Every AI coding agent I've used shares one habit: it writes the plausible thing. The code compiles. The tests pass. And a senior engineer reviewing it would reach for a red pen. any where a union belongs. Tests that assert on implementation so they survive any refactor. catch (e) {} blocks that quietly swallow production errors.
The fix isn't a better model or a cleverer prompt. It's a set of rules at the repo level, written in a format the agent is guaranteed to read.
What rules files are
Cursor reads .cursor/rules/*.mdc. Claude Code reads CLAUDE.md and AGENTS.md. The .mdc format is plain markdown with YAML frontmatter. Here's the opening of the TypeScript rule file from the AgentForge sample pack:
description: "Strict TypeScript discipline for production code"
