Subissue Orchestration

Hierarchical issue management using GitHub's native sub-issues API with automatic PR-subissue coordination.

Purpose

Subissue Orchestration enables breaking down large epics or features into smaller, trackable tasks. Uses GitHub's native sub-issues API (GA 2025) for proper parent-child relationships that appear in GitHub's UI and Projects, with markdown checklist fallback for compatibility.

Native Sub-Issues (Primary)

GitHub's native sub-issues provide:

• Proper parent-child relationships visible in GitHub UI
• Integration with GitHub Projects (filtering, grouping by parent)
• Up to 100 sub-issues per parent, 8 levels of nesting
• Cross-repository support

The sync-task-to-subissue hook automatically links created subissues using the native API.

When to Use

• Breaking down epics into implementation tasks
• Creating subtasks from a task list
• Tracking progress with automated checklists
• Managing complex feature development with multiple developers

Core Capabilities

Native Sub-Issues API

Utilities from native-subissues.ts:

• addNativeSubissue(cwd, parentIssue, subissueNumber) - Link as native sub-issue
• listNativeSubissues(cwd, parentIssue) - List native sub-issues
• removeNativeSubissue(cwd, parentIssue, subissueNumber) - Unlink sub-issue
• getParentIssue(cwd, subissueNumber) - Get parent of a sub-issue
• isNativeSubissuesAvailable(cwd) - Check if API is available

Subissue Creation

Create child issues with native linking:

PARENT=42
TITLE="Implement OAuth integration"

# Create subissue
SUBISSUE=$(gh issue create \
  --title "$TITLE" \
  --label "task" \
  --body "**Parent Issue:** #$PARENT

Implementation details for OAuth integration..." \
  --json number -q .number)

# Link as native sub-issue (preferred)
SUBISSUE_ID=$(gh api repos/{owner}/{repo}/issues/$SUBISSUE --jq '.id')
gh api repos/{owner}/{repo}/issues/$PARENT/sub_issues -X POST -f sub_issue_id=$SUBISSUE_ID

Checklist Management (Fallback)

For repos without native sub-issues, markdown checklists are still supported.

Utilities from subissue-checklist.ts:

• hasNativeSubissues(cwd, parentIssue) - Check if native sub-issues exist
• generateChecklistMarkdown(subissues) - Create checklist from array
• updateParentIssueChecklist(cwd, parentIssue, subissues) - Sync checklist
• addSubissueToChecklist(cwd, parentIssue, subissue) - Add single item
• markSubissueComplete(cwd, parentIssue, subissueNumber) - Check off item
• syncSubissueStates(cwd, parentIssue, subissueNumbers) - Sync all states

Bulk Creation

# Create multiple subissues from list
PARENT=42
TASKS=("OAuth integration" "Email auth" "Password reset" "2FA support")

for task in "${TASKS[@]}"; do
  gh issue create \
    --title "$task" \
    --label "task" \
    --body "**Parent Issue:** #$PARENT" \
    --json number -q .number
done

# Generate and update parent checklist
syncSubissueStates "$PWD" $PARENT

Examples

Create Epic with Subtasks

# Create parent epic
PARENT=$(gh issue create \
  --title "Authentication System" \
  --label "epic" \
  --body "## Subtasks

- [ ] Implement OAuth
- [ ] Implement email auth
- [ ] Add password reset
- [ ] Add 2FA support" \
  --json number -q .number)

# Create subissues
for task in "Implement OAuth" "Implement email auth" "Add password reset" "Add 2FA support"; do
  gh issue create --title "$task" --label "task" --body "**Parent Issue:** #$PARENT"
done

Auto-Sync Checklist

# Mark subissue as complete
gh issue close 43

# Update parent checklist
markSubissueComplete "$PWD" 42 43
# Changes "- [ ] #43 OAuth integration" to "- [x] #43 OAuth integration"

PR-Subissue Coordination

When using stacked PRs with subagents, PRs automatically include Closes #X to close the associated subissue when merged.

Workflow:

1. Task tool spawns subagent → sync-task-to-subissue creates subissue
2. Subagent makes changes → stacked-pr-subagent-stop creates PR
3. PR body includes Closes #subissueNumber (looked up from task-subissues.json)
4. PR merges → GitHub auto-closes the linked subissue

This provides end-to-end tracking from task → subissue → PR → merge.

Best Practices

1. Native sub-issues are preferred when available
2. Link subissues with "Parent Issue: #N" in body for compatibility
3. Use consistent labeling (epic → task hierarchy)
4. Keep subissues focused and atomic
5. Let stacked PR workflow handle PR-subissue linking automatically