# `WardrikPolicy.Decision`

What a policy decided about a call, and why. Returned by `WardrikPolicy.explain/3`.

  * `:effect` - `:allow`, `:ask` or `:deny`.
  * `:message` - the prompt or refusal. `nil` for an allow.
  * `:rule` - the rule that decided, when `:cause` is `:rule` or `:label`.
  * `:policy` - the name of the policy that decided, if it has one.
  * `:cause` - what decided. See below.
  * `:measurements` - what a judge's model call used.

The `:cause` is one of:

  * `:rule` - a rule named the call.
  * `:no_rule` - no rule covered the whole call, so `default` decided.
  * `:judge` - the policy's judge decided.
  * `:budget` - a model call reached the policy's budget.
  * `:label` - a rule allowed a gated call, but the run had read labelled content.

# `t`

```elixir
@type t() :: %WardrikPolicy.Decision{
  cause: :rule | :no_rule | :judge | :budget | :label,
  effect: :allow | :ask | :deny,
  measurements: %{optional(term()) => number()},
  message: String.t() | nil,
  policy: String.t() | nil,
  rule: String.t() | nil
}
```

# `strictest`

```elixir
@spec strictest([t()]) :: t()
```

Returns the strictest decision. A deny beats an ask, and an ask beats an allow.

On a tie, a decision from a rule or judge beats one from a default. An empty list allows. The
result carries the summed measurements of all of them.

# `strictness`

```elixir
@spec strictness(:allow | :ask | :deny) :: 0..2
```

Ranks an effect: `0` for `:deny`, `1` for `:ask`, `2` for `:allow`.

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*Consult [api-reference.md](api-reference.md) for complete listing*