Teknium review: keeping one durable session id must NOT come at the cost of
destroying history. The prior in-place implementation used replace_messages,
which hard-DELETEs the pre-compaction turns (they also drop out of the FTS
index) — same id, but the original conversation is gone with no recovery path
and the summary becomes the only record. Rotation today is non-destructive
(the old session's full transcript survives under the old id); in-place must
match that durability contract, not weaken it.
Fix: compact in place by SOFT-ARCHIVING, reusing the existing messages.active
flag (the /undo soft-delete mechanic), instead of deleting:
- New SessionDB.archive_and_compact(session_id, compacted): in one atomic
write, UPDATE messages SET active=0 on the live turns, then insert the
compacted set as fresh active=1 rows. Nothing is deleted.
- The insert loop is extracted into a shared _insert_message_rows() helper so
archive_and_compact and replace_messages don't duplicate the 60-line
column/encoding block (extend-don't-duplicate).
- Agent in-place branch calls archive_and_compact instead of replace_messages.
Durability outcome (proven by test + E2E across repeated compactions):
- Live context load (get_messages_as_conversation / get_messages) filters
active=1, so a resume reloads ONLY the compacted set — compaction still
shrinks the live session.
- The pre-compaction turns stay on disk at active=0, recoverable via
get_messages(include_inactive=True) / restore_rewound.
- They remain FTS-searchable: the messages_fts* triggers index on INSERT and
remove on DELETE only — they do NOT key on active, and active=0 is a
content-preserving UPDATE. session_search still finds them.
- Verified across TWO successive compactions: the 1st compaction's originals
are still recoverable + searchable after the 2nd (answers the "no recovery
path after the next compaction" concern directly).
message_count now reflects the LIVE (active/compacted) count, matching the
live load. replace_messages keeps its DELETE semantics (still correct for
/retry, /undo) and gains a docstring note pointing compaction at the
non-destructive method.
Tests: test_in_place_keeps_same_session_id strengthened to assert the 8
seeded originals survive at active=0 alongside the 2 compacted rows AND stay
FTS-searchable. Mutation check: swapping archive_and_compact back to a hard
DELETE fails the test, so the non-destructive contract is bound. 285
hermes_state + in-place tests green; rotation/persistence/compress-command/cli
suites green; ruff clean.
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