Function maskPreview

lib/redact-engine.ts:172–176

(span: string)

/** Show ≤4 leading chars, mask the rest. Never reconstructable. */
export function maskPreview(span: string): string {
  const visible = span.slice(0, 4);
  const masked = span.length > 4 ? "*".repeat(Math.min(span.length - 4, 8)) : "";
  return `${visible}${masked}${span.length > 12 ? "…" : ""}`;
}

// ── Tool-attributed fence detection ───────────────────────────────────────────