CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

A cross-platform system information application built with Tauri v2, React, TypeScript, and C++. The architecture demonstrates FFI (Foreign Function Interface) integration across multiple layers:

Frontend: React + TypeScript (UI layer)
Backend: Rust via Tauri (application framework)
System Library: Cross-platform C++ library loaded dynamically via
```
libloading
```

The C++ library provides low-level system operations (computer name, memory info, process ID, factorial calculation) that are exposed through Rust to the React frontend.

Common Development Commands

Development

# Start dev server (works without C++ library - will show errors but UI functions)
npm run tauri dev

# Build frontend only
npm run build

C++ Library Development

# Build the C++ library (required for full functionality)
cd cpp_cross_platform
mkdir build
cd build
cmake ..
cmake --build . --config Release

# The library will be built to:
# - Windows: cpp_cross_platform/build/bin/Release/systemapi.dll
# - macOS: cpp_cross_platform/build/lib/libsystemapi.dylib
# - Linux: cpp_cross_platform/build/lib/libsystemapi.so

Production Build

# Build the Tauri application
npm run tauri build

Architecture

FFI Integration Flow

C++ Layer (

cpp_cross_platform/

Header:
```
include/systemapi.h
```
- defines FFI-compatible C ABI functions
Implementation:
```
src/systemapi.cpp
```
- platform-specific implementations

Exports:

GetComputerNameString

GetTotalPhysicalMemory

GetCurrentProcessID

CalculateFactorial

Rust Layer (
```
src-tauri/src/lib.rs
```
):
- Uses
```
libloading
```
  crate to dynamically load the C++ shared library
- Loads library from multiple paths (see
```
load_cpp_library()
```
  function)
- Exposes Tauri commands that call into C++ via FFI
- State management:
```
CppLibrary
```
  struct with
```
Mutex<Option<Library>>
```

React Layer (

src/

Calls Tauri commands via
```
@tauri-apps/api/core
```
Example:
```
invoke<string>("get_computer_name")
```

Library Loading Strategy

The Rust code searches for the C++ library in this order:

Same directory as executable
Windows:
```
resources/
```
folder next to exe
macOS:
```
../Resources/
```
(app bundle structure)
Development path:
```
../cpp_cross_platform/build/...
```

CI/CD (GitHub Actions)

The

.github/workflows/release.yml

workflow:

Builds C++ library for each platform (Windows x64, macOS ARM64)
Copies library to
```
src-tauri/lib/
```
before Tauri build
On macOS: Code signs the library with Developer ID
Creates draft releases on version tags (
```
v*
```
)

Key Implementation Details

Tauri Commands

All Tauri commands in

src-tauri/src/lib.rs

follow this pattern:

Take
```
State<CppLibrary>
```
as parameter
Lock the mutex to access the library
Use
```
Symbol<FunctionTypeFn>
```
to get function pointer
Call unsafe FFI function
Return
```
Result<T, String>
```
for error handling

C++ Library Notes

Uses
```
extern "C"
```
to prevent name mangling
Platform-specific export macros (
```
SYSTEMAPI_API
```
)
CMake builds shared library (
```
.dll
```
/
```
.dylib
```
/
```
.so
```
)
Windows:
```
WINDOWS_EXPORT_ALL_SYMBOLS
```
enabled

Frontend Error Handling

If C++ library fails to load, app shows error UI with retry button
All system info calls are wrapped in try-catch
Graceful degradation: UI works without library (shows errors)

Platform-Specific Requirements

Windows

Visual Studio or Build Tools required
CMake generates Visual Studio project files

macOS

Xcode Command Line Tools
For distribution: Code signing certificates required (Developer ID Application & Installer)
Library must be signed with hardened runtime for notarization

Linux

GCC/G++ compiler
GTK 3 and WebKit2GTK development packages
CMake for building C++ library

Project Structure

```
src/
```
- React frontend
```
src-tauri/
```
- Tauri Rust backend
- ```
src/lib.rs
```
  - Main application logic and FFI integration
- ```
src/main.rs
```
  - Entry point (minimal, calls lib.rs)
- ```
build.rs
```
  - Tauri build script
```
cpp_cross_platform/
```
- C++ system library
- ```
include/
```
  - Header files
- ```
src/
```
  - Implementation
- ```
CMakeLists.txt
```
  - CMake build configuration
```
.github/workflows/
```
- CI/CD automation

Testing the C++ Integration

After building the C++ library, verify integration:

Start dev server:
```
npm run tauri dev
```
Check console for "✓ C++ library loaded successfully!"
UI should display computer name, memory, and process ID
Factorial calculator should work without errors

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Frontend: React + TypeScript (UI layer)
Backend: Rust via Tauri (application framework)
System Library: Cross-platform C++ library loaded dynamically via
```
libloading
```

The C++ library provides low-level system operations (computer name, memory info, process ID, factorial calculation) that are exposed through Rust to the React frontend.

Common Development Commands

Development

# Start dev server (works without C++ library - will show errors but UI functions)
npm run tauri dev

# Build frontend only
npm run build

C++ Library Development

# Build the C++ library (required for full functionality)
cd cpp_cross_platform
mkdir build
cd build
cmake ..
cmake --build . --config Release

# The library will be built to:
# - Windows: cpp_cross_platform/build/bin/Release/systemapi.dll
# - macOS: cpp_cross_platform/build/lib/libsystemapi.dylib
# - Linux: cpp_cross_platform/build/lib/libsystemapi.so

Production Build

# Build the Tauri application
npm run tauri build

Architecture

FFI Integration Flow

C++ Layer (

cpp_cross_platform/

Header:
```
include/systemapi.h
```
- defines FFI-compatible C ABI functions
Implementation:
```
src/systemapi.cpp
```
- platform-specific implementations

Exports:

GetComputerNameString

GetTotalPhysicalMemory

GetCurrentProcessID

CalculateFactorial

Rust Layer (
```
src-tauri/src/lib.rs
```
):
- Uses
```
libloading
```
  crate to dynamically load the C++ shared library
- Loads library from multiple paths (see
```
load_cpp_library()
```
  function)
- Exposes Tauri commands that call into C++ via FFI
- State management:
```
CppLibrary
```
  struct with
```
Mutex<Option<Library>>
```

React Layer (

src/

Calls Tauri commands via
```
@tauri-apps/api/core
```
Example:
```
invoke<string>("get_computer_name")
```

Library Loading Strategy

The Rust code searches for the C++ library in this order:

Same directory as executable
Windows:
```
resources/
```
folder next to exe
macOS:
```
../Resources/
```
(app bundle structure)
Development path:
```
../cpp_cross_platform/build/...
```

CI/CD (GitHub Actions)

The

.github/workflows/release.yml

workflow:

Builds C++ library for each platform (Windows x64, macOS ARM64)
Copies library to
```
src-tauri/lib/
```
before Tauri build
On macOS: Code signs the library with Developer ID
Creates draft releases on version tags (
```
v*
```
)

Key Implementation Details

Tauri Commands

All Tauri commands in

src-tauri/src/lib.rs

follow this pattern:

Take
```
State<CppLibrary>
```
as parameter
Lock the mutex to access the library
Use
```
Symbol<FunctionTypeFn>
```
to get function pointer
Call unsafe FFI function
Return
```
Result<T, String>
```
for error handling

C++ Library Notes

Uses
```
extern "C"
```
to prevent name mangling
Platform-specific export macros (
```
SYSTEMAPI_API
```
)
CMake builds shared library (
```
.dll
```
/
```
.dylib
```
/
```
.so
```
)
Windows:
```
WINDOWS_EXPORT_ALL_SYMBOLS
```
enabled

Frontend Error Handling

If C++ library fails to load, app shows error UI with retry button
All system info calls are wrapped in try-catch
Graceful degradation: UI works without library (shows errors)

Platform-Specific Requirements

Windows

Visual Studio or Build Tools required
CMake generates Visual Studio project files

macOS

Xcode Command Line Tools
For distribution: Code signing certificates required (Developer ID Application & Installer)
Library must be signed with hardened runtime for notarization

Linux

GCC/G++ compiler
GTK 3 and WebKit2GTK development packages
CMake for building C++ library

Project Structure

```
src/
```
- React frontend
```
src-tauri/
```
- Tauri Rust backend
- ```
src/lib.rs
```
  - Main application logic and FFI integration
- ```
src/main.rs
```
  - Entry point (minimal, calls lib.rs)
- ```
build.rs
```
  - Tauri build script
```
cpp_cross_platform/
```
- C++ system library
- ```
include/
```
  - Header files
- ```
src/
```
  - Implementation
- ```
CMakeLists.txt
```
  - CMake build configuration
```
.github/workflows/
```
- CI/CD automation

Testing the C++ Integration

After building the C++ library, verify integration:

Start dev server:
```
npm run tauri dev
```
Check console for "✓ C++ library loaded successfully!"
UI should display computer name, memory, and process ID
Factorial calculator should work without errors

CLAUDE.md

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