feat: add schema validation and pre-commit hook

.pre-commit-config.yaml

@@ -28,6 +28,7 @@ repos:
       - id: check-json
       - id: check-executables-have-shebangs
       - id: pretty-format-json
+        args: ['--autofix']
       - id: check-merge-conflict
       - id: check-symlinks
       - id: check-toml

.pre-commit-config.yaml.example

@@ -0,0 +1,10 @@
+# Example pre-commit configuration for generate_parameter_library projects
+# Copy this to .pre-commit-config.yaml in your project root
+
+repos:
+  # Validate parameter YAML files against JSON schema
+  - repo: https://github.com/Greenroom-Robotics/generate_parameter_library
+    rev: main
+    hooks:
+      - id: validate-parameter-schema
+        files: .*parameters\.yaml$

.pre-commit-hooks.yaml

@@ -0,0 +1,8 @@
+- id: validate-parameter-schema
+  name: Validate ROS2 PickNikRobotics Generate Parameter Library Schema
+  description: Validates generate_parameter_library YAML files against JSON schema
+  entry: python -m validate_schema
+  language: python
+  types: [yaml]
+  files: .*parameters\.yaml$
+  additional_dependencies: ['./schema_validator']

pyproject.toml

@@ -0,0 +1,19 @@
+[build-system]
+requires = ["setuptools>=45", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "generate-parameter-library-hooks"
+version = "0.1.0"
+description = "Pre-commit hooks for generate_parameter_library"
+authors = [
+    {name = "Greenroom Robotics"}
+]
+requires-python = ">=3.6"
+dependencies = [
+    "pyyaml>=5.0",
+    "jsonschema>=3.0",
+]
+
+[tool.setuptools]
+packages = []

schema_validator/MANIFEST.in

@@ -0,0 +1,2 @@
+include *.json
+include README.md

schema_validator/README.md

@@ -0,0 +1,120 @@
+# Parameter Schema Validator
+
+A pre-commit hook to validate `generate_parameter_library` YAML files against the JSON schema.
+
+## Installation
+
+### As a pre-commit hook
+
+Add this to your `.pre-commit-config.yaml`:
+
+```yaml
+repos:
+  - repo: https://github.com/Greenroom-Robotics/generate_parameter_library
+    rev: main  # Use a specific tag/version in production
+    hooks:
+      - id: validate-parameter-schema
+```
+
+Then install the hook:
+
+```bash
+pre-commit install
+```
+
+### Standalone usage
+
+Install dependencies:
+
+```bash
+pip install pyyaml jsonschema
+```
+
+Run the validator:
+
+```bash
+python schema_validator/validate_schema.py path/to/your/parameters.yaml
+```
+
+Or with a custom schema:
+
+```bash
+python schema_validator/validate_schema.py --schema path/to/schema.json path/to/parameters.yaml
+```
+
+To also validate `additional_constraints` JSON content against the UI schema:
+
+```bash
+python schema_validator/validate_schema.py --ui-schema path/to/parameters.yaml
+```
+
+## What it validates
+
+The validator checks:
+
+1. **YAML syntax**: Ensures the file is valid YAML
+2. **Single root element**: The YAML must have exactly one root element (the namespace)
+3. **Required fields**: Each parameter must have a `type` field
+4. **Valid types**: Type must be one of the supported parameter types
+5. **Valid field names**: Only recognized fields are allowed (type, default_value, description, read_only, validation, additional_constraints)
+6. **Nested structure**: Validates nested parameter groups and mapped parameters
+7. **Validation syntax**: Ensures validation rules follow the correct structure
+8. **Additional constraints (optional)**: When `--ui-schema` is provided, validates that the `additional_constraints` field contains valid JSON that conforms to the UI schema
+
+## Example output
+
+Successful validation:
+```
+✓ config/parameters.yaml is valid
+```
+
+Failed validation:
+```
+❌ Validation failed for config/parameters.yaml:
+  Path: my_controller -> pid -> p
+  Error: 'type' is a required property
+  Value: {'default_value': 1.0, 'description': 'Proportional gain'}
+```
+
+## Alpha UI Schema for additional_constraints
+
+The `alpha_ui_schema.json` defines the expected format for JSON content embedded in the `additional_constraints` field. This is useful when `additional_constraints` contains UI metadata for form generation.
+
+### Format
+
+The `additional_constraints` field should contain a JSON-encoded string like:
+
+```yaml
+my_parameter:
+  type: double
+  default_value: 100.0
+  additional_constraints: '{"type": "number", "units": "hertz"}'
+```
+
+The JSON content can include:
+- `type` (required): JSON Schema type (number, string, integer, boolean, array, object)
+- `units` (optional): Physical units (seconds, hertz, metersPerSecond, meters, radians, degrees, etc.)
+- Any React JSON Schema Form properties: `minimum`, `maximum`, `enum`, `pattern`, `title`, etc.
+
+### Validation
+
+To validate `additional_constraints` content:
+
+```bash
+python schema_validator/validate_schema.py --ui-schema path/to/parameters.yaml
+```
+
+This will:
+1. Parse the JSON string in each `additional_constraints` field
+2. Validate it conforms to the UI schema structure
+3. Report any malformed JSON or schema violations
+
+## Limitations
+
+Note that this validator checks the **structure** of the YAML file, but does not perform:
+
+- Type checking of default values against declared types (use generate_parameter_library for this)
+- Custom validator verification
+- Deep semantic validation
+
+For complete validation, always run `generate_parameter_library` during your build process.

schema_validator/__main__.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python3
+"""Allow running validate_schema as a module: python -m validate_schema"""
+import sys
+from validate_schema import main
+
+if __name__ == '__main__':
+    sys.exit(main())