# `Statifier.Send.Routes`
[🔗](https://github.com/riddler/statifier-ex/blob/v2.0.0/lib/statifier/send/routes.ex#L1)

A caller-declared, point-in-time claim about which `<send>` routes are
live (ADR-0048 decision 1) - a plain value in `Statifier.Send.Target`'s
neutral namespace (ADR-0047 decision 3), carrying exactly what
`Statifier.Session.deliver/5` resolves today: the set of session ids
reachable by `{:session, sid}`, whether a parent exists for `:parent`,
and the set of live invoke ids reachable by `{:invoke, id}`.

This is a claim, not an observation. It is stamped by the caller once per
core drive (ADR-0048 decision 2) and carries no obligation to track
anything between writes - point-in-time is its definition, not its
failure mode (ADR-0048 decision 2's answer to ADR-0030's ground 2). It is
deliberately **not** `Statifier.MachineState.active_invocations`: that
field is the algorithm's own view of which invocations are active per
Appendix D, while this struct's `invokes` set is the session's live
table - a different fact that happens to share a shape.

`:self` and `:internal` routes need no entry in this struct at all -
they are reachable by construction (ADR-0048 decision 1) - so
`reachable?/2` answers them without consulting any field.

# `t`

```elixir
@type t() :: %Statifier.Send.Routes{
  invokes: MapSet.t(String.t()),
  parent?: boolean(),
  sessions: MapSet.t(String.t())
}
```

# `new`

```elixir
@spec new(opts :: keyword()) :: t()
```

Builds a snapshot from `opts`: `:sessions` (default empty, a `MapSet` or
any `Enum` of session ids - `MapSet.new/1` accepts either), `:parent?`
(default `false`), and `:invokes` (default empty, same shape as
`:sessions`).

# `reachable?`

```elixir
@spec reachable?(routes :: t(), route :: Statifier.Send.Target.route()) :: boolean()
```

Whether `route` is reachable per this snapshot. `:self` and `:internal`
are always reachable; `{:session, sid}`, `:parent`, and `{:invoke, id}`
are judged against this snapshot's own fields; `{:invalid, _target}` is
always unreachable - covered here for completeness, though ADR-0047's
static check in `Statifier.Machine.Content.Send.execute/2` rejects an
`{:invalid, _}` target before this predicate is ever asked.

---

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