Concurrent Text Editing with CRDTs

Notion has implemented a Conflict-free Replicated Data Type (CRDT) system, specifically based on Replicated Growable Array (RGA) and Peritext algorithms, to handle concurrent rich-text editing across its block-based document model. This system ensures that simultaneous edits from multiple users are merged deterministically without data loss, supporting complex operations like insertions, deletions, and rich text annotations (bold, italics, hyperlinks) with improved accuracy and intent preservation. The implementation also addresses challenges with text splitting and movement between blocks by introducing the concept of 'text slices' and 'text slice trees' to maintain data integrity across block boundaries.