Better LSP error handling

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2026 MARTe Community
+Copyright (c) 2026 Martino G. Ferrari <manda.mgf@gmail.com>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -4,11 +4,22 @@
 
 ## Features
 
+- **Portability**: A single statically compiled executable compatible with any Linux 3.2+ machine (as well as possible to compile and run on Windows and Mac OS X)
 - **LSP Server**: Real-time syntax checking, validation, autocomplete, hover documentation, and navigation (Go to Definition/References).
 - **Builder**: Merges multiple configuration files into a single, ordered output file.
 - **Formatter**: Standardizes configuration file formatting.
 - **Validator**: Advanced semantic validation using [CUE](https://cuelang.org/) schemas, ensuring type safety and structural correctness.
 
+### MARTe extended configuration language
+
+Few additional features have been added to the standard MARTe configuration language:
+
+- Multi file configuration support
+  - Multi file definition merging
+  - File level namespace / node
+- Doc-strings support
+- Pragmas for warning suppression / documentation
+
 ## Installation
 
 ### From Source
@@ -47,6 +58,7 @@ go install github.com/marte-community/marte-dev-tools/cmd/mdt@latest
 ## MARTe Configuration
 
 The tools support the MARTe configuration format with extended features:
+
 - **Objects**: `+Node = { Class = ... }`
 - **Signals**: `Signal = { Type = ... }`
 - **Namespaces**: `#package PROJECT.NODE` for organizing multi-file projects.
@@ -59,6 +71,7 @@ Validation is fully schema-driven using CUE.
 - **Custom Schema**: Add a `.marte_schema.cue` file to your project root to extend or override definitions.
 
 **Example `.marte_schema.cue`:**
+
 ```cue
 package schema
 
@@ -83,14 +96,17 @@ Use comments starting with `//!` to control validation behavior:
 ## Development
 
 ### Building
+
 ```bash
 go build ./cmd/mdt
 ```
 
 ### Running Tests
+
 ```bash
 go test ./...
 ```
 
 ## License
+
 MIT

internal/index/index.go

@@ -5,7 +5,6 @@ import (
 	"path/filepath"
 	"strings"
 
-	"github.com/marte-community/marte-dev-tools/internal/logger"
 	"github.com/marte-community/marte-dev-tools/internal/parser"
 )
 
@@ -120,8 +119,11 @@ func (pt *ProjectTree) removeFileFromNode(node *ProjectNode, file string) {
 	node.Metadata = make(map[string]string)
 	pt.rebuildMetadata(node)
 
-	for _, child := range node.Children {
+	for name, child := range node.Children {
 		pt.removeFileFromNode(child, file)
+		if len(child.Fragments) == 0 && len(child.Children) == 0 {
+			delete(node.Children, name)
+		}
 	}
 }
 
@@ -181,13 +183,8 @@ func (pt *ProjectTree) AddFile(file string, config *parser.Configuration) {
 
 	node := pt.Root
 	parts := strings.Split(config.Package.URI, ".")
-	// Skip first part as per spec (Project Name is namespace only)
+	
-	startIdx := 0
+	for i := 0; i < len(parts); i++ {
-	if len(parts) > 0 {
-		startIdx = 1
-	}
-
-	for i := startIdx; i < len(parts); i++ {
 		part := strings.TrimSpace(parts[i])
 		if part == "" {
 			continue
@@ -458,9 +455,7 @@ type QueryResult struct {
 }
 
 func (pt *ProjectTree) Query(file string, line, col int) *QueryResult {
-	logger.Printf("File: %s:%d:%d", file, line, col)
 	for i := range pt.References {
-		logger.Printf("%s", pt.Root.Name)
 		ref := &pt.References[i]
 		if ref.File == file {
 			if line == ref.Position.Line && col >= ref.Position.Column && col < ref.Position.Column+len(ref.Name) {

internal/lsp/server.go

@@ -20,12 +20,10 @@ import (
 	"cuelang.org/go/cue"
 )
 
-
-
 type CompletionParams struct {
 	TextDocument TextDocumentIdentifier `json:"textDocument"`
 	Position     Position               `json:"position"`
-	Context      CompletionContext      `json:"context,omitempty"`
+	Context      CompletionContext      `json:"context"`
 }
 
 type CompletionContext struct {
@@ -161,6 +159,16 @@ type DocumentFormattingParams struct {
 	Options      FormattingOptions      `json:"options"`
 }
 
+type RenameParams struct {
+	TextDocument TextDocumentIdentifier `json:"textDocument"`
+	Position     Position               `json:"position"`
+	NewName      string                 `json:"newName"`
+}
+
+type WorkspaceEdit struct {
+	Changes map[string][]TextEdit `json:"changes"`
+}
+
 type FormattingOptions struct {
 	TabSize      int  `json:"tabSize"`
 	InsertSpaces bool `json:"insertSpaces"`
@@ -171,7 +179,6 @@ type TextEdit struct {
 	NewText string `json:"newText"`
 }
 
-
 func RunServer() {
 	reader := bufio.NewReader(os.Stdin)
 	for {
@@ -215,6 +222,12 @@ func readMessage(reader *bufio.Reader) (*JsonRpcMessage, error) {
 }
 
 func HandleMessage(msg *JsonRpcMessage) {
+	defer func() {
+		if r := recover(); r != nil {
+			logger.Printf("Panic in HandleMessage: %v", r)
+		}
+	}()
+
 	switch msg.Method {
 	case "initialize":
 		var params InitializeParams
@@ -244,6 +257,7 @@ func HandleMessage(msg *JsonRpcMessage) {
 				"definitionProvider":         true,
 				"referencesProvider":         true,
 				"documentFormattingProvider": true,
+				"renameProvider":             true,
 				"completionProvider": map[string]any{
 					"triggerCharacters": []string{"=", " "},
 				},
@@ -300,6 +314,11 @@ func HandleMessage(msg *JsonRpcMessage) {
 		if err := json.Unmarshal(msg.Params, &params); err == nil {
 			respond(msg.ID, HandleFormatting(params))
 		}
+	case "textDocument/rename":
+		var params RenameParams
+		if err := json.Unmarshal(msg.Params, &params); err == nil {
+			respond(msg.ID, HandleRename(params))
+		}
 	}
 }
 
@@ -382,7 +401,7 @@ func HandleFormatting(params DocumentFormattingParams) []TextEdit {
 	}
 }
 
-func runValidation(uri string) {
+func runValidation(_ string) {
 	v := validator.NewValidator(Tree, ProjectRoot)
 	v.ValidateProject()
 	v.CheckUnused()
@@ -567,10 +586,7 @@ func HandleCompletion(params CompletionParams) *CompletionList {
 	}
 	lineStr := lines[params.Position.Line]
 
-	col := params.Position.Character
+	col := min(params.Position.Character, len(lineStr))
-	if col > len(lineStr) {
-		col = len(lineStr)
-	}
 
 	prefix := lineStr[:col]
 
@@ -601,12 +617,88 @@ func HandleCompletion(params CompletionParams) *CompletionList {
 	// Case 2: Typing a key inside an object
 	container := Tree.GetNodeContaining(path, parser.Position{Line: params.Position.Line + 1, Column: col + 1})
 	if container != nil {
+		if container.Parent != nil && isGAM(container.Parent) {
+			if container.Name == "InputSignals" {
+				return suggestGAMSignals(container, "Input")
+			}
+			if container.Name == "OutputSignals" {
+				return suggestGAMSignals(container, "Output")
+			}
+		}
 		return suggestFields(container)
 	}
 
 	return nil
 }
 
+func suggestGAMSignals(_ *index.ProjectNode, direction string) *CompletionList {
+	var items []CompletionItem
+
+	processNode := func(node *index.ProjectNode) {
+		if !isDataSource(node) {
+			return
+		}
+
+		cls := node.Metadata["Class"]
+		if cls == "" {
+			return
+		}
+
+		dir := "NIL"
+		if GlobalSchema != nil {
+			classPath := cue.ParsePath(fmt.Sprintf("#Classes.%s.direction", cls))
+			val := GlobalSchema.Value.LookupPath(classPath)
+			if val.Err() == nil {
+				var s string
+				if err := val.Decode(&s); err == nil {
+					dir = s
+				}
+			}
+		}
+		compatible := false
+		switch direction {
+		case "Input":
+			compatible = dir == "IN" || dir == "INOUT"
+		case "Output":
+			compatible = dir == "OUT" || dir == "INOUT"
+		default:
+			compatible = false
+		}
+
+		if !compatible {
+			return
+		}
+
+		signalsContainer := node.Children["Signals"]
+		if signalsContainer == nil {
+			return
+		}
+
+		for _, sig := range signalsContainer.Children {
+			dsName := node.Name
+			sigName := sig.Name
+
+			label := fmt.Sprintf("%s:%s", dsName, sigName)
+			insertText := fmt.Sprintf("%s = {\n DataSource = %s \n}", sigName, dsName)
+
+			items = append(items, CompletionItem{
+				Label:            label,
+				Kind:             6, // Variable
+				Detail:           "Signal from " + dsName,
+				InsertText:       insertText,
+				InsertTextFormat: 2, // Snippet
+			})
+		}
+	}
+
+	Tree.Walk(processNode)
+
+	if len(items) > 0 {
+		return &CompletionList{Items: items}
+	}
+	return nil
+}
+
 func suggestClasses() *CompletionList {
 	if GlobalSchema == nil {
 		return nil
@@ -783,11 +875,11 @@ func suggestCUEEnums(container *index.ProjectNode, field string) *CompletionList
 		if err != nil {
 			continue
 		}
-        
+
-        // Ensure strings are quoted
+		// Ensure strings are quoted
-        if v.Kind() == cue.StringKind && !strings.HasPrefix(str, "\"") {
+		if v.Kind() == cue.StringKind && !strings.HasPrefix(str, "\"") {
-            str = fmt.Sprintf("\"%s\"", str)
+			str = fmt.Sprintf("\"%s\"", str)
-        }
+		}
 
 		items = append(items, CompletionItem{
 			Label:  str,
@@ -811,14 +903,11 @@ func suggestObjects(root *index.ProjectNode, filter string) *CompletionList {
 	var walk func(*index.ProjectNode)
 	walk = func(node *index.ProjectNode) {
 		match := false
-		if filter == "GAM" {
+		switch filter {
-			if isGAM(node) {
+		case "GAM":
-				match = true
+			match = isGAM(node)
-			}
+		case "DataSource":
-		} else if filter == "DataSource" {
+			match = isDataSource(node)
-			if isDataSource(node) {
-				match = true
-			}
 		}
 
 		if match {
@@ -981,6 +1070,14 @@ func formatNodeInfo(node *index.ProjectNode) string {
 	typ := node.Metadata["Type"]
 	ds := node.Metadata["DataSource"]
 
+	if ds == "" {
+		if node.Parent != nil && node.Parent.Name == "Signals" {
+			if node.Parent.Parent != nil {
+				ds = node.Parent.Parent.Name
+			}
+		}
+	}
+
 	if typ != "" || ds != "" {
 		sigInfo := "\n"
 		if typ != "" {
@@ -1053,14 +1150,192 @@ func formatNodeInfo(node *index.ProjectNode) string {
 		}
 	}
 
+	// Find GAM usages
+	var gams []string
+
+	// 1. Check References (explicit text references)
+	for _, ref := range Tree.References {
+		if ref.Target == node {
+			container := Tree.GetNodeContaining(ref.File, ref.Position)
+			if container != nil {
+				curr := container
+				for curr != nil {
+					if isGAM(curr) {
+						gams = append(gams, curr.RealName)
+						break
+					}
+					curr = curr.Parent
+				}
+			}
+		}
+	}
+
+	// 2. Check Direct Usages (Nodes targeting this node)
+	Tree.Walk(func(n *index.ProjectNode) {
+		if n.Target == node {
+			if n.Parent != nil && (n.Parent.Name == "InputSignals" || n.Parent.Name == "OutputSignals") {
+				if n.Parent.Parent != nil && isGAM(n.Parent.Parent) {
+					gams = append(gams, n.Parent.Parent.RealName)
+				}
+			}
+		}
+	})
+
+	if len(gams) > 0 {
+		uniqueGams := make(map[string]bool)
+		info += "\n\n**Used in GAMs**:\n"
+		for _, g := range gams {
+			if !uniqueGams[g] {
+				uniqueGams[g] = true
+				info += fmt.Sprintf("- %s\n", g)
+			}
+		}
+	}
+
 	return info
 }
 
+func HandleRename(params RenameParams) *WorkspaceEdit {
+	path := uriToPath(params.TextDocument.URI)
+	line := params.Position.Line + 1
+	col := params.Position.Character + 1
+
+	res := Tree.Query(path, line, col)
+	if res == nil {
+		return nil
+	}
+
+	var targetNode *index.ProjectNode
+	var targetField *parser.Field
+	if res.Node != nil {
+		if res.Node.Target != nil {
+			targetNode = res.Node.Target
+		} else {
+			targetNode = res.Node
+		}
+	} else if res.Field != nil {
+		targetField = res.Field
+	} else if res.Reference != nil {
+		if res.Reference.Target != nil {
+			targetNode = res.Reference.Target
+		} else {
+			return nil
+		}
+	}
+
+	changes := make(map[string][]TextEdit)
+
+	addEdit := func(file string, rng Range, newText string) {
+		uri := "file://" + file
+		changes[uri] = append(changes[uri], TextEdit{Range: rng, NewText: newText})
+	}
+
+	if targetNode != nil {
+		// 1. Rename Definitions
+		prefix := ""
+		if len(targetNode.RealName) > 0 {
+			first := targetNode.RealName[0]
+			if first == '+' || first == '$' {
+				prefix = string(first)
+			}
+		}
+		normNewName := strings.TrimLeft(params.NewName, "+$")
+		finalDefName := prefix + normNewName
+
+		for _, frag := range targetNode.Fragments {
+			if frag.IsObject {
+				rng := Range{
+					Start: Position{Line: frag.ObjectPos.Line - 1, Character: frag.ObjectPos.Column - 1},
+					End:   Position{Line: frag.ObjectPos.Line - 1, Character: frag.ObjectPos.Column - 1 + len(targetNode.RealName)},
+				}
+				addEdit(frag.File, rng, finalDefName)
+			}
+		}
+
+		// 2. Rename References
+		for _, ref := range Tree.References {
+			if ref.Target == targetNode {
+				// Handle qualified names (e.g. Pkg.Node)
+				if strings.Contains(ref.Name, ".") {
+					if strings.HasSuffix(ref.Name, "."+targetNode.Name) {
+						prefixLen := len(ref.Name) - len(targetNode.Name)
+						rng := Range{
+							Start: Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1 + prefixLen},
+							End:   Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1 + len(ref.Name)},
+						}
+						addEdit(ref.File, rng, normNewName)
+					} else if ref.Name == targetNode.Name {
+						rng := Range{
+							Start: Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1},
+							End:   Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1 + len(ref.Name)},
+						}
+						addEdit(ref.File, rng, normNewName)
+					}
+				} else {
+					rng := Range{
+						Start: Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1},
+						End:   Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1 + len(ref.Name)},
+					}
+					addEdit(ref.File, rng, normNewName)
+				}
+			}
+		}
+
+		// 3. Rename Implicit Node References (Signals in GAMs relying on name match)
+		Tree.Walk(func(n *index.ProjectNode) {
+			if n.Target == targetNode {
+				hasAlias := false
+				for _, frag := range n.Fragments {
+					for _, def := range frag.Definitions {
+						if f, ok := def.(*parser.Field); ok && f.Name == "Alias" {
+							hasAlias = true
+						}
+					}
+				}
+
+				if !hasAlias {
+					for _, frag := range n.Fragments {
+						if frag.IsObject {
+							rng := Range{
+								Start: Position{Line: frag.ObjectPos.Line - 1, Character: frag.ObjectPos.Column - 1},
+								End:   Position{Line: frag.ObjectPos.Line - 1, Character: frag.ObjectPos.Column - 1 + len(n.RealName)},
+							}
+							addEdit(frag.File, rng, normNewName)
+						}
+					}
+				}
+			}
+		})
+
+		return &WorkspaceEdit{Changes: changes}
+	} else if targetField != nil {
+		container := Tree.GetNodeContaining(path, targetField.Position)
+		if container != nil {
+			for _, frag := range container.Fragments {
+				for _, def := range frag.Definitions {
+					if f, ok := def.(*parser.Field); ok {
+						if f.Name == targetField.Name {
+							rng := Range{
+								Start: Position{Line: f.Position.Line - 1, Character: f.Position.Column - 1},
+								End:   Position{Line: f.Position.Line - 1, Character: f.Position.Column - 1 + len(f.Name)},
+							}
+							addEdit(frag.File, rng, params.NewName)
+						}
+					}
+				}
+			}
+		}
+		return &WorkspaceEdit{Changes: changes}
+	}
+
+	return nil
+}
+
 func respond(id any, result any) {
-	msg := JsonRpcMessage{
+	msg := map[string]any{
-		Jsonrpc: "2.0",
+		"jsonrpc": "2.0",
-		ID:      id,
+		"id":      id,
-		Result:  result,
+		"result":  result,
 	}
 	send(msg)
 }

internal/schema/marte.cue

@@ -13,7 +13,7 @@ package schema
 	StateMachineEvent: {
 		NextState!:                                                  string
 		NextStateError!:                                             string
-		Timeout:                                                     uint32
+		Timeout?:                                                    uint32
 		[_= !~"^(Class|NextState|Timeout|NextStateError|[#_$].+)$"]: Message
 		...
 	}

internal/validator/validator.go

@@ -542,11 +542,6 @@ func isValidType(t string) bool {
 	return false
 }
 
-func (v *Validator) checkType(val parser.Value, expectedType string) bool {
-	// Legacy function, replaced by CUE.
-	return true
-}
-
 func (v *Validator) getFileForField(f *parser.Field, node *index.ProjectNode) string {
 	for _, frag := range node.Fragments {
 		for _, def := range frag.Definitions {

specification.md

@@ -34,6 +34,13 @@ The LSP server should provide the following capabilities:
   - **Reference Suggestions**:
     - `DataSource` fields suggest available DataSource objects.
     - `Functions` (in Threads) suggest available GAM objects.
+  - **Signal Completion**: Inside `InputSignals` or `OutputSignals` of a GAM:
+    - Suggests available signals from valid DataSources (filtering by direction: `IN`/`INOUT` for Inputs, `OUT`/`INOUT` for Outputs).
+    - Format: `SIGNAL_NAME:DATASOURCE_NAME`.
+    - Auto-inserts: `SIGNAL_NAME = { DataSource = DATASOURCE_NAME }`.
+- **Rename Symbol**: Rename an object, field, or reference across the entire project scope.
+  - Supports renaming of Definitions (`+Name` or `Name`), preserving any modifiers (`+`/`$`).
+  - Updates all references to the renamed symbol, including qualified references (e.g., `Pkg.Name`).
 - **Code Snippets**: Provide snippets for common patterns (e.g., `+Object = { ... }`).
 - **Formatting**: Format the document using the same rules and engine as the `fmt` command.
 

test/index_cleanup_test.go

@@ -0,0 +1,58 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+)
+
+func TestIndexCleanup(t *testing.T) {
+	idx := index.NewProjectTree()
+	file := "cleanup.marte"
+	content := `
+#package Pkg
++Node = { Class = Type }
+`
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	idx.AddFile(file, cfg)
+
+	// Check node exists
+	// Root -> Pkg -> Node
+	pkgNode := idx.Root.Children["Pkg"]
+	if pkgNode == nil {
+		t.Fatal("Pkg node should exist")
+	}
+	if pkgNode.Children["Node"] == nil {
+		t.Fatal("Node should exist")
+	}
+
+	// Update file: remove +Node
+	content2 := `
+#package Pkg
+// Removed node
+`
+	p2 := parser.NewParser(content2)
+	cfg2, _ := p2.Parse()
+	idx.AddFile(file, cfg2)
+
+	// Check Node is gone
+	pkgNode = idx.Root.Children["Pkg"]
+	if pkgNode == nil {
+		// Pkg should exist because of #package Pkg
+		t.Fatal("Pkg node should exist after update")
+	}
+	if pkgNode.Children["Node"] != nil {
+		t.Error("Node should be gone")
+	}
+
+	// Test removing file completely
+	idx.RemoveFile(file)
+	if len(idx.Root.Children) != 0 {
+		t.Errorf("Root should be empty after removing file, got %d children", len(idx.Root.Children))
+	}
+}

test/lsp_completion_signals_robustness_test.go

@@ -0,0 +1,90 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/schema"
+)
+
+func TestSuggestSignalsRobustness(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+	lsp.ProjectRoot = "."
+	lsp.GlobalSchema = schema.NewSchema()
+
+	// Inject schema with INOUT
+	custom := []byte(`
+package schema
+#Classes: {
+    InOutReader: { direction: "INOUT" }
+}
+`)
+	val := lsp.GlobalSchema.Context.CompileBytes(custom)
+	lsp.GlobalSchema.Value = lsp.GlobalSchema.Value.Unify(val)
+
+	content := `
++DS = {
+    Class = InOutReader
+    +Signals = {
+        Sig = { Type = uint32 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    +InputSignals = {
+        
+    }
+    +OutputSignals = {
+        
+    }
+}
+`
+	uri := "file://robust.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("robust.marte", cfg)
+
+	// Check Input (Line 10)
+	paramsIn := lsp.CompletionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 10, Character: 8},
+	}
+	listIn := lsp.HandleCompletion(paramsIn)
+	found := false
+	if listIn != nil {
+		for _, item := range listIn.Items {
+			if item.Label == "DS:Sig" {
+				found = true
+			}
+		}
+	}
+	if !found {
+		t.Error("INOUT signal not found in InputSignals")
+	}
+
+	// Check Output (Line 13)
+	paramsOut := lsp.CompletionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 13, Character: 8},
+	}
+	listOut := lsp.HandleCompletion(paramsOut)
+	found = false
+	if listOut != nil {
+		for _, item := range listOut.Items {
+			if item.Label == "DS:Sig" {
+				found = true
+			}
+		}
+	}
+	if !found {
+		t.Error("INOUT signal not found in OutputSignals")
+	}
+}

test/lsp_completion_signals_test.go

@@ -0,0 +1,128 @@
+package integration
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/schema"
+)
+
+func TestSuggestSignalsInGAM(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+	lsp.ProjectRoot = "."
+	lsp.GlobalSchema = schema.NewSchema()
+
+	// Inject schema for directionality
+	custom := []byte(`
+package schema
+#Classes: {
+    FileReader: { direction: "IN" }
+    FileWriter: { direction: "OUT" }
+}
+`)
+	val := lsp.GlobalSchema.Context.CompileBytes(custom)
+	lsp.GlobalSchema.Value = lsp.GlobalSchema.Value.Unify(val)
+
+	content := `
++InDS = {
+    Class = FileReader
+    +Signals = {
+        InSig = { Type = uint32 }
+    }
+}
++OutDS = {
+    Class = FileWriter
+    +Signals = {
+        OutSig = { Type = uint32 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    +InputSignals = {
+        
+    }
+    +OutputSignals = {
+        
+    }
+}
+`
+	uri := "file://signals.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("signals.marte", cfg)
+
+	// 1. Suggest in InputSignals
+	// Line 16 (empty line inside InputSignals)
+	paramsIn := lsp.CompletionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 16, Character: 8},
+	}
+
+	listIn := lsp.HandleCompletion(paramsIn)
+	if listIn == nil {
+		t.Fatal("Expected suggestions in InputSignals")
+	}
+
+	foundIn := false
+	foundOut := false
+	for _, item := range listIn.Items {
+		if item.Label == "InDS:InSig" {
+			foundIn = true
+			// Normalize spaces for check
+			insert := strings.ReplaceAll(item.InsertText, " ", "")
+			expected := "InSig={DataSource=InDS}"
+			if !strings.Contains(insert, expected) && !strings.Contains(item.InsertText, "InSig = {") {
+				// Snippet might differ slightly, but should contain essentials
+				t.Errorf("InsertText mismatch: %s", item.InsertText)
+			}
+		}
+		if item.Label == "OutDS:OutSig" {
+			foundOut = true
+		}
+	}
+
+	if !foundIn {
+		t.Error("Did not find InDS:InSig")
+	}
+	if foundOut {
+		t.Error("Should not find OutDS:OutSig in InputSignals")
+	}
+
+	// 2. Suggest in OutputSignals
+	// Line 19
+	paramsOut := lsp.CompletionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 19, Character: 8},
+	}
+	listOut := lsp.HandleCompletion(paramsOut)
+	if listOut == nil {
+		t.Fatal("Expected suggestions in OutputSignals")
+	}
+
+	foundIn = false
+	foundOut = false
+	for _, item := range listOut.Items {
+		if item.Label == "InDS:InSig" {
+			foundIn = true
+		}
+		if item.Label == "OutDS:OutSig" {
+			foundOut = true
+		}
+	}
+
+	if foundIn {
+		t.Error("Should not find InDS:InSig in OutputSignals")
+	}
+	if !foundOut {
+		t.Error("Did not find OutDS:OutSig in OutputSignals")
+	}
+}

test/lsp_crash_test.go

@@ -0,0 +1,74 @@
+package integration
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+)
+
+func TestLSPCrashOnUndefinedReference(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
++App = {
+    Class = RealTimeApplication
+    +State = {
+        Class = RealTimeState
+        +Thread = {
+            Class = RealTimeThread
+            Functions = { UndefinedGAM }
+        }
+    }
+}
+`
+	uri := "file://crash.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("crash.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Line 7: "            Functions = { UndefinedGAM }"
+	// 12 spaces + "Functions" (9) + " = { " (5) = 26 chars prefix.
+	// UndefinedGAM starts at 26.
+	params := lsp.DefinitionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 7, Character: 27},
+	}
+
+	// This should NOT panic
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("Recovered from panic: %v", r)
+		}
+	}()
+
+	res := lsp.HandleDefinition(params)
+
+	if res != nil {
+		t.Error("Expected nil for undefined reference definition")
+	}
+
+	// 2. Hover
+	hParams := lsp.HoverParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 7, Character: 27},
+	}
+	hover := lsp.HandleHover(hParams)
+	if hover == nil {
+		t.Error("Expected hover for unresolved reference")
+	} else {
+		content := hover.Contents.(lsp.MarkupContent).Value
+		if !strings.Contains(content, "Unresolved") {
+			t.Errorf("Expected 'Unresolved' in hover, got: %s", content)
+		}
+	}
+}

test/lsp_hover_datasource_test.go

@@ -0,0 +1,81 @@
+package integration
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+)
+
+func TestHoverDataSourceName(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
++DS1 = {
+    Class = FileReader
+    +Signals = {
+        Sig1 = { Type = uint32 }
+    }
+}
++GAM1 = {
+    Class = IOGAM
+    +InputSignals = {
+        S1 = {
+            DataSource = DS1
+            Alias = Sig1
+        }
+    }
+}
+`
+	uri := "file://test_ds.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatalf("Parse error: %v", err)
+	}
+	lsp.Tree.AddFile("test_ds.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Test 1: Explicit Signal (Sig1)
+	// Position: "Sig1" at line 5 (0-based 4)
+	// Line 4: "        Sig1 = { Type = uint32 }"
+	// Col: 8
+	params1 := lsp.HoverParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 4, Character: 9},
+	}
+
+	hover1 := lsp.HandleHover(params1)
+	if hover1 == nil {
+		t.Fatal("Expected hover for Sig1")
+	}
+
+	content1 := hover1.Contents.(lsp.MarkupContent).Value
+	// Expectation: explicit signal shows owner datasource
+	if !strings.Contains(content1, "**DataSource**: `+DS1`") && !strings.Contains(content1, "**DataSource**: `DS1`") {
+		t.Errorf("Expected DataSource: +DS1 in hover for Sig1, got: %s", content1)
+	}
+
+	// Test 2: Implicit Signal (S1)
+	// Position: "S1" at line 11 (0-based 10)
+	params2 := lsp.HoverParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 10, Character: 9},
+	}
+
+	hover2 := lsp.HandleHover(params2)
+	if hover2 == nil {
+		t.Fatal("Expected hover for S1")
+	}
+
+	content2 := hover2.Contents.(lsp.MarkupContent).Value
+	// Expectation: implicit signal shows referenced datasource
+	if !strings.Contains(content2, "**DataSource**: `DS1`") {
+		t.Errorf("Expected DataSource: DS1 in hover for S1, got: %s", content2)
+	}
+}

test/lsp_hover_gam_usage_test.go

@@ -0,0 +1,75 @@
+package integration
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+)
+
+func TestHoverGAMUsage(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
++DS1 = {
+    Class = FileReader
+    +Signals = {
+        Sig1 = { Type = uint32 }
+    }
+}
++GAM1 = {
+    Class = IOGAM
+    +InputSignals = {
+        S1 = {
+            DataSource = DS1
+            Alias = Sig1
+        }
+    }
+}
++GAM2 = {
+    Class = IOGAM
+    +OutputSignals = {
+        S2 = {
+             DataSource = DS1
+             Alias = Sig1
+        }
+    }
+}
+`
+	uri := "file://test_gam_usage.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("test_gam_usage.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Query hover for Sig1 (Line 5)
+	// Line 4: Sig1... (0-based)
+	params := lsp.HoverParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 4, Character: 9},
+	}
+
+	hover := lsp.HandleHover(params)
+	if hover == nil {
+		t.Fatal("Expected hover")
+	}
+
+	contentHover := hover.Contents.(lsp.MarkupContent).Value
+	if !strings.Contains(contentHover, "**Used in GAMs**") {
+		t.Errorf("Expected 'Used in GAMs' section, got:\n%s", contentHover)
+	}
+	if !strings.Contains(contentHover, "- +GAM1") {
+		t.Error("Expected +GAM1 in usage list")
+	}
+	if !strings.Contains(contentHover, "- +GAM2") {
+		t.Error("Expected +GAM2 in usage list")
+	}
+}

test/lsp_rename_implicit_test.go

@@ -0,0 +1,89 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/validator"
+)
+
+func TestRenameImplicitToDefinition(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
++DS = {
+    Class = FileReader
+    +Signals = {
+        Sig1 = { Type = uint32 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    +InputSignals = {
+        // Implicit usage
+        Sig1 = { DataSource = DS }
+    }
+}
+`
+	uri := "file://rename_imp.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("rename_imp.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Run validator to link targets
+	v := validator.NewValidator(lsp.Tree, ".")
+	v.ValidateProject()
+
+	// Rename Implicit Sig1 (Line 11, 0-based 11)
+	// Line 11: "        Sig1 = { DataSource = DS }"
+	params := lsp.RenameParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 11, Character: 9},
+		NewName:      "NewSig",
+	}
+
+	edit := lsp.HandleRename(params)
+	if edit == nil {
+		t.Fatal("Expected edits")
+	}
+
+	edits := edit.Changes[uri]
+
+	// Expect:
+	// 1. Rename Implicit Sig1 (Line 9) -> NewSig
+	// 2. Rename Definition Sig1 (Line 4) -> NewSig
+
+	if len(edits) != 2 {
+		t.Errorf("Expected 2 edits, got %d", len(edits))
+		for _, e := range edits {
+			t.Logf("Edit at line %d", e.Range.Start.Line)
+		}
+	}
+
+	foundDef := false
+	foundImp := false
+	for _, e := range edits {
+		if e.Range.Start.Line == 4 {
+			foundDef = true
+		}
+		if e.Range.Start.Line == 11 {
+			foundImp = true
+		}
+	}
+
+	if !foundDef {
+		t.Error("Definition not renamed")
+	}
+	if !foundImp {
+		t.Error("Implicit usage not renamed")
+	}
+}

test/lsp_rename_signal_test.go

@@ -0,0 +1,110 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/validator"
+)
+
+func TestRenameSignalInGAM(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
++DS = {
+    Class = FileReader
+    +Signals = {
+        Sig1 = { Type = uint32 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    +InputSignals = {
+        // Implicit match
+        Sig1 = { DataSource = DS }
+        // Explicit Alias
+        S2 = { DataSource = DS Alias = Sig1 }
+    }
+}
+`
+	uri := "file://rename_sig.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("rename_sig.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Run validator to populate Targets
+	v := validator.NewValidator(lsp.Tree, ".")
+	v.ValidateProject()
+
+	// Rename DS.Sig1 to NewSig
+	// Sig1 is at Line 5.
+	// Line 0: empty
+	// Line 1: +DS
+	// Line 2: Class
+	// Line 3: +Signals
+	// Line 4: Sig1
+	params := lsp.RenameParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 4, Character: 9}, // Sig1
+		NewName:      "NewSig",
+	}
+
+	edit := lsp.HandleRename(params)
+	if edit == nil {
+		t.Fatal("Expected edits")
+	}
+
+	edits := edit.Changes[uri]
+
+	// Expect:
+	// 1. Definition of Sig1 in DS (Line 5) -> NewSig
+	// 2. Definition of Sig1 in GAM (Line 10) -> NewSig (Implicit match)
+	// 3. Alias reference in S2 (Line 12) -> NewSig
+
+	// Line 10: Sig1 = ... (0-based 9)
+	// Line 12: S2 = ... Alias = Sig1 (0-based 11)
+
+	expectedCount := 3
+	if len(edits) != expectedCount {
+		t.Errorf("Expected %d edits, got %d", expectedCount, len(edits))
+		for _, e := range edits {
+			t.Logf("Edit: %s at %d", e.NewText, e.Range.Start.Line)
+		}
+	}
+
+	// Check Implicit Signal Rename
+	foundImplicit := false
+	for _, e := range edits {
+		if e.Range.Start.Line == 11 {
+			if e.NewText == "NewSig" {
+				foundImplicit = true
+			}
+		}
+	}
+	if !foundImplicit {
+		t.Error("Did not find implicit signal rename")
+	}
+
+	// Check Alias Rename
+	foundAlias := false
+	for _, e := range edits {
+		if e.Range.Start.Line == 13 {
+			// Alias = Sig1. Range should cover Sig1.
+			if e.NewText == "NewSig" {
+				foundAlias = true
+			}
+		}
+	}
+	if !foundAlias {
+		t.Error("Did not find alias reference rename")
+	}
+}

test/lsp_rename_test.go

@@ -0,0 +1,92 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+)
+
+func TestHandleRename(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
+#package Some
++MyNode = {
+    Class = Type
+}
++Consumer = {
+    Link = MyNode
+    PkgLink = Some.MyNode
+}
+`
+	uri := "file://rename.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	lsp.Tree.AddFile("rename.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	// Rename +MyNode to NewNode
+	// +MyNode is at Line 2 (after #package)
+	// Line 0: empty
+	// Line 1: #package
+	// Line 2: +MyNode
+	params := lsp.RenameParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Position:     lsp.Position{Line: 2, Character: 4}, // +MyNode
+		NewName:      "NewNode",
+	}
+
+	edit := lsp.HandleRename(params)
+	if edit == nil {
+		t.Fatal("Expected edits")
+	}
+
+	edits := edit.Changes[uri]
+	if len(edits) != 3 {
+		t.Errorf("Expected 3 edits (Def, Link, PkgLink), got %d", len(edits))
+	}
+
+	// Verify Definition change (+MyNode -> +NewNode)
+	foundDef := false
+	for _, e := range edits {
+		if e.NewText == "+NewNode" {
+			foundDef = true
+			if e.Range.Start.Line != 2 {
+				t.Errorf("Definition edit line wrong: %d", e.Range.Start.Line)
+			}
+		}
+	}
+	if !foundDef {
+		t.Error("Did not find definition edit +NewNode")
+	}
+
+	// Verify Link change (MyNode -> NewNode)
+	foundLink := false
+	for _, e := range edits {
+		if e.NewText == "NewNode" && e.Range.Start.Line == 6 { // Link = MyNode
+			foundLink = true
+		}
+	}
+	if !foundLink {
+		t.Error("Did not find Link edit")
+	}
+
+	// Verify PkgLink change (Some.MyNode -> Some.NewNode)
+	foundPkg := false
+	for _, e := range edits {
+		if e.NewText == "NewNode" && e.Range.Start.Line == 7 { // PkgLink = Some.MyNode
+			foundPkg = true
+		}
+	}
+	if !foundPkg {
+		t.Error("Did not find PkgLink edit")
+	}
+}

test/validator_multifile_test.go

@@ -107,7 +107,11 @@ func TestHierarchicalPackageMerge(t *testing.T) {
 	}
 
 	// We can also inspect the tree to verify FieldX is there (optional, but good for confidence)
-	baseNode := idx.Root.Children["Base"]
+	projNode := idx.Root.Children["Proj"]
+	if projNode == nil {
+		t.Fatal("Proj node not found")
+	}
+	baseNode := projNode.Children["Base"]
 	if baseNode == nil {
 		t.Fatal("Base node not found")
 	}