Supporting Undo and Redo for Local-First Software. An Implementation in Automerge

Abstract

With the advance of cloud computing and centralization of data, a new effort goes entirely in the other direction and aims for decentralization of data through local-first software. Collaborative applications created this way need strong undo and redo support to handle the inevitable mistakes that take place in a collaborative setting.

Local-first software can be effectively built using Conflict-Free Replicated Data Types (CRDTs), where all the application data is stored locally at the user.

This paper presents the design and implementation of a new approach for undoing and redoing operations in a modern open-source operation-based CRDT. The current approach is severely limited and can only undo local operations. Our approach allows for generic and selective undo and redo for consistently replicated registers.