# `WardrikPolicy.Middleware`

A `WardrikCore.Middleware` that holds an agent to one or more policies.

    middleware: [{WardrikPolicy.Middleware, WardrikPolicy.new!(deny: ["shell/*"])}]

Pass a list to hold an agent to several policies, such as its org's and its own:

    middleware: [{WardrikPolicy.Middleware, [org_policy, agent_policy]}]

For each tool call, it decides by the rules and judge before the call runs. A judge asks its
model with `WardrikCore.evaluate/4`. A refused call returns the refusal as its error, so the
model can carry on.

For each model call, it checks the budgets before the call and counts the cost after.
What was spent is kept in the context's private data, so it survives restarts.

## Answering an ask

A call that asks parks on a `WardrikPolicy.Ask`. Answer it with `WardrikCore.resume/2`, keyed
by the tool call's id, or `"model"` for a model call:

    WardrikCore.resume(agent, %{"call_123" => :approve})
    WardrikCore.resume(agent, %{"call_123" => {:approve, "Checked with finance."}})
    WardrikCore.resume(agent, %{"model" => {:deny, "Over budget for today."}})

A note reaches the model beside the call's result. A reason reaches it as the call's error.
Pass `%{by: who}` as `WardrikCore.resume/3`'s metadata to record who answered.

A call parked `:in_doubt`, because it may already have run, takes the answer given for that.
The person isn't asked twice.

## Events

Each decision is set on the step's span as the `"wardrik.policy.decision"` attribute. See
`WardrikCore.Context.attribute/3`.

These events go through `WardrikCore.Event`, so they reach the agent's events sink and
`:telemetry`:

  * `[:wardrik_policy, :decision]` - every decision.
  * `[:wardrik_policy, :answer]` - every answer. Carries the `metadata` given to
    `WardrikCore.resume/3`.
  * `[:wardrik, :tool_call, :denied]` - a tool call refused by a policy or a person.
  * `[:wardrik, :interrupt, :resolved]` - an ask answered.

The first two carry `agent_id`, the step's `span`, the `call` (`nil` for a model call) and the
run's `labels`. See `WardrikCore.Context.labels/1`.

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