README

fast-jev-compaction

Claude Code plugin that replaces the compaction summary with Jev decisions:
every tool call and result is scored in one fast request, stale ones are
dropped or truncated, everything kept stays verbatim. Also usable as an npm
library.

 What and why

Most context compaction asks an LLM to summarize old turns. A summary is
lossy: a file path, exact error, constraint, or command can disappear even when
it matters later. This library never rewrites anything. It only deletes tool
calls and tool results Jev says are no longer needed, and it asks Jev while
showing it the whole conversation. User and assistant text stays verbatim and
in order.

The repository is both an npm package (src/) and a Claude Code plugin
(hooks/, .claude-plugin/) that uses the package to replace Claude Code's
built-in compaction summary with the original messages.

 How it works

1. Every tool_use is paired with its tool_result by tool_use_id. Calls in
   the first message or in the newest preserveRecentMessages messages are
   pinned and never touched.
2. The state sent to Jev is the whole conversation so far, oldest first,
   with every tool result replaced by a short note (ok, 4213 chars (omitted)).
   Tool inputs are included, texts are included, nothing is summarized.
3. The state is fitted into maxStateTokens (25k by default) in stages, each
   applied only if the previous one was not enough: tool inputs truncated to
   1000, then 200, then 60 characters; long texts abridged to head + tail,
   oldest non-pinned messages first; old non-pinned messages collapsed to a
   [… N chars omitted …] note; old tool calls reduced to one line each
   (t12 Read file_path=src/a.ts → ok 480ch); old call-less messages left
   out; runs of old call-only messages folded into one entry. If it still
   does not fit, compaction throws. Tokens are estimated without a tokenizer (a
   word per six letters, half a token per digit, ~one per other symbol),
   calibrated to land a little above the counts Jev reports.
4. For every non-pinned call Jev gets two noul questions: should the call
   stay (knowing it was made, with its input, still matters), and should the
   result stay verbatim (its contents are still needed and re-running the
   tool would not do).
5. Questions are split into as many requests as needed so state plus questions
   stays under maxRequestTokens (30k by default, under Jev's 32k request
   limit). The same full state is resent with every request; requests run
   concurrently and their answers are merged.
6. Decisions per call, against keepThreshold:
   - keepResult ≥ threshold → keep call and result;
   - else keepCall ≥ threshold → keep the call, truncate the result to its
     first truncateHeadChars characters plus a one-line note;
   - else → remove the call together with its result.
7. The message list is rebuilt: a message that loses all its content is
   removed, untouched messages are returned as the same objects, and no result
   is ever left withou