docs: remove obsolete temporary README file

Refactor the calc-02 demo to use a single popup menu component for angle mode and constants, align the menus to their trigger buttons, and update the README/project notes to reflect the portrait-first demo layout and constant API.

.memory/project.md

@@ -1,6 +1,8 @@
-# Project memory
+# State
-
+- Core engine: `src/rpn-calculator.js`
-- RPN calculator JS project.
+- Reference demo: `samples/calc-02/` (portrait-first HP48GX layout, compact mode/constants popups; Const button comes before Mode in the display row)
-- Read `.memory/state.md` for current state.
+- Important UI behavior: mode button shows the current angle mode; keyboard focus stays on the hidden input on desktop; clipboard paste is supported
-- Keep names and commands in English.
+- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`, `listConstants`, `setConstant`, `removeConstant`, `hasConstant`
-- Update memory files based on events: engine, demo, API, commands, exports, docs, or tasks.
+- Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
+- Commands: arithmetic, stack, trigonometry, constants `pi` and `e`; arithmetic includes `root`; constants can be added or removed dynamically through the core API
+- Exports: browser `window.RpnCalculator`, CommonJS `module.exports`

.memory/state.md

@@ -1,7 +1,8 @@
 # State
 - Core engine: `src/rpn-calculator.js`
-- Active demo: `samples/dev/` (HP48-style UI)
+- Default demo: `samples/dev/` classic browser demo; `samples/calc-02/` remains the portrait-first HP48GX-inspired reference
-- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`
+- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`, `listConstants`, `setConstant`, `removeConstant`, `hasConstant`
 - Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
-- Commands: arithmetic, stack, trigonometry, constants `pi` and `e`
+- Commands: arithmetic, stack, trigonometry, constants `pi`, `e`, `phi`, `g`, and `c`; arithmetic includes `root` with `y√x`, `yroot`, and `nroot` aliases; constants can be added or removed dynamically through the core API
+- Demo behavior: `samples/dev/` keeps hidden input focus on desktop and supports clipboard paste; `samples/calc-02/` uses compact mode/constants popups, a 4-column display-adjacent row, stack selection/move mode, and paste through the hidden input
 - Exports: browser `window.RpnCalculator`, CommonJS `module.exports`

README.md

@@ -1,30 +1,28 @@
 # RPN Virtual Calculator
 
-A browser-friendly RPN calculator built around a small, generic JavaScript API.
+A browser-friendly RPN calculator built around a small JavaScript API.
 
 ## Overview
 
 This project provides:
 
 - a reusable JavaScript RPN engine in `src/rpn-calculator.js`
-- a browser demo in `samples/dev/`
+- a classic browser demo in `samples/dev/`
-- a command system centralized in a single operation dictionary
+- a portrait-first HP48GX-inspired demo in `samples/calc-02/`
-- a small public API focused on stack operations and generic command dispatch
+- a centralized command system with aliases
+- a compact public API focused on stack operations, editing, and command dispatch
 
 The main class is `RpnCalculator`.
 
 ## Project structure
 
 - `src/rpn-calculator.js`: calculator engine
-- `samples/dev/index.html`: active browser demo entry point
+- `samples/dev/index.html`: browser demo entry point
 - `samples/dev/index.css`: demo styles
 - `samples/dev/index.js`: demo UI and keyboard logic
-- `samples/calc-01/index.html`: active browser demo entry point
+- `samples/calc-02/index.html`: portrait-first HP48GX-style demo entry point
-- `samples/calc-01/index.css`: demo styles
+- `samples/calc-02/index.css`: portrait-first demo styles
-- `samples/calc-01/index.js`: demo UI and keyboard logic
+- `samples/calc-02/index.js`: portrait-first HP48GX-style demo UI and keyboard logic
-- `samples/calc-01/index.html`: alternate browser demo entry point
-- `samples/calc-01/index.css`: alternate demo styles
-- `samples/calc-01/index.js`: alternate demo UI and keyboard logic
 - `samples/calc-XX/`: placeholder name for future demo variants
 
 ## Public API
@@ -45,6 +43,10 @@ Instance helpers also available:
 
 - `getOperationsByCategory()`
 - `getConstants()`
+- `listConstants()`
+- `setConstant(name, value)`
+- `removeConstant(name)`
+- `hasConstant(name)`
 
 Static helpers also available:
 
@@ -84,6 +86,10 @@ Available constants:
 
 - `pi`
 - `e`
+- `phi`
+- `g`
+- `c`
+- plus any user-defined constants added through the engine API
 
 They can be used through `command(...)`:
 
@@ -110,6 +116,7 @@ calc.command('e');
 - `div` alias: `/`
 - `mod` alias: `%`
 - `pow` aliases: `^`, `y^x`
+- `root` aliases: `y√x`, `yroot`, `nroot`
 - `sqr`
 - `neg`
 - `sqrt` alias: `sqrt(x)`
@@ -134,6 +141,7 @@ calc.command('e');
 - `sqrt` accepts alias `sqrt(x)`
 - `recip` accepts alias `1/x`
 - `div` and `recip` throw `Division by zero` when needed
+- `root` computes the y-th root as `x^(1/y)` and throws `Invalid input for root` for invalid inputs
 - `sqrt` throws `Invalid input for sqrt` for negative values
 - `asin` and `acos` throw explicit domain errors outside `[-1, 1]`
 - `log` throws `Invalid input for log` for values `<= 0`
@@ -232,7 +240,7 @@ console.log(calc.pop()); // 0.5
 
 ## Demo
 
-The active demo lives in `samples/dev/`.
+The default demo lives in `samples/dev/`.
 
 Main UI features:
 
@@ -242,7 +250,12 @@ Main UI features:
 - angle mode selector for `deg`, `rad`, and `grad`
 - status pills for `inputValue` and `isEditing`
 - grouped panels for `Stack`, `Arithmetic`, `Trigonometry`, and `Constants`
-- error display area
+- keyboard-friendly hidden input on desktop
+
+## Calc 02 demo
+
+`samples/calc-02/` is a portrait-first HP48GX-inspired demo.
+It keeps the display-adjacent button row aligned in four columns, uses compact popup menus for mode and constants, and supports clipboard paste plus the `y√x` root operation.
 
 The demo loads the engine from:
 

_serve.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-PORT="${1:-8000}"
+PORT="${1:-3000}"
 ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
 cd "$ROOT_DIR"

samples/calc-02/index.css

@@ -0,0 +1,426 @@
+
+:root {
+	--bg0: #10151e;
+	--bg1: #1b2432;
+	--panel: #2c3442;
+	--panel2: #394354;
+	--edge: #0c1118;
+	--display: #cfe0ae;
+	--display2: #b9cd8a;
+	--displayText: #1f2a12;
+	--buttonText: #f4f7fb;
+	--shadow: rgba(0, 0, 0, 0.35);
+	--btnTop: #444c58;
+	--btnBottom: #2f3640;
+	--btnAccentTop: #3f526b;
+	--btnAccentBottom: #2b394c;
+	--btnAltTop: #525c69;
+	--btnAltBottom: #3a434f;
+	--btnDangerTop: #584042;
+	--btnDangerBottom: #402d2f;
+	--btnEscapeTop: #6a4a2a;
+	--btnEscapeBottom: #4a331d;
+	--btnEnterTop: #4f7f4d;
+	--btnEnterBottom: #355a34;
+	--btnText: #eef2f7;
+}
+
+* {
+	box-sizing: border-box;
+}
+
+html, body {
+	margin: 0;
+	min-height: 100%;
+}
+
+body {
+	min-height: 100vh;
+	font-family: Arial, sans-serif;
+	color: var(--buttonText);
+	background: var(--bg0);
+}
+
+.app-shell {
+	min-height: 100vh;
+	display: grid;
+	align-items: start;
+	justify-items: center;
+	padding: 0;
+}
+
+.calculator {
+	width: 100%;
+	height: auto;
+	display: grid;
+	padding: 8px;
+	border-radius: 8px;
+	background: var(--panel);
+	box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
+	grid-template-columns: 1fr;
+	grid-template-rows: auto auto auto auto auto;
+	row-gap: 6px;
+	grid-template-areas:
+		"display"
+		"display-buttons"
+		"keypad"
+		"functions"
+		"trigo";
+}
+
+.display-block,
+.display-panel,
+.keypad-panel,
+.functions-panel,
+.trigo-panel {
+	border-radius: 8px;
+	border: 1px solid rgba(255, 255, 255, 0.06);
+	background: rgba(6, 10, 16, 0.16);
+	box-shadow: none;
+}
+
+.display-buttons-panel {
+	border-radius: 8px;
+	border: 1px solid rgba(255, 255, 255, 0.06);
+	background: rgba(6, 10, 16, 0.16);
+	box-shadow: none;
+}
+
+.display-block {
+	grid-area: display;
+	display: grid;
+	gap: 0;
+	align-self: start;
+	justify-items: stretch;
+	grid-template-rows: auto auto;
+	row-gap: 0;
+}
+
+.display-panel {
+	position: relative;
+	width: 100%;
+	padding: 16px;
+	padding-bottom: 8px;
+	background: var(--display);
+	color: var(--displayText);
+	font-family: "Courier New", monospace;
+	overflow: hidden;
+	box-sizing: border-box;
+	height: 138px;
+	min-height: 138px;
+	max-height: 138px;
+	margin-bottom: 0;
+}
+.display-grid {
+	height: 100%;
+	display: grid;
+	grid-template-columns: 1fr;
+	grid-template-rows: repeat(4, minmax(0, auto));
+	align-content: start;
+	gap: 2px;
+}
+
+.stack-cell {
+	display: grid;
+	grid-template-columns: 2.2ch auto minmax(0, 1fr);
+	align-items: center;
+	gap: 8px;
+	font-size: 20px;
+	line-height: 1;
+	min-height: 0;
+	padding-block: 0;
+}
+
+.stack-label {
+	text-align: right;
+	opacity: 0.78;
+}
+
+.stack-value {
+	min-height: 0;
+	white-space: nowrap;
+	overflow: hidden;
+	text-overflow: ellipsis;
+	text-align: right;
+	justify-self: end;
+	font-size: 20px;
+}
+.display-buttons-panel {
+	grid-area: display-buttons;
+	padding: 8px;
+	align-self: start;
+	min-height: 0;
+}
+
+.display-buttons-grid {
+	display: grid;
+	grid-template-columns: repeat(4, minmax(0, 1fr));
+	gap: 8px;
+	align-content: start;
+	align-items: stretch;
+}
+
+.display-button-spacer {
+	pointer-events: none;
+	visibility: hidden;
+	background: transparent;
+	border-color: transparent;
+	box-shadow: none;
+}
+
+.display-button {
+	background: linear-gradient(180deg, var(--btnTop), var(--btnBottom));
+	color: #eef2f7;
+	box-shadow: none;
+}
+
+.display-button-symbol {
+	display: inline-flex;
+	align-items: center;
+	justify-content: center;
+	min-width: 1.2em;
+	font-size: 1.05em;
+	line-height: 1;
+	font-weight: 800;
+	transform: translateY(-0.01em);
+}
+
+.paste-symbol {
+	font-size: 1em;
+}
+
+.display-buttons-grid > button {
+	padding: 6px 8px;
+}
+
+.menu-popup {
+	position: fixed;
+	z-index: 20;
+	display: flex;
+	flex-direction: column;
+	gap: 4px;
+	padding: 6px;
+	border-radius: 6px;
+	background: rgba(16, 21, 30, 0.96);
+	border: 1px solid rgba(255, 255, 255, 0.12);
+	box-shadow: 0 10px 24px rgba(0, 0, 0, 0.32);
+	backdrop-filter: blur(2px);
+}
+
+.menu-popup-item {
+	width: 100%;
+	min-width: 0;
+	padding: 6px 10px;
+	border-radius: 5px;
+	background: linear-gradient(180deg, var(--btnAltTop), var(--btnAltBottom));
+	text-align: left;
+	font-weight: 700;
+}
+
+.menu-popup-item.is-active {
+	outline: 1px solid rgba(207, 224, 174, 0.7);
+	outline-offset: 0;
+}
+
+.key-escape {
+	background: linear-gradient(180deg, var(--btnEscapeTop), var(--btnEscapeBottom));
+	color: #eef2f7;
+}
+
+.keypad-panel,
+.functions-panel,
+.trigo-panel {
+	padding: 8px;
+	align-self: start;
+	min-height: 0;
+}
+
+.status-bar {
+	position: absolute;
+	top: 0;
+	left: 0;
+	right: 0;
+	z-index: 2;
+	padding: 8px 12px;
+	min-height: 30px;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	font-size: 13px;
+	font-weight: 700;
+	letter-spacing: 0.02em;
+	color: rgba(31, 42, 18, 0.96);
+	background: rgba(255, 246, 170, 0.92);
+	border-bottom: 1px solid rgba(31, 42, 18, 0.2);
+	transform: translateY(-100%);
+	opacity: 0;
+	transition: transform 180ms ease, opacity 180ms ease;
+	pointer-events: none;
+}
+
+.status-bar.is-visible {
+	transform: translateY(0);
+	opacity: 1;
+}
+
+.status-bar.is-error {
+	color: #fff;
+	background: rgba(72, 14, 14, 0.98);
+	border-bottom-color: rgba(255, 255, 255, 0.12);
+}
+
+.keypad-grid,
+.functions-grid,
+.trigo-grid {
+	display: grid;
+	gap: 8px;
+}
+
+.keypad-grid {
+	grid-template-columns: repeat(4, minmax(0, 1fr));
+	grid-template-rows: repeat(5, minmax(0, 1.7fr));
+}
+
+.functions-grid,
+.trigo-grid {
+	grid-template-columns: repeat(4, minmax(0, 1fr));
+	grid-template-rows: repeat(2, minmax(0, 1fr));
+}
+
+button {
+	border: 1px solid rgba(14, 18, 25, 0.85);
+	border-radius: 8px;
+	padding: 8px 8px;
+
+	font: inherit;
+	font-weight: 700;
+	color: var(--btnText);
+	text-shadow: 0 1px 0 rgba(0, 0, 0, 0.35);
+	cursor: pointer;
+	box-shadow: none;
+	transition: filter 120ms ease, opacity 120ms ease;
+	line-height: 1;
+}
+
+button:hover {
+	filter: brightness(1.06);
+}
+
+button:active {
+	transform: none;
+	box-shadow: none;
+}
+
+.stack-copy-button:active {
+	animation: stack-copy-flash 140ms ease-out;
+}
+
+@keyframes stack-copy-flash {
+	0% {
+		opacity: 0.7;
+	}
+	50% {
+		opacity: 1;
+	}
+	100% {
+		opacity: 0.7;
+	}
+}
+.stack-copy-button {
+	padding: 4px;
+	min-width: 24px;
+	width: 24px;
+	height: 24px;
+	display: inline-grid;
+	place-items: center;
+	opacity: 0;
+	pointer-events: none;
+	transform: scale(1);
+	background: transparent;
+	border: none;
+	box-shadow: none;
+	color: rgba(31, 42, 18, 0.58);
+	margin-left: 0;
+}
+
+.stack-cell:last-child {
+	margin-bottom: 4px;
+}
+
+.stack-copy-button svg {
+	width: 15px;
+	height: 15px;
+	fill: #0a0a0a;
+	display: block;
+}
+
+.stack-copy-button.is-visible {
+	opacity: 0.7;
+	pointer-events: auto;
+	transform: scale(1);
+}
+
+.stack-copy-button:hover {
+	opacity: 1;
+	filter: none;
+	color: rgba(31, 42, 18, 0.85);
+}
+
+.stack-copy-button:active {
+	transform: scale(1);
+	color: rgba(31, 42, 18, 0.95);
+}
+
+.stack-copy-button:focus-visible {
+	outline: 1px solid rgba(31, 42, 18, 0.35);
+	outline-offset: 2px;
+}
+
+.key-default {
+	background: linear-gradient(180deg, var(--btnTop), var(--btnBottom));
+	color: #eef2f7;
+}
+
+.keypad-grid > button {
+	min-height: 1.7em;
+}
+
+#keypadGrid > button {
+	min-height: calc(1.7em * 1.7);
+	padding-top: calc(8px * 1.7);
+	padding-bottom: calc(8px * 1.7);
+}
+
+#keypadGrid > button.key-default,
+#keypadGrid > button.key-accent,
+#keypadGrid > button.key-danger,
+#keypadGrid > button.key-enter {
+	min-height: calc(1.7em * 1.7);
+}
+
+.key-accent {
+	background: linear-gradient(180deg, var(--btnAccentTop), var(--btnAccentBottom));
+	color: #eef2f7;
+}
+
+.key-danger {
+	background: linear-gradient(180deg, var(--btnDangerTop), var(--btnDangerBottom));
+	color: #eef2f7;
+}
+
+.key-enter {
+	background: linear-gradient(180deg, var(--btnEnterTop), var(--btnEnterBottom));
+	color: #eef2f7;
+	padding-inline: 6px;
+}
+
+.hidden-input {
+	position: absolute;
+	left: -9999px;
+	width: 1px;
+	height: 1px;
+	opacity: 0;
+	pointer-events: none;
+}
+
+

samples/calc-02/index.html

@@ -0,0 +1,58 @@
+<!doctype html>
+<html lang="en">
+<head>
+	<meta charset="utf-8">
+	<meta name="viewport" content="width=device-width, initial-scale=1">
+	<title>HP48GX RPN Calculator</title>
+	<link rel="stylesheet" href="./index.css">
+</head>
+<body>
+	<main class="app-shell">
+		<section class="calculator calculator-portrait" aria-label="HP48GX style RPN calculator">
+			<div class="display-block">
+				<div class="display-panel">
+					<div class="status-bar" id="statusLine" aria-live="polite"></div>
+					<div class="display-frame">
+						<div class="display-grid">
+							<div class="stack-cell"><span class="stack-label">T:</span><button type="button" class="stack-copy-button" data-copy-stack="T" aria-label="Copy T value"><svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M15.5 4h-7A2.5 2.5 0 0 0 6 6.5V8H5.5A1.5 1.5 0 0 0 4 9.5v8A2.5 2.5 0 0 0 6.5 20H13a1 1 0 0 0 1-1v-1.5H17.5A2.5 2.5 0 0 0 20 15V6.5A2.5 2.5 0 0 0 17.5 4h-2Zm.5 2h1.5a.5.5 0 0 1 .5.5V14a.5.5 0 0 1-.5.5H13V6.5A2.5 2.5 0 0 0 15.5 6Zm-1.5 12H6.5a.5.5 0 0 1-.5-.5v-8a.5.5 0 0 1 .5-.5h7.5V18Zm-1.5-8h-4V8.5A.5.5 0 0 1 9 8h4a.5.5 0 0 1 .5.5V10Z"/></svg></button><span id="stackT" class="stack-value"></span></div>
+							<div class="stack-cell"><span class="stack-label">Z:</span><button type="button" class="stack-copy-button" data-copy-stack="Z" aria-label="Copy Z value"><svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M15.5 4h-7A2.5 2.5 0 0 0 6 6.5V8H5.5A1.5 1.5 0 0 0 4 9.5v8A2.5 2.5 0 0 0 6.5 20H13a1 1 0 0 0 1-1v-1.5H17.5A2.5 2.5 0 0 0 20 15V6.5A2.5 2.5 0 0 0 17.5 4h-2Zm.5 2h1.5a.5.5 0 0 1 .5.5V14a.5.5 0 0 1-.5.5H13V6.5A2.5 2.5 0 0 0 15.5 6Zm-1.5 12H6.5a.5.5 0 0 1-.5-.5v-8a.5.5 0 0 1 .5-.5h7.5V18Zm-1.5-8h-4V8.5A.5.5 0 0 1 9 8h4a.5.5 0 0 1 .5.5V10Z"/></svg></button><span id="stackZ" class="stack-value"></span></div>
+							<div class="stack-cell"><span class="stack-label">Y:</span><button type="button" class="stack-copy-button" data-copy-stack="Y" aria-label="Copy Y value"><svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M15.5 4h-7A2.5 2.5 0 0 0 6 6.5V8H5.5A1.5 1.5 0 0 0 4 9.5v8A2.5 2.5 0 0 0 6.5 20H13a1 1 0 0 0 1-1v-1.5H17.5A2.5 2.5 0 0 0 20 15V6.5A2.5 2.5 0 0 0 17.5 4h-2Zm.5 2h1.5a.5.5 0 0 1 .5.5V14a.5.5 0 0 1-.5.5H13V6.5A2.5 2.5 0 0 0 15.5 6Zm-1.5 12H6.5a.5.5 0 0 1-.5-.5v-8a.5.5 0 0 1 .5-.5h7.5V18Zm-1.5-8h-4V8.5A.5.5 0 0 1 9 8h4a.5.5 0 0 1 .5.5V10Z"/></svg></button><span id="stackY" class="stack-value"></span></div>
+							<div class="stack-cell"><span class="stack-label">X:</span><button type="button" class="stack-copy-button" data-copy-stack="X" aria-label="Copy X value"><svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M15.5 4h-7A2.5 2.5 0 0 0 6 6.5V8H5.5A1.5 1.5 0 0 0 4 9.5v8A2.5 2.5 0 0 0 6.5 20H13a1 1 0 0 0 1-1v-1.5H17.5A2.5 2.5 0 0 0 20 15V6.5A2.5 2.5 0 0 0 17.5 4h-2Zm.5 2h1.5a.5.5 0 0 1 .5.5V14a.5.5 0 0 1-.5.5H13V6.5A2.5 2.5 0 0 0 15.5 6Zm-1.5 12H6.5a.5.5 0 0 1-.5-.5v-8a.5.5 0 0 1 .5-.5h7.5V18Zm-1.5-8h-4V8.5A.5.5 0 0 1 9 8h4a.5.5 0 0 1 .5.5V10Z"/></svg></button><span id="stackX" class="stack-value"></span></div>
+						</div>
+					</div>
+				</div>
+			</div>
+
+			<div class="display-buttons-panel">
+				<div class="display-buttons-grid">
+					<button id="constButton" class="display-button">π</button>
+					<button id="pasteButton" class="display-button"><span class="display-button-symbol paste-symbol">⎘</span></button>
+					<button id="upButton" class="display-button"><span class="display-button-symbol arrow-symbol">↑</span></button>
+					<button id="modeButton" class="display-button">Mode</button>
+					<div class="display-button-spacer"></div>
+					<button id="leftButton" class="display-button display-button-offset"><span class="display-button-symbol arrow-symbol">←</span></button>
+					<button id="downButton" class="display-button"><span class="display-button-symbol arrow-symbol">↓</span></button>
+					<button id="rightButton" class="display-button"><span class="display-button-symbol arrow-symbol">→</span></button>
+				</div>
+			</div>
+			
+			<div class="keypad-panel">
+				<div class="keypad-grid" id="keypadGrid"></div>
+			</div>
+
+			<div class="functions-panel">
+				<div class="functions-grid" id="functionsGrid"></div>
+			</div>
+
+			<div class="trigo-panel">
+				<div class="trigo-grid" id="trigoGrid"></div>
+			</div>
+
+			<input id="hiddenInput" class="hidden-input" type="text" autocomplete="off" aria-hidden="true" tabindex="-1">
+		</section>
+	</main>
+
+	<script src="../../src/rpn-calculator.js"></script>
+	<script src="./index.js"></script>
+</body>
+</html>

samples/calc-02/index.js

@@ -0,0 +1,521 @@
+const calc = new RpnCalculator({ angleMode: 'deg' });
+
+const hiddenInput = document.getElementById('hiddenInput');
+const modeButton = document.getElementById('modeButton');
+const pasteButton = document.getElementById('pasteButton');
+const upButton = document.getElementById('upButton');
+const constButton = document.getElementById('constButton');
+const leftButton = document.getElementById('leftButton');
+const downButton = document.getElementById('downButton');
+const rightButton = document.getElementById('rightButton');
+
+const stackEls = {
+	T: document.getElementById('stackT'),
+	Z: document.getElementById('stackZ'),
+	Y: document.getElementById('stackY'),
+	X: document.getElementById('stackX'),
+};
+
+const stackCopyButtons = {
+	T: document.querySelector('[data-copy-stack="T"]'),
+	Z: document.querySelector('[data-copy-stack="Z"]'),
+	Y: document.querySelector('[data-copy-stack="Y"]'),
+	X: document.querySelector('[data-copy-stack="X"]'),
+};
+
+const keypadGrid = document.getElementById('keypadGrid');
+const functionsGrid = document.getElementById('functionsGrid');
+const trigoGrid = document.getElementById('trigoGrid');
+const calculatorEl = document.querySelector('.calculator');
+const statusLine = document.getElementById('statusLine');
+
+const keypadKeys = [
+	{ label: 'ENTER', action: 'enter', className: 'key-enter' },
+	{ label: '⎋', action: 'escape', className: 'key-escape' },
+	{ label: 'C', action: 'clear', className: 'key-danger' },
+	{ label: '⌫', action: 'backspace', className: 'key-danger' },
+	{ label: '7', input: '7', className: 'key-default' },
+	{ label: '8', input: '8', className: 'key-default' },
+	{ label: '9', input: '9', className: 'key-default' },
+	{ label: '÷', action: 'div', className: 'key-accent' },
+	{ label: '4', input: '4', className: 'key-default' },
+	{ label: '5', input: '5', className: 'key-default' },
+	{ label: '6', input: '6', className: 'key-default' },
+	{ label: '×', action: 'mul', className: 'key-accent' },
+	{ label: '1', input: '1', className: 'key-default' },
+	{ label: '2', input: '2', className: 'key-default' },
+	{ label: '3', input: '3', className: 'key-default' },
+	{ label: '−', action: 'sub', className: 'key-accent' },
+	{ label: '0', input: '0', className: 'key-default' },
+	{ label: '.', input: '.', className: 'key-default' },
+	{ label: '±', action: 'neg', className: 'key-default' },
+	{ label: '+', action: 'add', className: 'key-accent' },
+];
+
+const functionKeys = [
+	{ label: 'x²', action: 'sqr', className: 'key-default' },
+	{ label: 'yˣ', action: 'pow', className: 'key-default' },
+	{ label: '1/x', action: 'recip', className: 'key-default' },
+	{ label: '%', action: 'mod', className: 'key-default' },
+	{ label: '√x', action: 'sqrt', className: 'key-default' },
+	{ label: 'y√x', action: 'root', className: 'key-default' },
+	{ label: '10ˣ', action: 'pow10', className: 'key-default' },
+	{ label: '', spacer: true },
+	{ label: 'log', action: 'log', className: 'key-default' },
+	{ label: 'ln', action: 'ln', className: 'key-default' },
+	{ label: 'eˣ', action: 'exp', className: 'key-default' },
+	{ label: '', spacer: true },
+];
+
+const trigoKeys = [
+	{ label: 'sin', action: 'sin', className: 'key-default' },
+	{ label: 'cos', action: 'cos', className: 'key-default' },
+	{ label: 'tan', action: 'tan', className: 'key-default' },
+	{ label: '', spacer: true },
+	{ label: 'asin', action: 'asin', className: 'key-default' },
+	{ label: 'acos', action: 'acos', className: 'key-default' },
+	{ label: 'atan', action: 'atan', className: 'key-default' },
+	{ label: '', spacer: true },
+];
+
+const isTouchDevice = window.matchMedia('(pointer: coarse)').matches || 'ontouchstart' in window;
+
+function focusInput() {
+	if (!hiddenInput || isTouchDevice) return;
+	hiddenInput.focus({ preventScroll: true });
+	window.requestAnimationFrame(() => {
+		if (document.activeElement !== hiddenInput) {
+			hiddenInput.focus({ preventScroll: true });
+		}
+		if (typeof hiddenInput.select === 'function') {
+			hiddenInput.select();
+		}
+	});
+}
+
+let statusTimer = null;
+
+function setStatus(message, isError = false, timeoutMs = 1400) {
+	if (!statusLine) return;
+	clearTimeout(statusTimer);
+	statusLine.textContent = message;
+	statusLine.classList.toggle('is-error', isError);
+	statusLine.classList.toggle('is-visible', Boolean(message));
+	if (!message || timeoutMs <= 0) return;
+	statusTimer = window.setTimeout(() => {
+		statusLine.textContent = '';
+		statusLine.classList.remove('is-visible');
+		statusLine.classList.remove('is-error');
+	}, timeoutMs);
+}
+
+function clearStatus() {
+	clearTimeout(statusTimer);
+	statusTimer = null;
+	if (!statusLine) return;
+	statusLine.textContent = '';
+	statusLine.classList.remove('is-visible');
+	statusLine.classList.remove('is-error');
+}
+
+function normalizeStack() {
+	while (calc.stack.length > 4) {
+		calc.stack.shift();
+	}
+}
+
+function getStackLine(indexFromTop) {
+	return indexFromTop >= 0 && indexFromTop < calc.stack.length ? calc.stack[indexFromTop] : '';
+}
+
+function getStackDisplayValue(label) {
+	if (label === 'X') {
+		return calc.isEditing ? calc.inputValue : (calc.formatNumber(getStackLine(0)) || '');
+	}
+	if (label === 'Y') {
+		return calc.isEditing ? (calc.formatNumber(getStackLine(0)) || '') : (calc.formatNumber(getStackLine(1)) || '');
+	}
+	if (label === 'Z') {
+		return calc.isEditing ? (calc.formatNumber(getStackLine(1)) || '') : (calc.formatNumber(getStackLine(2)) || '');
+	}
+	return calc.isEditing ? (calc.formatNumber(getStackLine(2)) || '') : (calc.formatNumber(getStackLine(3)) || '');
+}
+
+function updateCopyButtons() {
+	for (const label of ['T', 'Z', 'Y', 'X']) {
+		const value = getStackDisplayValue(label);
+		const button = stackCopyButtons[label];
+		if (!button) continue;
+		button.classList.toggle('is-visible', Boolean(value));
+		button.disabled = !value;
+		button.setAttribute('aria-hidden', value ? 'false' : 'true');
+	}
+}
+
+function render() {
+	normalizeStack();
+	const isPortrait = window.matchMedia('(orientation: portrait)').matches || window.innerWidth <= 860;
+	calculatorEl?.classList.toggle('portrait', isPortrait);
+	calculatorEl?.classList.toggle('landscape', !isPortrait);
+	stackEls.X.textContent = getStackDisplayValue('X');
+	stackEls.Y.textContent = getStackDisplayValue('Y');
+	stackEls.Z.textContent = getStackDisplayValue('Z');
+	stackEls.T.textContent = getStackDisplayValue('T');
+	updateCopyButtons();
+	modeButton.textContent = calc.angleMode;
+}
+
+function pushEditingValueIfNeeded() {
+	if (!calc.isEditing) return;
+	if (calc.inputValue !== '') {
+		calc.push(calc.parseInputValue(calc.inputValue));
+	}
+	calc.inputValue = '';
+	calc.isEditing = false;
+}
+
+function inputToX(value) {
+	if (!calc.isEditing) {
+		calc.isEditing = true;
+		calc.inputValue = '';
+	}
+	if (value === 'Backspace') {
+		calc.inputValue = calc.inputValue.slice(0, -1);
+	} else {
+		calc.inputValue += value;
+	}
+	if (calc.inputValue === '') {
+		calc.isEditing = false;
+	}
+}
+
+function pasteTextIntoStack(text) {
+	if (!text) {
+		setStatus('Clipboard empty');
+		return;
+	}
+	const value = calc.parseInputValue(text);
+	if (!Number.isFinite(value)) {
+		setStatus('Clipboard is not a number');
+		return;
+	}
+	pushEditingValueIfNeeded();
+	calc.push(value);
+	calc.isEditing = false;
+	calc.inputValue = '';
+	setStatus('Pasted');
+	render();
+}
+
+function execute(name) {
+	try {
+		if (name === 'enter') {
+			if (calc.isEditing) {
+				pushEditingValueIfNeeded();
+			} else if (calc.isValidIndex(0)) {
+				calc.push(calc.stack[0]);
+			}
+		} else if (name === 'clear') {
+			calc.clear();
+			calc.inputValue = '';
+			calc.isEditing = false;
+		} else if (name === 'escape') {
+			calc.inputValue = '';
+			calc.isEditing = false;
+		} else if (name === 'backspace') {
+			if (calc.isEditing) {
+				inputToX('Backspace');
+			} else if (calc.isValidIndex(0)) {
+				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) : `-${calc.inputValue}`;
+			} else {
+				calc.push(calc.pop() * -1);
+			}
+		} else if (name === 'pow10') {
+			pushEditingValueIfNeeded();
+			const exponent = calc.stack[0];
+			calc.remove(0);
+			calc.push(10);
+			calc.push(exponent);
+			calc.command('pow');
+		} else if (name === 'exp') {
+			pushEditingValueIfNeeded();
+			const exponent = calc.stack[0];
+			calc.remove(0);
+			calc.push(Math.E);
+			calc.push(exponent);
+			calc.command('pow');
+		} else {
+			pushEditingValueIfNeeded();
+			calc.command(name);
+		}
+		render();
+	} catch (error) {
+		setStatus(error?.message || 'Operation error', true);
+	}
+}
+
+function createKeyButton({ label, input, action, spacer, className }) {
+	if (spacer) {
+		const div = document.createElement('div');
+		return div;
+	}
+	const button = document.createElement('button');
+	button.type = 'button';
+	button.textContent = label;
+	button.className = className;
+	button.addEventListener('click', () => {
+		if (input) {
+			inputToX(input);
+			render();
+			return;
+		}
+		execute(action);
+	});
+	return button;
+}
+
+function buildGrid(container, keys) {
+	container.innerHTML = '';
+	keys.forEach((key) => container.appendChild(createKeyButton(key)));
+}
+
+async function copyStackValue(label) {
+	const value = getStackDisplayValue(label);
+	if (!value) return;
+	try {
+		await navigator.clipboard.writeText(value);
+		clearStatus();
+	} catch (error) {
+		setStatus('Copy unavailable', true);
+	}
+}
+
+function handleKeyboard(event) {
+	if (event.defaultPrevented) return;
+	const key = event.key;
+	if (/^[0-9.]$/.test(key)) {
+		event.preventDefault();
+		inputToX(key);
+		render();
+		return;
+	}
+	const map = {
+		Enter: 'enter',
+		Backspace: 'backspace',
+		Escape: 'escape',
+		Delete: 'clear',
+		'+': 'add',
+		'-': 'sub',
+		'*': 'mul',
+		'/': 'div',
+		'%': 'mod',
+		'^': 'pow',
+	};
+	const arrowMap = {
+		ArrowUp: upButton,
+		ArrowDown: downButton,
+		ArrowLeft: leftButton,
+		ArrowRight: rightButton,
+	};
+	if (arrowMap[key]) {
+		event.preventDefault();
+		arrowMap[key].click();
+		return;
+	}
+	if (map[key]) {
+		event.preventDefault();
+		execute(map[key]);
+	}
+}
+
+const modeOptions = ['deg', 'rad', 'grad'];
+let activeMenuEl = null;
+
+function closeModeMenu() {
+	if (activeMenuEl) {
+		activeMenuEl.remove();
+		activeMenuEl = null;
+	}
+}
+
+function openMenu(anchorButton, items, onSelect) {
+	const rect = anchorButton.getBoundingClientRect();
+	const menu = document.createElement('div');
+	menu.className = 'menu-popup';
+	menu.style.top = `${rect.bottom + 6 + window.scrollY}px`;
+	menu.style.left = `${rect.left + window.scrollX}px`;
+	menu.style.minWidth = `${rect.width}px`;
+	for (const item of items) {
+		const button = document.createElement('button');
+		button.type = 'button';
+		button.className = `menu-popup-item${item.active ? ' is-active' : ''}`;
+		button.textContent = item.label;
+		button.addEventListener('click', () => onSelect(item.value));
+		menu.appendChild(button);
+	}
+	document.body.appendChild(menu);
+	return menu;
+}
+
+function toggleModeMenu() {
+	if (activeMenuEl) {
+		closeModeMenu();
+		return;
+	}
+	closeConstMenu();
+	activeMenuEl = openMenu(modeButton, modeOptions.map((mode) => ({
+		label: mode,
+		value: mode,
+		active: mode === calc.angleMode,
+	})), (mode) => {
+		calc.angleMode = mode;
+		render();
+		closeModeMenu();
+	});
+}
+
+modeButton.addEventListener('click', (event) => {
+	event.stopPropagation();
+	toggleModeMenu();
+});
+
+window.addEventListener('resize', () => {
+	closeModeMenu();
+	closeConstMenu();
+	render();
+});
+window.addEventListener('scroll', () => {
+	closeModeMenu();
+	closeConstMenu();
+}, true);
+
+window.addEventListener('click', (event) => {
+	const stackCopyButton = event.target.closest('.stack-copy-button');
+	if (stackCopyButton) {
+		const label = stackCopyButton.dataset.copyStack;
+		if (label) copyStackValue(label);
+		return;
+	}
+	if (activeMenuEl && !event.target.closest('.menu-popup') && event.target !== modeButton && event.target !== constButton) {
+		closeModeMenu();
+		closeConstMenu();
+	}
+});
+
+pasteButton.addEventListener('click', async () => {
+	try {
+		const text = await navigator.clipboard.readText();
+		pasteTextIntoStack(text);
+		clearStatus();
+	} catch (error) {
+		setStatus('Paste unavailable', true);
+	}
+});
+
+hiddenInput.addEventListener('paste', (event) => {
+	event.preventDefault();
+	const text = event.clipboardData?.getData('text') ?? '';
+	pasteTextIntoStack(text);
+});
+
+upButton.addEventListener('click', () => {});
+
+const constantLabels = {
+	pi: 'π',
+	e: 'e',
+	phi: 'φ',
+	g: 'g',
+	c: 'c',
+};
+const constantOrder = ['pi', 'e', 'phi', 'g', 'c'];
+
+
+function closeConstMenu() {
+	if (activeMenuEl) {
+		activeMenuEl.remove();
+		activeMenuEl = null;
+	}
+}
+
+function toggleConstMenu() {
+	if (activeMenuEl) {
+		closeConstMenu();
+		return;
+	}
+	closeModeMenu();
+	const availableConstants = calc.listConstants();
+	const keys = [...constantOrder, ...Object.keys(availableConstants).filter((name) => !constantOrder.includes(name))]
+		.filter((name) => Object.prototype.hasOwnProperty.call(availableConstants, name));
+	activeMenuEl = openMenu(constButton, keys.map((name) => ({
+		label: constantLabels[name] ?? name,
+		value: name,
+	})), (name) => {
+		pushEditingValueIfNeeded();
+		calc.push(availableConstants[name]);
+		render();
+		clearStatus();
+		closeConstMenu();
+		focusInput();
+	});
+}
+
+constButton.addEventListener('click', (event) => {
+	event.stopPropagation();
+	toggleConstMenu();
+});
+
+leftButton.addEventListener('click', () => {});
+downButton.addEventListener('click', () => {
+	if (!calc.isEditing && calc.isValidIndex(0)) {
+		const value = calc.stack[0];
+		calc.remove(0);
+		calc.isEditing = true;
+		calc.inputValue = calc.formatNumber(value);
+		render();
+		focusInput();
+	}
+});
+
+rightButton.addEventListener('click', () => {
+	execute('swap');
+});
+
+window.addEventListener('keydown', handleKeyboard, { capture: true });
+window.addEventListener('load', focusInput);
+window.addEventListener('pageshow', focusInput);
+window.addEventListener('focus', focusInput);
+window.addEventListener('pointerdown', focusInput, true);
+window.addEventListener('mousedown', focusInput, true);
+
+hiddenInput.setAttribute('inputmode', 'none');
+hiddenInput.setAttribute('readonly', 'readonly');
+hiddenInput.addEventListener('focus', () => {
+	if (isTouchDevice) {
+		hiddenInput.blur();
+		return;
+	}
+	window.requestAnimationFrame(() => {
+		hiddenInput.select();
+	});
+});
+
+document.addEventListener('click', (event) => {
+	if (!isTouchDevice && !event.target.closest('.menu-popup')) {
+		focusInput();
+	}
+});
+
+buildGrid(keypadGrid, keypadKeys);
+buildGrid(functionsGrid, functionKeys);
+buildGrid(trigoGrid, trigoKeys);
+render();
+focusInput();

samples/calc-02/visual-portrait.md

@@ -0,0 +1,52 @@
+# Calc 02 Visual Portrait
+
+## Display
+
+```
+┌──────────── Display ────────────┐
+| T:                              |
+| Z:                              |
+| Y:                              |
+| X:                              |
+└─────────────────────────────────┘
+```
+
+## Display Buttons
+
+```
+┌──────── Display Buttons ────────┐
+| Const | Paste  | Up    | Mode   |
+|       | Left   | Down  | Right  |
+└─────────────────────────────────┘
+```
+
+## Keypad
+
+```
+┌──────────── Keypad ─────────────┐
+| +/- | Clear | Esc   | backspace |
+| 7   | 8     | 9     | /         |
+| 4   | 5     | 6     | *         |
+| 1   | 2     | 3     | -         |
+| 0   | .     | Enter | +         |
+└─────────────────────────────────┘
+```
+
+## Functions
+
+```
+┌──────────── Functions ──────────┐
+| x^2  | y^x   | 1/x   | %        |
+| √x   | y√x   | 10^x  |          |
+| log  | ln    |       |          |
+└─────────────────────────────────┘
+```
+
+## Trigo
+
+```
+┌──────────── Trigo ──────────────┐
+| sin  | cos   | tan   |          |
+| asin | acos  | atan  |          |
+└─────────────────────────────────┘
+```

src/rpn-calculator.js

@@ -2,6 +2,9 @@ class RpnCalculator {
   static CONSTANTS = {
     pi: Math.PI,
     e: Math.E,
+    phi: (1 + Math.sqrt(5)) / 2,
+    g: 9.80665,
+    c: 299792458,
   };
 
   static OPERATIONS = {
@@ -46,6 +49,20 @@ class RpnCalculator {
       aliases: ['^', 'y^x'],
       execute: (calc, a, b) => Math.pow(a, b),
     },
+    root: {
+      category: 'Arithmetic',
+      argCount: 2,
+      aliases: ['y√x', 'yroot', 'nroot'],
+      execute: (calc, a, b) => {
+        if (b === 0) {
+          throw new Error('Invalid input for root');
+        }
+        if (a < 0 && b % 2 === 0) {
+          throw new Error('Invalid input for root');
+        }
+        return Math.pow(a, 1 / b);
+      },
+    },
     sqr: {
       category: 'Arithmetic',
       argCount: 1,
@@ -178,7 +195,7 @@ class RpnCalculator {
   static getOperationsByCategory() {
     return {
       Stack: ['dup', 'drop', 'swap', 'clear', 'enter'],
-      Arithmetic: ['add', 'sub', 'mul', 'div', 'mod', 'pow', 'sqr', 'neg', 'sqrt', 'recip', 'log', 'ln'],
+      Arithmetic: ['add', 'sub', 'mul', 'div', 'mod', 'pow', 'root', 'sqr', 'neg', 'sqrt', 'recip', 'log', 'ln'],
       Trigonometry: ['sin', 'cos', 'tan', 'asin', 'acos', 'atan'],
     };
   }
@@ -198,6 +215,15 @@ class RpnCalculator {
     this.enabledCommands = new Set(selectedCommands.map((name) => this.normalizeCommandName(name)).filter((name) => RpnCalculator.OPERATIONS[name]));
   }
 
+  static isValidConstantName(name) {
+    return typeof name === 'string' && name.trim() !== '';
+  }
+
+  static isReservedName(name) {
+    const normalized = typeof name === 'string' ? name.toLowerCase() : '';
+    return Boolean(RpnCalculator.OPERATIONS[normalized]);
+  }
+
   toRadians(value) {
     if (this.angleMode === 'grad') {
       return (value * Math.PI) / 200;
@@ -243,6 +269,45 @@ class RpnCalculator {
     return typeof name === 'string' && Object.prototype.hasOwnProperty.call(this.constants, name.toLowerCase());
   }
 
+  setConstant(name, value) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      throw new Error('Invalid constant name');
+    }
+    if (!Number.isFinite(value)) {
+      throw new Error('Invalid constant value');
+    }
+
+    const normalized = name.trim().toLowerCase();
+    if (RpnCalculator.isReservedName(normalized)) {
+      throw new Error(`Constant name conflicts with a command: ${name}`);
+    }
+
+    this.constants[normalized] = value;
+    return value;
+  }
+
+  removeConstant(name) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      throw new Error('Invalid constant name');
+    }
+
+    const normalized = name.trim().toLowerCase();
+    if (!this.isConstantName(normalized)) {
+      return false;
+    }
+
+    delete this.constants[normalized];
+    return true;
+  }
+
+  hasConstant(name) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      return false;
+    }
+
+    return this.isConstantName(name.trim().toLowerCase());
+  }
+
   push(value) {
     if (this.stack.length >= this.maxSize) {
       throw new Error('Stack overflow');
@@ -394,6 +459,10 @@ class RpnCalculator {
   getConstants() {
     return { ...this.constants };
   }
+
+  listConstants() {
+    return this.getConstants();
+  }
 }
 
 if (typeof window !== 'undefined') {