/**
 * Gemini CLI backend.
 *
 * Implements the {@link AIBackend} interface for the Gemini CLI (`gemini`).
 * Parses the JSON output format produced by `gemini -p <prompt> --output-format json`,
 * extracts token metrics from `stats.models`, and maps ARE model aliases
 * to Gemini model identifiers.
 *
 * @module
 */
import type { AIBackend, AICallOptions, AIResponse } from '../types.js';
/**
 * Gemini CLI backend.
 *
 * @example
 * ```typescript
 * const backend = new GeminiBackend();
 * if (await backend.isAvailable()) {
 *   const args = backend.buildArgs({ prompt: 'Hello', model: 'flash' });
 *   // → ['-p', 'Hello', '--output-format', 'json', '-m', 'gemini-3-flash-preview']
 * }
 * ```
 */
export declare class GeminiBackend implements AIBackend {
    readonly name = "gemini";
    readonly cliCommand = "gemini";
    isAvailable(): Promise<boolean>;
    /**
     * Build CLI arguments for a Gemini invocation.
     *
     * Uses `-p <prompt>` for headless mode and `--output-format json` for
     * structured output. Unlike the Claude CLI (where `-p` means
     * "non-interactive mode" and the prompt goes to stdin), Gemini CLI's
     * `-p`/`--prompt` flag requires the prompt text as its argument value.
     *
     * The system prompt is folded into the prompt using XML tags since
     * Gemini CLI has no `--system-prompt` flag.
     */
    buildArgs(options: AICallOptions): string[];
    /**
     * Compose stdin input for the subprocess.
     *
     * Returns an empty string because Gemini CLI receives the prompt via
     * the `-p` argument, not stdin.
     */
    composeStdinInput(_options: AICallOptions): string;
    /**
     * Parse Gemini CLI JSON output into a normalized {@link AIResponse}.
     *
     * Handles the `{ response, stats, error }` shape produced by
     * `gemini -p --output-format json`. Token metrics are extracted from
     * `stats.models[modelName].tokens` when available.
     */
    parseResponse(stdout: string, durationMs: number, exitCode: number): AIResponse;
    getInstallInstructions(): string;
    /**
     * Extract the JSON object from stdout, handling potential prefix text
     * (e.g., version notices, warnings) before the JSON body.
     */
    private extractJson;
    /**
     * Extract token counts and model name from the `stats.models` map.
     *
     * If multiple models appear (e.g., routing), tokens are aggregated and
     * the first model name is used. Returns zeros if stats are absent.
     */
    private extractMetrics;
}
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