It tracks and finalises the Filecoin chain.
Tipsets that have been finalised by F3 cannot be reorganised.
The result? Finality in a couple of minutes.
Not at all! EC remains Filecoin's consensus protocol and block creation still takes place according to the EC procedure. F3 will finalise prefixes (i.e. past subsets) of the EC chain, preventing their future reorganisation. EC will only be modified so that the fork choice rule respects finalised prefixes.
In the unlikely event of F3 halting, EC will continue appending blocks to the chain and the network will remain operational, but the finality guarantees will degrade accordingly.
Given F3's integration with the existing validation pipeline and the low marginal cost, we don't expect additional participation incentives will be necessary.
F3 requires a network upgrade. We foresee it being included in the upcoming nv23. Activation will be delayed for security testing, and is expected to take place in Q3 2024.