How I solved cascading context drift in multi-agent Claude Code

I built a multi-agent system with 6 Claude Code instances running in parallel. Three weeks in, it fell apart. Not dramatically. Gradually. One agent would forget what another had decided. A downstream agent would contradict upstream work. By the time I caught it, I had 400 lines of conflicting output and no clean way to reconcile them. This is cascading context drift. And it will kill your multi-agent system if you do not solve it. What context drift actually is Each Claude Code session has its own context window.