Block Validation mechanism & behavior is implemented

[danlessa]

Note: this happens at Network Time rather than L1 Time

eg.

First, the proposer sends both their block proposal, and their block content through the network (not on L1)
Then, each validator ”simulates” the block, and signs the block header if it is valid (this is not proving, just "checking"), sending the signed header back to the proposer
Invalid Proposals:
Block is not provable - An invalid proposal can land on the pending chain, if the committee signs it, eg. due to:
Committee tries to "attack"
Committee is compromised
Committee runs buggy client software (might not be intentionally compromised by someone)
Definition of "Land on the pending chain" = Received enough signatures to be considered "valid" for now, even though it will not be proven later but instead reorged
Then, the Proposer sends the signed block header of the proposal to L1