Function readCapped

src/utils/readEditContext.ts:123–145

(handle: FileHandle)

 * chunks + concat. Reads directly into the right offset; no intermediate copies.
 */
export async function readCapped(handle: FileHandle): Promise<string | null> {
  let buf = Buffer.allocUnsafe(CHUNK_SIZE)
  let total = 0
  for (;;) {
    if (total === buf.length) {
      const grown = Buffer.allocUnsafe(
        Math.min(buf.length * 2, MAX_SCAN_BYTES + CHUNK_SIZE),
      )
      buf.copy(grown, 0, 0, total)
      buf = grown
    }
    const { bytesRead } = await handle.read(
      buf,
      total,
      buf.length - total,
      total,
    )
    if (bytesRead === 0) break
    total += bytesRead
    if (total > MAX_SCAN_BYTES) return null
  }
  return normalizeCRLF(buf, total)
}

/** buf.indexOf bounded to [0, end) without allocating a view. */
function indexOfWithin(buf: Buffer, needle: Buffer, end: number): number {