> ## Documentation Index
> Fetch the complete documentation index at: https://docs.erna.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Priority

```ts theme={null}
type Priority = "LOW" | "MEDIUM" | "HIGH" | "MANDATORY";
```

How strictly the solver enforces a rule.

Priority is part of the schedule design, not a cosmetic option. Use it to
preserve the distinction between hard requirements and softer preferences
from the requirements. In practice, words like "must", "at least", "needs", and
"cannot" usually map to `"MANDATORY"`, while words like "ideally",
"prefer", "mainly", and "where possible" usually map to a soft priority.
The same coverage shape or rule scope can be modeled with different
priorities when the business language is subtler than a pure hard limit.

* `"LOW"`, `"MEDIUM"`, `"HIGH"`: soft constraints with increasing penalty for violations
* `"MANDATORY"`: hard constraint; the solver will not produce a solution that violates it