DevLoop Runner

Introduction

When working on a single issue, related problems have a way of surfacing one after another.

While fixing a bug, you discover the same pattern exists elsewhere
While implementing a feature, you realize additional tasks are needed
During code review, improvement suggestions come up that deserve their own issues

Manually creating issues for each of these "derived tasks" is tedious. But if you ignore them, they become impossible to track later.

DevLoop Runner's Sub Issue mode solves this problem. Starting from a parent issue, AI analyzes the codebase and the issue's content to automatically file derived tasks as child issues.

What Is Sub Issue?

Sub Issue is the fourth mode in DevLoop Runner's Issue Run.

You provide the URL of an existing GitHub issue (the parent issue) along with a description of what kind of child issues you want to create. AI then analyzes the parent issue's content and the repository's codebase, filing related tasks as new issues.

How It Differs from Create Issue

Let's clarify the difference between Sub Issue and Create Issue, both part of Issue Run.

	Create Issue	Sub Issue
Starting point	Entire repository	Specific parent issue
Purpose	Detect problems across the codebase	File tasks derived from a parent issue
Input	Repository name + category	Parent issue URL + description
Use case	Regular code health checks	Managing related tasks found during work

While Create Issue takes a bird's-eye view of the repository to find problems, Sub Issue digs deeper into a specific issue to discover tasks that stem from it.

The Four Issue Run Modes

Issue Run consists of four modes:

Mode	Role	Details
Create Issue	Analyzes a repository and creates issues for improvements	Create Issue Guide
Rewrite Issue	Rewrites existing issues to improve clarity	Rewrite Issue Guide
Close Issue	Analyzes and closes stale issues	Close Issue Guide
Sub Issue	Files derived tasks as child issues from a parent issue	This article

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Sub Issue was added to this cycle to efficiently manage "derived tasks" that emerge after implementation work with Dev Run.

How to Use

Step 1: Enter the Parent Issue URL

Navigate to the Run page and select the "Issue Run" tab
Choose "Sub Issue" from the mode selection (look for the cyan branch icon)
Enter the parent GitHub issue URL in the Issue URL field

https://github.com/owner/repo/issues/123

The parent issue's content becomes the basis for AI analysis. The more detailed the issue description, the more accurate the generated child issues will be.

Step 2: Describe the Sub Issues You Want

In the "Sub Issue Description" field, describe what kind of child issues you want to create (1–1,000 characters, required).

Examples:

"Investigate whether the same bug pattern exists in other modules related to this fix, and file separate issues for each occurrence"
"Identify prerequisite tasks needed for this feature implementation (DB migrations, API changes, frontend work, test plans) and create individual issues"
"File separate issues for the UI improvements pointed out during review"

The more specific your description, the better AI can generate child issues that match your intent.

Step 3: Select an Issue Type (Optional)

Optionally, select the type of child issues to generate.

Type	Use for
Bug	Filing derived bugs
Task	Filing related tasks and work items
Enhancement	Filing feature improvement proposals

If you don't select a type, AI will determine the appropriate type based on the content. Only select one if you want to limit the scope to a specific kind of issue.

Step 4: Execute and Review Results

Select a GitHub account
Optionally add a custom instruction (see below)
Click "Start Sub Issue"

After execution completes, review results on the job detail page:

List of created child issues
Links to each issue
Content that clearly references the parent issue

Use Cases

Filing Related Bugs Found During Bug Fixes

While investigating a bug, you may discover the root cause affects multiple areas.

Example: Working on an issue to fix an authentication bug

→ Use Sub Issue with: "Investigate whether the same authentication pattern exists in other endpoints and file issues for any occurrences"

AI analyzes related code and files child issues for each location with similar problems.

Identifying Related Tasks for Feature Implementation

When implementing a large feature, it's crucial to identify prerequisite tasks upfront.

Example: An issue to add a new notification feature

→ Use Sub Issue with: "Identify prerequisite work for this feature (API design, DB changes, frontend integration, test planning) and create separate issues for each"

AI organizes the related tasks needed for implementation and files each as an independent issue.

Converting Review Feedback into Trackable Issues

Turn improvement suggestions from code reviews or retrospectives into trackable issues.

Example: A PR review pointed out that "error handling should be improved"

→ Use the original issue as the parent and run Sub Issue with: "File issues for the error handling improvements identified during review"

AI identifies specific areas for improvement and files them as actionable issues.

Workflow with Dev Run

Child issues created by Sub Issue can be passed directly to Dev Run for automatic implementation.

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The workflow:

Implement the parent issue with Dev Run → a PR is created
Additional tasks are discovered during review
Use Sub Issue to file derived tasks as child issues
Implement each child issue with Dev Run in sequence

This combination lets you efficiently cycle from discovering derived tasks to implementing them.

Custom Instruction Examples

Sub Issue includes an optional Custom Instruction field. By providing additional instructions to the AI, you can control the accuracy and direction of generated child issues.