StripUnresolvedLinks logs a warning and returns the content unchanged when the link index cannot be built (e.g. an unreadable subdirectory), instead of failing every brain_write/brain_update and losing the learning. Nothing is unwrapped on a partial index. Fixes #178. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Co-authored-by: Mathias <mthbqv@gmail.com>