motief/.mindmodel/patterns/validation.md

title	category
Validation Pattern	patterns

Validation Pattern

Rules

• Validate inputs early and raise ValueError or domain-specific exceptions (ProviderError) for invalid contract inputs.
• Tests should assert that invalid inputs raise the expected exceptions.
• Use explicit checks for types and shapes on public APIs (e.g., ensure text is str before embedding).

Examples

ai_provider.py - Type validation

if not isinstance(text, str):
    raise ProviderError("text must be a string")

pipeline/ai_provider_wrapper.py - Defensive empty handling

if not texts:
    return []
if motion_ids is None:
    motion_ids = [None for _ in texts]

Anti-Patterns

Bad: Invalid values into computation

Problem: Allowing invalid values to propagate into heavy computation (e.g., non-string into embedding pipeline).

Remediation: Fail fast with a typed exception and add unit tests to cover validations.