Unwrap nested "preview" key in MuEdToPreviewFeedback for proper wrapping (#27)

Author: m-messer

runtime/mued.go

@@ -192,7 +192,11 @@ func MuEdToEvaluateFeedback(result map[string]any) []map[string]any {
 }
 
 // MuEdToPreviewFeedback wraps a legacy preview result as [{"preSubmissionFeedback": result}].
+// Unwraps the nested "preview" key produced by legacy preview functions before wrapping.
 func MuEdToPreviewFeedback(result map[string]any) []map[string]any {
+	if inner, ok := result["preview"].(map[string]any); ok {
+		result = inner
+	}
 	return []map[string]any{
 		{"preSubmissionFeedback": result},
 	}

runtime/mued_test.go

@@ -271,8 +271,9 @@ func TestMuEdToEvalFeedback(t *testing.T) {
 }
 
 func TestMuEdToPreviewFeedback(t *testing.T) {
-	result := map[string]any{"preview": map[string]any{"latex": "x^2"}}
+	inner := map[string]any{"latex": "x^2"}
+	result := map[string]any{"preview": inner}
 	fb := runtime.MuEdToPreviewFeedback(result)
 	require.Len(t, fb, 1)
-	assert.Equal(t, result, fb[0]["preSubmissionFeedback"])
+	assert.Equal(t, inner, fb[0]["preSubmissionFeedback"])
 }