# Project rules — RPN Virtual Calculator

- Build a browser-friendly RPN calculator as a JavaScript class, preferably in a single file.
- Keep code names, categories, and API identifiers in English.
- Use only read-only / generic public API methods: `push`, `pop`, `clear`, `swap(index1, index2)`, `remove(index)`, `edit(index)`, `isValidIndex(index)`, `input(command)`, and `command(name, ...args)`.
- Expose `inputValue` as a string and `isEditing` as a boolean.
- Constructor options:
  - `maxSize` (default `2048`)
  - `base` (default `10`)
  - `angleMode` (`deg` default; also `rad` and `grad`)
  - `enabledCommands`
- Available constants: `pi`, `e`.
- Supported operations must be centralized in one dictionary containing at least:
  - `argCount`
  - `category`
  - `aliases`
- Allowed categories are limited to: `Stack`, `Arithmetic`, and `Trigonometry`.

## Supported commands

- Current commands:
  - `add`, `sub`, `mul`, `div`, `mod`, `pow`, `sqr`, `neg`, `sqrt`, `recip`,
    `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `log`, `ln`,
    `dup`, `drop`, `swap`, `clear`, `enter`
- Aliases:
  - `+`, `-`, `*`, `/`, `%`, `^`, `y^x`, `1/x`

## Behavior rules

- `mod` is the percentage operator: `a b % => (a * b) / 100`
- `sqrt`, `asin`, `acos`, `log`, and `ln` must throw clear, explicit domain errors
- `log` uses `Math.log10`
- `ln` uses `Math.log`
- Trigonometric functions use degrees in the demo:
  - `sin`, `cos`, `tan` convert degrees to radians
  - inverse trig functions return degrees
- `inputValue` must remain a string to preserve future hexadecimal input support
- The example HTML must group buttons by `Stack`, `Arithmetic`, and `Trigonometry`
- The example HTML must call `command(...)` for actions

## Maintenance

- Keep this file updated after each project change using the provided editing tools.