Addresses #6854.
PeerDAS requires unsubscribing a Gossip topic at a fork boundary. This is not possible with our current topic machinery.
Instead of defining which topics have to be **added** at a given fork, we define the complete set of topics at a given fork. The new start of the show and key function is:
```rust
pub fn core_topics_to_subscribe<E: EthSpec>(
fork_name: ForkName,
opts: &TopicConfig,
spec: &ChainSpec,
) -> Vec<GossipKind> {
// ...
if fork_name.deneb_enabled() && !fork_name.fulu_enabled() {
// All of deneb blob topics are core topics
for i in 0..spec.blob_sidecar_subnet_count(fork_name) {
topics.push(GossipKind::BlobSidecar(i));
}
}
// ...
}
```
`core_topics_to_subscribe` only returns the blob topics if `fork < Fulu`. Then at the fork boundary, we subscribe with the new fork digest to `core_topics_to_subscribe(next_fork)`, which excludes the blob topics.
I added `is_fork_non_core_topic` to carry on to the next fork the aggregator topics for attestations and sync committee messages. This approach is future-proof if those topics ever become fork-dependent.
Closes https://github.com/sigp/lighthouse/issues/6854
0055af56b6