add-feature

# Add Feature Guide for adding new functionality to Syncpack. ## Quick Decision What are you adding? - **New CLI command** (lint, fix, format, etc.) → See [adding-command.md](adding-command.md) - **New validation logic** (InstanceState variant) → See [adding-instance-state.md](adding-instance-state.md) - **Both** → Start with instance state, then add command ## Prerequisites Before adding any feature: 1. Understand the 3-phase pattern: Create Context → Inspect Context → Run Command 2. Know which phase your feature affects 3. Check if similar code exists (use `ast-grep -p 'PATTERN' src/`) ## Feature Types ### Commands Commands are user-facing operations (`syncpack lint`, `syncpack fix`, etc.). **When to create a new command:** - New user-facing operation that doesn't fit existing commands - Different output format or behaviour needed **Registration points (all three required):** 1. `src/cli.rs` - Add to `Subcommand` enum 2. `src/main.rs` - Add match arm for dispatch 3. `src/commands/*.rs` - Implement `pub fn run(ctx: Context) -> i32` → Full guide: [adding-command.md](adding-command.md) ### Instance States InstanceState variants describe validation results (valid, fixable, unfixable, suspect). **When to add a new state:** - New validation rule needed - New type of error/warning to report - New auto-fix capability **Location:** `src/instance_state.rs` + `src/visit_packages/*.rs` → Full guide: [adding-instance-state.md](adding-instance-state.md) ## Common Workflow 1. Write failing test using TestBuilder 2. Implement minimal code to pass 3. Run `cargo clippy` and fix warnings 4. Refactor if needed 5. Update documentation ## Checklist Before submitting: - [ ] Tests pass (`just test`) - [ ] Zero clippy warnings - [ ] Follows existing patterns - [ ] Registered in all required places (for commands) - [ ] Uses TDD approach