nesquena APPROVED 2026-05-22. Cherry-picked onto post-v0.51.127
master via 3-way apply. Resolved api/routes.py conflict: master had
the inline correctness fix from the deep-review iteration; PR
refactors it into _metadata_only_message_summary() helper. Took the
helper AND added profile= threading (post-#2827 master adds
profile-aware state.db reads). Kept master's pre-existing
test_api_session_reload_drops_stale_cached_user_tail_after_saved_assistant
alongside the PR's new test_metadata_fast_path_matches_reconciliation_for_restamped_replays.
Co-authored-by: dobby-d-elf <dobby.the.agent@gmail.com>