/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
import type { Content, PartListUnion } from '@google/genai';
import type { BaseLlmClient } from '../core/baseLlmClient.js';
import type { Config } from '../config/config.js';
import type { LocalLiteRtLmClient } from '../core/localLiteRtLmClient.js';
/**
 * The output of a routing decision. It specifies which model to use and why.
 */
export interface RoutingDecision {
    /** The model identifier string to use for the next API call (e.g., 'gemini-2.5-pro'). */
    model: string;
    /**
     * Metadata about the routing decision for logging purposes.
     */
    metadata: {
        source: string;
        latencyMs: number;
        reasoning: string;
        error?: string;
    };
}
/**
 * The context provided to the router for making a decision.
 */
export interface RoutingContext {
    /** The full history of the conversation. */
    history: readonly Content[];
    /** The immediate request parts to be processed. */
    request: PartListUnion;
    /** An abort signal to cancel an LLM call during routing. */
    signal: AbortSignal;
    /** The model string requested for this turn, if any. */
    requestedModel?: string;
}
/**
 * The core interface that all routing strategies must implement.
 * Strategies implementing this interface may decline a request by returning null.
 */
export interface RoutingStrategy {
    /** The name of the strategy (e.g., 'fallback', 'override', 'composite'). */
    readonly name: string;
    /**
     * Determines which model to use for a given request context.
     * @param context The full context of the request.
     * @param config The current configuration.
     * @param client A reference to the GeminiClient, allowing the strategy to make its own API calls if needed.
     * @returns A promise that resolves to a RoutingDecision, or null if the strategy is not applicable.
     */
    route(context: RoutingContext, config: Config, baseLlmClient: BaseLlmClient, localLiteRtLmClient: LocalLiteRtLmClient): Promise<RoutingDecision | null>;
}
/**
 * A strategy that is guaranteed to return a decision. It must not return null.
 * This is used to ensure that a composite chain always terminates.
 */
export interface TerminalStrategy extends RoutingStrategy {
    /**
     * Determines which model to use for a given request context.
     * @returns A promise that resolves to a RoutingDecision.
     */
    route(context: RoutingContext, config: Config, baseLlmClient: BaseLlmClient, localLiteRtLmClient: LocalLiteRtLmClient): Promise<RoutingDecision>;
}