// The run's distributed-trace ledger (traces.json): every request the// session made against the target, with the trace id that names its// click→server→DB waterfall in the OTLP store the run exported to.//// Two writers share it — the browser surface (ids harvested off the wire,// the web app sends traceparent itself) and the MCP surface (ids MINTED// here, since mcporter's plain fetch sends none; the server joins whatever// traceparent arrives). Append is read-merge-write so neither clobbers the// other; entries stay sorted by wall clock.import { existsSync, readFileSync, writeFileSync } from "node:fs";import { join } from "node:path"; export interface TraceEntry {  readonly id: string;  readonly at: number;  readonly url: string;  readonly ms?: number;  readonly status?: number;  /** Which window made the request — the viewer's rail tags rows with it. */  readonly source?: "terminal" | "browser";  /** Readable name when the URL alone says nothing (MCP: every call POSTs   *  the same endpoint; the JSON-RPC method/tool is the real identity). */  readonly label?: string;} const fileFor = (runDir: string) => join(runDir, "traces.json"); export const appendTraces = (runDir: string, entries: ReadonlyArray<TraceEntry>): void => {  if (entries.length === 0) return;  const file = fileFor(runDir);  const existing: TraceEntry[] = existsSync(file)    ? (JSON.parse(readFileSync(file, "utf8")) as TraceEntry[])    : [];  const merged = [...existing, ...entries].sort((a, b) => a.at - b.at);  writeFileSync(file, JSON.stringify(merged, null, 1));};