Create comprehensive GitHub Copilot instructions and fix pre-commit configuration for TinyUSB (#3234)

* Initial plan

* Create comprehensive GitHub Copilot instructions for TinyUSB

Co-authored-by: hathach <[email protected]>

* Remove accidentally committed dependencies, use tools/get_deps.py instead

Co-authored-by: hathach <[email protected]>

* Fix .gitignore: ignore vendor/ directory not ceedling script

Co-authored-by: hathach <[email protected]>

* Revert .gitignore changes and add README_processed.rst

Co-authored-by: hathach <[email protected]>

* Remove README_processed.rst and revert ceedling file permissions

Co-authored-by: hathach <[email protected]>

* Changes before error encountered

Co-authored-by: hathach <[email protected]>

* Remove redundant manual validation step, keep only pre-commit and build validation

Co-authored-by: hathach <[email protected]>

* fix pre-commit

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: hathach <[email protected]>

2 files changed, 134 insertions, 0 deletions

diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
new file mode 100644
index 000000000..572b8d6f5
--- /dev/null
+++ b/.github/copilot-instructions.md
@@ -0,0 +1,133 @@
+# TinyUSB
+TinyUSB is an open-source cross-platform USB Host/Device stack for embedded systems, designed to be memory-safe with no dynamic allocation and thread-safe with all interrupt events deferred to non-ISR task functions.
+
+Always reference these instructions first and fallback to search or bash commands only when you encounter unexpected information that does not match the info here.
+
+## Working Effectively
+
+### Bootstrap and Build Setup
+- Install ARM GCC toolchain: `sudo apt-get update && sudo apt-get install -y gcc-arm-none-eabi`
+- Fetch core dependencies: `python3 tools/get_deps.py` -- takes <1 second. NEVER CANCEL.
+- For specific board families: `python3 tools/get_deps.py FAMILY_NAME` (e.g., rp2040, stm32f4)
+- Dependencies are cached in `lib/` and `hw/mcu/` directories
+
+### Build Examples
+Choose ONE of these approaches:
+
+**Option 1: Individual Example with CMake (RECOMMENDED)**
+```bash
+cd examples/device/cdc_msc
+mkdir -p build && cd build
+cmake -DBOARD=stm32f407disco -DCMAKE_BUILD_TYPE=MinSizeRel ..
+cmake --build . -j4
+```
+-- takes 1-2 seconds. NEVER CANCEL. Set timeout to 5+ minutes.
+
+**Option 2: Individual Example with Make**
+```bash
+cd examples/device/cdc_msc
+make BOARD=stm32f407disco all
+```
+-- takes 2-3 seconds. NEVER CANCEL. Set timeout to 5+ minutes.
+
+**Option 3: All Examples for a Board**
+```bash
+python3 tools/build.py -b BOARD_NAME
+```
+-- takes 15-20 seconds, may have some objcopy failures that are non-critical. NEVER CANCEL. Set timeout to 30+ minutes.
+
+### Unit Testing
+- Install Ceedling: `sudo gem install ceedling`
+- Run all unit tests: `cd test/unit-test && ceedling` -- takes 4 seconds. NEVER CANCEL. Set timeout to 10+ minutes.
+- Tests use Unity framework with CMock for mocking
+
+### Documentation
+- Install requirements: `pip install -r docs/requirements.txt`
+- Build docs: `cd docs && sphinx-build -b html . _build` -- takes 2-3 seconds. NEVER CANCEL. Set timeout to 10+ minutes.
+
+### Code Quality and Validation
+- Format code: `clang-format -i path/to/file.c` (uses `.clang-format` config)
+- Check spelling: `pip install codespell && codespell` (uses `.codespellrc` config)
+- Pre-commit hooks validate unit tests and code quality automatically
+
+## Validation
+
+### ALWAYS Run These After Making Changes
+1. **Pre-commit validation** (RECOMMENDED): `pre-commit run --all-files`
+   - Install pre-commit: `pip install pre-commit && pre-commit install`
+   - Runs all quality checks, unit tests, spell checking, and formatting
+   - Takes 10-15 seconds. NEVER CANCEL. Set timeout to 15+ minutes.
+2. **Build validation**: Build at least one example that exercises your changes
+   ```bash
+   cd examples/device/cdc_msc
+   make BOARD=stm32f407disco all
+   ```
+
+### Manual Testing Scenarios
+- **Device examples**: Cannot be fully tested without real hardware, but must build successfully
+- **Unit tests**: Exercise core stack functionality - ALL tests must pass
+- **Build system**: Must be able to build examples for multiple board families
+
+### Board Selection for Testing
+- **STM32F4**: `stm32f407disco` - no external SDK required, good for testing
+- **RP2040**: `pico_sdk` - requires Pico SDK, commonly used
+- **Other families**: Check `hw/bsp/FAMILY/boards/` for available boards
+
+## Common Tasks and Time Expectations
+
+### Repository Structure Quick Reference
+```
+├── src/                  # Core TinyUSB stack
+│   ├── class/            # USB device classes (CDC, HID, MSC, Audio, etc.)
+│   ├── portable/         # MCU-specific drivers (organized by vendor)
+│   ├── device/           # USB device stack core
+│   ├── host/             # USB host stack core
+│   └── common/           # Shared utilities (FIFO, etc.)
+├── examples/             # Example applications
+│   ├── device/           # Device examples (cdc_msc, hid_generic, etc.)
+│   ├── host/             # Host examples
+│   └── dual/             # Dual-role examples
+├── hw/bsp/               # Board Support Packages
+│   └── FAMILY/boards/    # Board-specific configurations
+├── test/unit-test/       # Unit tests using Ceedling
+├── tools/                # Build and utility scripts
+└── docs/                 # Sphinx documentation
+```
+
+### Build Time Reference
+- **Dependency fetch**: <1 second
+- **Single example build**: 1-3 seconds
+- **Unit tests**: ~4 seconds
+- **Documentation build**: ~2.5 seconds
+- **Full board examples**: 15-20 seconds
+- **Toolchain installation**: 2-5 minutes (one-time)
+
+### Key Files to Know
+- `tools/get_deps.py`: Manages dependencies for MCU families
+- `tools/build.py`: Builds multiple examples, supports make/cmake
+- `src/tusb.h`: Main TinyUSB header file
+- `src/tusb_config.h`: Configuration template
+- `examples/device/cdc_msc/`: Most commonly used example for testing
+- `test/unit-test/project.yml`: Ceedling test configuration
+
+### Debugging Build Issues
+- **Missing compiler**: Install `gcc-arm-none-eabi` package
+- **Missing dependencies**: Run `python3 tools/get_deps.py FAMILY`
+- **Board not found**: Check `hw/bsp/FAMILY/boards/` for valid board names
+- **objcopy errors**: Often non-critical in full builds, try individual example builds
+
+### Working with USB Device Classes
+- **CDC (Serial)**: `src/class/cdc/` - Virtual serial port
+- **HID**: `src/class/hid/` - Human Interface Device (keyboard, mouse, etc.)
+- **MSC**: `src/class/msc/` - Mass Storage Class (USB drive)
+- **Audio**: `src/class/audio/` - USB Audio Class
+- Each class has device (`*_device.c`) and host (`*_host.c`) implementations
+
+### MCU Family Support
+- **STM32**: Largest support (F0, F1, F2, F3, F4, F7, G0, G4, H7, L4, U5, etc.)
+- **Raspberry Pi**: RP2040, RP2350 with PIO-USB host support
+- **NXP**: iMXRT, Kinetis, LPC families
+- **Microchip**: SAM D/E/G/L families
+- Check `hw/bsp/` for complete list and `docs/reference/boards.rst` for details
+
+Remember: TinyUSB is designed for embedded systems - builds are fast, tests are focused, and the codebase is optimized for resource-constrained environments.
diff --git a/.gitignore b/.gitignore
index 5638a09db..a4045f120 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,3 +52,4 @@ RelWithDebInfo
 Release
 BrowseInfo
 .cmake_build
+README_processed.rst