[Glamsterdam] Staked Builder API

[hangleang]

Implement client side of ethereum/builder-specs#138 into block production

[NikhilSharmaWe]

Can I take this up? If no one has been assigned yet.

[NikhilSharmaWe]

@hangleang I'd like to take this issue if it's still unassigned.

After reviewing glamsterdam-devnet-7, most of the Gloas consensus work already looks in place: execution payload bid validation, envelope handling, fork choice integration, and proposer preferences gossip (publish/receive on the validator/p2p side).

What still seems missing is the Gloas builder API HTTP client in builder_api:

• getExecutionPayloadBid
• submitBuilderPreferences
• submitSignedBeaconBlock

…and wiring that into block production for the HTTP staked-builder path. The branch already supports gossip-based bid selection and self-build with SignedExecutionPayloadBid, so this looks more like adding the builder-specs#138 client flow than replacing the pre-Gloas blinded-block path.

A couple of questions before I start:

1. On devnet-7, should external builders use this HTTP path, or is gossip bid reception enough for now?
2. When using the HTTP path, should the proposer stop gossiping the block after submitSignedBeaconBlock returns 202 (per spec)?

Happy to land this incrementally, starting with a builder_api-only PR. Please let me know if that approach works.

[hangleang]

@NikhilSharmaWe please complete this PR first #801

[NikhilSharmaWe]

@hangleang I've addressed the failing CI in #801.

Could you please share your thoughts on the questions above when you have a chance? I'd like to confirm my understanding of the expected scope before I start working on this.

[hangleang]

1. On devnet-7, should external builders use this HTTP path, or is gossip bid reception enough for now?

Not a hard requirement for devnet, it's nice to have it test

2. When using the HTTP path, should the proposer stop gossiping the block after submitSignedBeaconBlock returns 202 (per spec)?

the endpoint is just sent signed beacon block to the builder over http, proposer still need to gossip the block to the network for other validators to validate