Reverse Engineering Context Compaction in Open-Source Codex CLI
Kangwook_Lee · x · 2026-08-13
An article investigates how the open-source Codex CLI handles context compaction locally.
- Non-Codex Models: For non-Codex models, the CLI compacts context locally by having an LLM summarize the conversation using a specific compaction prompt.
- Mechanism: When the compacted context is later used, the system processes it via the responses.create() API. This mechanism allows the CLI to maintain long conversation coherence within limited context windows.
Related event: Reverse Engineering Reveals Codex CLI Context Compaction Mechanism(2 posts)→
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