Force the proposer to reorg late payloads

specs/gloas/fork-choice.md

@@ -17,12 +17,15 @@
   - [New `notify_ptc_messages`](#new-notify_ptc_messages)
   - [New `is_payload_verified`](#new-is_payload_verified)
   - [New `is_payload_timely`](#new-is_payload_timely)
+  - [New `ptc_voted_payload_untimely`](#new-ptc_voted_payload_untimely)
   - [New `is_payload_data_available`](#new-is_payload_data_available)
+  - [New `ptc_voted_data_unavailable`](#new-ptc_voted_data_unavailable)
   - [New `get_parent_payload_status`](#new-get_parent_payload_status)
   - [New `is_parent_node_full`](#new-is_parent_node_full)
   - [Modified `get_ancestor`](#modified-get_ancestor)
   - [Modified `get_checkpoint_block`](#modified-get_checkpoint_block)
   - [New `is_supporting_vote`](#new-is_supporting_vote)
+  - [New `should_build_on_full`](#new-should_build_on_full)
   - [New `should_extend_payload`](#new-should_extend_payload)
   - [New `get_payload_status_tiebreaker`](#new-get_payload_status_tiebreaker)
   - [New `should_apply_proposer_boost`](#new-should_apply_proposer_boost)
@@ -261,6 +264,26 @@ def is_payload_timely(store: Store, root: Root) -> bool:
     return sum(vote is True for vote in votes) > PAYLOAD_TIMELY_THRESHOLD
 ```
 
+### New `ptc_voted_payload_untimely`
+
+```python
+def ptc_voted_payload_untimely(store: Store, root: Root) -> bool:
+    """
+    Return whether the execution payload for the beacon block with root ``root``
+    was voted as not present by the PTC.
+    """
+    # The beacon block root must be known
+    assert root in store.payload_timeliness_vote
+
+    # If the payload is not locally available, the payload
+    # is not considered available regardless of the PTC vote
+    if not is_payload_verified(store, root):
+        return True
+
+    votes = store.payload_timeliness_vote[root]
+    return sum(vote is False for vote in votes) > PAYLOAD_TIMELY_THRESHOLD
+```
+
 ### New `is_payload_data_available`
 
 ```python
@@ -281,6 +304,26 @@ def is_payload_data_available(store: Store, root: Root) -> bool:
     return sum(vote is True for vote in votes) > DATA_AVAILABILITY_TIMELY_THRESHOLD
 ```
 
+### New `ptc_voted_data_unavailable`
+
+```python
+def ptc_voted_data_unavailable(store: Store, root: Root) -> bool:
+    """
+    Return whether the execution payload for the beacon block with root ``root``
+    was voted as unavailable by the PTC.
+    """
+    # The beacon block root must be known
+    assert root in store.payload_timeliness_vote
+
+    # If the payload is not locally available, the blob data
+    # is not considered available regardless of the PTC vote
+    if not is_payload_verified(store, root):
+        return True
+
+    votes = store.payload_data_availability_vote[root]
+    return sum(vote is False for vote in votes) > DATA_AVAILABILITY_TIMELY_THRESHOLD
+```
+
 ### New `get_parent_payload_status`
 
 ```python
@@ -365,6 +408,24 @@ def is_supporting_vote(store: Store, node: ForkChoiceNode, message: LatestMessag
         )
 ```
 
+### New `should_build_on_full`
+
+*Note*: `should_build_on_full` is called by the proposer before deciding if he
+should build on top of the empty or full parent pending node. This function is
+similar to `should_extend_payload` but it takes into consideration the PTC view
+on DA
+
+```python
+def should_build_on_full(store: Store, head: ForkChoiceNode) -> bool:
+    assert head.payload_status != PAYLOAD_STATUS_PENDING
+    if head.payload_status == PAYLOAD_STATUS_EMPTY:
+        return False
+
+    if ptc_voted_data_unavailable(store, head.root):
+        return False
+    return not ptc_voted_payload_untimely
+```
+
 ### New `should_extend_payload`
 
 *Note*: `should_extend_payload` decides whether to extend an available payload

specs/gloas/validator.md

@@ -231,12 +231,13 @@ construct the `payload_attestations` field in `BeaconBlockBody`:
 ##### Parent execution requests
 
 The `parent_execution_requests` field contains the execution requests from the
-parent's execution payload. The proposer constructs this field as follows:
+parent's execution payload. Let `head = get_head(store)`. The proposer
+constructs this field as follows:
 
 - If the parent block is pre-Gloas (first Gloas block), set
   `parent_execution_requests` to an empty `ExecutionRequests()`.
-- If `should_extend_payload(store, block.parent_root)` is true (the proposer is
-  building on the parent's full payload), set `parent_execution_requests` to
+- If `should_build_on_full(store, head)` is true (the proposer is building on
+  the parent's full payload), set `parent_execution_requests` to
   `store.payloads[block.parent_root].execution_requests`.
 - Otherwise (the proposer is building on the parent's empty variant), set
   `parent_execution_requests` to an empty `ExecutionRequests()`.
@@ -254,19 +255,21 @@ are computed against the post-processing state.
 def prepare_execution_payload(
     # [New in Gloas:EIP7732]
     store: Store,
-    state: BeaconState,
+    slot: Slot,
     safe_block_hash: Hash32,
     finalized_block_hash: Hash32,
     suggested_fee_recipient: ExecutionAddress,
     execution_engine: ExecutionEngine,
 ) -> Optional[PayloadId]:
     # [New in Gloas:EIP7732]
+    head = get_head(store)
+    state = store.block_states[head.root]
+    # Make a copy of the state to avoid mutability issues
+    state = copy(state)
+    process_slots(state, slot)
     parent_bid = state.latest_execution_payload_bid
-    parent_root = hash_tree_root(state.latest_block_header)
-    if should_extend_payload(store, parent_root):
-        envelope = store.payloads[parent_root]
-        # Make a copy of the state to avoid mutability issues
-        state = copy(state)
+    if should_build_on_full(store, head):
+        envelope = store.payloads[head.root]
         # Apply parent payload before computing withdrawals
         apply_parent_execution_payload(state, envelope.execution_requests)
         withdrawals = get_expected_withdrawals(state).withdrawals
@@ -277,14 +280,14 @@ def prepare_execution_payload(
 
     # Set the forkchoice head and initiate the payload build process
     payload_attributes = PayloadAttributes(
-        timestamp=compute_time_at_slot(state, state.slot),
-        prev_randao=get_randao_mix(state, get_current_epoch(state)),
+        timestamp=compute_time_at_slot(state, slot),
+        prev_randao=get_randao_mix(state, compute_epoch_at_slot(slot)),
         suggested_fee_recipient=suggested_fee_recipient,
         # [Modified in Gloas:EIP7732]
         withdrawals=withdrawals,
         parent_beacon_block_root=hash_tree_root(state.latest_block_header),
         # [New in Gloas:EIP7843]
-        slot_number=state.slot,
+        slot_number=slot,
     )
     return execution_engine.notify_forkchoice_updated(
         # [Modified in Gloas:EIP7732]