archive_and_compact() soft-archives every active row with compacted=1 and
then re-inserts compacted_messages as fresh live rows. When the
compressor's protected tail rides inside that list verbatim - which is
the normal batch-compaction shape ([summary] + tail) - the tail's
ORIGINALS end up stored twice per compaction: (active=0, compacted=1)
next to their live clones. search_messages() recalls both flags without
DISTINCT, so every carried-forward message came back once per compaction
(measured up to 4 identical hits) and was mislabeled to users and the
agent as archived "summarized away" content.
Add an optional tail_count parameter: the last tail_count archived rows
are superseded byte-identical duplicates, stamped rewind-style
(active=0, compacted=0, hidden from recall) instead of compacted=1.
Callers:
- batch in-place compaction counts the compressor-tagged tail dicts
(_COMPACTION_TAIL_MARKER set by compress() on every carried-forward
message);
- micro-compaction splices [prefix, marker, suffix] - everything except
the single marker row is carried forward, so tail_count=len-1;
- proactive tool-result pruning rewrites content in place (not verbatim),
keeping the historical archive-everything behavior.
Fixes#86366
BrunoBza