rare for tags) are concatenated. PURE. */
export declare function mergeParametersByKey(existing: Param[], provided: Param[]): Param[];
/** Add GA4 event parameters to a GA4 Event tag (type 'gaawe') by appending them to the
 *  tag's `eventSettingsTable` (the GTM-correct place — NOT top-level params), creating
 *  that table if absent. A param whose name already exists has its VALUE updated rather
 *  than duplicated. Every other field of the tag is preserved. PURE — returns a NEW tag
 *  resource (the caller PUTs it back). */
export declare function addEventParameters(tag: Tag, params: Array<{
    name: string;
    value: string;
}>): Tag;
export {};
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