Fast Compaction Dsh

It replaces the lossy compaction summary in DeepSeek Harness with fast per-call keep, truncate or drop verdicts from jev-latest. Everything kept stays verbatim and nothing is ever rewritten, so file paths, exact errors, constraints and commands do not disappear into a summary.

Most compaction asks an LLM to summarize old turns, which is lossy: a file path, an exact error, a constraint or a command can disappear even when it matters later. This plugin rewrites nothing — every tool call and result in the compacted region is scored, stale calls are deleted, half-stale results are truncated, and the rest stays byte-for-byte.

On any failure — a missing TYPESAFE_API_KEY, a Jev error, malformed answers, an unfittable history or an insufficient reduction — it falls back to the shipped compaction-basic summarizer, exactly like the original Claude Code hook falls back to Claude Code's built-in summary.

Calls are paired with their results by call id, and the first message plus the newest preserveRecentMessages (default 6) messages are pinned. For every non-pinned call Jev answers two Noul questions: whether knowing the call was made still matters, and whether the result's contents are still needed. Defaults: maxStateTokens 25k, maxRequestTokens 30k, truncateHeadChars 300, keepThreshold 0.5.

DSH exposes compaction as a capability seam: a ctx.compaction service, a compaction-basic engine provider and a /compact consumer. The plugin subclasses BasicCompactionEngine and overrides only the summarize() hook, so region selection, the durable transaction, checkpoint framing and /compact keep working unchanged.

The standard agent preset mounts compaction-basic inside an isolated compaction realm, so mounting the engine row from a profile-level cordis.patch.yml does not reach it; the README shows an agent preset patch instead. The captured README was truncated inside that YAML example.

It is a DSH port of tamaratran/fast-jev-compaction, which the README describes as MIT and says it adapted to the DSH compaction capability seam. The repository's own GitHub license metadata reads NOASSERTION, so check the repo before redistributing.