Fast Jev Compaction Pi

A Pi extension that guides context compaction with Jev. Before Pi compacts old session records, the extension has Jev judge separately whether each completed tool call and its full result still have value, and local deterministic rules keep, truncate or delete them.

Kept tool evidence is not rewritten by a summary model; it is written into Pi's compaction summary as original text. The README says this suits preserving test failure logs, key command output, configuration contents, file reads and exact error messages.

User and assistant text plus tool names, arguments, result lengths and error markers — not the tool output bodies. The state degrades through seven stages until it fits FAST_JEV_MAX_STATE_TOKENS; calls that fall out are left unscored with their output preserved verbatim.

If keepResult meets the threshold, the call and full original result are kept (degrading to truncation if the summary budget is tight). If only keepCall meets it, the call is kept with a prefix plus a can-rerun note. If both fall below, neither is written to the summary.

Clone the repo and run npm install, add the extension entry to ~/.pi/agent/settings.json (or test with pi -e /absolute/path/to/src/index.ts), and set TYPESAFE_API_KEY in the environment. It requires Node.js 18 or newer and a working Pi install.

TYPESAFE_API_KEY is required; the rest have defaults: FAST_JEV_KEEP_THRESHOLD 0.5, FAST_JEV_MAX_STATE_TOKENS 25000, FAST_JEV_MAX_WINDOW_CHARS 60000, FAST_JEV_MAX_SUMMARY_TOKENS 12000, FAST_JEV_CONCURRENCY 3, FAST_JEV_TIMEOUT_MS 20000 and FAST_JEV_TRUNCATE_HEAD_CHARS 300.

All of Pi's native compaction entry points: manual /compact, automatic compaction near the context-window threshold, and automatic compaction with retry after context overflow. Timing stays managed by Pi's compaction setting, and the extension does not modify Pi's session tree, cut algorithm or JSONL session format.