gh-sub-issue

name	gh-sub-issue
description	Manage GitHub parent-child issue relationships using the gh-sub-issue extension. Link existing issues as sub-tasks, create new sub-issues, list relationships, and remove links. Use when working with GitHub issue hierarchies, Epic breakdowns, phased development, or when users mention sub-issues, sub-tasks, parent issues, or issue hierarchies.

GitHub Sub-Issues Management

Manage GitHub parent-child issue relationships using the gh-sub-issue extension. Link existing issues, create new sub-issues, query relationships, and maintain issue hierarchies.

Overview

gh-sub-issue is a GitHub CLI extension that provides commands for managing official parent-child relationships between GitHub issues. Unlike custom solutions that close and recreate issues, gh-sub-issue links existing issues directly while preserving their numbers.

Key Advantage: Non-destructive linking - issues keep their original numbers and history.

Installation

The extension is pre-installed in the Langstar devcontainer. To verify:

gh extension list | grep sub-issue

To install manually:

gh extension install yahsan2/gh-sub-issue

Core Commands

Link Existing Issues

Command: gh sub-issue add <parent> <child>

Links an existing issue as a sub-task of another issue without closing or recreating it.

Usage:

# Link issue #103 as sub-task of #92
gh sub-issue add 92 103

# With explicit repository
gh sub-issue add 92 103 --repo owner/repo

What it does:

• Establishes official parent-child relationship via GitHub API
• Preserves both issue numbers
• Shows child in parent's "Sub-issues" dropdown
• Shows parent reference on child issue
• Fully reversible with gh sub-issue remove

Example:

$ gh sub-issue add 92 103
Successfully linked #103 as a sub-issue of #92

Create New Sub-Issue

Command: gh sub-issue create --parent <num> --title "Title"

Creates a new issue with a parent relationship established from the start.

Usage:

# Create new sub-issue under #92
gh sub-issue create --parent 92 --title "Implement authentication"

# With body text
gh sub-issue create --parent 92 \
  --title "Add user login" \
  --body "Implement JWT-based authentication"

# With labels and assignees
gh sub-issue create --parent 92 \
  --title "Add tests" \
  --label "testing" \
  --assignee "username"

What it does:

• Creates issue with parent relationship already set
• Avoids need to link separately
• Supports full issue creation options (body, labels, assignees)

List Related Issues

Command: gh sub-issue list <issue>

Shows all related issues: children, parent, and siblings.

Usage:

# List all relationships for #92
gh sub-issue list 92

# Show only children (sub-issues)
gh sub-issue list 92 --relation children

# Show only parent
gh sub-issue list 92 --relation parent

# Show siblings (issues with same parent)
gh sub-issue list 92 --relation siblings

# Filter by state
gh sub-issue list 92 --state open
gh sub-issue list 92 --state closed
gh sub-issue list 92 --state all

# JSON output for scripting
gh sub-issue list 92 --json number,title,state

What it does:

• Queries GitHub API for issue relationships
• Displays formatted table of related issues
• Supports filtering by relation type and state
• Provides JSON output for automation

Example:

$ gh sub-issue list 92 --relation children --state open

#     TITLE                                    STATE
103   feat(cli): Add deployment management    open
104   feat(cli): Add thread management         open
105   feat(cli): Add run operations            open

Remove Link

Command: gh sub-issue remove <parent> <child> [<child2> ...]

Removes parent-child relationship without deleting issues.

Usage:

# Remove single link
gh sub-issue remove 92 103

# Remove multiple links at once
gh sub-issue remove 92 103 104 105

# Skip confirmation prompt
gh sub-issue remove 92 103 --force

What it does:

• Breaks parent-child relationship
• Keeps both issues intact
• Child issue becomes standalone again
• Supports batch operations

When to Use This Skill

Use Cases

1. Linking Existing Issues When issues were created separately but need hierarchical organization:

# You have epic #83 and phases #90-95 already created
gh sub-issue add 83 90  # Link phase 1
gh sub-issue add 83 91  # Link phase 2
gh sub-issue add 83 92  # Link phase 3

2. Creating Issue Hierarchies When planning multi-level work breakdown:

# Epic #83 → Phase #92 → Sub-tasks
gh sub-issue add 83 92                          # Link phase to epic
gh sub-issue create --parent 92 --title "Task 1"  # Create sub-task
gh sub-issue create --parent 92 --title "Task 2"  # Create sub-task

3. Querying Relationships When you need to understand issue structure:

# What are the sub-tasks of this phase?
gh sub-issue list 92 --relation children

# What's the parent epic of this issue?
gh sub-issue list 103 --relation parent

# What other issues are at the same level?
gh sub-issue list 103 --relation siblings

4. Maintaining Hierarchies When relationships need adjustment:

# Move issue #103 from parent #92 to parent #93
gh sub-issue remove 92 103
gh sub-issue add 93 103

Comparison: Old vs New Approach

Old Approach (Python Script)

Process:

1. Close child issue with comment
2. Recreate with same content but new parent
3. Child gets NEW issue number
4. All references broken

Problems:

• ❌ Issue number changes (breaks references)
• ❌ History fragmented across two issues
• ❌ Comments/discussions on original issue orphaned
• ❌ Links in PRs, docs become invalid

New Approach (gh-sub-issue)

Process:

1. Link issues via GitHub API
2. Both issues unchanged
3. Relationship established

Benefits:

• ✅ Issue numbers preserved
• ✅ History intact
• ✅ All references remain valid
• ✅ Reversible without data loss

Integration with Other Skills

With github-issue-breakdown

Use github-issue-breakdown for: Creating multiple sub-issues from task list

<!-- In issue #92 -->
## Tasks
- [ ] Task 1
- [ ] Task 2
- [ ] Task 3

Then run github-issue-breakdown to create #103, #104, #105 as sub-issues of #92.

Use gh-sub-issue add for: Linking issues created outside the breakdown workflow

# Someone created #106 manually
gh sub-issue add 92 106  # Add to the same parent

With update-github-issue-project-status

After linking issues, update project board status:

# Link sub-tasks to parent
gh sub-issue add 92 103
gh sub-issue add 92 104

# Update status in GitHub Projects
# (Use update-github-issue-project-status skill)

Workflows

Workflow 1: Create Epic with Phases

Goal: Break down large feature into phases

# Step 1: Create epic issue manually or with gh
gh issue create --title "Epic: User Authentication System" \
  --body "Complete authentication system with OAuth, JWT, and 2FA"
# Created issue #100

# Step 2: Create phase issues
gh sub-issue create --parent 100 --title "Phase 1: Research authentication options"
# Created issue #101

gh sub-issue create --parent 100 --title "Phase 2: Implement JWT authentication"
# Created issue #102

gh sub-issue create --parent 100 --title "Phase 3: Add OAuth providers"
# Created issue #103

# Step 3: Verify structure
gh sub-issue list 100 --relation children

Result: Epic #100 → Phases #101, #102, #103

Workflow 2: Retrofit Existing Issues

Goal: Add structure to issues already created

# Scenario: Issues #50-54 exist but aren't linked to epic #40

# Link all at once
for issue in 50 51 52 53 54; do
  gh sub-issue add 40 $issue
done

# Verify
gh sub-issue list 40 --json number,title

Workflow 3: Two-Level Hierarchy

Goal: Epic → Phases → Sub-tasks

# Level 1: Epic #83
# Level 2: Phase #92 (already linked to #83)

# Add sub-tasks to phase #92
gh sub-issue create --parent 92 --title "Design authentication API"
# Created #110

gh sub-issue create --parent 92 --title "Implement JWT tokens"
# Created #111

gh sub-issue create --parent 92 --title "Add authentication tests"
# Created #112

# View hierarchy
echo "Epic #83 children:"
gh sub-issue list 83 --relation children

echo "Phase #92 children:"
gh sub-issue list 92 --relation children

Result:

• Epic #83 → Phase #92
• Phase #92 → Sub-tasks #110, #111, #112

Workflow 4: Reorganize Hierarchy

Goal: Move issues between parents

# Issue #105 is under #92 but should be under #93

# Step 1: Remove from current parent
gh sub-issue remove 92 105

# Step 2: Add to new parent
gh sub-issue add 93 105

# Step 3: Verify
gh sub-issue list 105 --relation parent

Best Practices

Planning Ahead

Preferred: Use github-issue-breakdown when creating issues from task list

• Creates sub-issues correctly from the start
• Avoids manual linking work
• Maintains clean history

Acceptable: Use gh-sub-issue add when:

• Issues already exist
• Issues were created manually
• Fixing missing relationships

Consistent Hierarchy

Establish clear levels:

• Level 1: Epic (major feature)
• Level 2: Phase (implementation stage)
• Level 3: Task (specific work item)

Example structure:

#83 Epic: CLI Implementation
├── #90 Phase 1: Research
├── #91 Phase 2: Design
└── #92 Phase 3: Implementation
    ├── #103 Task: Deployment management
    ├── #104 Task: Thread management
    └── #105 Task: Run operations

Documentation

Always document hierarchy in epic issue:

## Epic Structure

### Phases
- #90 - Phase 1: Research
- #91 - Phase 2: Design
- #92 - Phase 3: Implementation

### Sub-tasks (Phase 3)
- #103 - Deployment management
- #104 - Thread management
- #105 - Run operations

Verification

After creating hierarchy:

# Check parent's children
gh sub-issue list <parent> --relation children --state all

# Check child's parent
gh sub-issue list <child> --relation parent

# Verify structure is correct before proceeding with implementation

Troubleshooting

"Extension not found"

Cause: gh-sub-issue not installed

Solution:

gh extension install yahsan2/gh-sub-issue
gh extension list | grep sub-issue

"Issue not found"

Cause: Issue number doesn't exist or no repository access

Solution:

• Verify issue exists: gh issue view <number>
• Check repository: gh sub-issue add <parent> <child> --repo owner/name
• Confirm access permissions

"Could not create relationship"

Cause: GitHub API limitations or permissions

Solution:

• Verify both issues exist: gh issue view <number>
• Check authentication: gh auth status
• Ensure repository write access: gh auth refresh -s repo

"Operation failed"

Cause: Various GitHub API errors

Solution:

• Check issue state (can't link closed issues in some cases)
• Verify you're in correct repository
• Try with explicit repo: --repo owner/name
• Check for circular dependencies (A parent of B, B parent of A)

Environment Requirements

Prerequisites:

• gh CLI installed and authenticated
• Repository access with write permissions
• gh-sub-issue extension installed (v0.5.1+ recommended)

Verification:

# Check gh CLI
gh --version

# Check authentication
gh auth status

# Check extension
gh extension list | grep sub-issue

# Test command
gh sub-issue --help

Command Reference

Quick Reference Table

Command	Purpose	Preserves Issue #	Example
add	Link existing issues	✅ Yes	gh sub-issue add 92 103
create	Create new sub-issue	N/A (new)	gh sub-issue create --parent 92 --title "Task"
list	Query relationships	N/A (read-only)	gh sub-issue list 92
remove	Unlink issues	✅ Yes	gh sub-issue remove 92 103

Common Flag Combinations

# Link with explicit repo
gh sub-issue add 92 103 --repo owner/name

# Create with all options
gh sub-issue create --parent 92 \
  --title "Title" \
  --body "Description" \
  --label "bug" \
  --label "priority:high" \
  --assignee "username"

# List with filters
gh sub-issue list 92 \
  --relation children \
  --state open \
  --json number,title,state

# Remove multiple without confirmation
gh sub-issue remove 92 103 104 105 --force

See Also

• github-issue-breakdown - Create sub-issues from task lists in parent issue
• update-github-issue-project-status - Update GitHub Projects status fields
• GitHub Workflow Documentation - @docs/dev/github-workflow.md
• gh-sub-issue repository - https://github.com/yahsan2/gh-sub-issue