Add comprehensive .github/copilot-instructions.md for GitHub Copilot coding agent

.github/copilot-instructions.md

@@ -0,0 +1,205 @@
+# Protols - Protocol Buffers Language Server
+
+Protols is an open-source Language Server Protocol (LSP) implementation for Protocol Buffers (proto) files, written in Rust. It provides intelligent code assistance for protobuf development, including auto-completion, diagnostics, formatting, go-to-definition, hover information, and more.
+
+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
+- Install dependencies and build the project:
+  - Rust toolchain is already available (cargo 1.89.0, rustc 1.89.0)
+  - Install protoc: `sudo apt update && sudo apt install -y protobuf-compiler` -- takes 2-3 minutes. NEVER CANCEL. Installs libprotoc 3.21.12.
+  - clang-format is already installed and available at `/usr/bin/clang-format` (Ubuntu clang-format version 18.1.3)
+  - `cargo build --verbose` -- takes about 1 minute to complete. NEVER CANCEL. Set timeout to 90+ minutes for safety.
+  - `cargo test --verbose` -- takes about 6 seconds, runs 22 tests. NEVER CANCEL. Set timeout to 30+ minutes.
+
+### Essential Commands
+- Check code formatting: `cargo fmt --check` -- takes under 1 second
+- Run linter: `cargo clippy` -- takes about 15 seconds. NEVER CANCEL. Set timeout to 30+ minutes.
+- Run the binary: `./target/debug/protols --help` or `./target/debug/protols --version`
+- Build release version: `cargo build --release` -- takes about 1 minute. NEVER CANCEL. Set timeout to 90+ minutes.
+- Test specific functionality: `cargo test <test_name>` for individual tests
+
+### External Dependencies Verification
+- **protoc (Protocol Buffers Compiler)**: Required for advanced diagnostics. Install with `sudo apt install -y protobuf-compiler`. Verify with `protoc --version`.
+- **clang-format**: Required for code formatting. Already available. Verify with `clang-format --version`.
+
+## Validation and Testing
+
+### Manual Validation Scenarios
+After making changes to the LSP functionality, ALWAYS test these scenarios:
+
+1. **Basic Build and Test Validation**:
+   - `cargo build` -- should complete in ~1 minute without errors
+   - `cargo test --verbose` -- should pass all 22 tests in ~6 seconds  
+   - `cargo fmt --check` -- should pass formatting check
+   - `cargo clippy` -- should pass linting with no warnings
+   - `./target/debug/protols --help` -- should show help message
+   - `./target/debug/protols --version` -- should show version 0.12.8
+
+2. **External Dependencies Validation**:
+   - `protoc --version` -- should show libprotoc 3.21.12
+   - `clang-format --version` -- should show Ubuntu clang-format version 18.1.3
+   - Test protoc with sample file: `protoc sample/simple.proto --descriptor_set_out=/tmp/test.desc`
+   - Test clang-format with sample file: `clang-format sample/simple.proto`
+
+3. **LSP Functionality Testing**:
+   - Test specific LSP features: `cargo test parser::hover::test::test_hover`
+   - Test workspace functionality: `cargo test workspace`
+   - Test with include paths: `./target/debug/protols --include-paths=/tmp,/home` (will start LSP server)
+   - Verify LSP server starts correctly (shows logging directory and waits for input)
+
+4. **Sample File Validation**:
+   - Ensure sample proto files in `/sample/` directory are valid
+   - Test parsing with `sample/simple.proto`, `sample/everything.proto`, `sample/test.proto`
+   - Verify protoc can process sample files without errors
+
+### CRITICAL Build and Test Timing
+- **NEVER CANCEL builds or tests** - they may take longer than expected
+- **cargo build**: 1 minute typical, set timeout to 90+ minutes
+- **cargo test**: 6 seconds typical, set timeout to 30+ minutes  
+- **cargo clippy**: 15 seconds typical, set timeout to 30+ minutes
+- **External dependency installation**: 2-3 minutes, set timeout to 30+ minutes
+
+### CI Validation Requirements
+Always run these commands before committing changes:
+- `cargo fmt --check` -- validates code formatting
+- `cargo clippy` -- validates code quality and catches common issues
+- `cargo test --verbose` -- runs full test suite
+- `cargo build --release` -- ensures release build works
+
+## Key Project Structure
+
+### Root Directory
+```
+├── Cargo.toml              # Main project configuration
+├── Cargo.lock              # Dependency lock file
+├── README.md               # Project documentation
+├── protols.toml            # LSP configuration file
+├── .clang-format           # Formatting configuration for proto files
+├── src/                    # Main source code
+├── sample/                 # Sample proto files for testing
+└── .github/workflows/      # CI/CD pipelines
+```
+
+### Important Source Files
+- `src/main.rs` - Entry point, command-line argument parsing, LSP server setup
+- `src/server.rs` - Core LSP server implementation
+- `src/lsp.rs` - LSP message handling and protocol implementation
+- `src/parser/` - Tree-sitter based proto file parsing
+- `src/formatter/` - Code formatting using clang-format
+- `src/workspace/` - Workspace and multi-file support
+- `src/config/` - Configuration management
+
+### Key Features to Test
+When modifying functionality, always validate:
+- **Code Completion**: Auto-complete messages, enums, keywords
+- **Diagnostics**: Syntax errors from tree-sitter and protoc
+- **Document Symbols**: Navigate symbols in proto files
+- **Code Formatting**: Format proto files using clang-format
+- **Go to Definition**: Jump to symbol definitions
+- **Hover Information**: Documentation on hover
+- **Rename Symbols**: Rename and propagate changes
+- **Find References**: Find symbol usage across files
+
+## Configuration Details
+
+### protols.toml Example
+```toml
+[config]
+include_paths = ["src/workspace/input"]
+
+[config.path]
+clang_format = "clang-format"
+protoc = "protoc"
+```
+
+### Command Line Options
+- `-i, --include-paths <PATHS>`: Comma-separated include paths for proto files
+- `-V, --version`: Print version information
+- `-h, --help`: Print help information
+
+## Common Development Tasks
+
+### Common Development Tasks
+
+### Adding New Features
+1. Write tests first in appropriate `src/*/test/` directories or `src/*/input/` test data
+2. Implement feature in relevant module (`src/parser/`, `src/workspace/`, `src/formatter/`, etc.)
+3. Update LSP message handlers in `src/lsp.rs` if needed
+4. Test with sample proto files in `sample/` directory
+5. Run all validation commands before committing
+
+### Debugging Issues
+- Check logs in system temp directory (output shows location on startup: "file logging at directory: /tmp")
+- Use `cargo test <module_name>` to run specific test modules
+- Use `cargo test <test_name> --verbose` for detailed test output
+- Test with sample files: `sample/simple.proto`, `sample/everything.proto`, `sample/test.proto`
+- Test files available in `src/parser/input/` and `src/workspace/input/` for unit tests
+- Verify external dependencies: `protoc --version`, `clang-format --version`
+
+### Working with Proto Files
+- Sample files available in `sample/` directory for testing
+- Test input files in `src/parser/input/test_*.proto` for specific functionality
+- Test workspace files in `src/workspace/input/` for multi-file scenarios  
+- Always test with various proto3 syntax features: messages, enums, services, imports
+- Use `protoc <file.proto> --descriptor_set_out=/tmp/test.desc` to validate proto syntax
+
+### Performance and Timing Expectations
+- Small project: ~1400 lines of Rust code
+- Fast incremental builds after first build
+- Test suite is comprehensive but fast (22 tests in 6 seconds)
+- LSP server starts quickly but will wait for client input (normal behavior)
+
+## Environment Notes
+- This is a Rust project using edition 2024
+- Uses tree-sitter for parsing proto files
+- Integrates with external tools (protoc, clang-format) for enhanced functionality
+- Logging goes to system temp directory with daily rotation
+- Supports both Unix pipes and fallback I/O for cross-platform compatibility
+
+## Common Command Outputs (for reference)
+
+### Repository Structure
+```
+├── Cargo.toml              # Main project configuration
+├── Cargo.lock              # Dependency lock file  
+├── README.md               # Project documentation
+├── protols.toml            # LSP configuration file
+├── .clang-format           # Formatting configuration for proto files
+├── LICENSE                 # MIT license
+├── .gitignore              # Git ignore rules
+├── src/                    # Main source code (~1400 lines)
+│   ├── main.rs            # Entry point (3956 bytes)
+│   ├── lsp.rs             # LSP implementation (19116 bytes)
+│   ├── server.rs          # Server logic (3561 bytes)
+│   ├── state.rs           # State management (9991 bytes)
+│   ├── parser/            # Tree-sitter parsing
+│   ├── workspace/         # Multi-file support
+│   ├── formatter/         # Code formatting
+│   ├── config/            # Configuration management
+│   └── docs/              # Documentation generation
+├── sample/                # Sample proto files
+│   ├── simple.proto       # Basic examples
+│   ├── everything.proto   # Comprehensive features
+│   └── test.proto         # Test scenarios
+└── .github/workflows/     # CI/CD pipelines
+    ├── ci.yml             # Build and test
+    └── release.yml        # Release automation
+```
+
+### Key Project Metadata
+```
+name = "protols"
+description = "Language server for proto3 files"
+version = "0.12.8"
+edition = "2024"
+license = "MIT"
+```
+
+### Test Output Summary
+- **Total tests**: 22 tests across parser, workspace, config, and formatter modules
+- **Test categories**: hover, definition, rename, document symbols, diagnostics, workspace operations
+- **Performance**: All tests complete in under 6 seconds
+- **Coverage**: Core LSP features, configuration, and multi-file workspace scenarios