/**
 * ResponseDecorator — Causal Invalidation Signal Injection
 *
 * Pure function. Single responsibility: prepend a `[System: ...]`
 * content block to a tool call result when causal invalidation
 * is triggered.
 *
 * The system block goes at **index 0** — a deliberate design choice:
 * it survives response truncation and appears before the developer's
 * payload, maximizing LLM attention.
 *
 * @example
 * ```
 * Before: [{ type: 'text', text: '{"ok": true}' }]
 * After:  [
 *   { type: 'text', text: '<cache_invalidation cause="sprints.update" domains="sprints.*" />' },
 *   { type: 'text', text: '{"ok": true}' },
 * ]
 * ```
 *
 * @module
 */
import type { ToolResponse } from '../core/response.js';
/**
 * Prepend a System invalidation content block to a tool call response.
 *
 * @param result    - The original tool call result (developer's response)
 * @param patterns  - Domain patterns that were invalidated (e.g. `['sprints.*']`)
 * @param causedBy  - The tool name that caused the invalidation
 * @returns A new result with the System block at index 0
 */
export declare function decorateResponse(result: ToolResponse, patterns: readonly string[], causedBy: string): ToolResponse;
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