replica(rechner): recon, feature matrix, reference screenshots

Co-Authored-By: Claude Opus 5.5 <[email protected]>

replica/rechner/features.csv

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+feature,area,priority,original,clone,notes
+Basic arithmetic + − × ÷,core,must,yes,no,
+Live result preview while typing,core,must,yes,no,
+Equals makes the result the new expression,core,must,yes,no,
+Parentheses smart toggle key,core,must,yes,no,
+Percent,core,must,yes,no,
+Backspace and long-press to clear,core,must,yes,no,
+AC clears,core,must,yes,no,
+Exact arithmetic (no floating point errors),core,must,yes,no,BigDecimal/rational
+Errors shown (division by zero domain errors),core,must,yes,no,
+Auto-shrinking display for long input,display,must,yes,no,
+Scientific row √ π ^ !,science,must,yes,no,
+Expanded panel sin cos tan ln log e,science,must,yes,no,
+Deg/Rad switch,science,must,yes,no,
+Inv swaps to inverse functions,science,must,yes,no,
+Implicit multiplication (2π 3(4)),core,should,yes,no,
+History grouped by day,history,must,yes,no,
+Tap a history entry to reuse,history,must,yes,no,
+Clear history,history,should,yes,no,
+Pull down the display to open history,history,should,yes,no,
+Copy result / paste into expression,clipboard,must,yes,no,
+Memory store and recall (MS MR),clipboard,should,yes,no,
+Big numbers like 100! with scrolling,core,should,yes,no,
+Locale decimal separator,display,should,yes,no,comma in German
+Expressive keys with press morph,design,must,yes,no,
+Dynamic colour (wallpaper) and dark mode,design,must,yes,no,
+Haptic key feedback,design,should,yes,no,
+Tablet / landscape layout with all functions,layout,could,yes,no,
+Feedback and help,other,could,yes,skip,Google service

replica/rechner/recon.md

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+# Recon map: Google Calculator / Pixel Calculator (Android)
+
+Scope: the whole app: keypad, scientific functions, live result, history, memory, copy/paste, settings
+For: personal use, a calculator without Google services (project NoGooleApps)
+Date: 2026-10-17
+
+## Sources
+
+| # | source | URL | notes |
+| --- | --- | --- | --- |
+| 1 | app store listing | https://play.google.com/store/apps/details?id=com.google.android.calculator | page did not load via fetch; listing images supplied by the user (ref-01..03) |
+| 2 | screenshots | replica/rechner/screens/ref-01..07.png | supplied by user: history with "Current expression" sheet and MS/Copy menu (ref-01, -02, -06), scientific panel open (ref-03), launcher icon (ref-04), selection with Cut/Copy/MS (ref-05), empty dark state with Material You colours (ref-07). Reference only, never shipped |
+| 3 | general knowledge of the app as a user | – | precise arithmetic (no 0.1+0.2 errors), very long results scroll, Deg/Rad, Inv swaps functions |
+
+## Core loop
+
+Type a calculation and see the result update live, then tap = to make it the new start value.
+
+## Screens
+
+| ID | screen | how to reach | purpose | key components | states seen |
+| --- | --- | --- | --- | --- | --- |
+| S01 | Calculator | launch | type and evaluate | display (expression + live result, right aligned, auto-shrinking font), scientific row (√ π ^ !) with expand chevron, keypad 4×5 (AC, ( ), %, ÷ / 7-9 × / 4-6 − / 1-3 + / 0 . ⌫ =), history button, overflow | empty (cursor), typing, live result, result after =, error ("Kann nicht durch 0 teilen"), too long (scrolls) (ref-05..07) |
+| S02 | Scientific panel | chevron or swipe up on the row | more functions | extra rows: Deg/Rad, sin cos tan, Inv, e ln log, (with Inv: sin⁻¹ cos⁻¹ tan⁻¹, eˣ, 10ˣ, x²) | collapsed, expanded (ref-03) |
+| S03 | History | pull the display down / history button | past calculations | list grouped by day ("Heute"), each expression + result, "Current expression" at the bottom of the sheet, tap to reuse, clear history | empty, filled (ref-01, -02, -06) |
+| S04 | Context menu | long press on display or a history result | reuse values | Cut, Copy, Paste, MS (memory store), MR when memory set | (ref-01, -05) |
+| S05 | Settings / overflow | ⋮ | options | history clear, choose theme, about, (original: send feedback) | |
+
+## Flows
+
+```
+F01 Quick sum
+    S01: 1 2 + 3 4 → live result 46 → =
+    happy path taps: 6
+F02 Scientific
+    S01 → expand → sin ( Deg … ) → =
+F03 Reuse an old result
+    S01 pull down → S03 → tap a result → it is inserted at the cursor
+F04 Copy the result
+    S01 long press → S04 Copy
+F05 Store a value and recall it
+    long press → MS … later long press → MR
+    edge: memory survives app restart
+edge cases everywhere: division by zero, unbalanced parentheses (auto close), 0.1+0.2 exact, 100! (big), %, implicit multiplication "2π", leading minus, very long input
+```
+
+## Components
+
+| component | variants | states | used on |
+| --- | --- | --- | --- |
+| Key | digit (surface), operator (secondary container), AC (tertiary), equals (primary, fully round), function (text only in the collapsed row / tonal pills when expanded) | default, pressed (shape squishes to a squircle), disabled | S01, S02 |
+| Display | expression (large, shrinks with length), result preview (smaller, accent colour), cursor | empty, typing, final, error | S01 |
+| Sheet | history over display with drag handle | collapsed, expanded | S03 |
+| History row | expression muted, result bold | pressed | S03 |
+| Context menu | floating pill menu | | S04 |
+| Chevron | expand/collapse | | S02 |
+
+## Inferred data model
+
+```
+HistoryEntry  id, expression (text), result (text), created_at
+              evidence: S03 "Today" grouping  confidence: high
+Memory        value (exact number as text)   confidence: high (MS/MR)
+Settings      angle_unit (deg|rad), theme      confidence: high
+```
+
+## Feature matrix
+
+See `features.csv`.
+
+## Out of scope
+
+- Google's feedback/help integration.
+- Google's own number fonts and icons: Roboto Flex and own icon.
+
+## Size
+
+Screens 5, flows 5, entities 3. Hard parts: (1) exact arithmetic with big numbers and correct rounding/display of irrational results, (2) a parser that tolerates partial input for the live result (implicit multiplication, auto-closing parentheses, percent rules), (3) the expressive keypad (shape morph on press, auto-sizing display). Size: S–M.