Method getSessionUsage

src/node/services/sessionUsageService.ts:341–367

* Read current session usage. Returns undefined if file missing/corrupted * and no messages to rebuild from.

(workspaceId: string)

   * and no messages to rebuild from.
   */
  async getSessionUsage(workspaceId: string): Promise<SessionUsageFile | undefined> {
    return this.fileLocks.withLock(workspaceId, async () => {
      try {
        const filePath = this.getFilePath(workspaceId);
        const data = await fs.readFile(filePath, "utf-8");
        return JSON.parse(data) as SessionUsageFile;
      } catch (error) {
        // File missing or corrupted - try to rebuild from messages
        if (error && typeof error === "object" && "code" in error && error.code === "ENOENT") {
          const messages = await this.collectFullHistory(workspaceId);
          if (messages.length > 0) {
            await this.rebuildFromMessagesInternal(workspaceId, messages);
            return this.readFile(workspaceId);
          }
          return undefined; // Truly empty session
        }
        // Parse error - try rebuild
        log.warn(`session-usage.json corrupted for ${workspaceId}, rebuilding`);
        const messages = await this.collectFullHistory(workspaceId);
        if (messages.length > 0) {
          await this.rebuildFromMessagesInternal(workspaceId, messages);
          return this.readFile(workspaceId);
        }
        return undefined;
      }
    });
  }

  /**
   * Reset a workspace's persisted cost ledger while keeping copied chat history intact.