Function scanChunkLines

src/utils/sessionStoragePortable.ts:614–661

(
  s: LoadState,
  buf: Buffer,
  boundaryMarker: Buffer,
)

// Strip attr-snaps, truncate on boundaries. Kept lines write as runs.
function scanChunkLines(
  s: LoadState,
  buf: Buffer,
  boundaryMarker: Buffer,
): { lastSnapStart: number; lastSnapEnd: number; trailStart: number } {
  let boundaryAt = buf.indexOf(boundaryMarker)
  let runStart = 0
  let lineStart = 0
  let lastSnapStart = -1
  let lastSnapEnd = -1
  let nl = buf.indexOf(LF)
  while (nl !== -1) {
    const lineEnd = nl + 1
    if (boundaryAt !== -1 && boundaryAt < lineStart) {
      boundaryAt = buf.indexOf(boundaryMarker, lineStart)
    }
    if (hasPrefix(buf, ATTR_SNAP_PREFIX, lineStart, lineEnd)) {
      sinkWrite(s.out, buf, runStart, lineStart)
      lastSnapStart = lineStart
      lastSnapEnd = lineEnd
      runStart = lineEnd
    } else if (
      boundaryAt >= lineStart &&
      boundaryAt < Math.min(lineStart + BOUNDARY_SEARCH_BOUND, lineEnd)
    ) {
      const hit = parseBoundaryLine(buf.toString('utf-8', lineStart, nl))
      if (hit?.hasPreservedSegment) {
        s.hasPreservedSegment = true // don't truncate; preserved msgs already in output
      } else if (hit) {
        s.out.len = 0
        s.boundaryStartOffset = s.bufFileOff + lineStart
        s.hasPreservedSegment = false
        s.lastSnapSrc = null
        lastSnapStart = -1
        s.straddleSnapCarryLen = 0
        runStart = lineStart
      }
      boundaryAt = buf.indexOf(
        boundaryMarker,
        boundaryAt + boundaryMarker.length,
      )
    }
    lineStart = lineEnd
    nl = buf.indexOf(LF, lineStart)
  }
  sinkWrite(s.out, buf, runStart, lineStart)
  return { lastSnapStart, lastSnapEnd, trailStart: lineStart }
}

// In-buf snap wins over straddle (later in file). carryBuf still valid here.
function captureSnap(