# `TypeSafeAPI.SystemOne.Prepared`
[🔗](https://github.com/typesend/typesafe_ai/blob/v0.1.0-alpha.3/lib/typesafe_api/system_one/prepared.ex#L1)

A question set that has been validated, encoded, and had its caller keys
recorded, ready to send with any number of states.

Doing this work once is what makes `TypeSafeAPI.evaluate_many/4` cheap: the
validation, the wire encoding and the `TypeSafeAPI.Keys` registry are identical
for every state, so they are built once and shared across tasks. `encoded`
holds JSON bytes, not a term to be serialized again, so a request body is a
splice of the cached iodata rather than another walk of the question set. It
is a struct rather than a bare map so the functions that take one can match
on it and fail loudly when handed something else.

## Do not modify one by hand

`count`, `encoded` and `keys` are all derived from `questions` when the
struct is built, and nothing revalidates them afterwards.
`%{prepared | questions: other_questions}` compiles and still matches every
`%Prepared{}` guard, but it sends the *old* questions on the wire and decodes
the answers under a stale key registry. Build a new one with
`TypeSafeAPI.prepare/1` instead.

# `t`

```elixir
@type t() :: %TypeSafeAPI.SystemOne.Prepared{
  count: pos_integer(),
  encoded: TypeSafeAPI.JSON.Encoded.t(),
  keys: TypeSafeAPI.Keys.t(),
  questions: [{TypeSafeAPI.Keys.key(), TypeSafeAPI.Question.t()}]
}
```

# `new`

```elixir
@spec new([{TypeSafeAPI.Keys.key(), TypeSafeAPI.Question.t()}]) :: t()
```

Builds a prepared question set from an already normalized `[{id, question}]`
list, deriving the count, the wire encoding and the key registry from it.

`TypeSafeAPI.prepare/1` is the public entry point; it normalizes and validates
first.

---

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