# ListPipelineLabelsByPipeline

## Overview

Lists all labels defined on a given pipeline, ordered by `name` ascending. Returns an empty list when the pipeline has no labels yet.

## Business Rules

- Pipeline ID is required and must reference an existing pipeline
- Results are ordered by `name` ascending
- Returns an empty list when the pipeline has no labels

## Process Flow

```mermaid
flowchart TD
    A[Receive listPipelineLabelsByPipeline input] --> B{Pipeline exists?}
    B -->|No| C[Return PIPELINE_NOT_FOUND]
    B -->|Yes| D[Fetch labels where pipelineId matches]
    D --> E[Order by name ascending]
    E --> F[Return list of PipelineLabel]
```

## External Dependencies

- None

## Error Scenarios

- **PIPELINE_NOT_FOUND**: Specified pipeline ID does not exist

## Test Cases

- returns labels ordered by name ascending
- returns empty list for a pipeline with no labels
- returns error when pipeline does not exist