feat: Show LSP diagnostic errors in Project Errors

src/main/java/com/redhat/devtools/lsp4ij/features/diagnostics/LSPDiagnosticHandler.java

@@ -15,11 +15,14 @@
 
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.problems.WolfTheProblemSolver;
+import com.intellij.util.containers.ContainerUtil;
 import com.redhat.devtools.lsp4ij.ClosedDocument;
 import com.redhat.devtools.lsp4ij.LSPIJUtils;
 import com.redhat.devtools.lsp4ij.LanguageServerWrapper;
 import com.redhat.devtools.lsp4ij.OpenedDocument;
 import com.redhat.devtools.lsp4ij.client.features.FileUriSupport;
+import org.eclipse.lsp4j.DiagnosticSeverity;
 import org.eclipse.lsp4j.PublishDiagnosticsParams;
 import org.jetbrains.annotations.NotNull;
 
@@ -53,7 +56,8 @@ private void updateDiagnostics(@NotNull PublishDiagnosticsParams params, @NotNul
         if (project.isDisposed()) {
             return;
         }
-        VirtualFile file = FileUriSupport.findFileByUri(params.getUri(), languageServerWrapper.getClientFeatures());
+        var clientFeatures = languageServerWrapper.getClientFeatures();
+        VirtualFile file = FileUriSupport.findFileByUri(params.getUri(), clientFeatures);
         if (file == null) {
             return;
         }
@@ -71,6 +75,13 @@ private void updateDiagnostics(@NotNull PublishDiagnosticsParams params, @NotNul
             ClosedDocument closedDocument = languageServerWrapper.getClosedDocument(fileURI, true);
             closedDocument.updateDiagnostics(params.getDiagnostics());
         }
+
+        WolfTheProblemSolver wolf = WolfTheProblemSolver.getInstance(project);
+        if (ContainerUtil.exists(params.getDiagnostics(), diagnostic -> diagnostic.getSeverity() == DiagnosticSeverity.Error)) {
+            wolf.reportProblemsFromExternalSource(file, languageServerWrapper);
+        } else {
+            wolf.clearProblemsFromExternalSource(file, languageServerWrapper);
+        }
     }
 
 }

src/main/java/com/redhat/devtools/lsp4ij/features/diagnostics/LSPProblemFileHighlightFilter.java

@@ -0,0 +1,24 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Red Hat Inc. and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ * which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ *
+ * Contributors:
+ *     Red Hat Inc. - initial API and implementation
+ *******************************************************************************/
+package com.redhat.devtools.lsp4ij.features.diagnostics;
+
+import com.intellij.openapi.util.Condition;
+import com.intellij.openapi.vfs.VirtualFile;
+
+public class LSPProblemFileHighlightFilter implements Condition<VirtualFile> {
+  @Override
+  public boolean value(VirtualFile file) {
+    return true;
+  }
+}

src/main/resources/META-INF/plugin.xml

@@ -294,6 +294,8 @@
                          groupName="Language Servers"
                          displayName="Diagnostics"
                          implementationClass="com.redhat.devtools.lsp4ij.inspections.LSPLocalInspectionTool"/>
+        <problemFileHighlightFilter id ="LSPProblemFileHighlightFilter"
+                                    implementation="com.redhat.devtools.lsp4ij.features.diagnostics.LSPProblemFileHighlightFilter"/>
 
         <!-- LSP textDocument/completion request support -->
         <typedHandler id="LSPCompletionTriggerTypedHandler"