Codex Session Compact Collapse

This repository is a Codex-derived experimental source release for session-level compact-collapse. It is based on OpenAI Codex rust-v0.124.0 and adds an opt-in compaction route designed for long-running coding sessions.

The goal is durable continuity after repeated /compact or auto-compaction events: instead of producing a one-off handoff summary, the session route asks the model to maintain a stable <session_compact_state> block with active memory, inactive changes, current handoff, and evidence pointers.

Warning

This is an independent derivative of the open-source OpenAI Codex project. It is not an official OpenAI release.

What Changed

• Added compact_strategy = "session" as an explicit opt-in route.
• Routed manual /compact and auto compact through the same selector.
• Ensured the session strategy wins before provider-based remote compaction.
• Added a dedicated session-compact prompt contract under codex-rs/core/templates/session_compact/prompt.md.
• Preserved continuity through replacement_history while keeping a bounded recent structured frontier.
• Added sidecar metadata for recent user images without replaying old images into later prompts.
• Added docs and benchmark harness material for repeated compact recovery checks.

Default Codex behavior remains unchanged unless the session strategy is explicitly enabled.

Enable It

Build from source using the existing Codex build flow:

• Installing and building
• Configuration docs
• Contributing

Then add this to ~/.codex/config.toml:

compact_strategy = "session"

With this setting, both manual /compact and automatic compaction use the session route. Without it, Codex keeps the upstream default compact behavior.

Design Notes

• Active contract
• Design harness
• RCR benchmark notes
• Staged orchestration notes

The benchmark runner is available at:

python3 scripts/session_compact_rcr_benchmark.py --help

The included benchmark manifest is intentionally small and source-reviewable. Private copied-session artifacts and local result journals are not included.

Upstream Lineage

This repository is derived from the open-source openai/codex codebase and remains under the same Apache-2.0 licensing terms for upstream material.

See DERIVATION.md for source lineage and public-release scope.

License

This repository includes upstream Codex material under the Apache-2.0 License. Additional attribution notices remain in NOTICE.