Method recordUsage

src/node/services/sessionUsageService.ts:146–155

* Record usage from a completed stream. Accumulates with existing usage * AND updates lastRequest in a single atomic write. * Model should already be normalized via normalizeToCanonical().

(workspaceId: string, model: string, usage: ChatUsageDisplay)

   * Model should already be normalized via normalizeToCanonical().
   */
  async recordUsage(workspaceId: string, model: string, usage: ChatUsageDisplay): Promise<void> {
    return this.fileLocks.withLock(workspaceId, async () => {
      const current = await this.readFile(workspaceId);
      const existing = current.byModel[model];
      // CRITICAL: Accumulate, don't overwrite
      current.byModel[model] = existing ? sumUsageHistory([existing, usage])! : usage;
      current.lastRequest = { model, usage, timestamp: Date.now() };
      await this.writeFile(workspaceId, current);
    });
  }

  /**
   * Persist derived token stats (consumer + file breakdown) as a cache.