The profile pass map-reduced every session gist (~851) on every consolidation
firing — the biggest redundant-work and MI50-heat source left after the eras fix.
Now: skip when nothing's new, fold only the gists added since last build into the
existing profile, and full-rebuild only when there's no profile, too much has
accumulated to fold safely (>FOLD_LIMIT), on a periodic cadence (anti-drift), or
when forced.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
