diff --git a/internal/lsp/server.go b/internal/lsp/server.go
index 46f2a5b..8a9178e 100644
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@@ -614,12 +614,90 @@ 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(container *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 := "INOUT"
+		if GlobalSchema != nil {
+			classPath := cue.ParsePath(fmt.Sprintf("#Classes.%s.direction", cls))
+			val := GlobalSchema.Value.LookupPath(classPath)
+			if val.Err() == nil {
+				s, err := val.String()
+				if err == nil {
+					dir = s
+				}
+			}
+		}
+
+		compatible := false
+		if direction == "Input" {
+			if dir == "IN" || dir == "INOUT" {
+				compatible = true
+			}
+		} else if direction == "Output" {
+			if dir == "OUT" || dir == "INOUT" {
+				compatible = true
+			}
+		}
+
+		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", sigName, dsName)
+			insertText := fmt.Sprintf("%s = { DataSource = %s }", 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
diff --git a/test/lsp_completion_signals_test.go b/test/lsp_completion_signals_test.go
new file mode 100644
index 0000000..47a4a9d
--- /dev/null
+++ b/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 == "InSig:InDS" {
+			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 == "OutSig:OutDS" {
+			foundOut = true
+		}
+	}
+
+	if !foundIn {
+		t.Error("Did not find InSig:InDS")
+	}
+	if foundOut {
+		t.Error("Should not find OutSig:OutDS 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 == "InSig:InDS" {
+			foundIn = true
+		}
+		if item.Label == "OutSig:OutDS" {
+			foundOut = true
+		}
+	}
+
+	if foundIn {
+		t.Error("Should not find InSig:InDS in OutputSignals")
+	}
+	if !foundOut {
+		t.Error("Did not find OutSig:OutDS in OutputSignals")
+	}
+}