How I Run Two AI Coding Agents on One Codebase

Parallel coding agents create a concurrency problem before they create a productivity gain. Two autonomous processes that edit the same checkout can overwrite files, invalidate assumptions, contaminate test state, or produce changes that are individually correct but jointly incompatible. A safer operating model treats each agent as an isolated contributor with a dedicated Git worktree, an explicit file-level contract, deterministic validation commands, and no authority to integrate directly into the protected branch.