/**
 * EgressGuard — Payload Size Limiter (FinOps + OOM Shield)
 *
 * Prevents oversized tool responses from:
 * 1. Crashing the Node process with OOM (JSON.stringify of 30MB)
 * 2. Overflowing the LLM context window ($15 per wasted request)
 * 3. Saturating the transport layer
 *
 * This is a **brute-force safety net** — the last line of defense.
 * Presenter `.agentLimit()` is the domain-aware guard; this is the
 * byte-level guard for when `.agentLimit()` is not configured.
 *
 * Architecture:
 *   ┌──────────────────────────────────────────────┐
 *   │  ToolResponse from handler/Presenter         │
 *   │                                              │
 *   │  ┌──────────┐  within limit? ┌───────────┐  │
 *   │  │ measure  ├────YES────────►│ pass-thru │  │
 *   │  │ bytes    │                └───────────┘  │
 *   │  │          │  exceeds?      ┌───────────┐  │
 *   │  │          ├────YES────────►│ truncate  │  │
 *   │  └──────────┘                │ + inject  │  │
 *   │                              │ guidance  │  │
 *   │                              └───────────┘  │
 *   └──────────────────────────────────────────────┘
 *
 * Properties:
 * - Zero overhead when not configured (guard returns input directly)
 * - Measures byte length via Buffer.byteLength (UTF-8 accurate)
 * - Truncates at the text level, preserving valid ToolResponse shape
 * - Injects system intervention message for LLM self-correction
 *
 * @module
 * @internal
 */
import { type ToolResponse } from '../response.js';
/**
 * Egress guard configuration.
 *
 * @example
 * ```typescript
 * registry.attachToServer(server, {
 *     contextFactory: createContext,
 *     maxPayloadBytes: 2 * 1024 * 1024, // 2MB safety net
 * });
 * ```
 */
export interface EgressConfig {
    /**
     * Maximum total payload size in bytes.
     * When a response exceeds this limit, the text content is
     * truncated and a system intervention message is appended.
     *
     * @minimum 1024 (1KB minimum to avoid unusable responses)
     */
    readonly maxPayloadBytes: number;
}
/**
 * Apply egress guard to a ToolResponse.
 *
 * Measures the total byte length of all text content blocks.
 * If the total exceeds `maxPayloadBytes`, truncates the LAST
 * text block and appends a system intervention message.
 *
 * @param response - The ToolResponse to guard
 * @param maxPayloadBytes - Maximum allowed bytes
 * @returns The original response (if within limit) or a truncated copy
 *
 * @internal
 */
export declare function applyEgressGuard(response: ToolResponse, maxPayloadBytes: number): ToolResponse;
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