Cannot exit validator using remote signing

[twoeths]

Describe the bug

The voluntaryExitRemoteSigner.test.ts failed post-deneb, see https://github.com/ChainSafe/lodestar/actions/runs/20592632915/job/59140702960?pr=8721

5929: 2025-12-30 09:02:04.255+0000 | pool-2-thread-1 | INFO  | Eth2Runner | Keys loaded from local keystores: [2], with error count: [0]
5929: 2025-12-30 09:02:04.257+0000 | pool-2-thread-1 | INFO  | DefaultArtifactSignerProvider | Total signers (keys) currently loaded in memory: 2
5929: 2025-12-30 09:02:04.329+0000 | main | INFO  | Runner | Web3Signer has started with TLS disabled, and ready to handle signing requests on 0.0.0.0:9090
5929: 2025-12-30 09:02:15.579+0000 | vert.x-eventloop-thread-0 | ERROR | LogErrorHandler | Failed request: http://127.0.0.1:9090/api/v1/eth2/sign/0xa99a76ed7796f7be22d5b7e85deeb7c5677e88e511e0b337618f8c4eb61349b4bf2d153f649f7b53359fe8b94a38e44c
java.lang.IllegalArgumentException: Signing root 0x5fd2f37414733e3c2f6b32bbb4f89ade39ef5fffcf945548cd64a4d342d05753 must match signing computed signing root 0x383568b603ab44ebf3b4dc704478c92df13d2b2eb2895be26af4363e054c5152 from data
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:445)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:102)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:56)
	at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
	at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$5(ContextImpl.java:205)
	at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:270)
	at io.vertx.core.impl.ContextImpl$1.execute(ContextImpl.java:221)
	at io.vertx.core.impl.WorkerTask.run(WorkerTask.java:56)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
5929: 2025-12-30 09:02:15.580+0000 | vert.x-eventloop-thread-0 | ERROR | RoutingContext | Unhandled exception in router
java.lang.IllegalArgumentException: Signing root 0x5fd2f37414733e3c2f6b32bbb4f89ade39ef5fffcf945548cd64a4d342d05753 must match signing computed signing root 0x383568b603ab44ebf3b4dc704478c92df13d2b2eb2895be26af4363e054c5152 from data
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:445)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:102)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:56)
	at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
	at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$5(ContextImpl.java:205)
	at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:270)
	at io.vertx.core.impl.ContextImpl$1.execute(ContextImpl.java:221)
	at io.vertx.core.impl.WorkerTask.run(WorkerTask.java:56)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
5929: 2025-12-30 09:02:15.586+0000 | vert.x-eventloop-thread-0 | ERROR | LogErrorHandler | Failed request: http://127.0.0.1:9090/api/v1/eth2/sign/0xb89bebc699769726a318c8e9971bd3171297c61aea4a6578a7a4f94b547dcba5bac16a89108b6b6a1fe3695d1a874a0b
java.lang.IllegalArgumentException: Signing root 0xdcae64f2abb39389c22cd9a519a1384f2709656a2cc2385655eab28b138c359e must match signing computed signing root 0x370331c1a155e53b1863023122ceb61cb76c498a2c75710bc6256612d9d6836b from data
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:445)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:102)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:56)
	at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
	at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$5(ContextImpl.java:205)
	at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:270)
	at io.vertx.core.impl.ContextImpl$1.execute(ContextImpl.java:221)
	at io.vertx.core.impl.WorkerTask.run(WorkerTask.java:56)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
5929: 2025-12-30 09:02:15.586+0000 | vert.x-eventloop-thread-0 | ERROR | RoutingContext | Unhandled exception in router
java.lang.IllegalArgumentException: Signing root 0xdcae64f2abb39389c22cd9a519a1384f2709656a2cc2385655eab28b138c359e must match signing computed signing root 0x370331c1a155e53b1863023122ceb61cb76c498a2c75710bc6256612d9d6836b from data
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:445)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:102)
	at tech.pegasys.web3signer.core.service.http.handlers.signing.eth2.Eth2SignForIdentifierHandler.handle(Eth2SignForIdentifierHandler.java:56)
	at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
	at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$5(ContextImpl.java:205)
	at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:270)
	at io.vertx.core.impl.ContextImpl$1.execute(ContextImpl.java:221)
	at io.vertx.core.impl.WorkerTask.run(WorkerTask.java:56)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
stdout | packages/cli/test/e2e/voluntaryExitRemoteSigner.test.ts > voluntaryExit using remote signer
Attempting to stop container

there is a discrepancy between and web3 signer. It seems lodestar computed voluntary exit signing root correctly but we send wrong fork_info to web3 signer

lodestar/packages/validator/src/util/externalSignerClient.ts

Line 150 in b255111

const forkInfo = config.getForkInfo(signingSlot);

post-deneb, we use capella fork to compute domain for voluntary_exit message, but we send the fork of slot instead, which could be electra or fulu

cc @nflaig if he can confirm that

Expected behavior

no error

Steps to reproduce

No response

Additional context

No response

Operating system

Linux

Lodestar version or commit hash

v1.38.0

[twoeths]

this happens in an effort to migrate all tests to run from electra to fulu instead of phase0 #8721