Class FileSnapshotStore

packages/agent-tracing/src/store/file-store.ts:10–169

const PARTIAL_DIR = '_partial';

export class FileSnapshotStore implements ISnapshotStore {
  private dir: string;

  constructor(rootDir?: string) {
    this.dir = path.resolve(rootDir ?? process.cwd(), DEFAULT_DIR);
  }

  // ==================== Completed snapshots ====================

  async save(snapshot: ExecutionSnapshot): Promise<void> {
    await fs.mkdir(this.dir, { recursive: true });

    const ts = new Date(snapshot.startedAt).toISOString().replaceAll(':', '-');
    const shortId = snapshot.traceId.slice(0, 12);
    const filename = `${ts}_${shortId}.json`;
    const filePath = path.join(this.dir, filename);

    await fs.writeFile(filePath, JSON.stringify(snapshot, null, 2), 'utf8');

    // Update latest symlink
    const latestPath = path.join(this.dir, 'latest.json');
    try {
      await fs.unlink(latestPath);
    } catch {
      // ignore if doesn't exist
    }
    await fs.symlink(filename, latestPath);
  }

  async get(traceId: string): Promise<ExecutionSnapshot | null> {
    if (traceId === 'latest') return this.getLatest();

    // Search completed snapshots first
    const files = await this.listFiles();
    const match = files.find((f) => f.includes(traceId.slice(0, 12)));
    if (match) {
      const content = await fs.readFile(path.join(this.dir, match), 'utf8');
      return JSON.parse(content) as ExecutionSnapshot;
    }

    // Fallback to partials
    const partial = await this.getPartial(traceId);
    if (partial) return partialToSnapshot(partial);

    return null;
  }

  async list(options?: { limit?: number }): Promise<SnapshotSummary[]> {
    const files = await this.listFiles();
    const limit = options?.limit ?? 10;
    const recent = files.slice(0, limit);

    const summaries: SnapshotSummary[] = [];

    for (const file of recent) {
      try {
        const content = await fs.readFile(path.join(this.dir, file), 'utf8');
        const snapshot = JSON.parse(content) as ExecutionSnapshot;