# Komponenten: Rechner

```
Display (S01)
  expression  right aligned, expr 72sp shrinking to expr-min as it grows, then scrolls horizontally; cursor; selectable (long press → S04)
  result      live preview below (result 36sp, muted); on "=" it animates up into the expression
  states      empty (blinking cursor), typing, final, error (error colour, message), overflow (scroll)
  tokens      display bg, radius display at the bottom corners, drag handle 32×4 at the bottom edge

FunctionRow (S01) / ScientificPanel (S02)
  collapsed   √ π ^ ! as text keys + chevron button (circle)
  expanded    tonal pills: √ π ^ ! / Deg|Rad sin cos tan / Inv e ln log; Inv toggles labels (sin⁻¹ cos⁻¹ tan⁻¹ / eˣ 10ˣ x²)
  motion      expand with the keypad sliding down (sheet spring)

Key
  variants    digit, op (÷ × − +, ( ), %), ac, eq, fn
  shape       circle at rest → squircle (key-pressed radius) while pressed, spring back; haptic KEYBOARD_TAP
  a11y        content descriptions in words ("geteilt durch", "Klammer", "Wurzel"), backspace long-press = clear

HistorySheet (S03)
  pull the display down (or ⏱ button) to reveal; groups by day ("Heute", "Gestern", date); row = expression muted + result large, right aligned;
  tap inserts the result; "Aktuelle Eingabe" label above the live expression; empty state text; clear in the overflow menu

ContextMenu (S04)
  floating pill: Ausschneiden, Kopieren, Einfügen, MS, MR (when memory set)
```