Codex Compression Pattern

The Codex Compaction Pattern (CCP) defines a lossless, self-describing compression method for large prompts, instruction sets, and agent contexts. CCP v1.2 formalizes a unified framework for lossless codex compression, structured prompt engineering, and secure LLM-internal context compaction.

This version formally distinguishes two trust domains: externally verified lossless decoding (deterministic tools with cryptographic guarantees) and LLM-internal operational compaction (behaviorally equivalent under security constraints). The specification elevates LLM-internal use from an informal pattern to a security-defined operating mode with normative invariants including schema supremacy, section inertness, sticky constraints, and deterministic parsing.

CCP v1.2 introduces a normative LLM-Internal Security Profile that addresses prompt injection, constraint loss, drift over time, and accidental disclosure through explicit controls: section and key whitelisting, size limits on raw data sections, inertness guarantees for verbatim content, and failure handling that requires explicit reissue rather than silent repair.

The pattern enables bounded-memory, long-lived sessions while maintaining strict security controls. Payloads consist of four section types: configuration, constraints, telemetry, and raw/verbatim data. The specification includes a formal EBNF grammar and comprehensive conformance checklists for both external deterministic mode and LLM-internal security mode.