Wraps every step of a turn: the turn, each model call and each tool call.

defmodule MyApp.NoShell do
  @behaviour WardrikCore.Middleware

  @impl true
  def call(%{step: {:tool_call, %{name: "shell"}}} = context, _next, _opts),
    do: {:ok, %{context | response: {:error, "No shell."}}}

  def call(context, next, _opts), do: next.(context)
end

Give it to an agent as middleware: [MyApp.NoShell] or [{MyApp.NoShell, opts}]. The first runs outermost.

Return values

• next.(context) - carries on.
• {:ok, context} - answers the step with context.response.
• {:park, reason, context} - waits for WardrikCore.resume/3.
• {:error, reason} - ends the step.