Follow-ups to the salvaged #84009 commits:
- Add 'session_switch' to _RESET_END_REASONS: a reset continuation's
parent can be promoted to session_switch (resume the reset parent,
then switch away), which permanently hid pre-marker legacy children —
reopen-time stamping cannot rescue them because the parent is being
ended, not reopened. Probe-verified before/after.
- Share the legacy reset-child heuristic via _legacy_reset_child_sql()
so _RESET_CHILD_SQL and reopen_session()'s stamping UPDATE cannot
drift, and derive find_latest_gateway_session_for_peer's two recovery
fence literals from _RESET_END_REASONS_SQL (was a third hand-written
copy of the same set).
- Exclude reset children (marker + legacy shape) from the
resolve_resume_session_id forward walker: resuming a reset parent
could redirect into the post-reset conversation — the exact context
the user reset away. Regression tests cover both shapes plus the
walker's original compression-tip behavior; mutation-checked.
91c7a67f44