Codex maintains a context (history of messages) that is sent to the model in inference requests. 1. No history rewrite - the context must be built up incrementally. 2. Avoid frequent changes to context that cause cache misses. 3. No unbounded items - everything injected in the model context must have a bounded size and a hard cap. 4. No items larger than 10K tokens. 5. Highlight new individual items that can cross 1k tokens as P0. These need an additional manual review. 6. All injected fragments must be defined as structs in and implement ContextualUserFragment trait ---