# `BB.Reactor.Middleware.Safety`
[🔗](https://github.com/beam-bots/bb_reactor/blob/main/lib/bb/reactor/middleware/safety.ex#L5)

Middleware that bridges reactor errors to the BB safety event stream.

When a reactor fails (returns an error), this middleware publishes the
error via `BB.Safety.report_error/3`. The result is a
`BB.Safety.HardwareError` message on `[:safety, :error]` that observers
(dashboards, alerting, custom recovery logic) can subscribe to.

This middleware does **not** disarm the robot or otherwise change safety
state. Escalation in BB happens through the supervision tree: if a process
crashes often enough to exhaust the topology supervisor's restart budget,
the safety controller force-disarms the robot. Reactor errors are
recovered at the saga level (compensation, retries) and do not crash
processes, so they will not trigger escalation on their own. If a
particular reactor failure warrants disarm, subscribe to `[:safety, :error]`
and call `BB.Safety.disarm/1` explicitly.

This middleware is **not** automatically added by the `BB.Reactor`
extension - add it manually if you want reactor errors published as
hardware error events.

## Usage

```elixir
defmodule MyRobot.PickAndPlace do
  use Reactor, extensions: [BB.Reactor]

  middlewares do
    middleware BB.Reactor.Middleware.Safety
  end

  # ... steps
end
```

## Safety State Changes Within Steps

Individual steps (like `BB.Reactor.Step.Command`) are responsible for
detecting safety state changes during execution and returning
`{:halt, :safety_disarmed}` when appropriate. This middleware only
publishes notifications for reactor-level errors.

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