Codex is powerful but this one setting made it far more useful for real-world projects

OpenAI Codex's default behavior treats every session as a fresh start, forcing developers to re-explain project context repeatedly. Two settings dramatically improve this: Custom Instructions (via AGENTS.md), which injects persistent project rules into every prompt, and the experimental Memories toggle, which tracks real-time adjustments across sessions. Together, these features transform Codex from a generic code generator into a context-aware collaborator that remembers your stack, design decisions, and architectural preferences without manual re-prompting.