chore(consume): retry logic for initial consume engine fcu (#1815)

* chore(consume): add exponential retry logic for initial fcu in consume engine.

* chore(docs): changelog.

Author: spencer-tb

docs/CHANGELOG.md

@@ -45,6 +45,7 @@ Users can select any of the artifacts depending on their testing needs for their
 
 - 🔀 `consume` now automatically avoids GitHub API calls when using direct release URLs (better for CI environments), while release specifiers like `stable@latest` continue to use the API for version resolution ([#1788](https://github.com/ethereum/execution-spec-tests/pull/1788)).
 - 🔀 Refactor consume simulator architecture to use explicit pytest plugin structure with forward-looking architecture ([#1801](https://github.com/ethereum/execution-spec-tests/pull/1801)).
+- 🔀 Add exponential retry logic to initial fcu within consume engine ([#1815](https://github.com/ethereum/execution-spec-tests/pull/1815)).
 
 #### `execute`
 

src/pytest_plugins/consume/simulators/hive_tests/test_via_engine.py

@@ -5,6 +5,8 @@
 Each `engine_newPayloadVX` is verified against the appropriate VALID/INVALID responses.
 """
 
+import time
+
 from ethereum_test_exceptions import UndefinedException
 from ethereum_test_fixtures import BlockchainEngineFixture
 from ethereum_test_rpc import EngineRPC, EthRPC
@@ -42,16 +44,28 @@ def test_blockchain_via_engine(
     # Send a initial forkchoice update
     with timing_data.time("Initial forkchoice update"):
         logger.info("Sending initial forkchoice update to genesis block...")
-        forkchoice_response = engine_rpc.forkchoice_updated(
-            forkchoice_state=ForkchoiceState(
-                head_block_hash=fixture.genesis.block_hash,
-            ),
-            payload_attributes=None,
-            version=fixture.payloads[0].forkchoice_updated_version,
-        )
-        status = forkchoice_response.payload_status.status
-        logger.info(f"Initial forkchoice update response: {status}")
+        delay = 0.5
+        for attempt in range(3):
+            forkchoice_response = engine_rpc.forkchoice_updated(
+                forkchoice_state=ForkchoiceState(
+                    head_block_hash=fixture.genesis.block_hash,
+                ),
+                payload_attributes=None,
+                version=fixture.payloads[0].forkchoice_updated_version,
+            )
+            status = forkchoice_response.payload_status.status
+            logger.info(f"Initial forkchoice update response attempt {attempt + 1}: {status}")
+            if status != PayloadStatusEnum.SYNCING:
+                break
+            if attempt < 2:
+                time.sleep(delay)
+                delay *= 2
+
         if forkchoice_response.payload_status.status != PayloadStatusEnum.VALID:
+            logger.error(
+                f"Client failed to initialize properly after 3 attempts, "
+                f"final status: {forkchoice_response.payload_status.status}"
+            )
             raise LoggedError(
                 f"unexpected status on forkchoice updated to genesis: {forkchoice_response}"
             )