ExecutionPayloadEnvelopesByRange & ExecutionPayloadEnvelopesByRoot Boilerplate

[shane-moore]

Changes

• added boilerplate for ExecutionPayloadEnvelopesByRange v1 per spec
• added boilerplate for ExecutionPayloadEnvelopesByRoot v1 per spec

Todo:

• inbound requests will need to fetch stored envelopes from the BN as mentioned in a todo
• creating outbound requests will need to be orchestrated via range sync/backfill sync pipelines as mentioned in a todo

[shane-moore]

Closing — fully upstreamed.

sigp#8896 ("Gloas serve envelope rpc", commit c7055b604, merged 2026-03-25) implements both protocols and goes further than this PR's boilerplate by actually serving them.

Concrete evidence in upstream/unstable:

• beacon_node/lighthouse_network/src/rpc/methods.rs: PayloadEnvelopesByRangeRequest (line 368), PayloadEnvelopesByRootRequest (line 521), RpcSuccessResponse::PayloadEnvelopesByRange (line 627)
• rpc/codec.rs lines 80-81, 362-363, 556-562, 671-695 cover encode/decode for both v1 protocols
• rpc/config.rs lines 92-93, 146-147, 181-186, 216-279 register rate-limit quotas
• rpc/handler.rs:957 dispatches RequestType::PayloadEnvelopesByRange
• New PayloadEnvelopeStreamer plus 386 lines of tests, integrated with rpc_methods, router, and beacon_processor

Naming differs slightly (upstream uses PayloadEnvelopesByRange/Root vs this PR's ExecutionPayloadEnvelopesByRange/Root) but protocol IDs and behavior are equivalent.