Codex Losing Task Context After Compaction

Melvin Vivas · X post · 2026-09-11 · Open on X

Topics: Prompt & Context Engineering, AI Dev Tools & Productivity · Level: intermediate

Summary

Melvin Vivas reports that Codex forgot what he had asked it to do after context compaction. He wonders whether an experimental context-management setting is the cause, which is a reminder that compaction can drop task instructions.

Key points

• Context compaction in coding agents can drop the original task instructions.
• Suspected cause: the experimental context-management config [features.context_management] experimental_mode = true.
• If an agent loses track after compaction, try turning experimental context settings off or restating the task.

Resources mentioned

• OpenAI Codex · tool · openai.com · paid
  OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
  Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more