Your .cursorrules file is not broken. It is just being applied to the wrong problem. Most developers write one big .cursorrules file and put it at the root of their monorepo. One file. Every rule. Every stack. Every service — frontend, backend, infra, scripts, tests — all governed by the same blob of instructions. Then they switch to Cursor Agent Mode and discover the rules are being ignored. Not partially ignored. Silently, completely ignored. Here is why. The Real Reason .cursorrules Breaks in Agent Mode Cursor Agent Mode does not use the legacy .cursorrules format in the same way as Chat Mode. When Agent Mode runs, it loads context differently. If your .cursorrules file is large, broad, or not scoped to the current task, the agent either ignores it or loads it with low priority — and no warning appears in the UI. The file exists. Cursor reads it. It just does not honor it in the way you expect when the agent is autonomously navigating your codebase. The real issue is scope.…