FileVectorIndex persists one binary file per model under index/ with atomic tmp+rename writes; FileDocumentCatalog persists a single catalog.json, rebuilding the link graph via WikiLinks.Extract on every upsert. Both start empty and report health Ok with a reset detail if their file on disk is corrupt, rather than crashing. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>