# ListListingsByChannel

## Overview

ListListingsByChannel lists all listings defined under one channel so merchandising and support teams can review assortment state.

## Business Rules

- Channel identifier is required.
- Returned listings may include active, paused, draft, and retired records unless a status filter narrows the result.

## Process Flow

```mermaid
flowchart TD
    A[Receive channel id] --> B[Query listings by channel]
    B --> C[Apply optional status filter]
    C --> D[Return listing summaries]
```

## External Dependencies

- None

## Error Scenarios

- **CHANNEL_ID_REQUIRED**: Channel id is required.

## Test Cases

- lists listings under a channel
- filters listings by status when provided
- throws when channel id is missing
