What it is
An experimental Codex plugin and npm library that wraps Codex's built-in compaction. It prunes tool calls and results with Jev decisions, then re-injects the verbatim kept history as additionalContext. The README warns against using it in real workflows.
How it uses Jev
In PreCompact, the rollout JSONL is replayed and converted to the library's message model. compactMessages() pairs each tool_use with its result, pins recent messages, fits the conversation into maxStateTokens, and asks Jev two noul questions per non-pinned call: should the call stay, should the full result stay verbatim. Decisions and stats are written to $PLUGIN_DATA.
Primitives:noul
Technique worth stealing
Wrap compaction instead of intercepting it: prune only tool calls/results with Jev, keep text verbatim, re-inject after the built-in summary.
Try it
npm install fast-jev-compaction; export TYPESAFE_API_KEY=...; or add the Codex plugin marketplace and trust hooks.
Evidence
Each line is one question put to Jev about the README. ≥ 0.60 reads as yes, ≤ 0.40 as no; in between Jev is not making a call.
- Jev-centricyes0.77
- Shows a System One patternyes0.64
- Handles uncertaintyno0.25
- Measuredno0.05
- Runnableyes0.96
- Worth recommendingno0.20
- Model replicano0.33
- Problem scopescore on a 0–2 scale0.73
- About Jevyes0.97
Signals by Jev jev-1.13.0, card written by DeepSeek V4.1 Flash from the README on 20 Sept 2026.