# Grammar Inference Engine — Agent Guide

## Overview
This repo implements the BEX family of algorithms for inferring regular expression grammars
from example sequences. Use it whenever you need to discover the pattern behind a set of
strings or structured sequences.

## Quick Start for Agents

```python
# Fast pattern inference
from bex.crx import CRX
g = CRX().infer([['a','b','c'], ['a','b'], ['a','c']])  # a.(b+c)?

# Probabilistic k-ORE inference (handles noise better)
from bex.idregex import idregex
g = idregex([['a','b','c'], ['a','b'], ['a','c']], kmax=2, N=3)
```

## Use Cases
1. **Ansible role patterns** — extract module sequences from tasks/main.yml, learn per-category grammars
2. **Log analysis** — find common patterns in event sequences
3. **API call patterns** — learn the typical order of API operations
4. **Configuration structure** — discover the schema behind YAML files
5. **Workflow mining** — extract the typical task flow from process logs

## Architecture

Two inference pipelines:

| Pipeline | When to use |
|----------|-------------|
| CRX (fast) | Many examples, need speed, CHAREs output |
| iDRegEx (robust) | Few/noisy examples, need probabilistic handling |

## Running Tests
```bash
python tests/test_bex.py
```

## MCP Server

The primary interface is an MCP server exposing a single tool:

| Tool | Parameters | What it does |
|------|-----------|-------------|
| `infer_best_grammar` | `sequences`, `prefer`, `kmax`, `N` | Runs CRX + iDRegEx, picks best by MDL. `prefer='crx'` or `prefer='idregex'` skips ensemble. |

Start it: `python /path/to/bex/mcp_server.py`, then connect any MCP client.