Stamping DB_ROW_SNAPSHOT on every repair_alternation load also moved the
include_row_ids=True resume loaders (resume conversations, rewind, TUI
gateway, turn lease) onto the CAS-match rewrite path. That path writes
every owned column from the live dict, and replay never decodes
token_count, so a rewrite of a resumed row nulled the stored
token_count. Only the unaddressed live replay needs the digest (it is
the proof that recovers a lost _row_id), so stamp it only when
repair_alternation and not include_row_ids.
The token_count column stays in _CONVERSATION_ROW_COLUMNS: the digest
hashes every owned column of these rows, so the projection must stay a
superset of _OWNED_COLUMNS; the comment now states that contract.
Also index (session_id, message_uid) over active rows so the logical
identity lookup, which runs inside the write lock, is a SEARCH instead
of a full-session scan; tighten the twin test so a copied uid without a
snapshot is still not adopted.
d037aba450