Questions about README

[rootulp]

I had a few questions while reading the README and figured I would ask them here.

Context

https://github.com/rollchains/tiablob/blob/main/README.md

Questions

Feegrant clarification?

An ICA on Celestia controlled by the rollchain protocol feegrants all of the validator's Celestia addresses. The proposing validator publishes any outstanding block data above the last proven height to Celestia. This is paid for by the ICA account via feegrant. The proposer also relays any unrelayed ShareCommitment proofs back to the rollchain.

To clarify: it is the roll-up's proposing validator duty to construct the MsgPayForBlobs and submit a tx with that message to Celestia? The fees for the MsgPayForBlobs are deducted from an ICA account on Celestia that has authorized all of the roll-up validator's Celestia addresses.

If a roll-up validator drains the ICA account on Celestia funds then it will be slashed on the roll-up layer?

Rollchain light client?

What is the Rollchain light client in this diagram?