fix(postprocess): use Src map for T1 node lookup in FilterPunctuation

internal/postprocess/punctuation.go

@@ -44,7 +44,7 @@ func FilterPunctuation(es *actions.EditScript, ms *engine.Mapping) *actions.Edit
 				Node: a.Node,
 			})
 
-			dstNode := ms.Dst()[a.Node]
+			dstNode := ms.Src()[a.Node]
 			if dstNode != nil {
 				filtered.Add(actions.Action{
 					Type:     actions.Insert,

internal/postprocess/punctuation_test.go

@@ -0,0 +1,66 @@
+package postprocess
+
+import (
+	"testing"
+
+	"github.com/HarshK97/diffmantic/internal/actions"
+	"github.com/HarshK97/diffmantic/internal/engine"
+	"github.com/HarshK97/diffmantic/internal/testutil"
+)
+
+func TestFilterPunctuation_StrictPunctuationMoveSplit(t *testing.T) {
+	// Create T1 (source) and T2 (destination) strict punctuation nodes (e.g. double quote or colon)
+	srcPunct := testutil.Leaf("string_delimiter", "\"")
+	dstPunct := testutil.Leaf("string_delimiter", "\"")
+	dstParent := testutil.Leaf("string_literal", "")
+
+	ms := engine.NewMapping()
+	ms.Add(srcPunct, dstPunct)
+
+	es := actions.NewEditScript()
+	es.Add(actions.Action{
+		Type:     actions.Move,
+		Node:     srcPunct,
+		Parent:   dstParent,
+		Position: 0,
+	})
+
+	filtered := FilterPunctuation(es, ms)
+	if filtered == nil {
+		t.Fatal("expected non-nil edit script")
+	}
+
+	acts := filtered.Actions()
+	if len(acts) != 2 {
+		t.Fatalf("expected 2 actions (Delete + Insert), got %d", len(acts))
+	}
+
+	if acts[0].Type != actions.Delete || acts[0].Node != srcPunct {
+		t.Errorf("expected first action to be Delete of srcPunct, got %+v", acts[0])
+	}
+
+	if acts[1].Type != actions.Insert || acts[1].Node != dstPunct {
+		t.Errorf("expected second action to be Insert of dstPunct, got %+v", acts[1])
+	}
+}
+
+func TestFilterPunctuation_SkipSemicolonAndComma(t *testing.T) {
+	semiNode := testutil.Leaf("semicolon", ";")
+	commaNode := testutil.Leaf("comma", ",")
+
+	ms := engine.NewMapping()
+	es := actions.NewEditScript()
+	es.Add(actions.Action{Type: actions.Insert, Node: semiNode})
+	es.Add(actions.Action{Type: actions.Delete, Node: commaNode})
+
+	filtered := FilterPunctuation(es, ms)
+	if filtered.Size() != 0 {
+		t.Errorf("expected 0 actions after filtering commas and semicolons, got %d", filtered.Size())
+	}
+}
+
+func TestFilterPunctuation_NilScript(t *testing.T) {
+	if FilterPunctuation(nil, engine.NewMapping()) != nil {
+		t.Error("expected nil for nil edit script")
+	}
+}