issue-splitter Skill

Analyze a single GitHub issue for distinct concerns, classify each by recipe route, and—when concerns route differently—create focused sub-issues with bidirectional cross-references. The parent issue is left open as a tracking issue.

This skill is intentionally lightweight: concern analysis is performed as in-context LLM reasoning. No subagents are used.

When to Use

• Invoked by triage-issues as a parallel per-issue pre-classification step
• Directly by a user who suspects an issue mixes bug fixes and feature requests
• With --dry-run to preview what would be split without mutating GitHub

Arguments

/autoskillit:issue-splitter --issue N [--url URL] [--repo owner/repo] [--no-label] [--dry-run] [--max-sub-issues N]

• --issue N — issue number to analyze (required, OR --url)
• --url URL — full GitHub issue URL (alternative to --issue; number extracted automatically)
• --repo owner/repo — target repository (optional; defaults to gh repo context)
• --no-label — skip all GitHub label/comment/create mutations; only emit analysis result
• --dry-run — analyze and show what would be split, but skip GitHub mutations
• --max-sub-issues N — maximum sub-issues to create (default: 4)

Critical Constraints

NEVER:

• Use subagents — concern analysis is in-context LLM reasoning, not subagent delegation
• Close the parent issue — it becomes a tracking issue
• Apply batch:N labels to any GitHub object
• Create files outside temp/issue-splitter/ (for any dry-run reports)

ALWAYS:

• Use --force on all gh label create calls for idempotency
• Respect --no-label and --dry-run (skip all GitHub mutations when either is set)
• Cap sub-issues at --max-sub-issues (default: 4)
• Emit the result block even on dry-run or no-split decisions

Workflow

Step 0 — Parse Arguments

Extract from ARGUMENTS:

• --issue N → issue_number = N
• --url URL → extract number with echo URL | grep -oE '[0-9]+$' → issue_number
• --repo owner/repo → repo = "owner/repo" (omit --repo flag from gh commands if not provided)
• --no-label → no_label = true
• --dry-run → dry_run = true
• --max-sub-issues N → max_sub_issues = N (default: 4)

Fail fast if neither --issue nor --url is provided:

decision = error, rationale = "--issue N or --url URL is required"

Step 1 — Authenticate

gh auth status

If auth fails, emit result block with decision=error, rationale="gh auth failed" and exit.

Step 2 — Fetch Issue

gh issue view {N} [--repo {repo}] --json number,title,body,labels,url,state

Handle these guard conditions:

• If issue not found: emit decision=error, rationale="issue not found" and exit.
• If state == "closed": emit decision=no-split, rationale="issue is closed" and exit.
• If the label list contains "split": emit decision=no-split, rationale="already split" and exit.

Step 3 — LLM Concern Analysis

Analyze the issue title + body to enumerate distinct concerns. For each concern identify:

• Summary: one sentence describing the concern
• Type: bug | feature | investigation | refactor | docs
• Recipe route: classify using the behavioral heuristic:
  • Existing behavior broken / error traceback / unclear root cause → recipe:remediation
  • New capability / enhancement / clearly unimplemented feature → recipe:implementation
  • "X doesn't support Y" / missing config / missing validation → recipe:implementation
  • "X crashes" / wrong result / unknown cause → recipe:remediation
• Affected component(s): brief list

This step is in-context reasoning only — do not spawn subagents.

Step 4 — Split Decision

Apply these rules in order:

1. If only 1 concern identified → no-split, proceed to Step 5.
2. If all concerns share the same recipe route → no-split, proceed to Step 5.
3. If concerns route differently → split, proceed to Step 6.

Cap enforcement: If more than max_sub_issues distinct concerns are found, merge the lowest-priority same-route concerns into a single combined sub-issue rather than dropping them.

Step 5 — No-split Path

Emit result block:

---issue-splitter-result---
{
  "decision": "no-split",
  "original_issue": {"number": N, "url": "https://github.com/..."},
  "route": "recipe:implementation",
  "rationale": "All concerns route to recipe:implementation"
}
---/issue-splitter-result---

Exit. No GitHub mutations.

Step 6 — Dry-run / no-label Path

If --dry-run or --no-label is set, emit the split result block with sub_issues populated with what would be created, but skip all GitHub mutations. Proceed directly to Step 9.

Step 7 — Create Sub-issues

For each concern (up to max_sub_issues):

# Ensure the split-from label exists (idempotent)
gh label create "split-from:#N" --force \
  --description "Sub-issue created from parent #N" \
  --color "e4e669" [--repo {repo}]

# Ensure the recipe route label exists (idempotent)
gh label create "recipe:implementation" --force \
  --description "Route through implementation recipe" \
  --color "0E8A16" [--repo {repo}]
# or:
gh label create "recipe:remediation" --force \
  --description "Route through remediation recipe" \
  --color "D93F0B" [--repo {repo}]

# Create the sub-issue
gh issue create \
  --title "{concern summary} (from #{N})" \
  --body "{concern description}\n\n---\n_Split from #{parent_url}_" \
  --label "split-from:#N" \
  --label "recipe:{route}" \
  [--repo {repo}]

Capture the new issue URL and number from stdout.

Step 8 — Label Parent and Add Tracking Comment

# Ensure the split label exists (idempotent)
gh label create "split" --force \
  --description "Issue decomposed into focused sub-issues" \
  --color "0075ca" [--repo {repo}]

# Label the parent as split
gh issue edit {N} --add-label "split" [--repo {repo}]

# Add tracking comment with cross-references
gh issue comment {N} \
  --body "## Split into sub-issues

This issue covers multiple concerns and has been decomposed into focused sub-issues:

{bullet list of sub-issue links with route labels}

This issue remains open as a tracking issue." \
  [--repo {repo}]

Do not close the parent — it serves as a tracking issue for all sub-issues.

Step 9 — Emit Result Block

Output to stdout for triage-issues subagent parsing:

Split result:

---issue-splitter-result---
{
  "decision": "split",
  "original_issue": {"number": N, "url": "https://github.com/.../issues/N"},
  "sub_issues": [
    {
      "number": M,
      "url": "https://github.com/.../issues/M",
      "route": "recipe:implementation",
      "concern": "One-sentence summary of this concern",
      "title": "Concern title (from #N)"
    }
  ],
  "rationale": "Issue contained both a bug (remediation) and a feature request (implementation)"
}
---/issue-splitter-result---

No-split result:

---issue-splitter-result---
{
  "decision": "no-split",
  "original_issue": {"number": N, "url": "https://github.com/.../issues/N"},
  "route": "recipe:implementation",
  "rationale": "All concerns route to recipe:implementation"
}
---/issue-splitter-result---

Error result:

---issue-splitter-result---
{
  "decision": "error",
  "original_issue": {"number": N, "url": null},
  "rationale": "Description of what went wrong"
}
---/issue-splitter-result---

Output Location

Dry-run reports (if any): temp/issue-splitter/

Error Handling

• Auth failure → emit error result, exit
• Issue not found → emit error result, exit
• gh issue create fails → log the failure, emit partial split result with "error" noted in rationale, do not abort silently