An overlay pair switches the acp demo's packChunks on; the authored fixture
(text-turn's recording refreshed through that overlay) commits a session.jsonl
whose reasoning run persists as one packed reasoning-chunks row while the
short text run stays verbatim. Keyless replay proves the packed fixture
derives the same model script (fixture reading is layout-blind) and the
re-persisted log packs identically — the transcript surface of the packChunks
switch is now pinned without touching any existing golden.
Tianyi Cui
kingwl