refactor: smenatics and facades

Also moves model metadata into language-web, since we only use it on the
frontent.

17 files changed, 368 insertions, 44 deletions

diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationSuccessResult.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationSuccessResult.java
index 21be4e08..0abe116e 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationSuccessResult.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationSuccessResult.java
@@ -6,8 +6,8 @@
 package tools.refinery.language.web.generator;
 
 import com.google.gson.JsonObject;
-import tools.refinery.language.semantics.metadata.NodeMetadata;
-import tools.refinery.language.semantics.metadata.RelationMetadata;
+import tools.refinery.language.web.semantics.metadata.NodeMetadata;
+import tools.refinery.language.web.semantics.metadata.RelationMetadata;
 
 import java.util.List;
 import java.util.UUID;
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationWorker.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationWorker.java
index 7b4f957c..a3b6ca82 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationWorker.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/generator/ModelGenerationWorker.java
@@ -9,12 +9,14 @@ import com.google.inject.Inject;
 import org.eclipse.xtext.service.OperationCanceledManager;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import tools.refinery.generator.ModelGeneratorBuilder;
+import tools.refinery.generator.ModelGenerator;
+import tools.refinery.generator.ModelGeneratorFactory;
+import tools.refinery.language.web.semantics.metadata.MetadataCreator;
+import tools.refinery.generator.ProblemLoader;
 import tools.refinery.generator.ValidationErrorsException;
 import tools.refinery.language.web.semantics.PartialInterpretation2Json;
 import tools.refinery.language.web.xtext.server.ThreadPoolExecutorServiceProvider;
 import tools.refinery.language.web.xtext.server.push.PushWebDocument;
-import tools.refinery.store.reasoning.literal.Concreteness;
 import tools.refinery.store.util.CancellationToken;
 
 import java.io.IOException;
@@ -38,7 +40,13 @@ public class ModelGenerationWorker implements Runnable {
         private OperationCanceledManager operationCanceledManager;
 
         @Inject
-        private ModelGeneratorBuilder generatorBuilder;
+        private ProblemLoader problemLoader;
+
+        @Inject
+        private ModelGeneratorFactory generatorFactory;
+
+        @Inject
+        private MetadataCreator metadataCreator;
 
         @Inject
         private PartialInterpretation2Json partialInterpretation2Json;
@@ -127,9 +135,10 @@ public class ModelGenerationWorker implements Runnable {
 
         public ModelGenerationResult doRun() throws IOException {
                 cancellationToken.checkCancelled();
+                var problem = problemLoader.cancellationToken(cancellationToken).loadString(text);
+                ModelGenerator generator;
                 try {
-                        generatorBuilder.cancellationToken(cancellationToken);
-                        generatorBuilder.fromString(text);
+                        generator = generatorFactory.cancellationToken(cancellationToken).createGenerator(problem);
                 } catch (ValidationErrorsException e) {
                         var errors = e.getErrors();
                         if (errors != null && !errors.isEmpty()) {
@@ -137,20 +146,19 @@ public class ModelGenerationWorker implements Runnable {
                         }
                         throw e;
                 }
-                var generator = generatorBuilder.build();
                 notifyResult(new ModelGenerationStatusResult(uuid, "Generating model"));
                 generator.setRandomSeed(randomSeed);
-                if (!generator.tryRun()) {
+                if (!generator.tryGenerate()) {
                         return new ModelGenerationErrorResult(uuid, "Problem is unsatisfiable");
                 }
                 notifyResult(new ModelGenerationStatusResult(uuid, "Saving generated model"));
                 cancellationToken.checkCancelled();
-                var nodesMetadata = generator.getNodesMetadata();
+                metadataCreator.setProblemTrace(generator.getProblemTrace());
+                var nodesMetadata = metadataCreator.getNodesMetadata(generator.getModel(), false);
                 cancellationToken.checkCancelled();
-                var relationsMetadata = generator.getProblemTrace().getRelationsMetadata();
+                var relationsMetadata = metadataCreator.getRelationsMetadata();
                 cancellationToken.checkCancelled();
-                var partialInterpretation = partialInterpretation2Json.getPartialInterpretation(generator,
-                                Concreteness.CANDIDATE, cancellationToken);
+                var partialInterpretation = partialInterpretation2Json.getPartialInterpretation(generator, cancellationToken);
                 return new ModelGenerationSuccessResult(uuid, nodesMetadata, relationsMetadata, partialInterpretation);
         }
 
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/PartialInterpretation2Json.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/PartialInterpretation2Json.java
index 7afed5c0..efe04592 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/PartialInterpretation2Json.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/PartialInterpretation2Json.java
@@ -9,12 +9,10 @@ import com.google.gson.JsonArray;
 import com.google.gson.JsonObject;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
-import tools.refinery.generator.AbstractRefinery;
-import tools.refinery.language.semantics.model.SemanticsUtils;
+import tools.refinery.generator.ModelFacade;
+import tools.refinery.language.semantics.SemanticsUtils;
 import tools.refinery.store.map.Cursor;
 import tools.refinery.store.model.Model;
-import tools.refinery.store.reasoning.ReasoningAdapter;
-import tools.refinery.store.reasoning.literal.Concreteness;
 import tools.refinery.store.reasoning.representation.PartialRelation;
 import tools.refinery.store.reasoning.translator.multiobject.MultiObjectTranslator;
 import tools.refinery.store.tuple.Tuple;
@@ -27,15 +25,13 @@ public class PartialInterpretation2Json {
         @Inject
         private SemanticsUtils semanticsUtils;
 
-        public JsonObject getPartialInterpretation(AbstractRefinery refinery, Concreteness concreteness,
-                                                                                           CancellationToken cancellationToken) {
-                var model = refinery.getModel();
-                var adapter = model.getAdapter(ReasoningAdapter.class);
+        public JsonObject getPartialInterpretation(ModelFacade facade, CancellationToken cancellationToken) {
+                var model = facade.getModel();
                 var json = new JsonObject();
-                for (var entry : refinery.getProblemTrace().getRelationTrace().entrySet()) {
+                for (var entry : facade.getProblemTrace().getRelationTrace().entrySet()) {
                         var relation = entry.getKey();
                         var partialSymbol = entry.getValue();
-                        var tuples = getTuplesJson(adapter, concreteness, partialSymbol);
+                        var tuples = getTuplesJson(facade, partialSymbol);
                         var name = semanticsUtils.getName(relation).orElse(partialSymbol.name());
                         json.add(name, tuples);
                         cancellationToken.checkCancelled();
@@ -44,9 +40,8 @@ public class PartialInterpretation2Json {
                 return json;
         }
 
-        private static JsonArray getTuplesJson(ReasoningAdapter adapter, Concreteness concreteness,
-                                                                                   PartialRelation partialSymbol) {
-                var interpretation = adapter.getPartialInterpretation(concreteness, partialSymbol);
+        private static JsonArray getTuplesJson(ModelFacade facade, PartialRelation partialSymbol) {
+                var interpretation = facade.getPartialInterpretation(partialSymbol);
                 var cursor = interpretation.getAll();
                 return getTuplesJson(cursor);
         }
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsSuccessResult.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsSuccessResult.java
index 350b0b2b..f26fa2b2 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsSuccessResult.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsSuccessResult.java
@@ -6,8 +6,8 @@
 package tools.refinery.language.web.semantics;
 
 import com.google.gson.JsonObject;
-import tools.refinery.language.semantics.metadata.NodeMetadata;
-import tools.refinery.language.semantics.metadata.RelationMetadata;
+import tools.refinery.language.web.semantics.metadata.NodeMetadata;
+import tools.refinery.language.web.semantics.metadata.RelationMetadata;
 
 import java.util.List;
 
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsWorker.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsWorker.java
index a8f16c84..44974869 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsWorker.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/SemanticsWorker.java
@@ -16,10 +16,10 @@ import org.eclipse.xtext.validation.IDiagnosticConverter;
 import org.eclipse.xtext.validation.Issue;
 import org.eclipse.xtext.web.server.validation.ValidationResult;
 import tools.refinery.generator.ModelSemantics;
-import tools.refinery.generator.ModelSemanticsBuilder;
+import tools.refinery.generator.ModelSemanticsFactory;
 import tools.refinery.language.model.problem.Problem;
-import tools.refinery.language.semantics.model.TracedException;
-import tools.refinery.store.reasoning.literal.Concreteness;
+import tools.refinery.language.web.semantics.metadata.MetadataCreator;
+import tools.refinery.language.semantics.TracedException;
 import tools.refinery.store.reasoning.translator.TranslationException;
 import tools.refinery.store.util.CancellationToken;
 
@@ -30,16 +30,19 @@ class SemanticsWorker implements Callable<SemanticsResult> {
         private static final String DIAGNOSTIC_ID = "tools.refinery.language.semantics.SemanticError";
 
         @Inject
-        private PartialInterpretation2Json partialInterpretation2Json;
-
-        @Inject
         private OperationCanceledManager operationCanceledManager;
 
         @Inject
         private IDiagnosticConverter diagnosticConverter;
 
         @Inject
-        private ModelSemanticsBuilder semanticsBuilder;
+        private ModelSemanticsFactory semanticsFactory;
+
+        @Inject
+        private MetadataCreator metadataCreator;
+
+        @Inject
+        private PartialInterpretation2Json partialInterpretation2Json;
 
         private Problem problem;
 
@@ -56,13 +59,10 @@ class SemanticsWorker implements Callable<SemanticsResult> {
 
         @Override
         public SemanticsResult call() {
-                semanticsBuilder.cancellationToken(cancellationToken);
                 cancellationToken.checkCancelled();
                 ModelSemantics semantics;
                 try {
-                        semanticsBuilder.problem(problem);
-                        cancellationToken.checkCancelled();
-                        semantics = semanticsBuilder.build();
+                        semantics = semanticsFactory.cancellationToken(cancellationToken).createSemantics(problem);
                 } catch (TranslationException e) {
                         return new SemanticsInternalErrorResult(e.getMessage());
                 } catch (TracedException e) {
@@ -72,12 +72,12 @@ class SemanticsWorker implements Callable<SemanticsResult> {
                         return getTracedErrorResult(e.getSourceElement(), message);
                 }
                 cancellationToken.checkCancelled();
-                var nodesMetadata = semantics.getNodesMetadata();
+                metadataCreator.setProblemTrace(semantics.getProblemTrace());
+                var nodesMetadata = metadataCreator.getNodesMetadata(semantics.getModel(), true);
                 cancellationToken.checkCancelled();
-                var relationsMetadata = semantics.getProblemTrace().getRelationsMetadata();
+                var relationsMetadata = metadataCreator.getRelationsMetadata();
                 cancellationToken.checkCancelled();
-                var partialInterpretation = partialInterpretation2Json.getPartialInterpretation(semantics,
-                                Concreteness.PARTIAL, cancellationToken);
+                var partialInterpretation = partialInterpretation2Json.getPartialInterpretation(semantics, cancellationToken);
                 return new SemanticsSuccessResult(nodesMetadata, relationsMetadata, partialInterpretation);
         }
 
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/BuiltInDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/BuiltInDetail.java
new file mode 100644
index 00000000..27eb7ad7
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/BuiltInDetail.java
@@ -0,0 +1,10 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record BuiltInDetail() implements RelationDetail {
+        public static final BuiltInDetail INSTANCE = new BuiltInDetail();
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ClassDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ClassDetail.java
new file mode 100644
index 00000000..42495950
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ClassDetail.java
@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record ClassDetail(boolean abstractClass) implements RelationDetail {
+        public static final ClassDetail CONCRETE_CLASS = new ClassDetail(false);
+
+        public static final ClassDetail ABSTRACT_CLASS = new ClassDetail(true);
+
+        public static ClassDetail ofAbstractClass(boolean abstractClass) {
+                return abstractClass ? ABSTRACT_CLASS : CONCRETE_CLASS;
+        }
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/Metadata.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/Metadata.java
new file mode 100644
index 00000000..5e1fac05
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/Metadata.java
@@ -0,0 +1,12 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public sealed interface Metadata permits NodeMetadata, RelationMetadata {
+        String name();
+
+        String simpleName();
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/MetadataCreator.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/MetadataCreator.java
new file mode 100644
index 00000000..3fbc5d2d
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/MetadataCreator.java
@@ -0,0 +1,202 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+import com.google.inject.Inject;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.xtext.naming.IQualifiedNameConverter;
+import org.eclipse.xtext.naming.IQualifiedNameProvider;
+import org.eclipse.xtext.naming.QualifiedName;
+import org.eclipse.xtext.scoping.IScope;
+import org.eclipse.xtext.scoping.IScopeProvider;
+import tools.refinery.language.model.problem.*;
+import tools.refinery.language.semantics.ProblemTrace;
+import tools.refinery.language.semantics.TracedException;
+import tools.refinery.language.utils.ProblemUtil;
+import tools.refinery.store.model.Model;
+import tools.refinery.store.reasoning.ReasoningAdapter;
+import tools.refinery.store.reasoning.representation.PartialRelation;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public class MetadataCreator {
+        @Inject
+        private IScopeProvider scopeProvider;
+
+        @Inject
+        private IQualifiedNameProvider qualifiedNameProvider;
+
+        @Inject
+        private IQualifiedNameConverter qualifiedNameConverter;
+
+        private ProblemTrace problemTrace;
+
+        private IScope nodeScope;
+
+        private IScope relationScope;
+
+        public void setProblemTrace(ProblemTrace problemTrace) {
+                if (this.problemTrace != null) {
+                        throw new IllegalArgumentException("Problem trace was already set");
+                }
+                this.problemTrace = problemTrace;
+                var problem = problemTrace.getProblem();
+                nodeScope = scopeProvider.getScope(problem, ProblemPackage.Literals.NODE_ASSERTION_ARGUMENT__NODE);
+                relationScope = scopeProvider.getScope(problem, ProblemPackage.Literals.ASSERTION__RELATION);
+        }
+
+        public static String unnamedNode(int nodeId) {
+                return "::" + nodeId;
+        }
+
+        public List<NodeMetadata> getNodesMetadata(Model model, boolean preserveNewNodes) {
+                int nodeCount = model.getAdapter(ReasoningAdapter.class).getNodeCount();
+                var nodeTrace = problemTrace.getNodeTrace();
+                var nodes = new NodeMetadata[Math.max(nodeTrace.size(), nodeCount)];
+                for (var entry : nodeTrace.keyValuesView()) {
+                        var node = entry.getOne();
+                        var id = entry.getTwo();
+                        nodes[id] = getNodeMetadata(id, node, preserveNewNodes);
+                }
+                for (int i = 0; i < nodes.length; i++) {
+                        if (nodes[i] == null) {
+                                var nodeName = unnamedNode(i);
+                                nodes[i] = new NodeMetadata(nodeName, nodeName, NodeKind.IMPLICIT);
+                        }
+                }
+                return List.of(nodes);
+        }
+
+        private NodeMetadata getNodeMetadata(int nodeId, Node node, boolean preserveNewNodes) {
+                var kind = getNodeKind(node);
+                if (!preserveNewNodes && kind == NodeKind.NEW) {
+                        var nodeName = unnamedNode(nodeId);
+                        return new NodeMetadata(nodeName, nodeName, NodeKind.IMPLICIT);
+                }
+                var qualifiedName = getQualifiedName(node);
+                var simpleName = getSimpleName(node, qualifiedName, nodeScope);
+                return new NodeMetadata(qualifiedNameConverter.toString(qualifiedName),
+                                qualifiedNameConverter.toString(simpleName), getNodeKind(node));
+        }
+
+        private NodeKind getNodeKind(Node node) {
+                if (ProblemUtil.isImplicitNode(node)) {
+                        return NodeKind.IMPLICIT;
+                } else if (ProblemUtil.isIndividualNode(node)) {
+                        return NodeKind.INDIVIDUAL;
+                } else if (ProblemUtil.isNewNode(node)) {
+                        return NodeKind.NEW;
+                } else {
+                        throw new TracedException(node, "Unknown node type");
+                }
+        }
+
+        public List<RelationMetadata> getRelationsMetadata() {
+                var relationTrace = problemTrace.getRelationTrace();
+                var relations = new ArrayList<RelationMetadata>(relationTrace.size());
+                for (var entry : relationTrace.entrySet()) {
+                        var relation = entry.getKey();
+                        var partialRelation = entry.getValue();
+                        var metadata = getRelationMetadata(relation, partialRelation);
+                        relations.add(metadata);
+                }
+                return Collections.unmodifiableList(relations);
+        }
+
+        private RelationMetadata getRelationMetadata(Relation relation, PartialRelation partialRelation) {
+                var qualifiedName = getQualifiedName(relation);
+                var qualifiedNameString = qualifiedNameConverter.toString(qualifiedName);
+                var simpleName = getSimpleName(relation, qualifiedName, relationScope);
+                var simpleNameString = qualifiedNameConverter.toString(simpleName);
+                var arity = partialRelation.arity();
+                var detail = getRelationDetail(relation, partialRelation);
+                return new RelationMetadata(qualifiedNameString, simpleNameString, arity, detail);
+        }
+
+        private RelationDetail getRelationDetail(Relation relation, PartialRelation partialRelation) {
+                if (ProblemUtil.isBuiltIn(relation) && !ProblemUtil.isError(relation)) {
+                        return getBuiltInDetail();
+                }
+                if (relation instanceof ClassDeclaration classDeclaration) {
+                        return getClassDetail(classDeclaration);
+                } else if (relation instanceof ReferenceDeclaration) {
+                        return getReferenceDetail(partialRelation);
+                } else if (relation instanceof EnumDeclaration) {
+                        return getEnumDetail();
+                } else if (relation instanceof PredicateDefinition predicateDefinition) {
+                        return getPredicateDetail(predicateDefinition);
+                } else {
+                        throw new TracedException(relation, "Unknown relation");
+                }
+        }
+
+        private RelationDetail getBuiltInDetail() {
+                return BuiltInDetail.INSTANCE;
+        }
+
+        private RelationDetail getClassDetail(ClassDeclaration classDeclaration) {
+                return ClassDetail.ofAbstractClass(classDeclaration.isAbstract());
+        }
+
+        private RelationDetail getReferenceDetail(PartialRelation partialRelation) {
+                var metamodel = problemTrace.getMetamodel();
+                var opposite = metamodel.oppositeReferences().get(partialRelation);
+                if (opposite == null) {
+                        boolean isContainment = metamodel.containmentHierarchy().containsKey(partialRelation);
+                        return ReferenceDetail.ofContainment(isContainment);
+                } else {
+                        boolean isContainer = metamodel.containmentHierarchy().containsKey(opposite);
+                        return new OppositeReferenceDetail(isContainer, opposite.name());
+                }
+        }
+
+        private RelationDetail getEnumDetail() {
+                return ClassDetail.CONCRETE_CLASS;
+        }
+
+        private RelationDetail getPredicateDetail(PredicateDefinition predicate) {
+                return PredicateDetail.ofError(predicate.isError());
+        }
+
+        private QualifiedName getQualifiedName(EObject eObject) {
+                var qualifiedName = qualifiedNameProvider.getFullyQualifiedName(eObject);
+                if (qualifiedName == null) {
+                        throw new TracedException(eObject, "Unknown qualified name");
+                }
+                return qualifiedName;
+        }
+
+        private QualifiedName getSimpleName(EObject eObject, QualifiedName qualifiedName, IScope scope) {
+                var descriptions = scope.getElements(eObject);
+                var names = new ArrayList<QualifiedName>();
+                for (var description : descriptions) {
+                        // {@code getQualifiedName()} will refer to the full name for objects that are loaded from the global
+                        // scope, but {@code getName()} returns the qualified name that we set in
+                        // {@code ProblemResourceDescriptionStrategy}.
+                        names.add(description.getName());
+                }
+                names.sort(Comparator.comparingInt(QualifiedName::getSegmentCount));
+                for (var simpleName : names) {
+                        if (names.contains(simpleName) && isUnique(scope, simpleName)) {
+                                return simpleName;
+                        }
+                }
+                throw new TracedException(eObject, "Ambiguous qualified name: " +
+                                qualifiedNameConverter.toString(qualifiedName));
+        }
+
+        private boolean isUnique(IScope scope, QualifiedName name) {
+                var iterator = scope.getElements(name).iterator();
+                if (!iterator.hasNext()) {
+                        return false;
+                }
+                iterator.next();
+                return !iterator.hasNext();
+        }
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeKind.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeKind.java
new file mode 100644
index 00000000..fa863bc2
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeKind.java
@@ -0,0 +1,12 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public enum NodeKind {
+        IMPLICIT,
+        INDIVIDUAL,
+        NEW
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeMetadata.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeMetadata.java
new file mode 100644
index 00000000..5da28acf
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/NodeMetadata.java
@@ -0,0 +1,9 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record NodeMetadata(String name, String simpleName, NodeKind kind) implements Metadata {
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/OppositeReferenceDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/OppositeReferenceDetail.java
new file mode 100644
index 00000000..98e7fec8
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/OppositeReferenceDetail.java
@@ -0,0 +1,9 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record OppositeReferenceDetail(boolean container, String opposite) implements RelationDetail {
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/PredicateDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/PredicateDetail.java
new file mode 100644
index 00000000..d4ac4b65
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/PredicateDetail.java
@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record PredicateDetail(boolean error) implements RelationDetail {
+        public static final PredicateDetail PREDICATE = new PredicateDetail(false);
+
+        public static final PredicateDetail ERROR_PREDICATE = new PredicateDetail(true);
+
+        public static PredicateDetail ofError(boolean error) {
+                return error ? ERROR_PREDICATE : PREDICATE;
+        }
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ReferenceDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ReferenceDetail.java
new file mode 100644
index 00000000..42799417
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/ReferenceDetail.java
@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record ReferenceDetail(boolean containment) implements RelationDetail {
+        public static final ReferenceDetail CROSS_REFERENCE = new ReferenceDetail(false);
+
+        public static final ReferenceDetail CONTAINMENT_REFERENCE = new ReferenceDetail(true);
+
+        public static ReferenceDetail ofContainment(boolean containment) {
+                return containment ? CONTAINMENT_REFERENCE : CROSS_REFERENCE;
+        }
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationDetail.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationDetail.java
new file mode 100644
index 00000000..bbe563cd
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationDetail.java
@@ -0,0 +1,10 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public sealed interface RelationDetail permits ClassDetail, ReferenceDetail, PredicateDetail, OppositeReferenceDetail,
+                BuiltInDetail {
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationMetadata.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationMetadata.java
new file mode 100644
index 00000000..e5d3a091
--- /dev/null
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/semantics/metadata/RelationMetadata.java
@@ -0,0 +1,9 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.language.web.semantics.metadata;
+
+public record RelationMetadata(String name, String simpleName, int arity, RelationDetail detail) implements Metadata {
+}
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/xtext/servlet/XtextWebSocket.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/xtext/servlet/XtextWebSocket.java
index 1fde1be5..818bd80e 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/xtext/servlet/XtextWebSocket.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/xtext/servlet/XtextWebSocket.java
@@ -17,7 +17,7 @@ import org.eclipse.xtext.resource.IResourceServiceProvider;
 import org.eclipse.xtext.web.server.ISession;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import tools.refinery.language.semantics.metadata.*;
+import tools.refinery.language.web.semantics.metadata.*;
 import tools.refinery.language.web.xtext.server.ResponseHandler;
 import tools.refinery.language.web.xtext.server.ResponseHandlerException;
 import tools.refinery.language.web.xtext.server.TransactionExecutor;