status: proposed date: 2025-06-25

How do we transmit cursor positions?

Context and Problem Statement

An important feature of collaborative editing is being able to see each other's cursors. How should we implement transmitting them?

Decision Drivers

Our solution should ideally be:

Fast
Correct (cursors never appear at wrong/shifted locations)
Simple (little protocol overhead, little complexity)
Take up little disk space

Considered Options

Store user state in automerge
Gossip user states to last-write-wins

Decision Outcome

Chosen option: "Gossip user states to last-write-wins", because we suspect that this improves the performance when using the same doc for a longer time.

Pros and Cons of the Options

More Information

See ADR 07 for more Information on this decision, which is superseded by this one.

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