/**
 * Layer 2: Agent lifecycle manager.
 *
 * In-memory singleton managing a single Claude Code subprocess.
 * Only one agent task runs at a time (single-developer workflow).
 * The server tracks the active process in module-level state.
 *
 * This module does not import from Layer 1.
 */
import type { Client } from '@libsql/client';
import type { ResolvedConfig } from '../../config.js';
import type { AgentState } from './types.js';
/**
 * Return the current agent state snapshot.
 */
export declare function getActiveAgent(): AgentState;
/**
 * Resolve the absolute path to the Claude CLI binary.
 * Returns the path if found, or null if not installed.
 *
 * Uses the first `claude` on PATH whose `--version` output
 * indicates a modern version (1.x+) that supports `--output-format`.
 */
export declare function resolveClaudePath(): Promise<string | null>;
/**
 * Check whether the Claude CLI is available on the system PATH.
 */
export declare function isClaudeAvailable(): Promise<boolean>;
/**
 * Start the AI agent on a task.
 *
 * Validates preconditions, fetches the task, generates fresh project
 * context, builds the prompt, spawns Claude Code as a child process,
 * and sets up stdout parsing for structured markers.
 *
 * @throws Error if an agent is already active, the task is not found,
 * or the Claude CLI is not installed.
 */
export declare function startAgent(taskId: string, db: Client, config: ResolvedConfig): Promise<AgentState>;
/**
 * Stop the currently running agent.
 *
 * Sends SIGTERM to the child process, resets state to idle,
 * and reverts the task status to backlog.
 *
 * @throws Error if no agent is currently active.
 */
export declare function stopAgent(db: Client): Promise<AgentState>;
/**
 * Unblock the agent by providing an answer to its question.
 *
 * Kills the current process, clears the blocked reason, and restarts
 * the agent with a new prompt that includes the developer's answer.
 *
 * @throws Error if the agent is not in the blocked state.
 */
export declare function unblockAgent(answer: string, db: Client, config: ResolvedConfig): Promise<AgentState>;
/**
 * Reset the agent state to idle. Exposed only for testing.
 * @internal
 */
export declare function _resetForTesting(): void;
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