Anyone successfully running 5+ AI agents on a single repo? How are you dealing with semantic merge conflicts?

My team recently started scaling up our autonomous agent swarm. We have about 5 agents running in the background picking up tickets, writing code, and submitting PRs.

The productivity is crazy, but we just hit a massive wall with standard Git.

Because the agents are coding concurrently, they keep silently breaking each other's logic. For example, yesterday Agent A renamed a core auth function. At the exact same time, Agent B wrote a new API endpoint that called the old function name.

Standard Git line-based merge said there were 0 conflicts and merged it cleanly because they edited different lines. The CI passed, but the code was completely broken at runtime. We are spending half our day tracking down these "phantom regressions."

For teams that are actually running multi-agent swarms in production: how are you managing this? Are you just using standard Git and hoping for the best? Is there any tool that does AST-aware merging for AI agents so they stop blindly overwriting each other?