feat(fw): add initial target blob count to header.

Author: spencer-tb

src/ethereum_clis/types.py

@@ -89,6 +89,7 @@ class Result(CamelModel):
     blob_gas_used: HexNumber | None = None
     requests_hash: Hash | None = None
     requests: List[Bytes] | None = None
+    target_blob_count: HexNumber | None = None
 
 
 class TransitionToolInput(CamelModel):

src/ethereum_test_fixtures/blockchain.py

@@ -111,6 +111,9 @@ class FixtureHeader(CamelModel):
         None
     )
     requests_hash: Annotated[Hash, HeaderForkRequirement("requests")] | None = Field(None)
+    target_blob_count: Annotated[
+        ZeroPaddedHexNumber, HeaderForkRequirement("blob_count")
+    ] | None = Field(None)
 
     fork: Fork | None = Field(None, exclude=True)
 
@@ -199,6 +202,8 @@ class FixtureExecutionPayload(CamelModel):
     blob_gas_used: HexNumber | None = Field(None)
     excess_blob_gas: HexNumber | None = Field(None)
 
+    target_blob_count: HexNumber | None = Field(None)
+
     block_hash: Hash
 
     transactions: List[Bytes]

src/ethereum_test_fixtures/tests/test_blockchain.py

@@ -668,6 +668,7 @@
                     excess_blob_gas=18,
                     parent_beacon_block_root=19,
                     requests_hash=20,
+                    target_blob_count=10,
                 ),
                 transactions=[
                     Transaction(
@@ -1191,6 +1192,7 @@ def test_json_deserialization(
                         withdrawals_root=Hash(16),
                         blob_gas_used=17,
                         excess_blob_gas=18,
+                        target_blob_count=10,
                     ),
                     transactions=[
                         Transaction(
@@ -1249,6 +1251,7 @@ def test_json_deserialization(
                     "baseFeePerGas": hex(15),
                     "blobGasUsed": hex(17),
                     "excessBlobGas": hex(18),
+                    "targetBlobCount": hex(10),
                     "blockHash": "0xd90115b7fde329f64335763a446af1"
                     "50ab67e639281dccdb07a007d18bb80211",
                     "transactions": [

src/ethereum_test_forks/base_fork.py

@@ -160,6 +160,14 @@ def header_requests_required(cls, block_number: int, timestamp: int) -> bool:
         """
         pass
 
+    @classmethod
+    @abstractmethod
+    def header_target_blob_count_required(cls, block_number: int, timestamp: int) -> bool:
+        """
+        Returns true if the header must contain target blob count
+        """
+        pass
+
     @classmethod
     @abstractmethod
     def blob_gas_per_blob(cls, block_number: int, timestamp: int) -> int:
@@ -168,6 +176,14 @@ def blob_gas_per_blob(cls, block_number: int, timestamp: int) -> int:
         """
         pass
 
+    @classmethod
+    @abstractmethod
+    def target_blob_count(cls, block_number: int, timestamp: int) -> int:
+        """
+        Returns the target blobs per block for a given fork.
+        """
+        pass
+
     @classmethod
     @abstractmethod
     def get_reward(cls, block_number: int = 0, timestamp: int = 0) -> int:

src/ethereum_test_forks/forks/forks.py

@@ -730,9 +730,16 @@ def header_beacon_root_required(cls, block_number: int = 0, timestamp: int = 0)
     @classmethod
     def blob_gas_per_blob(cls, block_number: int, timestamp: int) -> int:
         """
-        Blobs are enabled started from Cancun.
+        Blobs are enabled starting from Cancun.
         """
         return 2**17
+    
+    @classmethod
+    def target_blob_count(cls, block_number: int, timestamp: int) -> int:
+        """
+        Blobs are enabled starting from Cancun, with a static target of 3 blobs.
+        """
+        return 3
 
     @classmethod
     def tx_types(cls, block_number: int = 0, timestamp: int = 0) -> List[int]:
@@ -938,6 +945,14 @@ def header_requests_required(cls, block_number: int, timestamp: int) -> bool:
         """
         return True
 
+    @classmethod
+    def header_target_blob_count_required(cls, block_number: int = 0, timestamp: int = 0) -> bool:
+        """
+        Prague requires that the execution layer header contains the beacon
+        chain target blob count.
+        """
+        return True
+
     @classmethod
     def engine_new_payload_requests(cls, block_number: int = 0, timestamp: int = 0) -> bool:
         """

src/ethereum_test_specs/blockchain.py

@@ -119,6 +119,7 @@ class Header(CamelModel):
     excess_blob_gas: Removable | HexNumber | None = None
     parent_beacon_block_root: Removable | Hash | None = None
     requests_hash: Removable | Hash | None = None
+    target_blob_count: Removable | HexNumber | None = None
 
     REMOVE_FIELD: ClassVar[Removable] = Removable()
     """
@@ -353,12 +354,17 @@ def make_genesis(
             blob_gas_used=env.blob_gas_used,
             excess_blob_gas=env.excess_blob_gas,
             withdrawals_root=(
-                Withdrawal.list_root(env.withdrawals) if env.withdrawals is not None else None
+                Withdrawal.list_root(env.withdrawals)
+                if env.withdrawals is not None
+                else None
             ),
             parent_beacon_block_root=env.parent_beacon_block_root,
             requests_hash=Requests(max_request_type=fork.max_request_type(0, 0))
             if fork.header_requests_required(0, 0)
             else None,
+            target_blob_count=fork.target_blob_count(0, 0)
+            if fork.header_target_blob_count_required(0, 0)
+            else None,
             fork=fork,
         )
 

src/ethereum_test_types/types.py

@@ -390,6 +390,8 @@ class EnvironmentGeneric(CamelModel, Generic[NumberBoundTypeVar]):
     base_fee_per_gas: NumberBoundTypeVar | None = Field(None, alias="currentBaseFee")
     excess_blob_gas: NumberBoundTypeVar | None = Field(None, alias="currentExcessBlobGas")
 
+    target_blob_count: NumberBoundTypeVar | None = Field(None, alias="currentTargetBlobGasUsed")
+
     parent_difficulty: NumberBoundTypeVar | None = Field(None)
     parent_timestamp: NumberBoundTypeVar | None = Field(None)
     parent_base_fee_per_gas: NumberBoundTypeVar | None = Field(None, alias="parentBaseFee")
@@ -474,6 +476,9 @@ def set_fork_requirements(self, fork: Fork) -> "Environment":
         ):
             updated_values["parent_beacon_block_root"] = 0
 
+        if fork.header_target_blob_count_required(number, timestamp) and self.target_blob_count is None:
+            updated_values["target_blob_count"] = fork.target_blob_count(number, timestamp)
+
         return self.copy(**updated_values)
 
 

src/pytest_plugins/execute/rpc/hive.py

@@ -260,7 +260,16 @@ def base_pre_genesis(
                 timestamp=timestamp,
             ),
         )
-        if base_fork.header_requests_required(block_number=block_number, timestamp=timestamp)
+        if base_fork.header_requests_required(
+            block_number=block_number, timestamp=timestamp
+        )
+        else None,
+        target_blob_count=base_fork.target_blob_count(
+            block_number=block_number, timestamp=timestamp
+        )
+        if base_fork.header_target_blob_count_required(
+            block_number=block_number, timestamp=timestamp
+        )
         else None,
     )