# ListPipelineItemCommentsByItem

## Overview

Lists all comments on a given item, ordered by `createdAt` ascending (oldest first). Returns an empty list when the item has no comments.

## Business Rules

- PipelineItem ID is required and must reference an existing item
- Results are ordered by `createdAt` ascending
- Returns an empty list when the item has no comments
- Deleted comments are excluded from the result

## Process Flow

```mermaid
flowchart TD
    A[Receive listPipelineItemCommentsByItem input] --> B{PipelineItem exists?}
    B -->|No| C[Return ITEM_NOT_FOUND]
    B -->|Yes| D[Fetch comments where itemId matches]
    D --> E[Order by createdAt ascending]
    E --> F[Return list of PipelineItemComment]
```

## External Dependencies

- None

## Error Scenarios

- **ITEM_NOT_FOUND**: Specified item ID does not exist

## Test Cases

- returns empty list for an item with no comments
- returns comments ordered by createdAt ascending
- excludes deleted comments from result
- returns error when item does not exist