/**
 * Child file read operations for ChildWriter.
 *
 * Extracts read, merge, and path-resolution methods that don't need
 * direct queue infrastructure. Used by ChildWriter for all read-path
 * operations on child session `.json` files.
 *
 * @module session-tracker/persistence/child-reader
 */
import type { ChildSessionRecord } from "../types.js";
import type { HierarchyIndex } from "./hierarchy-index.js";
/**
 * Gets the absolute path to a child session `.json` file.
 *
 * @param projectRoot - Absolute path to the project root.
 * @param parentSessionID - The parent session identifier.
 * @param childSessionID - The child session identifier.
 * @returns Absolute path to the child `.json` file.
 */
export declare function getChildFilePath(projectRoot: string, parentSessionID: string, childSessionID: string): string;
/**
 * Reads and parses an existing child session `.json` file.
 *
 * @param projectRoot - Absolute path to the project root.
 * @param parentSessionID - The parent session identifier.
 * @param childSessionID - The child session identifier.
 * @returns The parsed child session record.
 * @throws If the file does not exist or cannot be parsed.
 */
export declare function readChildFile(projectRoot: string, parentSessionID: string, childSessionID: string): Promise<ChildSessionRecord>;
/**
 * Reads an existing child file if it exists (returns undefined on failure).
 *
 * @param projectRoot - Absolute path to the project root.
 * @param parentSessionID - The directory-owning parent session ID.
 * @param childSessionID - The child session identifier.
 * @returns Existing child record, or `undefined` when no file exists.
 */
export declare function readExistingChildFile(projectRoot: string, parentSessionID: string, childSessionID: string): Promise<ChildSessionRecord | undefined>;
/**
 * Checks if a child session `.json` file exists on disk.
 *
 * Resolves via hierarchy index (D-03 root main directory) first,
 * then falls back to scanning all session-tracker subdirectories.
 *
 * @param projectRoot - Absolute path to the project root.
 * @param hierarchyIndex - Optional hierarchy index for root main resolution.
 * @param parentSessionID - The parent session ID.
 * @param childSessionID - The child session ID.
 * @param resolveWriteParent - Function to resolve the correct write parent.
 * @returns True if the file exists on disk.
 */
export declare function childFileExists(projectRoot: string, _hierarchyIndex: HierarchyIndex | undefined, parentSessionID: string, childSessionID: string, resolveWriteParent: (childID: string, immediateParentID: string) => string): Promise<boolean>;
/**
 * Reads a child session record from disk using only the child session ID.
 *
 * Resolves the parent directory via hierarchy index, then falls back to
 * scanning all session-tracker subdirectories if the index is unavailable.
 *
 * @param projectRoot - Absolute path to the project root.
 * @param hierarchyIndex - Optional hierarchy index for parent resolution.
 * @param sessionID - The child session identifier to look up.
 * @returns The parsed child session record, or `undefined` if not found.
 */
export declare function readChildData(projectRoot: string, hierarchyIndex: HierarchyIndex | undefined, sessionID: string): Promise<ChildSessionRecord | undefined>;
/**
 * Merges new child metadata into an existing record without losing live data.
 *
 * @param existing - Existing child record from disk, if any.
 * @param metadata - New metadata to apply.
 * @returns Merged child record safe to write back to disk.
 */
export declare function mergeChildRecord(existing: ChildSessionRecord | undefined, metadata: ChildSessionRecord): ChildSessionRecord;
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