pydantic-model-validator-prod-safety-gate-pattern

A Pydantic model_validator(mode='after') on the Settings class that checks RDASH_ENV == 'production' and raises a structured error listing all dev-default fields prevents silent misconfiguration. This pattern catches 7 categories of dev secrets (known weak passwords, localhost URLs, placeholder tokens) in a single validation pass at app startup. The error message enumerates every failing field — no silent boot possible.