# Constraint Definitions -- Technical Specification

**Version**: v1.0.0 | **Status**: Placeholder | **Last Updated**: March 2026

## Overview

Reserved submodule for constraint type definitions within the FPF (Fetch-Parse-Format) framework. Intended to provide declarative constraint models for validating and filtering data during the parse and format stages of FPF pipelines.

## Architecture

This submodule currently contains only an empty `__init__.py` with `__all__ = []`. It serves as a namespace placeholder for future constraint implementations. When populated, it is expected to define dataclass-based constraint types that can be composed and evaluated against parsed data structures.

## Planned Components

| Component | Purpose |
|-----------|---------|
| Type constraints | Validate data types of parsed fields |
| Range constraints | Enforce numeric/temporal bounds |
| Pattern constraints | Regex-based string validation |
| Composite constraints | AND/OR/NOT composition of sub-constraints |

## Dependencies

- **Internal**: Expected to integrate with `fpf.models` for domain-specific validation and `fpf.optimization` for constraint solving
- **External**: None planned (Python stdlib)

## Constraints

- No implementation exists yet; all access will raise `ImportError` or `NotImplementedError`.
- Zero-mock: when implemented, real validation only; no stub data.
- Constraint definitions must be serializable for storage and transmission.

## Error Handling

- Unimplemented features raise `NotImplementedError`.
- All errors logged before propagation.

## Navigation

- **Self**: `SPEC.md`
- **Parent**: [../README.md](../README.md)
- **Readme**: [README.md](README.md)
- **Agents**: [AGENTS.md](AGENTS.md)
- **Repository Root**: [README.md](../../../../README.md)
