Add custom/projectFiles LSP request

internal/lsp/lsproto/_generate/generate.mts

@@ -421,6 +421,33 @@ const customStructures: Structure[] = [
         ],
         documentation: "Parameters for the custom/setLogVerbosity notification.",
     },
+    {
+        name: "ProjectFilesProject",
+        properties: [
+            {
+                name: "configFilePath",
+                type: { kind: "base", name: "string" },
+                documentation: "The absolute path to the config file (e.g. /path/to/tsconfig.json) for the project, or an empty string for an inferred project.",
+            },
+            {
+                name: "files",
+                type: { kind: "array", element: { kind: "base", name: "DocumentUri" } },
+                documentation: "The list of source file URIs in this project.",
+            },
+        ],
+        documentation: "A project and its source files.",
+    },
+    {
+        name: "ProjectFilesResult",
+        properties: [
+            {
+                name: "projects",
+                type: { kind: "array", element: { kind: "reference", name: "ProjectFilesProject" } },
+                documentation: "The list of projects and their source files.",
+            },
+        ],
+        documentation: "Result for the custom/projectFiles request.",
+    },
     {
         name: "PerformanceStatsTelemetryEvent",
         properties: [
@@ -776,6 +803,13 @@ const customRequests: Request[] = [
         messageDirection: "clientToServer",
         documentation: "Returns project information (e.g. the tsconfig.json path) for a given text document.",
     },
+    {
+        method: "custom/projectFiles",
+        typeName: "CustomProjectFilesRequest",
+        result: { kind: "reference", name: "ProjectFilesResult" },
+        messageDirection: "clientToServer",
+        documentation: "Returns all projects and the list of source files in each project.",
+    },
     {
         method: "custom/textDocument/sourceDefinition",
         typeName: "CustomTextDocumentSourceDefinitionRequest",

internal/lsp/server.go

@@ -775,6 +775,7 @@ var handlers = sync.OnceValue(func() handlerMap {
 
 	registerRequestHandler(handlers, lsproto.CustomInitializeAPISessionInfo, (*Server).handleInitializeAPISession)
 	registerRequestHandler(handlers, lsproto.CustomProjectInfoInfo, (*Server).handleProjectInfo)
+	registerRequestHandler(handlers, lsproto.CustomProjectFilesInfo, (*Server).handleProjectFiles)
 	return handlers
 })
 
@@ -1820,3 +1821,40 @@ func (s *Server) handleProjectInfo(ctx context.Context, params *lsproto.ProjectI
 		ConfigFilePath: configFilePath,
 	}, nil
 }
+
+func (s *Server) handleProjectFiles(_ context.Context, _ lsproto.NoParams, _ *lsproto.RequestMessage) (lsproto.CustomProjectFilesResponse, error) {
+	snapshot := s.session.Snapshot()
+	if snapshot == nil {
+		return &lsproto.ProjectFilesResult{
+			Projects: []*lsproto.ProjectFilesProject{},
+		}, nil
+	}
+
+	allProjects := snapshot.ProjectCollection.Projects()
+	result := make([]*lsproto.ProjectFilesProject, 0, len(allProjects))
+
+	for _, proj := range allProjects {
+		if proj.Program == nil {
+			continue
+		}
+		configFilePath := ""
+		if proj.Kind == project.KindConfigured {
+			configFilePath = proj.Name()
+		}
+
+		sourceFiles := proj.Program.GetSourceFiles()
+		files := make([]lsproto.DocumentUri, 0, len(sourceFiles))
+		for _, sf := range sourceFiles {
+			files = append(files, lsconv.FileNameToDocumentURI(sf.FileName()))
+		}
+
+		result = append(result, &lsproto.ProjectFilesProject{
+			ConfigFilePath: configFilePath,
+			Files:          files,
+		})
+	}
+
+	return &lsproto.ProjectFilesResult{
+		Projects: result,
+	}, nil
+}