diff --git a/modules/doobie-mssql/src/test/scala/DoobieMSSqlSuites.scala b/modules/doobie-mssql/src/test/scala/DoobieMSSqlSuites.scala
index 51ce66c1..3ac78006 100644
--- a/modules/doobie-mssql/src/test/scala/DoobieMSSqlSuites.scala
+++ b/modules/doobie-mssql/src/test/scala/DoobieMSSqlSuites.scala
@@ -233,6 +233,10 @@ final class TreeSuite extends DoobieMSSqlDatabaseSuite with SqlTreeSuite {
   lazy val mapping = new DoobieMSSqlTestMapping(transactor) with SqlTreeMapping[IO]
 }
 
+final class UnionOrderSuite extends DoobieMSSqlDatabaseSuite with SqlUnionOrderSuite {
+  lazy val mapping = new DoobieMSSqlTestMapping(transactor) with SqlUnionOrderMapping[IO]
+}
+
 final class UnionsSuite extends DoobieMSSqlDatabaseSuite with SqlUnionSuite {
   lazy val mapping = new DoobieMSSqlTestMapping(transactor) with SqlUnionsMapping[IO]
 }
diff --git a/modules/doobie-oracle/src/test/resources/scripts/01_create_user.sql b/modules/doobie-oracle/src/test/resources/scripts/01_create_user.sql
index 15da74de..fb5f06dc 100644
--- a/modules/doobie-oracle/src/test/resources/scripts/01_create_user.sql
+++ b/modules/doobie-oracle/src/test/resources/scripts/01_create_user.sql
@@ -3,3 +3,10 @@ ALTER SESSION SET CONTAINER=FREEPDB1;
 CREATE USER TEST IDENTIFIED BY test QUOTA UNLIMITED ON USERS;
 
 GRANT CONNECT, RESOURCE TO TEST;
+
+-- A schema is a user in Oracle, so a schema-qualified fixture needs a second user. The fixtures
+-- all run as TEST, so TEST needs ANY rights to populate it. CREATE ANY INDEX is required as well
+-- as CREATE ANY TABLE, because a PRIMARY KEY creates an index in the other schema.
+CREATE USER QUALIFIED IDENTIFIED BY test QUOTA UNLIMITED ON USERS;
+
+GRANT CREATE ANY TABLE, CREATE ANY INDEX, INSERT ANY TABLE, SELECT ANY TABLE TO TEST;
diff --git a/modules/doobie-oracle/src/test/scala/DoobieOracleSuites.scala b/modules/doobie-oracle/src/test/scala/DoobieOracleSuites.scala
index 56418c46..0e2f4b46 100644
--- a/modules/doobie-oracle/src/test/scala/DoobieOracleSuites.scala
+++ b/modules/doobie-oracle/src/test/scala/DoobieOracleSuites.scala
@@ -205,6 +205,10 @@ final class NullOrderingSuite extends DoobieOracleDatabaseSuite with SqlNullOrde
   lazy val mapping = new DoobieOracleTestMapping(transactor) with SqlNullOrderingMapping[IO]
 }
 
+final class UnionOrderSuite extends DoobieOracleDatabaseSuite with SqlUnionOrderSuite {
+  lazy val mapping = new DoobieOracleTestMapping(transactor) with SqlUnionOrderMapping[IO]
+}
+
 final class Paging1Suite extends DoobieOracleDatabaseSuite with SqlPaging1Suite {
   lazy val mapping = new DoobieOracleTestMapping(transactor) with SqlPaging1Mapping[IO]
 }
diff --git a/modules/doobie-pg/src/test/scala/DoobiePgSuites.scala b/modules/doobie-pg/src/test/scala/DoobiePgSuites.scala
index 89de1bb2..65f7b43f 100644
--- a/modules/doobie-pg/src/test/scala/DoobiePgSuites.scala
+++ b/modules/doobie-pg/src/test/scala/DoobiePgSuites.scala
@@ -225,6 +225,10 @@ final class TableNameSuite extends DoobiePgDatabaseSuite with SqlTableNameSuite
   lazy val mapping = new DoobiePgTestMapping(transactor) with SqlQualifiedNamesMapping[IO]
 }
 
+final class UnionOrderSuite extends DoobiePgDatabaseSuite with SqlUnionOrderSuite {
+  lazy val mapping = new DoobiePgTestMapping(transactor) with SqlUnionOrderMapping[IO]
+}
+
 final class RecursiveInterfacesSuite
     extends DoobiePgDatabaseSuite
     with SqlRecursiveInterfacesSuite {
diff --git a/modules/skunk/js-jvm/src/test/scala/SkunkSuites.scala b/modules/skunk/js-jvm/src/test/scala/SkunkSuites.scala
index 242c22bb..158fc028 100644
--- a/modules/skunk/js-jvm/src/test/scala/SkunkSuites.scala
+++ b/modules/skunk/js-jvm/src/test/scala/SkunkSuites.scala
@@ -230,6 +230,10 @@ final class TableNameSuite extends SkunkDatabaseSuite with SqlTableNameSuite {
   lazy val mapping = new SkunkTestMapping(pool) with SqlQualifiedNamesMapping[IO]
 }
 
+final class UnionOrderSuite extends SkunkDatabaseSuite with SqlUnionOrderSuite {
+  lazy val mapping = new SkunkTestMapping(pool) with SqlUnionOrderMapping[IO]
+}
+
 final class RecursiveInterfacesSuite
     extends SkunkDatabaseSuite
     with SqlRecursiveInterfacesSuite {
diff --git a/modules/sql-core/src/test/scala/SqlUnionOrderMapping.scala b/modules/sql-core/src/test/scala/SqlUnionOrderMapping.scala
new file mode 100644
index 00000000..3a4aea48
--- /dev/null
+++ b/modules/sql-core/src/test/scala/SqlUnionOrderMapping.scala
@@ -0,0 +1,168 @@
+// Copyright (c) 2016-2025 Association of Universities for Research in Astronomy, Inc. (AURA)
+// Copyright (c) 2016-2025 Grackle Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package grackle.sql.test
+
+import grackle._
+import grackle.Predicate._
+import grackle.Query.{Binding, Limit, OrderBy, OrderSelection, OrderSelections}
+import grackle.QueryCompiler.{Elab, SelectElaborator}
+import grackle.Value.{AbsentValue, EnumValue, IntValue, NullValue}
+import grackle.syntax._
+
+// Covers a gap that predates issue #342 entirely: no fixture anywhere combines a union-typed
+// field with both `order` and `limit`, which is the only condition under which
+// SqlUnion.addFilterOrderByOffsetLimit pushes ordering into individual union branches
+// (SqlMapping.scala: `branchOrderBy = limit.flatMap(_ => orderBy)`). On backends where
+// encapsulateUnionBranch does real work (MSSQL), this is also the only path that exercises it.
+// The table is schema-qualified on every backend, so union-branch encapsulation is exercised
+// against a qualified name rather than only on MSSQL. The name is "union_order_entities", not
+// "entities" - that name is already taken by testdata/{pg,mssql}/interfaces.sql on both backends.
+trait SqlUnionOrderMapping[F[_]] extends SqlTestMapping[F] {
+
+  object entities extends TableDef("qualified.union_order_entities") {
+    val id = col("id", text)
+    val entityType = col("entity_type", text)
+    val name = col("name", text)
+  }
+
+  val schema =
+    schema"""
+      type Query {
+        entities(order: Order, limit: Int): [Entity!]!
+      }
+      type ItemA {
+        id: String!
+        name: String!
+      }
+      type ItemB {
+        id: String!
+        name: String!
+      }
+      union Entity = ItemA | ItemB
+      enum Order {
+        ASC
+        DESC
+      }
+    """
+
+  val QueryType = schema.ref("Query")
+  val ItemAType = schema.ref("ItemA")
+  val ItemBType = schema.ref("ItemB")
+  val EntityType = schema.ref("Entity")
+
+  val typeMappings =
+    List(
+      ObjectMapping(
+        tpe = QueryType,
+        fieldMappings = List(
+          SqlObject("entities")
+        )
+      ),
+      SqlUnionMapping(
+        tpe = EntityType,
+        discriminator = entityTypeDiscriminator,
+        fieldMappings = List(
+          SqlField("id", entities.id, key = true, hidden = true),
+          SqlField("name", entities.name, hidden = true),
+          SqlField("entityType", entities.entityType, discriminator = true, hidden = true)
+        )
+      ),
+      ObjectMapping(
+        tpe = ItemAType,
+        fieldMappings = List(
+          SqlField("id", entities.id, key = true),
+          SqlField("name", entities.name)
+        )
+      ),
+      ObjectMapping(
+        tpe = ItemBType,
+        fieldMappings = List(
+          SqlField("id", entities.id, key = true),
+          SqlField("name", entities.name)
+        )
+      )
+    )
+
+  object entityTypeDiscriminator extends SqlDiscriminator {
+    def discriminate(c: Cursor): Result[Type] =
+      for {
+        et <- c.fieldAs[String]("entityType")
+      } yield et match {
+        case "ItemA" => ItemAType
+        case "ItemB" => ItemBType
+      }
+
+    def narrowPredicate(subtpe: Type): Result[Predicate] = {
+      def mkPredicate(tpe: String): Result[Predicate] =
+        Eql(EntityType / "entityType", Const(tpe)).success
+
+      subtpe match {
+        case ItemAType => mkPredicate("ItemA")
+        case ItemBType => mkPredicate("ItemB")
+        case _ => Result.internalError(s"Invalid discriminator: $subtpe")
+      }
+    }
+  }
+
+  sealed trait ListOrder {
+    def ascending: Boolean
+  }
+  object ListOrder {
+    case object Ascending extends ListOrder { def ascending = true }
+    case object Descending extends ListOrder { def ascending = false }
+
+    def fromGraphQLString(s: String): Option[ListOrder] =
+      s.trim.toUpperCase match {
+        case "ASC" => Some(Ascending)
+        case "DESC" => Some(Descending)
+        case _ => None
+      }
+  }
+
+  object OrderValue {
+    def unapply(ev: EnumValue): Option[ListOrder] =
+      ListOrder.fromGraphQLString(ev.name)
+  }
+
+  def mkLimit(query: Query, limit: Value): Result[Query] =
+    limit match {
+      case AbsentValue | NullValue => query.success
+      case IntValue(num) if num > 0 => Limit(num, query).success
+      case IntValue(num) => Result.failure(s"Expected limit > 0, found $num")
+      case other => Result.failure(s"Expected limit > 0, found $other")
+    }
+
+  def mkOrderBy(query: Query, order: Value): Result[Query] =
+    order match {
+      case AbsentValue | NullValue => query.success
+      case OrderValue(o) =>
+        OrderBy(
+          OrderSelections(
+            List(OrderSelection[String](EntityType / "name", ascending = o.ascending))),
+          query
+        ).success
+      case _ => Result.failure(s"Expected order value, found $order")
+    }
+
+  override val selectElaborator = SelectElaborator {
+    case (QueryType, "entities", List(Binding("order", order), Binding("limit", limit))) =>
+      Elab.transformChild(child =>
+        for {
+          oc <- mkOrderBy(child, order)
+          lc <- mkLimit(oc, limit)
+        } yield lc)
+  }
+}
diff --git a/modules/sql-core/src/test/scala/SqlUnionOrderSuite.scala b/modules/sql-core/src/test/scala/SqlUnionOrderSuite.scala
new file mode 100644
index 00000000..a601a5ba
--- /dev/null
+++ b/modules/sql-core/src/test/scala/SqlUnionOrderSuite.scala
@@ -0,0 +1,55 @@
+// Copyright (c) 2016-2025 Association of Universities for Research in Astronomy, Inc. (AURA)
+// Copyright (c) 2016-2025 Grackle Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package grackle.sql.test
+
+import cats.effect.IO
+import io.circe.literal._
+import munit.CatsEffectSuite
+
+import grackle._
+import grackle.test.GraphQLResponseTests.assertWeaklyEqualIO
+
+// Fixture rows (see testdata/pg/union-order.sql and testdata/mssql/qualified-union-order.sql) are
+// seeded out of alphabetical order on purpose: id 1 "Charlie", id 2 "Alpha", id 3 "Bravo", id 4
+// "Delta". If ordering silently doesn't apply, the top 2 by insertion order would be
+// Charlie/Alpha, not the correct Alpha/Bravo - the assertion can't pass by coincidence.
+trait SqlUnionOrderSuite extends CatsEffectSuite {
+  def mapping: Mapping[IO]
+
+  test("union branch ordering with limit") {
+    val query = """
+      query {
+        entities(order: ASC, limit: 2) {
+          ... on ItemA { name }
+          ... on ItemB { name }
+        }
+      }
+    """
+
+    val expected = json"""
+      {
+        "data" : {
+          "entities" : [
+            { "name" : "Alpha" },
+            { "name" : "Bravo" }
+          ]
+        }
+      }
+    """
+
+    assertWeaklyEqualIO(mapping.compileAndRun(query), expected)
+  }
+}
diff --git a/testdata/mssql/union-order.sql b/testdata/mssql/union-order.sql
new file mode 100644
index 00000000..6960c145
--- /dev/null
+++ b/testdata/mssql/union-order.sql
@@ -0,0 +1,16 @@
+CREATE SCHEMA qualified;
+GO
+
+CREATE TABLE qualified.union_order_entities (
+    id VARCHAR(100) NOT NULL PRIMARY KEY,
+    entity_type VARCHAR(100) NOT NULL,
+    name VARCHAR(100) NOT NULL
+);
+
+INSERT INTO qualified.union_order_entities (id, entity_type, name) VALUES
+('1', 'ItemA', 'Charlie'),
+('2', 'ItemB', 'Alpha'),
+('3', 'ItemA', 'Bravo'),
+('4', 'ItemB', 'Delta');
+
+GO
diff --git a/testdata/oracle/union-order.sql b/testdata/oracle/union-order.sql
new file mode 100644
index 00000000..5670feaa
--- /dev/null
+++ b/testdata/oracle/union-order.sql
@@ -0,0 +1,10 @@
+CREATE TABLE QUALIFIED.union_order_entities (
+    id VARCHAR2(100) NOT NULL PRIMARY KEY,
+    entity_type VARCHAR2(100) NOT NULL,
+    name VARCHAR2(100) NOT NULL
+);
+
+INSERT INTO QUALIFIED.union_order_entities (id, entity_type, name) VALUES ('1', 'ItemA', 'Charlie');
+INSERT INTO QUALIFIED.union_order_entities (id, entity_type, name) VALUES ('2', 'ItemB', 'Alpha');
+INSERT INTO QUALIFIED.union_order_entities (id, entity_type, name) VALUES ('3', 'ItemA', 'Bravo');
+INSERT INTO QUALIFIED.union_order_entities (id, entity_type, name) VALUES ('4', 'ItemB', 'Delta');
diff --git a/testdata/pg/union-order.sql b/testdata/pg/union-order.sql
new file mode 100644
index 00000000..27f6f974
--- /dev/null
+++ b/testdata/pg/union-order.sql
@@ -0,0 +1,12 @@
+-- schema `qualified` is created by qualified-names.sql, which loads first
+CREATE TABLE qualified.union_order_entities (
+    id text NOT NULL PRIMARY KEY,
+    entity_type text NOT NULL,
+    name text NOT NULL
+);
+
+INSERT INTO qualified.union_order_entities (id, entity_type, name) VALUES
+('1', 'ItemA', 'Charlie'),
+('2', 'ItemB', 'Alpha'),
+('3', 'ItemA', 'Bravo'),
+('4', 'ItemB', 'Delta');