# CLAUDE.md

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

## Project Overview

LIN Master Simulator GUI for BabyLIN hardware devices. Two parallel implementations maintained in feature parity: **Python (PyQt6)** and **C++ (Qt6)**. Each implementation step is built, verified with tests, then the other language catches up before moving forward.

## Build & Run Commands

### Python
```bash
cd python
pip install -r requirements.txt        # one-time setup
cd src && python main.py                # run GUI
cd .. && python -m pytest tests/ -v     # run all tests (from python/)
python -m pytest tests/test_main_window.py -v          # single test file
python -m pytest tests/test_main_window.py::test_name  # single test
```

### C++
```bash
cd cpp/build
cmake ..                    # one-time setup
cmake --build .             # build (produces lin_simulator, test_main_window)
./lin_simulator             # run GUI
./test_main_window          # run tests
ctest -V                    # run tests via CTest
```

## Architecture

Both implementations mirror the same GUI layout:
- **LDF Toolbar** — file path, browse, auto-reload checkbox
- **Connection Dock** (left, detachable) — device dropdown, baud rate, connect/disconnect, status indicator
- **Tx Table** (center-top) — master-published frames: name, ID, length, interval, data (hex), signals
- **Rx Table** (center-bottom) — slave-published frames: timestamp, name, ID, data, signals
- **Control Bar** (bottom) — schedule table dropdown, global send rate, start/stop/pause, manual send
- **Status Bar** — connection status

### Python-specific
- `python/src/main.py` — entry point
- `python/src/main_window.py` — all GUI layout and logic in `MainWindow` class
- `python/src/ldf_handler.py` — adapter around `ldfparser` library, exports `parse_ldf() -> LdfData` with dataclasses (`LdfData`, `FrameInfo`, `SignalInfo`, `ScheduleTableInfo`)

### C++-specific
- `cpp/src/main.cpp` — entry point
- `cpp/src/main_window.h/.cpp` — `MainWindow` class with Qt `Q_OBJECT` macro
- C++ uses camelCase methods (`createMenuBar`) vs Python snake_case (`_create_menu_bar`)
- Widget member variables use `m_` prefix
- Uses Qt parent-child ownership for memory management

### Testing
- **Python:** pytest. Tests in `python/tests/`.
- **C++:** Qt Test (QTest), not GoogleTest. Tests in `cpp/tests/`. One test executable contains all test classes.

### Shared Resources
- `resources/sample.ldf` — test LDF file (LIN 2.1, 2 nodes, 4 frames, 2 schedules, 19200 baud)

## Key ldfparser API Notes
- `ldf.baudrate` is in bps (divide by 1000 for display as kbps)
- `frame.signal_map` returns list of `(bit_offset, LinSignal)` tuples
- `frame.publisher` is `LinMaster` or `LinSlave` instance — use `isinstance()` to classify Tx vs Rx
- Schedule entry `delay` is in seconds — multiply by 1000 for ms

## Implementation Roadmap
See `PLAN.md` for the 8-step plan. Each step is implemented in Python first, then C++, with full test coverage before proceeding.