Clarify EIP-7928 api specs

Author: nerolation

src/engine/eip7928.md

@@ -75,9 +75,9 @@ This method follows the same specification as [`engine_newPayloadV4`](./prague.m
 
 1. Client software **MUST** return `-38005: Unsupported fork` error if the `timestamp` of the payload does not fall within the time frame of the EIP-7928 activation.
 
-2. The `blockAccessList` field **MUST** be validated and incorporated into the block hash computation.
+2. Client software **MUST** validate the `blockAccessList` field by executing the payload's transactions and verifying that the computed access list matches the provided one.
 
-3. If the `blockAccessList` field is missing or invalid, the call **MUST** return `{status: INVALID, latestValidHash: null, validationError: errorMessage | null}`.
+3. If the `blockAccessList` field is missing, malformed, or doesn't match the computed access list, the call **MUST** return `{status: INVALID, latestValidHash: null, validationError: errorMessage | null}`.
 
 ### engine_getPayloadV6
 
@@ -106,7 +106,7 @@ This method follows the same specification as [`engine_getPayloadV5`](./osaka.md
 
 1. Client software **MUST** return `-38005: Unsupported fork` error if the `timestamp` of the built payload does not fall within the time frame of the EIP-7928 activation.
 
-2. The `executionPayload` **MUST** contain the `blockAccessList` field populated with the RLP-encoded block access list data collected during block execution.
+2. When building the block, client software **MUST** collect all account accesses and state changes during transaction execution and populate the `blockAccessList` field in the returned `ExecutionPayloadV4` with the RLP-encoded access list.
 
 ### Update the methods of previous forks