// Session file helpers share bounded random-access reads across transcript consumers.

import type { FileHandle } from "node:fs/promises";

export async function readFileRangeAsync(

fileHandle: FileHandle,

position: number,

length: number,

): Promise<Buffer> {

const buffer = Buffer.alloc(length);

let offset = 0;

while (offset < length) {

const { bytesRead } = await fileHandle.read(buffer, offset, length - offset, position + offset);

if (bytesRead <= 0) {

break;

}

offset += bytesRead;

}

return offset === length ? buffer : buffer.subarray(0, offset);

}

// Transcript streaming reads large JSONL files forward or backward without whole-file buffering.

import fs from "node:fs";

import readline from "node:readline";

import { readFileRangeAsync } from "./file-range.js";

// Shared streaming helpers for JSONL session transcripts.

//

const trimmed = line.toString("utf-8").trim();

return trimmed;

}

async function readFileRangeAsync(

fileHandle: Awaited<ReturnType<typeof fs.promises.open>>,

position: number,

length: number,

): Promise<Buffer> {

const buffer = Buffer.alloc(length);

let offset = 0;

while (offset < length) {

const { bytesRead } = await fileHandle.read(buffer, offset, length - offset, position + offset);

if (bytesRead <= 0) {

break;

}

offset += bytesRead;

}

return offset === length ? buffer : buffer.subarray(0, offset);

}

SessionEntry,

} from "../config/sessions.js";

import { isCompactionCheckpointTranscriptFileName } from "../config/sessions/artifacts.js";

import { readFileRangeAsync } from "../config/sessions/file-range.js";

import { streamSessionTranscriptLines } from "../config/sessions/transcript-stream.js";

import { scanSessionTranscriptTree } from "../config/sessions/transcript-tree.js";

import { CURRENT_SESSION_VERSION } from "../config/sessions/version.js";

const SESSION_HEADER_READ_MAX_BYTES = 64 * 1024;

const SESSION_TAIL_READ_INITIAL_BYTES = 64 * 1024;

type AsyncTranscriptFileHandle = Awaited<ReturnType<typeof fs.open>>;

async function readFileRangeAsync(

fileHandle: AsyncTranscriptFileHandle,

position: number,

length: number,

): Promise<Buffer> {

const buffer = Buffer.alloc(length);

let offset = 0;

while (offset < length) {

const { bytesRead } = await fileHandle.read(buffer, offset, length - offset, position + offset);

if (bytesRead <= 0) {

break;

}

offset += bytesRead;

}

return offset === length ? buffer : buffer.subarray(0, offset);

}

async function readSessionHeaderFromTranscriptAsync(

sessionFile: string,

): Promise<{ id: string; cwd?: string } | null> {

let fileHandle: AsyncTranscriptFileHandle | undefined;

let fileHandle: Awaited<ReturnType<typeof fs.open>> | undefined;

try {

fileHandle = await fs.open(sessionFile, "r");

const buffer = await readFileRangeAsync(fileHandle, 0, SESSION_HEADER_READ_MAX_BYTES);

sessionFile: string,

maxBytes = MAX_COMPACTION_CHECKPOINT_LEAF_SCAN_BYTES,

): Promise<{ entryId: string; leafId: string | null } | null> {

let fileHandle: AsyncTranscriptFileHandle | undefined;

let fileHandle: Awaited<ReturnType<typeof fs.open>> | undefined;

try {

fileHandle = await fs.open(sessionFile, "r");

const stat = await fileHandle.stat();