"""Create reasoning_engine
Generated by Phi-Octopus Eden
2025-11-06 09:23:56.525671
"""

```python
from typing import List, Dict


class ReasoningEngine:
    """
    A basic reasoning engine that evaluates a set of rules against given facts to derive new conclusions.
    """

    def __init__(self):
        self.rules: List[Dict[str, str]] = []

    def add_rule(self, rule: Dict[str, str]) -> None:
        """
        Adds a rule to the reasoning engine. A rule is represented as a dictionary where
        'if' keys map to conditions and 'then' values provide conclusions.

        :param rule: A dictionary defining a rule.
        """
        self.rules.append(rule)

    def apply_rules(self, facts: Dict[str, bool]) -> List[str]:
        """
        Applies the rules to the given set of facts and returns a list of derived conclusions that are true.

        :param facts: A dictionary representing current known facts as key-value pairs where value is boolean.
        :return: A list of strings representing all valid conclusions derived from the rules and facts.
        """
        results = []
        for rule in self.rules:
            if all(facts.get(key) == value for key, value in rule['if'].items()):
                conclusion = rule['then']
                if isinstance(conclusion, str):
                    results.append(conclusion)
                elif isinstance(conclusion, list):
                    results.extend([c for c in conclusion if c not in results])
        return results


# Example usage
reasoning_engine = ReasoningEngine()
reasoning_engine.add_rule({'if': {'x': True}, 'then': 'y'})
reasoning_engine.add_rule({'if': {'z': False}, 'then': ['a', 'b']})
reasoning_engine.add_rule({'if': {'w': True, 'x': True}, 'then': 'c'})

facts = {'x': True, 'z': True}

conclusions = reasoning_engine.apply_rules(facts)
print(conclusions)  # Output should be ['y']
```

This code defines a basic reasoning engine that can add rules and apply them to a set of facts to derive conclusions. The `apply_rules` method checks each rule against the provided facts and collects any valid conclusions into a list, which is then returned.