# Distinguish a wrong carrier from other refusals

## Intent

I want to explain why an attempt did not change the state, without mixing reasons.

## Wrong form and why it stays silent

```text title="Incorrect form"
// Любая невалидная попытка якобы есть TRANSITION_CARRIER_TYPE_MISMATCH.
```

The code applies only to a mismatch with on Filed. Other reasons are read from procedure_step. Presentation to an entity without procedure_instance is a separate EVENT_OUTSIDE_PROCEDURE.

## Correct form

```law
language "law.core" version "0.2";
package recipes.k.r07 version "0.1.0";
namespace "urn:recipe:k-procedures:07";

entity Application;
event Filed { }
event ElectronicFiled: Filed { }
event Other { }
relation ready(app: Application);
relation approved(app: Application);
procedure Filing(app: Application) {
    state Draft initial;
    state Done terminal;
    transition Submit { from Draft; to Done; on Filed; when ready(app); requires approved(app); }
}
```

## Frozen execution scene

P and Q in the table are different instances; E1/E2/E3 are carriers with an explicitly given time.
All identifiers and instants are pinned in the scenes.

| Events and facts | Question | Answer |
|---|---|---|
| foreign carrier | `truth(current_state(P,Done))` | `truth_status == NEITHER;` / `COMPUTED` |
| state preserved | `truth(current_state(P,Draft))` | `truth_status == TRUE_ONLY;` / `COMPUTED` |
| false guard with the right type | `truth(current_state(P,Done))` | `truth_status == NEITHER;` / `COMPUTED` |
| no instance | `truth(current_state(P,Done))` | `truth_status == NEITHER;` / `COMPUTED` |
| on removed | `truth(current_state(P,Done))` | `truth_status == TRUE_ONLY;` / `COMPUTED` |
| repeat from a left state | `why_not(valid_transition(P,Submit,Filed { id: "urn:recipe:k:N:E2", time: @2026-09-03T09:00:00Z }))` | `blocked_by("urn:recipe:k-procedures:07#Filing/Submit","from");` / `COMPUTED` |

```law
test "foreign carrier leaves neither" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert procedure_instance(entity_ref("urn:recipe:k-procedures:07:p"));assert ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Other { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });
    }
    evaluate truth(current_state(entity_ref("urn:recipe:k-procedures:07:p"),Done));
    expect truth_status == NEITHER;
    expect evaluation_status == COMPUTED;
    expect issue(TRANSITION_CARRIER_TYPE_MISMATCH);
}
```

```law
test "draft state survives foreign carrier" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert procedure_instance(entity_ref("urn:recipe:k-procedures:07:p"));assert ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Other { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });
    }
    evaluate truth(current_state(entity_ref("urn:recipe:k-procedures:07:p"),Draft));
    expect truth_status == TRUE_ONLY;
    expect evaluation_status == COMPUTED;

}
```

```law
test "false guard blocks despite right type" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert procedure_instance(entity_ref("urn:recipe:k-procedures:07:p"));assert not ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Filed { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });
    }
    evaluate truth(current_state(entity_ref("urn:recipe:k-procedures:07:p"),Done));
    expect truth_status == NEITHER;
    expect evaluation_status == COMPUTED;
    expect not issue(TRANSITION_CARRIER_TYPE_MISMATCH);
}
```

```law
test "missing instance answers neither" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Filed { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });
    }
    evaluate truth(current_state(entity_ref("urn:recipe:k-procedures:07:p"),Done));
    expect truth_status == NEITHER;
    expect evaluation_status == COMPUTED;
    expect issue(EVENT_OUTSIDE_PROCEDURE);
}
```

```law
test "removed on admits other carrier" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert procedure_instance(entity_ref("urn:recipe:k-procedures:07:p"));assert ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Other { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });
    }
    evaluate truth(current_state(entity_ref("urn:recipe:k-procedures:07:p"),Done));
    expect truth_status == TRUE_ONLY;
    expect evaluation_status == COMPUTED;

}
```

```law
test "repeat from abandoned state names from" {
    given {
        context {
            legal_time @2026-09-13T09:00:00Z;
            decision_time @2026-09-13T09:00:00Z;
            knowledge_time @2026-09-13T09:00:00Z;
            timezone "UTC";
        }
        assert procedure_instance(entity_ref("urn:recipe:k-procedures:07:p"));assert ready(entity_ref("urn:recipe:k-procedures:07:p")); assert approved(entity_ref("urn:recipe:k-procedures:07:p"));assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Filed { id: "urn:recipe:k-procedures:07:E1", time: @2026-09-02T09:00:00Z });assert attempted_transition(entity_ref("urn:recipe:k-procedures:07:p"), Submit, Filed { id: "urn:recipe:k-procedures:07:E2", time: @2026-09-03T09:00:00Z });
    }
    evaluate why_not(valid_transition(entity_ref("urn:recipe:k-procedures:07:p"),Submit,Filed { id: "urn:recipe:k-procedures:07:E2", time: @2026-09-03T09:00:00Z }));
    expect blocked_by("urn:recipe:k-procedures:07#Filing/Submit","from");
    expect evaluation_status == COMPUTED;

}
```

```python
>>> import runpy
>>> check = runpy.run_path("docs/recipes/k-procedures/resources/check.py")
>>> check["check_steps"](https://github.com/arxohq/law/blob/master/docs/recipes/k-procedures/7)
'К7: причины шагов и отсутствие лишних предупреждений проверены; lawc = lawref'
```

## Counterfactual

Mutation check — LDC-E1344.

Original fragment:

```text
on Filed;
```

Replacement:

```text
on ready;
```

Scenes with a condition removed are marked separately; the same inputs get a different outcome.

## Boundary

A warning does not block computation; an order fatal from [Refuse when the order is undefined](/recipes/k-procedures/simultaneous-events/) does. A non-event in the carrier position is static E1347, and an unsuitable event type is a regular runtime outcome. A subtype is allowed — see [Check event type and transition conditions](/recipes/k-procedures/event-conditions/).