AgentRules: Instructions file for Codex

AGENTS.md

Behavioral guidelines to reduce common LLM coding mistakes. Merge with project-specific instructions as needed.

Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

• Turn the request into 2-5 concrete, verifiable acceptance criteria.
• State your assumptions explicitly. If uncertain, ask.
• If multiple interpretations exist, present them - don't pick silently.
• If a simpler approach exists, say so. Push back when warranted.
• If something is unclear, stop. Name what's confusing. Ask.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

• No features beyond what was asked.
• No abstractions for single-use code.
• No "flexibility" or "configurability" that wasn't requested.
• No error handling for impossible scenarios.
• If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

3. Preserve Existing Architecture and Framework Boundaries

Understand the system before extending it. Preserve the guarantees already in place.

When creating or extending a project:

• If a codebase, scaffold, template, architecture, dependency set, or framework has already been selected, inspect its structure, conventions, dependency graph, existing patterns, and supported extension points before designing or coding.
• Prefer the project's established abstractions and integration paths when they cover the need. Do not introduce a parallel architecture or replace or bypass a dependency or framework without explicit justification.
• Keep feature logic modular, but integrate it through the lifecycle and control boundaries of the adopted architecture and frameworks, such as dependency injection, routing, state management, persistence, middleware, and configuration.
• Do not make a feature work by bypassing those boundaries in a way that disables framework hooks, guarantees, cross-cutting behavior, or existing functionality.
• If the requirement does not fit the current boundaries, explain the mismatch and tradeoffs before changing the architecture or introducing or replacing dependencies.
• Verify the feature through the project's normal entry points and regression tests, confirming that the existing architecture and framework behavior remains effective.