[1949] Allow redefining a PartUsage with the same name

CHANGELOG.adoc

@@ -77,6 +77,7 @@ Additional ports can be created using the _New Port as end_ graphical node tool.
 - https://github.com/eclipse-syson/syson/issues/1863[#1863] [diagrams] Dropping an elements on a diagram which is already visible gives feedback again.
 - https://github.com/eclipse-syson/syson/issues/2004[#2004] [diagrams] The `ports` and `ends` compartments on a newly created `InterfaceDefinition` graphical nodes are not visible by default.
 They can be revealed if needed using the _Manage Visbility_ action on the graphical node.
+- https://github.com/eclipse-syson/syson/issues/1949[#1949] [diagrams] Allow redefining a `PartUsage` with the same name as the redefined usage.
 
 === New features
 

backend/application/syson-application/src/test/java/org/eclipse/syson/application/controllers/diagrams/general/view/GVDirectEditTests.java

@@ -34,8 +34,10 @@
 import org.eclipse.sirius.components.graphql.tests.ExecuteEditingContextFunctionSuccessPayload;
 import org.eclipse.sirius.web.tests.services.api.IGivenInitialServerState;
 import org.eclipse.syson.AbstractIntegrationTests;
+import org.eclipse.syson.GivenSysONServer;
 import org.eclipse.syson.application.data.GeneralViewDirectEditTestProjectData;
 import org.eclipse.syson.application.data.GeneralViewItemAndAttributeProjectData;
+import org.eclipse.syson.application.data.GeneralViewPartUsageRedefinitionProjectData;
 import org.eclipse.syson.services.SemanticRunnableFactory;
 import org.eclipse.syson.services.diagrams.api.IGivenDiagramSubscription;
 import org.eclipse.syson.sysml.PartUsage;
@@ -649,4 +651,70 @@ public void directEditMultiplicityWithOperation() {
                 .thenCancel()
                 .verify(Duration.ofSeconds(10));
     }
+
+    @DisplayName("GIVEN a diagram with a part WHEN creating a redefinition of another part of the same name through direct edit THEN the redefined part is correctly resolved")
+    @GivenSysONServer({ GeneralViewPartUsageRedefinitionProjectData.SCRIPT_PATH })
+    @Test
+    public void directEditRedefinitionWithSameName() {
+        var diagramEventInput = new DiagramEventInput(UUID.randomUUID(),
+                GeneralViewPartUsageRedefinitionProjectData.EDITING_CONTEXT_ID,
+                GeneralViewPartUsageRedefinitionProjectData.GraphicalIds.DIAGRAM_ID);
+
+        var flux = this.givenDiagramSubscription.subscribe(diagramEventInput);
+
+        var diagramId = new AtomicReference<String>();
+        var partNodeId = new AtomicReference<String>();
+        var partNodeLabelId = new AtomicReference<String>();
+
+        Consumer<Object> initialDiagramContentConsumer = assertRefreshedDiagramThat(diagram -> {
+            diagramId.set(diagram.getId());
+            var partNode = new DiagramNavigator(diagram).nodeWithId(GeneralViewPartUsageRedefinitionProjectData.GraphicalIds.Y_X_NODE_ID).getNode();
+            partNodeId.set(partNode.getId());
+            partNodeLabelId.set(partNode.getInsideLabel().getId());
+        });
+
+        Runnable editLabelWithRedfinitionOfSameName = () -> {
+            var input = new EditLabelInput(UUID.randomUUID(), GeneralViewPartUsageRedefinitionProjectData.EDITING_CONTEXT_ID, diagramId.get(), partNodeLabelId.get(), "x :>> x");
+            var result = this.editLabelMutationRunner.run(input);
+
+            String typename = JsonPath.read(result.data(), "$.data.editLabel.__typename");
+            assertThat(typename).isEqualTo(EditLabelSuccessPayload.class.getSimpleName());
+            List<String> messages = JsonPath.read(result.data(), "$.data.editLabel.messages[*].body");
+            assertThat(messages).hasSize(0);
+        };
+
+        Consumer<Object> updatedDiagramContentMatcherBefore = assertRefreshedDiagramThat(diagram -> {
+            var node = new DiagramNavigator(diagram).nodeWithId(partNodeId.get()).getNode();
+            DiagramAssertions.assertThat(node.getInsideLabel()).hasText(LabelConstants.OPEN_QUOTE + "part" + LabelConstants.CLOSE_QUOTE + "\nx :>> x");
+        });
+
+        Runnable redefinedElementsChecker = this.semanticRunnableFactory.createRunnable(GeneralViewPartUsageRedefinitionProjectData.EDITING_CONTEXT_ID,
+                (editingContext, executeEditingContextFunctionInput) -> {
+                    PartUsage yx = this.objectSearchService.getObject(editingContext, GeneralViewPartUsageRedefinitionProjectData.SemanticIds.Y_X_ID)
+                            .filter(PartUsage.class::isInstance)
+                            .map(PartUsage.class::cast)
+                            .orElse(null);
+                    assertThat(yx).isNotNull();
+
+                    PartUsage bx = this.objectSearchService.getObject(editingContext, GeneralViewPartUsageRedefinitionProjectData.SemanticIds.B_X_ID)
+                            .filter(PartUsage.class::isInstance)
+                            .map(PartUsage.class::cast)
+                            .orElse(null);
+                    assertThat(bx).isNotNull();
+
+                    assertThat(yx.getOwnedRedefinition()).hasSize(1);
+                    var redefinition = yx.getOwnedRedefinition().get(0);
+                    assertThat(redefinition.getRedefiningFeature()).isSameAs(yx);
+                    assertThat(redefinition.getRedefinedFeature()).isSameAs(bx);
+                    return new ExecuteEditingContextFunctionSuccessPayload(executeEditingContextFunctionInput.id(), true);
+                });
+
+        StepVerifier.create(flux)
+                .consumeNextWith(initialDiagramContentConsumer)
+                .then(editLabelWithRedfinitionOfSameName)
+                .consumeNextWith(updatedDiagramContentMatcherBefore)
+                .then(redefinedElementsChecker)
+                .thenCancel()
+                .verify(Duration.ofSeconds(10));
+    }
 }

backend/application/syson-application/src/test/java/org/eclipse/syson/application/data/GeneralViewPartUsageRedefinitionProjectData.java

@@ -0,0 +1,46 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.data;
+
+/**
+ * Ids for project "GeneralView-GeneralView-PartUsage-redefinition".
+ *
+ * @author pcdavid
+ */
+public class GeneralViewPartUsageRedefinitionProjectData {
+
+    public static final String EDITING_CONTEXT_ID = "d84a3d30-a8c8-47a2-a278-f6212169b959";
+
+    public static final String SCRIPT_PATH = "/scripts/database-content/GeneralView-PartUsage-redefinition.sql";
+
+    /**
+     * Ids of the graphical elements elements.
+     */
+    public static final class GraphicalIds {
+        public static final String DIAGRAM_ID = "72cccffa-81b6-4ed6-bc45-8b095440f11d";
+
+        public static final String B_X_NODE_ID = "efb2c50e-53c9-3f66-97f2-298c13666cb7";
+
+        public static final String Y_X_NODE_ID = "a32582de-926a-3f6c-8df3-72908e714121";
+    }
+
+    /**
+     * Ids of the semantic elements.
+     */
+    public static final class SemanticIds {
+        public static final String B_X_ID = "d43d7901-779e-4058-951a-0a0ad6e25733";
+
+        public static final String Y_X_ID = "aeee4482-d95c-44d8-900c-36463eca802a";
+    }
+
+}

backend/application/syson-application/src/test/java/org/eclipse/syson/application/imports/ImportSysMLModelTest.java

@@ -170,7 +170,7 @@ public void unnamedRedefinedReferenceFeature() throws IOException {
                     part l : Logical {
                         part :>> component;
                     }
-                
+
                     part c2  = l.component.component2;
                 }""";
         this.checker.checkImportedModel(resource -> {
@@ -181,6 +181,31 @@ public void unnamedRedefinedReferenceFeature() throws IOException {
         }).check(input);
     }
 
+    @DisplayName("GIVEN a redefinition of a part with the same name as the redefined part, WHEN importing the model, THEN the redefintion's redefined feature is correctly resolved.")
+    @Test
+    public void namedRedefinedReferenceFeature() throws IOException {
+        var input = """
+                package Package1 {
+                    part def A;
+                    part def B {
+                        part x : A [0..*];
+                    }
+
+                   part y : B {
+                        x :>> x; // The second x should point B::x, not to y::x
+                   }
+                }""";
+        this.checker.checkImportedModel(resource -> {
+            List<Redefinition> redefinitions = EMFUtils.allContainedObjectOfType(resource, Redefinition.class).toList();
+            assertThat(redefinitions).hasSize(1);
+            var xRedefinition = redefinitions.get(0);
+            // The redefin*ing* feature (the first "x") is in y
+            assertThat(xRedefinition.getRedefiningFeature().getOwner().getName()).isEqualTo("y");
+            // The redefin*ed* feature (the second "x") is the one from B
+            assertThat(xRedefinition.getRedefinedFeature().getOwningType().getName()).isEqualTo("B");
+        }).check(input);
+    }
+
     @Test
     @DisplayName("GIVEN a set of Usages, WHEN checking if the usage is referential, THEN the computation should be correct whether or not the ref keyword is present.")
     public void testReferentialUsages() throws IOException {
@@ -1177,7 +1202,7 @@ public void checkDoSendPayloadParameterResolution() throws IOException {
                 package Package1 {
                     attribute def Sig ;
                     part p;
-                
+
                     state state1 {
                         state s2;
                         state s3;

backend/services/syson-services/src/main/java/org/eclipse/syson/services/DiagramDirectEditListener.java

@@ -836,7 +836,7 @@ private void handleRedefintion(RedefinitionExpressionContext ctx, Usage redefini
         var identifier = ctx.qualifiedName();
         if (identifier != null) {
             var usageAsString = this.getFullText(identifier);
-            var usage = this.utilService.findByNameAndType(redefining, usageAsString, Feature.class);
+            var usage = this.resolveRedefinedUsage(redefining, usageAsString);
             if (usage == null && this.utilService.isQualifiedName(usageAsString)) {
                 this.feedbackMessageService.addFeedbackMessage(new Message("The qualified name used for the redefinition does not exist", MessageLevel.ERROR));
                 return;
@@ -860,6 +860,22 @@ private void handleRedefintion(RedefinitionExpressionContext ctx, Usage redefini
         }
     }
 
+    private Feature resolveRedefinedUsage(Usage redefiningUsage, String redefinedUsageName) {
+        // When the redefining usage has the same name as the *redefined* one,
+        // temporarily rename it so that this.utilService.findByNameAndType()
+        // correctly resolves the redefined one instead of returning redefiningUsage itself.
+        boolean nameConflict = Objects.equals(redefiningUsage.getName(), redefinedUsageName);
+        var originalName = redefiningUsage.getDeclaredName();
+        if (nameConflict) {
+            redefiningUsage.setDeclaredName("_" + redefinedUsageName);
+        }
+        var usage = this.utilService.findByNameAndType(redefiningUsage, redefinedUsageName, Feature.class);
+        if (nameConflict) {
+            redefiningUsage.setDeclaredName(originalName);
+        }
+        return usage;
+    }
+
     private void handleTriggerExpressionName(TransitionUsage transition, TriggerExpressionNameContext triggerExpressionName) {
         String name = triggerExpressionName.name().getText();
         TypingExpressionContext typingExpression = triggerExpressionName.typingExpression();

doc/content/modules/user-manual/pages/release-notes/2026.3.0.adoc

@@ -87,8 +87,9 @@ This tool allows to create a `SatisfyRequirementUsage` between the `Feature` and
 Additional ends can be created using the _New end_ graphical node tool (which replaces the _New Part as end_ previously available only on `AllocationDefinition` graphical nodes).
 ** Newly created `InterfaceDefinition` graphical nodes now have two initial _ports_ named _source_ and _target_.
 Additional ports can be created using the _New Port as end_ graphical node tool.
-- The `ports` and `ends` compartments on a newly created `InterfaceDefinition` graphical nodes are not visible by default.
+** The `ports` and `ends` compartments on a newly created `InterfaceDefinition` graphical nodes are not visible by default.
 They can be revealed if needed using the _Manage Visbility_ action on the graphical node.
+** Allow redefining a `PartUsage` with the same name as the redefined `Usage`.
 
 
 * In textual import/export: