diff --git a/.memory/state.md b/.memory/state.md
index 0ad015f..33648ef 100644
--- a/.memory/state.md
+++ b/.memory/state.md
@@ -1,6 +1,6 @@
 # State
 - Core engine: `src/rpn-calculator.js`
-- Active demo: `samples/calc-02/` responsive HP48GX layout driven by portrait/landscape text mockups; display-adjacent button row stays in 4 columns
+- Active demo: `samples/calc-02/` responsive HP48GX layout with HP48-like X-line editing; display-adjacent button row stays in 4 columns
 - Mode button shows the current angle mode only; selecting a mode uses a popup menu
 - Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`
 - Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
diff --git a/samples/calc-02/index.js b/samples/calc-02/index.js
index 03933df..a397d1b 100644
--- a/samples/calc-02/index.js
+++ b/samples/calc-02/index.js
@@ -86,8 +86,7 @@ function normalizeStack() {
 }
 
 function getStackLine(indexFromTop) {
-	const index = calc.stack.length - 1 - indexFromTop;
-	return index >= 0 ? calc.stack[index] : '';
+	return indexFromTop >= 0 && indexFromTop < calc.stack.length ? calc.stack[indexFromTop] : '';
 }
 
 function render() {
@@ -95,10 +94,11 @@ function render() {
 	const isPortrait = window.matchMedia('(orientation: portrait)').matches || window.innerWidth <= 860;
 	calculatorEl?.classList.toggle('portrait', isPortrait);
 	calculatorEl?.classList.toggle('landscape', !isPortrait);
-	stackEls.T.textContent = calc.formatNumber(getStackLine(3)) || '';
-	stackEls.Z.textContent = calc.formatNumber(getStackLine(2)) || '';
-	stackEls.Y.textContent = calc.formatNumber(getStackLine(1)) || '';
-	stackEls.X.textContent = calc.formatNumber(getStackLine(0)) || (calc.isEditing ? calc.inputValue : '');
+	const editingValue = calc.isEditing ? calc.inputValue : '';
+	stackEls.X.textContent = calc.isEditing ? editingValue : (calc.formatNumber(getStackLine(0)) || '');
+	stackEls.Y.textContent = calc.isEditing ? (calc.formatNumber(getStackLine(0)) || '') : (calc.formatNumber(getStackLine(1)) || '');
+	stackEls.Z.textContent = calc.isEditing ? (calc.formatNumber(getStackLine(1)) || '') : (calc.formatNumber(getStackLine(2)) || '');
+	stackEls.T.textContent = calc.isEditing ? (calc.formatNumber(getStackLine(2)) || '') : (calc.formatNumber(getStackLine(3)) || '');
 	modeButton.textContent = calc.angleMode;
 }
 
@@ -129,7 +129,11 @@ function inputToX(value) {
 function execute(name) {
 	try {
 		if (name === 'enter') {
-			pushEditingValueIfNeeded();
+			if (calc.isEditing) {
+				pushEditingValueIfNeeded();
+			} else if (calc.isValidIndex(0)) {
+				calc.push(calc.stack[0]);
+			}
 		} else if (name === 'clear') {
 			calc.clear();
 			calc.inputValue = '';
@@ -143,6 +147,11 @@ function execute(name) {
 			} else {
 				calc.remove(0);
 			}
+		} else if (name === 'swap') {
+			pushEditingValueIfNeeded();
+			if (calc.isValidIndex(1)) {
+				calc.swap(0, 1);
+			}
 		} else if (name === 'neg') {
 			if (calc.isEditing) {
 				calc.inputValue = calc.inputValue.startsWith('-') ? calc.inputValue.slice(1) : `-${calc.inputValue}`;
@@ -349,7 +358,10 @@ leftButton.addEventListener('click', () => {});
 
 downButton.addEventListener('click', () => {});
 
-rightButton.addEventListener('click', () => {});
+rightButton.addEventListener('click', () => {
+	execute('swap');
+});
+
 
 window.addEventListener('keydown', handleKeyboard);
 window.addEventListener('load', focusInput);