# `Mead.Router.Classifier`
[🔗](https://github.com/albertosca/mead/blob/main/lib/mead/router/classifier.ex#L1)

Decides whether a turn is routine enough for the local model or needs the cloud.

The decision is a pure function of the input and the history, so it is deterministic and
testable without a network. Local is chosen only when the input positively looks routine; any
doubt goes to the cloud, where the quality is. The rules are applied in this order:

  1. an input that is not a string, or not valid UTF-8, is `:cloud`, because it cannot be judged;
  2. an input longer than 280 characters is `:cloud`;
  3. a history of more than 20 turns is `:cloud`, because the context is heavy;
  4. an input that asks for reasoning or writing is `:cloud`;
  5. an input that asks for triage or formatting is `:local`;
  6. anything else is `:cloud`.

# `classify`

```elixir
@spec classify([Mead.Session.Turn.t()], term()) :: :local | :cloud
```

Returns the route the heuristic picks for `input` given the turns recorded so far.

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