update builder API registrations after keymanager API fee recipient change

beacon_chain/validators/beacon_validators.nim

@@ -1749,8 +1749,10 @@ proc registerValidatorsPerBuilder(
       validatorRegistrations.add @[validatorRegistration]
 
   # First, check for VC-added keys; cheaper because provided pre-signed
-  # See issue #5599: currently VC have no way to provide BN with per-validator builders per the specs, so we have to
-  #   resort to use the BN fallback default (--payload-builder-url value, obtained by calling getPayloadBuilderAddress)
+  # See issue #5599: currently VC have no way to provide BN with per-validator
+  #   builders per the specs, so we have to resort to use the BN fallback
+  #   default (--payload-builder-url value, obtained by calling
+  #   getPayloadBuilderAddress)
   var nonExitedVcPubkeys: HashSet[ValidatorPubKey]
   if  node.externalBuilderRegistrations.len > 0 and
       payloadBuilderAddress == node.config.getPayloadBuilderAddress.value:

beacon_chain/validators/keystore_management.nim

@@ -1481,6 +1481,7 @@ proc removeFeeRecipientFile*(host: KeymanagerHost,
   if fileExists(path):
     io2.removeFile(path).isOkOr:
       return err($uint(error) & " " & ioErrorMsg(error))
+    host.validatorPool[].invalidateValidatorRegistration(pubkey)
   ok()
 
 proc removeGasLimitFile*(host: KeymanagerHost,
@@ -1499,15 +1500,22 @@ proc removeGraffitiFile*(host: KeymanagerHost,
       return err($uint(error) & " " & ioErrorMsg(error))
   ok()
 
-proc setFeeRecipient*(host: KeymanagerHost, pubkey: ValidatorPubKey, feeRecipient: Eth1Address): Result[void, string] =
+proc setFeeRecipient*(
+    host: KeymanagerHost, pubkey: ValidatorPubKey, feeRecipient: Eth1Address):
+    Result[void, string] =
   let validatorKeystoreDir = host.validatorKeystoreDir(pubkey)
-
   ? secureCreatePath(validatorKeystoreDir).mapErr(proc(e: auto): string =
     "Could not create wallet directory [" & validatorKeystoreDir & "]: " & $e)
 
-  io2.writeFile(validatorKeystoreDir / FeeRecipientFilename, $feeRecipient)
+  let res = io2.writeFile(
+      validatorKeystoreDir / FeeRecipientFilename, $feeRecipient)
     .mapErr(proc(e: auto): string = "Failed to write fee recipient file: " & $e)
 
+  if res.isOk:
+    host.validatorPool[].invalidateValidatorRegistration(pubkey)
+
+  res
+
 proc setGasLimit*(host: KeymanagerHost,
                   pubkey: ValidatorPubKey,
                   gasLimit: uint64): Result[void, string] =

beacon_chain/validators/validator_pool.nim

@@ -288,6 +288,15 @@ proc updateValidator*(pool: var ValidatorPool,
 
     validator.activationEpoch = activationEpoch
 
+func invalidateValidatorRegistration*(
+    pool: var ValidatorPool, pubkey: ValidatorPubKey) =
+  # When the per-validator fee recipient changes via keymanager, the builder
+  # API validator registration needs to be recomputed. This will happen when
+  # next the registrations are sent, but ensure here that will happen rather
+  # than relying on a now-outdated, cached, validator registration.
+  pool.getValidator(pubkey).isErrOr:
+    value.externalBuilderRegistration.reset()
+
 proc close*(pool: var ValidatorPool) =
   ## Unlock and close all validator keystore's files managed by ``pool``.
   for validator in pool.validators.values():