cth9191

Jev Compaction Plus — Development skill for Claude Code

Development community

Claude Code compaction in ~0.5 s instead of ~35 s: Jev keeps what's still needed word for word and moves the rest to a drawer file.

How to install Jev Compaction Plus

This entry records only its repository, not the path inside it, so there is no exact command to give. Open cth9191/jev-compaction-plus and copy the folder into ~/.claude/skills/, or the file into ~/.claude/agents/.

What Jev Compaction Plus does

Claude Code compaction in ~0.5 s instead of ~35 s: Jev keeps what's still needed word for word and moves the rest to a drawer file. Fork of fast-jev-compaction.

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README

jev-compaction-plus

**Claude Code compaction in about half a second instead of about 35.**

When a Claude Code session fills up, `/compact` makes Opus stop, re-read the whole conversation and write a summary. This plugin hands that job to [Jev](https://typesafe.ai/blog/introducing-system-one-models-and-jev), TypeSafe's System One decision model. Jev doesn't write anything. It decides, for every old tool result, whether you still need it:

whatever it keeps stays word for word;
whatever it drops moves to a drawer file that Claude can read back.

It's a fork of [fast-jev-compaction](https://github.com/tamaratran/fast-jev-compaction) with three fixes that made the difference on a very large session (see below).

Results

One real Opus 5.5 session in Claude Code, grown to **591,489 tokens**: a whole demo codebase, an 8,000-line log and a test run. We compacted it inside the live session, then asked 6 questions about details from early in the session (a trace id, a config value, an exact buggy line, and so on), with no tools allowed.

	Time to compact	Memory quiz	Tokens left
Built-in `/compact` (Opus writes a summary)	35.1 s	6/6	~16k
fast-jev-compaction (original)	0.35 s	5/6	~7k
jev-compaction-plus	0.43–0.74 s	6/6 (3 runs)	~26k

Speed: about 50-80× faster than the built-in compaction.
Usage: it never calls Opus. Each compaction costs a fraction of a cent of Jev.
Memory: it matched the built-in compaction on the quiz.
- The original plugin forgot a config value. It had dropped an 833-character file without ever seeing what was inside.
Drawer test: after compacting, we asked for one exact line from an old pytest -v run that had been moved out, and said not to re-run anything. Claude noticed the output was gone, opened the drawer file and quoted the line.

These numbers come from one session and one quiz, so treat them as an example, not a benchmark.