diff --git a/apps/app/src/main/scala/org/lfdecentralizedtrust/splice/console/ScanAppReference.scala b/apps/app/src/main/scala/org/lfdecentralizedtrust/splice/console/ScanAppReference.scala
index 18eaf51dbf..c825a2c28d 100644
--- a/apps/app/src/main/scala/org/lfdecentralizedtrust/splice/console/ScanAppReference.scala
+++ b/apps/app/src/main/scala/org/lfdecentralizedtrust/splice/console/ScanAppReference.scala
@@ -24,6 +24,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.round.{
   OpenMiningRound,
 }
 import org.lfdecentralizedtrust.splice.codegen.java.splice.ans.AnsRules
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.config.NetworkAppClientConfig
 import org.lfdecentralizedtrust.splice.environment.SpliceConsoleEnvironment
 import org.lfdecentralizedtrust.splice.http.v0.definitions
@@ -196,6 +197,14 @@ abstract class ScanAppReference(
       httpCommand(HttpScanAppClient.LookupTransferPreapprovalByParty(party))
     }
 
+  @Help.Summary("Lookup the RegisteredSynchronizer for a dedicated synchronizer id")
+  def lookupSynchronizerRegistration(
+      synchronizerId: String
+  ): Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]] =
+    consoleEnvironment.run {
+      httpCommand(HttpScanAppClient.LookupSynchronizerRegistration(synchronizerId))
+    }
+
   @Help.Summary("Lookup a TransferCommandCounter by the receiver party")
   def lookupTransferCommandCounterByParty(
       party: PartyId
diff --git a/apps/app/src/test/scala/org/lfdecentralizedtrust/splice/integration/tests/SyncOperatorTrafficIntegrationTest.scala b/apps/app/src/test/scala/org/lfdecentralizedtrust/splice/integration/tests/SyncOperatorTrafficIntegrationTest.scala
index 298b5a8fc2..f654871ab1 100644
--- a/apps/app/src/test/scala/org/lfdecentralizedtrust/splice/integration/tests/SyncOperatorTrafficIntegrationTest.scala
+++ b/apps/app/src/test/scala/org/lfdecentralizedtrust/splice/integration/tests/SyncOperatorTrafficIntegrationTest.scala
@@ -3,7 +3,6 @@
 
 package org.lfdecentralizedtrust.splice.integration.tests
 
-import com.daml.ledger.javaapi.data.CreatedEvent
 import com.digitalasset.canton.SynchronizerAlias
 import com.digitalasset.canton.config.RequireTypes.NonNegativeLong
 import com.digitalasset.canton.data.CantonTimestamp
@@ -19,9 +18,7 @@ import org.lfdecentralizedtrust.splice.integration.tests.SpliceTests.{
   IntegrationTest,
   SpliceTestConsoleEnvironment,
 }
-import org.lfdecentralizedtrust.splice.store.MultiDomainAcsStore.ContractState
 import org.lfdecentralizedtrust.splice.util.{
-  Contract,
   ContractWithState,
   DisclosedContracts,
   SynchronizerFeesTestUtil,
@@ -84,10 +81,8 @@ class SyncOperatorTrafficIntegrationTest
         }
       }
 
-      val registration = clue("the DSO registers the synchronizer to this operator") {
-        // The purchase is submitted from alice's participant, which hosts neither the DSO nor
-        // the operator, so the registration must be disclosed with its created-event blob.
-        val tx = sv1Backend.participantClientWithAdminToken.ledger_api_extensions.commands
+      clue("the DSO registers the synchronizer to this operator") {
+        sv1Backend.participantClientWithAdminToken.ledger_api_extensions.commands
           .submitJava(
             actAs = Seq(dsoParty),
             readAs = Seq(dsoParty),
@@ -100,16 +95,14 @@ class SyncOperatorTrafficIntegrationTest
               .asScala
               .toSeq,
             userId = sv1Backend.config.ledgerApiUser,
-            includeCreatedEventBlob = true,
           )
-        val contract = tx.getEventsById.values.asScala
-          .collect { case ev: CreatedEvent => ev }
-          .flatMap(Contract.fromCreatedEvent(RegisteredSynchronizer.COMPANION)(_))
-          .loneElement
-        ContractWithState(
-          contract,
-          ContractState.Assigned(SynchronizerId.tryFromString(tx.getSynchronizerId)),
-        )
+      }
+
+      // Alice's participant hosts neither the DSO nor the operator, so the registration has to
+      // be disclosed, and Scan is the only source of its created-event blob.
+      sv1ScanBackend.lookupSynchronizerRegistration("dedicated::does-not-exist") shouldBe None
+      val registration = eventually() {
+        sv1ScanBackend.lookupSynchronizerRegistration(synchronizerId.toProtoPrimitive).value
       }
 
       val aliceParty = onboardWalletUser(aliceWalletClient, aliceValidatorBackend)
diff --git a/apps/common/src/main/resources/db/migration/canton-network/postgres/stable/V075__scan_acs_store_registered_synchronizer.sql b/apps/common/src/main/resources/db/migration/canton-network/postgres/stable/V075__scan_acs_store_registered_synchronizer.sql
new file mode 100644
index 0000000000..e0cfe59a99
--- /dev/null
+++ b/apps/common/src/main/resources/db/migration/canton-network/postgres/stable/V075__scan_acs_store_registered_synchronizer.sql
@@ -0,0 +1,4 @@
+-- The synchronizer id from a RegisteredSynchronizer, so Scan can serve a registration by
+-- synchronizer id without a JSON extraction on every candidate row.
+alter table scan_acs_store
+  add column registered_synchronizer_id text;
diff --git a/apps/common/src/main/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTrigger.scala b/apps/common/src/main/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTrigger.scala
index 9e72fdf48c..0cf497a95e 100644
--- a/apps/common/src/main/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTrigger.scala
+++ b/apps/common/src/main/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTrigger.scala
@@ -264,6 +264,15 @@ object SqlIndexInitializationTrigger {
           where reward_beneficiary_is_observer = false
         """,
       ),
+    IndexAction
+      .Create(
+        indexName = "scan_acs_store_sid_mid_pn_tid_rsid",
+        createAction = sqlu"""
+          create index concurrently if not exists scan_acs_store_sid_mid_pn_tid_rsid
+          on scan_acs_store (store_id, migration_id, package_name, template_id_qualified_name, registered_synchronizer_id)
+          where registered_synchronizer_id is not null
+        """,
+      ),
     IndexAction
       .Create(
         indexName = "scan_txlog_store_sid_effat_en_vot",
diff --git a/apps/common/src/test/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTriggerStoreTest.scala b/apps/common/src/test/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTriggerStoreTest.scala
index 0fbbcfe077..dec965b892 100644
--- a/apps/common/src/test/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTriggerStoreTest.scala
+++ b/apps/common/src/test/scala/org/lfdecentralizedtrust/splice/automation/SqlIndexInitializationTriggerStoreTest.scala
@@ -42,6 +42,7 @@ class SqlIndexInitializationTriggerStoreTest
     "updt_hist_crea_hi_mi_ci_import_updates",
     "updt_hist_tran_hi_eth",
     "dso_acs_store_sid_mid_pn_tid_rbio",
+    "scan_acs_store_sid_mid_pn_tid_rsid",
     "scan_txlog_store_sid_effat_en_vot",
   )
 
diff --git a/apps/scan/src/main/openapi/scan.yaml b/apps/scan/src/main/openapi/scan.yaml
index efbc94a9f4..1df9ead450 100644
--- a/apps/scan/src/main/openapi/scan.yaml
+++ b/apps/scan/src/main/openapi/scan.yaml
@@ -1124,6 +1124,32 @@ paths:
         "404":
           $ref: "../../../../common/src/main/openapi/common-external.yaml#/components/responses/404"
 
+  /v0/synchronizers/{synchronizer_id}/registration:
+    get:
+      tags: [internal, scan]
+      x-jvm-package: scan
+      operationId: "lookupSynchronizerRegistration"
+      description: |
+        Get the RegisteredSynchronizer authorizing Amulet-funded traffic for a dedicated
+        synchronizer.
+      parameters:
+        - name: "synchronizer_id"
+          description: |
+            The synchronizer ID whose registration to look up.
+          in: "path"
+          required: true
+          schema:
+            type: string
+      responses:
+        "200":
+          description: ok
+          content:
+            application/json:
+              schema:
+                "$ref": "#/components/schemas/LookupSynchronizerRegistrationResponse"
+        "404":
+          $ref: "../../../../common/src/main/openapi/common-external.yaml#/components/responses/404"
+
   /v0/transfer-command-counter/{party}:
     get:
       tags: [internal, scan]
@@ -3531,6 +3557,14 @@ components:
       properties:
         transfer_preapproval:
           "$ref": "../../../../common/src/main/openapi/common-internal.yaml#/components/schemas/ContractWithState"
+    LookupSynchronizerRegistrationResponse:
+      description: A Daml contract of template `Splice.DecentralizedSynchronizer:RegisteredSynchronizer`.
+      type: object
+      required: ["registration"]
+      properties:
+        registration:
+          "$ref": "../../../../common/src/main/openapi/common-internal.yaml#/components/schemas/ContractWithState"
+
     LookupTransferCommandCounterByPartyResponse:
       description: A Daml contract of template `Splice.ExternalPartyAmuletRules:TransferCommandCounter`.
       type: object
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/BftScanConnection.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/BftScanConnection.scala
index 30802acef6..4b3613889b 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/BftScanConnection.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/BftScanConnection.scala
@@ -104,6 +104,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationi
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationinstructionv2
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.transferinstructionv1
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.transferinstructionv2
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.codegen.java.splice.dsorules.{
   DsoRules,
   DsoRules_CloseVoteRequestResult,
@@ -483,6 +484,12 @@ class BftScanConnection(
   ): Future[Option[LookupTransferCommandStatusResponse]] =
     bftCall(_.lookupTransferCommandStatus(sender, nonce), "lookupTransferCommandStatus")
 
+  override def lookupSynchronizerRegistration(synchronizerId: String)(implicit
+      ec: ExecutionContext,
+      tc: TraceContext,
+  ): Future[Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]]] =
+    bftCall(_.lookupSynchronizerRegistration(synchronizerId), "lookupSynchronizerRegistration")
+
   override def lookupTransferPreapprovalByParty(receiver: PartyId)(implicit
       ec: ExecutionContext,
       tc: TraceContext,
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/ScanConnection.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/ScanConnection.scala
index 1aff1a2ffc..6ad82f6c8b 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/ScanConnection.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/ScanConnection.scala
@@ -20,6 +20,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.round.{
   OpenMiningRound,
 }
 import org.lfdecentralizedtrust.splice.codegen.java.splice.types.Round
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.config.UpgradesConfig
 import org.lfdecentralizedtrust.splice.environment.*
 import org.lfdecentralizedtrust.splice.http.HttpClient
@@ -308,6 +309,11 @@ trait ScanConnection
       tc: TraceContext,
   ): Future[Option[ContractWithState[TransferPreapproval.ContractId, TransferPreapproval]]]
 
+  def lookupSynchronizerRegistration(synchronizerId: String)(implicit
+      ec: ExecutionContext,
+      tc: TraceContext,
+  ): Future[Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]]]
+
   def listVoteRequestResults(
       filters: VoteResultsFilters,
       limit: Int,
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/SingleScanConnection.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/SingleScanConnection.scala
index a0af1d2526..75f3d986a7 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/SingleScanConnection.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/SingleScanConnection.scala
@@ -87,6 +87,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationv
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationv2
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationinstructionv1
 import org.lfdecentralizedtrust.splice.codegen.java.splice.api.token.allocationinstructionv2
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.http.v0.definitions.HoldingsSummaryRequest.RecordTimeMatch
 import org.lfdecentralizedtrust.splice.metrics.ScanConnectionMetrics
 import org.lfdecentralizedtrust.splice.scan.admin.api.client.commands.HttpScanAppClient.BftSequencer
@@ -490,6 +491,15 @@ class SingleScanConnection private[client] (
       HttpScanAppClient.GetMigrationId(),
     )
 
+  override def lookupSynchronizerRegistration(synchronizerId: String)(implicit
+      ec: ExecutionContext,
+      tc: TraceContext,
+  ): Future[Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]]] =
+    runHttpCmd(
+      config.adminApi.url,
+      HttpScanAppClient.LookupSynchronizerRegistration(synchronizerId),
+    )
+
   override def lookupTransferPreapprovalByParty(receiver: PartyId)(implicit
       ec: ExecutionContext,
       tc: TraceContext,
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/commands/HttpScanAppClient.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/commands/HttpScanAppClient.scala
index eb15cf4536..776d2aa4e5 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/commands/HttpScanAppClient.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/api/client/commands/HttpScanAppClient.scala
@@ -32,6 +32,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.round.{
 }
 import org.lfdecentralizedtrust.splice.codegen.java.splice.ans as ansCodegen
 import org.lfdecentralizedtrust.splice.codegen.java.splice.ans.AnsRules
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.config.SpliceInstanceNamesConfig
 import org.lfdecentralizedtrust.splice.http.v0.{definitions, scan as http}
 import org.lfdecentralizedtrust.tokenstandard.{
@@ -602,6 +603,30 @@ object HttpScanAppClient {
     }
   }
 
+  case class LookupSynchronizerRegistration(
+      synchronizerId: String
+  ) extends InternalBaseCommand[http.LookupSynchronizerRegistrationResponse, Option[
+        ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]
+      ]] {
+
+    override def submitRequest(
+        client: ScanClient,
+        headers: List[HttpHeader],
+    ) = client.lookupSynchronizerRegistration(synchronizerId, headers)
+
+    override def handleOk()(implicit
+        decoder: TemplateJsonDecoder
+    ) = {
+      case http.LookupSynchronizerRegistrationResponse.OK(response) =>
+        ContractWithState
+          .fromHttp(RegisteredSynchronizer.COMPANION)(response.registration)
+          .map(Some(_))
+          .leftMap(_.toString)
+      case http.LookupSynchronizerRegistrationResponse.NotFound(_) =>
+        Right(None)
+    }
+  }
+
   case class LookupTransferCommandCounterByParty(
       party: PartyId
   ) extends InternalBaseCommand[http.LookupTransferCommandCounterByPartyResponse, Option[
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/http/HttpScanHandler.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/http/HttpScanHandler.scala
index 1950aead98..9a139e24f8 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/http/HttpScanHandler.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/admin/http/HttpScanHandler.scala
@@ -1185,6 +1185,32 @@ class HttpScanHandler(
     }
   }
 
+  override def lookupSynchronizerRegistration(
+      respond: ScanResource.LookupSynchronizerRegistrationResponse.type
+  )(
+      synchronizerId: String
+  )(extracted: TraceContext): Future[ScanResource.LookupSynchronizerRegistrationResponse] = {
+    implicit val tc = extracted
+    withSpan(s"$workflowId.lookupSynchronizerRegistration") { _ => _ =>
+      store
+        .lookupSynchronizerRegistration(synchronizerId)
+        .map {
+          case Some(c) =>
+            v0.ScanResource.LookupSynchronizerRegistrationResponse.OK(
+              definitions.LookupSynchronizerRegistrationResponse(
+                c.toHttp
+              )
+            )
+          case None =>
+            v0.ScanResource.LookupSynchronizerRegistrationResponse.NotFound(
+              definitions.ErrorResponse(
+                s"No RegisteredSynchronizer found for synchronizer id: $synchronizerId"
+              )
+            )
+        }
+    }
+  }
+
   override def lookupTransferCommandCounterByParty(
       respond: ScanResource.LookupTransferCommandCounterByPartyResponse.type
   )(
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/CachingScanStore.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/CachingScanStore.scala
index dec98aef00..dba8190351 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/CachingScanStore.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/CachingScanStore.scala
@@ -17,6 +17,7 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.amuletrules.{
   TransferPreapproval,
 }
 import org.lfdecentralizedtrust.splice.codegen.java.splice.ans.{AnsEntry, AnsRules}
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.RegisteredSynchronizer
 import org.lfdecentralizedtrust.splice.codegen.java.splice.dso.svstate.SvNodeState
 import org.lfdecentralizedtrust.splice.codegen.java.splice.dsorules.{
   DsoRules_CloseVoteRequestResult,
@@ -181,6 +182,11 @@ class CachingScanStore(
       store.lookupTransferPreapprovalByParty,
     ).get(partyId)
 
+  override def lookupSynchronizerRegistration(synchronizerId: String)(implicit
+      tc: TraceContext
+  ): Future[Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]]] =
+    store.lookupSynchronizerRegistration(synchronizerId)
+
   override def lookupTransferCommandCounterByParty(partyId: PartyId)(implicit
       tc: TraceContext
   ): Future[Option[ContractWithState[TransferCommandCounter.ContractId, TransferCommandCounter]]] =
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/ScanStore.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/ScanStore.scala
index 6ba742e2be..eb49ef45a3 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/ScanStore.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/ScanStore.scala
@@ -204,6 +204,21 @@ trait ScanStore
     ]]
   ]
 
+  /** The registration authorizing Amulet-funded traffic for `synchronizerId`, if any.
+    *
+    * Comes from the ACS store, so the result carries the created event blob the buyer needs to
+    * disclose it. If more than one is live, returns one of them under a stable total order; no
+    * supersession is implied.
+    */
+  def lookupSynchronizerRegistration(
+      synchronizerId: String
+  )(implicit tc: TraceContext): Future[
+    Option[ContractWithState[
+      splice.decentralizedsynchronizer.RegisteredSynchronizer.ContractId,
+      splice.decentralizedsynchronizer.RegisteredSynchronizer,
+    ]]
+  ]
+
   def lookupTransferCommandCounterByParty(
       partyId: PartyId
   )(implicit tc: TraceContext): Future[
@@ -408,8 +423,14 @@ object ScanStore {
               pkgVersionSupport
                 .supportsDedicatedSynchronizers(Seq(key.dsoParty), now)(tc)
           },
-        )(
-          ScanAcsStoreRowData(_)
+        )(contract =>
+          // A String, not a SynchronizerId: DsoRules_RegisterSynchronizer only checks the id is
+          // non-empty, so tryFromString here would throw on a governance typo and take down the
+          // ingestion pipeline. The query compares it as text.
+          ScanAcsStoreRowData(
+            contract,
+            registeredSynchronizerId = Some(contract.payload.synchronizerId),
+          )
         ),
         mkFilter(splice.validatorlicense.ValidatorLicense.COMPANION)(co => co.payload.dso == dso) {
           contract =>
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/DbScanStore.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/DbScanStore.scala
index 871c2633b6..b9ea443974 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/DbScanStore.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/DbScanStore.scala
@@ -22,7 +22,10 @@ import org.lfdecentralizedtrust.splice.codegen.java.splice.amuletrules.{
   TransferPreapproval,
 }
 import org.lfdecentralizedtrust.splice.codegen.java.splice.ans.{AnsEntry, AnsRules}
-import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.MemberTraffic
+import org.lfdecentralizedtrust.splice.codegen.java.splice.decentralizedsynchronizer.{
+  MemberTraffic,
+  RegisteredSynchronizer,
+}
 import org.lfdecentralizedtrust.splice.codegen.java.splice.dso.svstate.SvNodeState
 import org.lfdecentralizedtrust.splice.codegen.java.splice.dsorules.{
   DsoRules_CloseVoteRequestResult,
@@ -365,6 +368,33 @@ class DbScanStore(
     } yield contractWithStateFromRow(TransferPreapproval.COMPANION)(row)).value
   }
 
+  override def lookupSynchronizerRegistration(
+      synchronizerId: String
+  )(implicit tc: TraceContext): Future[
+    Option[ContractWithState[RegisteredSynchronizer.ContractId, RegisteredSynchronizer]]
+  ] = waitUntilAcsIngested {
+    (for {
+      row <- storage
+        .querySingle(
+          selectFromAcsTableWithState(
+            ScanTables.acsTableName,
+            acsStoreId,
+            domainMigrationId,
+            RegisteredSynchronizer.COMPANION,
+            additionalWhere = sql"""
+                and registered_synchronizer_id = ${lengthLimited(synchronizerId)}
+            """,
+            // Uniqueness is not enforced on-ledger, so pick a total order: every Scan must
+            // return the same row for bftCall to agree.
+            orderLimit = sql"""
+                order by contract_id limit 1
+            """,
+          ).headOption,
+          "lookupSynchronizerRegistration",
+        )
+    } yield contractWithStateFromRow(RegisteredSynchronizer.COMPANION)(row)).value
+  }
+
   override def lookupTransferCommandCounterByParty(
       partyId: PartyId
   )(implicit tc: TraceContext): Future[
diff --git a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/ScanTables.scala b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/ScanTables.scala
index de109b94bf..20f6b0fa26 100644
--- a/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/ScanTables.scala
+++ b/apps/scan/src/main/scala/org/lfdecentralizedtrust/splice/scan/store/db/ScanTables.scala
@@ -56,6 +56,7 @@ object ScanTables extends AcsTables {
       transferPreapprovalReceiver: Option[PartyId] = None,
       transferPreapprovalValidFrom: Option[Timestamp] = None,
       walletParty: Option[PartyId] = None,
+      registeredSynchronizerId: Option[String] = None,
   ) extends AcsRowData.AcsRowDataFromContract {
     override def indexColumns: Seq[(String, IndexColumnValue[?])] = Seq(
       ScanAcsStoreRowData.IndexColumns.round -> round,
@@ -75,6 +76,8 @@ object ScanTables extends AcsTables {
       ScanAcsStoreRowData.IndexColumns.transfer_preapproval_receiver -> transferPreapprovalReceiver,
       ScanAcsStoreRowData.IndexColumns.transfer_preapproval_valid_from -> transferPreapprovalValidFrom,
       ScanAcsStoreRowData.IndexColumns.wallet_party -> walletParty,
+      ScanAcsStoreRowData.IndexColumns.registered_synchronizer_id -> registeredSynchronizerId
+        .map(lengthLimited),
     )
   }
 
@@ -101,6 +104,7 @@ object ScanTables extends AcsTables {
       val transfer_preapproval_receiver = "transfer_preapproval_receiver"
       val transfer_preapproval_valid_from = "transfer_preapproval_valid_from"
       val wallet_party = "wallet_party"
+      val registered_synchronizer_id = "registered_synchronizer_id"
       val All = Seq(
         round,
         validator,
@@ -119,6 +123,7 @@ object ScanTables extends AcsTables {
         transfer_preapproval_receiver,
         transfer_preapproval_valid_from,
         wallet_party,
+        registered_synchronizer_id,
       )
     }
   }
diff --git a/apps/scan/src/test/scala/org/lfdecentralizedtrust/splice/store/db/ScanStoreTest.scala b/apps/scan/src/test/scala/org/lfdecentralizedtrust/splice/store/db/ScanStoreTest.scala
index 7227c28b63..6f7e288b88 100644
--- a/apps/scan/src/test/scala/org/lfdecentralizedtrust/splice/store/db/ScanStoreTest.scala
+++ b/apps/scan/src/test/scala/org/lfdecentralizedtrust/splice/store/db/ScanStoreTest.scala
@@ -240,6 +240,42 @@ abstract class ScanStoreTest
       }
     }
 
+    "lookupSynchronizerRegistration" should {
+      "return the registration for the requested synchronizer id" in {
+        val wanted = registeredSynchronizer(userParty(1), "dedicated::1220aa")
+        val other = registeredSynchronizer(userParty(2), "dedicated::1220bb")
+        for {
+          store <- mkStore()
+          _ <- dummyDomain.create(wanted)(store.multiDomainAcsStore)
+          _ <- dummyDomain.create(other)(store.multiDomainAcsStore)
+        } yield {
+          store.lookupSynchronizerRegistration("dedicated::1220aa").futureValue should be(
+            Some(ContractWithState(wanted, Assigned(dummyDomain)))
+          )
+          store.lookupSynchronizerRegistration("dedicated::1220zz").futureValue should be(None)
+        }
+      }
+
+      // Governance can create two registrations for one synchronizer id: the template has no
+      // key and DsoRules_RegisterSynchronizer creates unconditionally. Every Scan must pick the
+      // same one, because bftCall compares responses structurally.
+      "pick deterministically when a synchronizer id has more than one registration" in {
+        // Ingest `lower` second so insertion order and contract-id order disagree.
+        val lower = registeredSynchronizer(userParty(1), "dedicated::1220aa")
+        val higher = registeredSynchronizer(userParty(2), "dedicated::1220aa")
+        lower.contractId.contractId should be < higher.contractId.contractId
+        for {
+          store <- mkStore()
+          _ <- dummyDomain.create(higher)(store.multiDomainAcsStore)
+          _ <- dummyDomain.create(lower)(store.multiDomainAcsStore)
+        } yield {
+          store.lookupSynchronizerRegistration("dedicated::1220aa").futureValue should be(
+            Some(ContractWithState(lower, Assigned(dummyDomain)))
+          )
+        }
+      }
+    }
+
     "lookupTransferPreapprovalByParty" should {
       "return the TransferPreapproval contract signed by the specified party if available" in {
         val wanted = transferPreapproval(userParty(1), providerParty(1), time(0), time(1))
@@ -1714,13 +1750,16 @@ trait AmuletTransferUtil { self: StoreTestBase =>
     )
   }
 
-  def registeredSynchronizer(operator: PartyId) =
+  def registeredSynchronizer(
+      operator: PartyId,
+      synchronizerId: String = dummyDomain.toProtoPrimitive,
+  ) =
     contract(
       RegisteredSynchronizer.TEMPLATE_ID_WITH_PACKAGE_ID,
       new RegisteredSynchronizer.ContractId(nextCid()),
       new RegisteredSynchronizer(
         dsoParty.toProtoPrimitive,
-        dummyDomain.toProtoPrimitive,
+        synchronizerId,
         operator.toProtoPrimitive,
       ),
     )
diff --git a/cluster/configs/shared/rate-limits/unlimited.yaml b/cluster/configs/shared/rate-limits/unlimited.yaml
index 6d9cd05373..b2115038d0 100644
--- a/cluster/configs/shared/rate-limits/unlimited.yaml
+++ b/cluster/configs/shared/rate-limits/unlimited.yaml
@@ -45,6 +45,10 @@ rateLimits:
     name: domains-v1
     type: unlimited
 
+  /api/scan/v0/synchronizers:
+    name: synchronizers
+    type: unlimited
+
   /api/scan/v0/closed-rounds:
     name: closed-rounds
     type: unlimited
diff --git a/cluster/deployment/scratchneta/config.resolved.yaml b/cluster/deployment/scratchneta/config.resolved.yaml
index 9ddf688b30..b9ba039558 100644
--- a/cluster/deployment/scratchneta/config.resolved.yaml
+++ b/cluster/deployment/scratchneta/config.resolved.yaml
@@ -333,6 +333,9 @@ sv:
         /api/scan/v0/synchronizer-identities:
           name: 'synchronizer-identities'
           type: 'unlimited'
+        /api/scan/v0/synchronizers:
+          name: 'synchronizers'
+          type: 'unlimited'
         /api/scan/v0/transfer-command:
           name: 'transfer-command-status'
           type: 'unlimited'
diff --git a/cluster/deployment/scratchnetb/config.resolved.yaml b/cluster/deployment/scratchnetb/config.resolved.yaml
index 9ddf688b30..b9ba039558 100644
--- a/cluster/deployment/scratchnetb/config.resolved.yaml
+++ b/cluster/deployment/scratchnetb/config.resolved.yaml
@@ -333,6 +333,9 @@ sv:
         /api/scan/v0/synchronizer-identities:
           name: 'synchronizer-identities'
           type: 'unlimited'
+        /api/scan/v0/synchronizers:
+          name: 'synchronizers'
+          type: 'unlimited'
         /api/scan/v0/transfer-command:
           name: 'transfer-command-status'
           type: 'unlimited'
diff --git a/cluster/deployment/scratchnetc/config.resolved.yaml b/cluster/deployment/scratchnetc/config.resolved.yaml
index 9ddf688b30..b9ba039558 100644
--- a/cluster/deployment/scratchnetc/config.resolved.yaml
+++ b/cluster/deployment/scratchnetc/config.resolved.yaml
@@ -333,6 +333,9 @@ sv:
         /api/scan/v0/synchronizer-identities:
           name: 'synchronizer-identities'
           type: 'unlimited'
+        /api/scan/v0/synchronizers:
+          name: 'synchronizers'
+          type: 'unlimited'
         /api/scan/v0/transfer-command:
           name: 'transfer-command-status'
           type: 'unlimited'
diff --git a/cluster/deployment/scratchnetd/config.resolved.yaml b/cluster/deployment/scratchnetd/config.resolved.yaml
index 9ddf688b30..b9ba039558 100644
--- a/cluster/deployment/scratchnetd/config.resolved.yaml
+++ b/cluster/deployment/scratchnetd/config.resolved.yaml
@@ -333,6 +333,9 @@ sv:
         /api/scan/v0/synchronizer-identities:
           name: 'synchronizer-identities'
           type: 'unlimited'
+        /api/scan/v0/synchronizers:
+          name: 'synchronizers'
+          type: 'unlimited'
         /api/scan/v0/transfer-command:
           name: 'transfer-command-status'
           type: 'unlimited'
diff --git a/cluster/deployment/scratchnete/config.resolved.yaml b/cluster/deployment/scratchnete/config.resolved.yaml
index 9ddf688b30..b9ba039558 100644
--- a/cluster/deployment/scratchnete/config.resolved.yaml
+++ b/cluster/deployment/scratchnete/config.resolved.yaml
@@ -333,6 +333,9 @@ sv:
         /api/scan/v0/synchronizer-identities:
           name: 'synchronizer-identities'
           type: 'unlimited'
+        /api/scan/v0/synchronizers:
+          name: 'synchronizers'
+          type: 'unlimited'
         /api/scan/v0/transfer-command:
           name: 'transfer-command-status'
           type: 'unlimited'
diff --git a/cluster/expected/sv-runbook/expected.json b/cluster/expected/sv-runbook/expected.json
index 201dda3b88..5eb098fc76 100644
--- a/cluster/expected/sv-runbook/expected.json
+++ b/cluster/expected/sv-runbook/expected.json
@@ -997,6 +997,10 @@
           "name": "synchronizer-identities",
           "type": "unlimited"
         },
+        "/api/scan/v0/synchronizers": {
+          "name": "synchronizers",
+          "type": "unlimited"
+        },
         "/api/scan/v0/transfer-command": {
           "name": "transfer-command-status",
           "type": "unlimited"
diff --git a/cluster/expected/sv/expected.json b/cluster/expected/sv/expected.json
index c0157a8b85..ff2f7234bc 100644
--- a/cluster/expected/sv/expected.json
+++ b/cluster/expected/sv/expected.json
@@ -1692,6 +1692,10 @@
           "name": "synchronizer-identities",
           "type": "unlimited"
         },
+        "/api/scan/v0/synchronizers": {
+          "name": "synchronizers",
+          "type": "unlimited"
+        },
         "/api/scan/v0/transfer-command": {
           "name": "transfer-command-status",
           "type": "unlimited"
@@ -2093,6 +2097,10 @@
           "name": "synchronizer-identities",
           "type": "unlimited"
         },
+        "/api/scan/v0/synchronizers": {
+          "name": "synchronizers",
+          "type": "unlimited"
+        },
         "/api/scan/v0/transfer-command": {
           "name": "transfer-command-status",
           "type": "unlimited"