move 4788 feature to deneb specs

specs/deneb/fork-choice.md

@@ -8,7 +8,8 @@
 - [Introduction](#introduction)
 - [Containers](#containers)
 - [Helpers](#helpers)
-    - [`is_data_available`](#is_data_available)
+  - [Extended `PayloadAttributes`](#extended-payloadattributes)
+  - [`is_data_available`](#is_data_available)
 - [Updated fork-choice handlers](#updated-fork-choice-handlers)
   - [`on_block`](#on_block)
 
@@ -23,7 +24,21 @@ This is the modification of the fork choice accompanying the Deneb upgrade.
 
 ## Helpers
 
-#### `is_data_available`
+### Extended `PayloadAttributes`
+
+`PayloadAttributes` is extended with the parent beacon block root.
+
+```python
+@dataclass
+class PayloadAttributes(object):
+    timestamp: uint64
+    prev_randao: Bytes32
+    suggested_fee_recipient: ExecutionAddress
+    withdrawals: Sequence[Withdrawal]
+    parent_beacon_block_root: Root  # [New in Deneb:EIP4788]
+```
+
+### `is_data_available`
 
 *[New in Deneb:EIP4844]*
 

specs/deneb/validator.md

@@ -19,6 +19,7 @@
 - [Beacon chain responsibilities](#beacon-chain-responsibilities)
   - [Block and sidecar proposal](#block-and-sidecar-proposal)
     - [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
+      - [ExecutionPayload](#executionpayload)
       - [Blob KZG commitments](#blob-kzg-commitments)
     - [Constructing the `SignedBlobSidecar`s](#constructing-the-signedblobsidecars)
       - [Sidecar](#sidecar)
@@ -88,11 +89,46 @@ All validator responsibilities remain unchanged other than those noted below.
 
 #### Constructing the `BeaconBlockBody`
 
+##### ExecutionPayload
+
+`prepare_execution_payload` is updated from the Capella specs to provide the parent beacon block root.
+
+*Note*: In this section, `state` is the state of the slot for the block proposal _without_ the block yet applied.
+That is, `state` is the `previous_state` processed through any empty slots up to the assigned slot using `process_slots(previous_state, slot)`.
+
+*Note*: The only change made to `prepare_execution_payload` is to add the parent beacon block root as an additional
+parameter to the `PayloadAttributes`.
+
+```python
+def prepare_execution_payload(state: BeaconState,
+                              safe_block_hash: Hash32,
+                              finalized_block_hash: Hash32,
+                              suggested_fee_recipient: ExecutionAddress,
+                              execution_engine: ExecutionEngine) -> Optional[PayloadId]:
+    # Verify consistency of the parent hash with respect to the previous execution payload header
+    parent_hash = state.latest_execution_payload_header.block_hash
+
+    # Set the forkchoice head and initiate the payload build process
+    payload_attributes = PayloadAttributes(
+        timestamp=compute_timestamp_at_slot(state, state.slot),
+        prev_randao=get_randao_mix(state, get_current_epoch(state)),
+        suggested_fee_recipient=suggested_fee_recipient,
+        withdrawals=get_expected_withdrawals(state),
+        parent_beacon_block_root=hash_tree_root(state.latest_block_header),  # [New in Deneb:EIP4788]
+    )
+    return execution_engine.notify_forkchoice_updated(
+        head_block_hash=parent_hash,
+        safe_block_hash=safe_block_hash,
+        finalized_block_hash=finalized_block_hash,
+        payload_attributes=payload_attributes,
+    )
+```
+
 ##### Blob KZG commitments
 
 *[New in Deneb:EIP4844]*
 
-1. After retrieving the execution payload from the execution engine as specified in Capella,
+1. After retrieving the execution payload from the execution engine as specified above,
 use the `payload_id` to retrieve `blobs`, `blob_kzg_commitments`, and `blob_kzg_proofs`
 via `get_payload(payload_id).blobs_bundle`.
 2. Set `block.body.blob_kzg_commitments = blob_kzg_commitments`.