/**
 * Snapshot store with atomic writes and per-instance namespaces.
 *
 * All instance state lives under `.aidlc/state/<instance-name>/`:
 *   - `instance.yaml` — instance metadata
 *   - `phase-<name>.yaml` — per-phase state (one per applicable phase)
 *
 * Write semantics:
 * - Snapshot files use write-to-tmp + rename for atomicity (Req 23.5).
 *   Readers never observe partial writes.
 * - Instance directories are fully isolated — edits to one instance
 *   never touch another instance's files (Req 23.1, 23.3, 6.1).
 *
 * Requirements: 4.1, 6.1, 23.1, 23.3, 23.5
 */
import type { SchemaValidator } from './yaml-helpers.js';
/**
 * Write content to a file atomically using tmp-file + rename.
 *
 * 1. Write to `<filePath>.tmp.<pid>` — unique per process, avoids collisions.
 * 2. Rename the tmp file to the target path — atomic on POSIX filesystems.
 *
 * Parent directories are created if they don't exist.
 */
export declare function atomicWrite(filePath: string, content: string): void;
/**
 * Compute the absolute directory path for an instance namespace.
 *
 * @param stateDir - Root state directory (e.g., `/project/.aidlc/state`).
 * @param instance - Instance name (URL-safe directory name).
 * @returns Absolute path: `<stateDir>/<instance>/`.
 */
export declare function instancePath(stateDir: string, instance: string): string;
/**
 * Create the namespace directory for a new lifecycle instance.
 *
 * @param stateDir - Root state directory.
 * @param name - Instance name.
 * @returns The absolute path to the created directory.
 */
export declare function createInstanceDir(stateDir: string, name: string): string;
/**
 * List all instance namespace directories under the state root.
 *
 * Returns an array of instance names (directory basenames).
 * Only directories are included — stray files at the state root are ignored.
 *
 * @param stateDir - Root state directory.
 * @returns Array of instance names (directory names).
 */
export declare function listInstanceDirs(stateDir: string): string[];
/**
 * Save a snapshot file atomically within an instance namespace.
 *
 * Serializes `data` to deterministic YAML and writes it using
 * tmp-file + rename to guarantee atomic writes (Req 23.5).
 *
 * @param stateDir - Root state directory.
 * @param instance - Instance name.
 * @param fileName - File name within the instance directory (e.g., `instance.yaml`).
 * @param data - Data to serialize and persist.
 */
export declare function saveSnapshot(stateDir: string, instance: string, fileName: string, data: unknown): void;
/**
 * Load and parse a snapshot file from an instance namespace.
 *
 * Optionally validates the parsed data using a schema validator.
 * Throws `YamlLoadError` on missing files, parse errors, or validation failures
 * — always naming the file in the error message (Req 4.7).
 *
 * @param stateDir - Root state directory.
 * @param instance - Instance name.
 * @param fileName - File name within the instance directory.
 * @param validate - Optional schema validator.
 * @returns The parsed (and validated) data cast to `T`.
 * @throws {YamlLoadError} If the file is missing, corrupt, or fails validation.
 */
export declare function loadSnapshot<T = unknown>(stateDir: string, instance: string, fileName: string, validate?: SchemaValidator<T>): T;
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