CalcSharp

The Goal

Create a C# / WPF replica of the Windows Calculator entirely with Claude.

Inspiration

Dave's Garage video https://youtu.be/KC31K-CUC5Y?si=ZCpKs0jT3eQy3FkL. I have deliberately not copied Dave's prompt.

Features

All modes in the navigation menu are implemented. Behaviour is verified against the real Calculator by replaying recorded key sequences (see "How exactness is checked"); modes marked unverified have not been compared yet.

Mode	Status
Standard	Verified: display and expression line match 1,300+ recorded sequences, including memory keys
Scientific	Verified on 158 recorded sequences; 32-digit arithmetic. Not yet verified: toggles (2nd, hyp, DEG/RAD/GRAD, F-E), inverse/hyperbolic names, number-format thresholds
Graphing	Unverified: y=, x= and implicit equations, colour-coded list, zoom and pan
Programmer	Unverified: HEX/DEC/OCT/BIN, QWORD..BYTE, bitwise ops, shifts and rotates, bit-flip panel
Date calculation	Unverified: difference between dates, add or subtract years/months/days
Converters	Unverified: Currency (offline rates), Volume, Length, Weight and mass, Temperature, Energy, Area, Speed, Time, Power, Data, Pressure, Angle

How exactness is checked

tools/CalcOracle.psm1 and tools/Record-Oracle.ps1 drive the installed Windows Calculator through UI Automation, press a key sequence from a map in tools/oracle/, and record the display and expression line to tests/CalcSharp.Core.Tests/GoldenData/*.tsv. The golden tests replay each sequence against the C# engine. This needs an interactive (unlocked, connected) desktop session.

Not yet exact

• Layout and visuals are approximate (no Mica/Fluent styling; some combo boxes are not dark themed).
• Programmer, Date calculation, Graphing and the converters have not been compared with the real app.
• Converter unit order, "fun" units and rounding, and Currency rates, are best recollection.
• Graphing has no tracing, analysis, settings or share.
• Single memory slot; no history or memory list pane.

Requirements

• Windows (WPF)
• .NET 10 SDK

Layout

• src/CalcSharp.Core – calculator engine (no UI dependencies)
• src/CalcSharp.App – WPF front end
• tests/CalcSharp.Core.Tests – xUnit tests for the engine

Run

dotnet test
dotnet run --project src/CalcSharp.App

Time spent

Wall-clock time (UTC+11). Each session starts when the prompt is given with implement @claude-prompt.md and stops when control is handed back.

Session	Start	Stop	Elapsed	Notes
2	2026-10-14 17:54	2026-10-14 18:53	59m	Navigation shell; parallel build of all modes; UI Automation oracle; Standard matched to real app (1,300+ sequences); Scientific rewritten on 32-digit BigNum and matched (158 sequences)
			59m	Total (session 1 predates the clock rule and is not counted)

Ground rules

No one else's calc.exe source code is read. Code decompiled from calc.exe by this project itself may be read. See GLOSSARY.md for the web addresses consulted and why.