import type { UsageDelta } from './cost.js';
export declare class InferenceError extends Error {
    readonly cause?: unknown | undefined;
    constructor(message: string, cause?: unknown | undefined);
}
export interface InferenceRequest {
    readonly system: string;
    readonly user: string;
    readonly model?: string;
    readonly maxTokens?: number;
}
export interface InferenceResponse {
    readonly text: string;
    readonly usage: UsageDelta;
    readonly backend: 'cli' | 'sdk';
}
export interface InferenceBackend {
    readonly kind: 'cli' | 'sdk';
    isAvailable(): Promise<boolean>;
    run(req: InferenceRequest): Promise<InferenceResponse>;
}
export declare class ClaudeCliBackend implements InferenceBackend {
    private readonly bin;
    readonly kind: "cli";
    constructor(bin?: string);
    isAvailable(): Promise<boolean>;
    run(req: InferenceRequest): Promise<InferenceResponse>;
}
export declare class AnthropicSdkBackend implements InferenceBackend {
    private readonly apiKey?;
    readonly kind: "sdk";
    constructor(apiKey?: string | undefined);
    isAvailable(): Promise<boolean>;
    run(req: InferenceRequest): Promise<InferenceResponse>;
}
export interface SelectBackendOptions {
    /** When true, the SDK fallback is allowed without prompting. */
    readonly allowApiKeyFallback?: boolean;
    /** When set, takes precedence over auto-selection. */
    readonly preferred?: 'cli' | 'sdk';
    /** Override the claude CLI binary path. */
    readonly claudeBin?: string;
    readonly logger?: (msg: string) => void;
    /** When true and stdin is a TTY, prompt before falling back to SDK. */
    readonly interactive?: boolean;
}
export interface SelectBackendResult {
    readonly backend: InferenceBackend | null;
    readonly reason: 'cli-available' | 'sdk-fallback-confirmed' | 'sdk-fallback-allowed-by-flag' | 'sdk-preferred' | 'declined-fallback' | 'no-backend-available';
    readonly insideClaudeCode: boolean;
}
export declare function isInsideClaudeCodeSession(): boolean;
export declare function selectBackend(options?: SelectBackendOptions): Promise<SelectBackendResult>;
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