Function parseBoundaryLine

src/utils/sessionStoragePortable.ts:491–509

* Confirm a byte-matched line is a real compact_boundary (marker can appear * inside user content) and check for preservedSegment.

(
  line: string,
)

 * inside user content) and check for preservedSegment.
 */
function parseBoundaryLine(
  line: string,
): { hasPreservedSegment: boolean } | null {
  try {
    const parsed = JSON.parse(line) as {
      type?: string
      subtype?: string
      compactMetadata?: { preservedSegment?: unknown }
    }
    if (parsed.type !== 'system' || parsed.subtype !== 'compact_boundary') {
      return null
    }
    return {
      hasPreservedSegment: Boolean(parsed.compactMetadata?.preservedSegment),
    }
  } catch {
    return null
  }
}

/**
 * Single forward chunked read for the --resume load path. Attr-snap lines