AI Dev Stacks Gained Five Agent Layers Fast — but One Critical Layer Is Still Missing

Over the past two years, AI-assisted development introduced several new infrastructure layers, including agent tools like Cursor and Codex, context files, MCP-based tool integrations, isolation via git worktrees, and orchestration systems for managing multiple agents. Each of these layers was adopted quickly because its absence caused immediate, visible problems. However, the article identifies a sixth layer that most teams still lack: a coordination layer that checks whether multiple agents' plans can logically coexist before any code is written. Without it, two agents can each complete their tasks cleanly, pass all checks, and merge without conflict — yet still break the system by working from incompatible assumptions. The proposed solution is a declarative ledger where agents register semantic scopes of intended changes, allowing deterministic conflict detection at the planning stage rather than after the damage is done.