chore: enhance root cause analysis for /create-bug skill (MetaMask#26722)

## **Description**

Updates the `/create-bug` Claude Code skill command to include a full
root cause analysis workflow (Step 6) with three phases:
- **6a**: Investigate root cause — trace through the code to identify
exact files, lines, and logic
- **6b**: Identify regression PRs — check git history against previous
releases
- **6c**: Scope analysis — search for same pattern across codebase, file
separate bugs for other affected features

Also updates the comment format to include all required sections.

## **Changelog**

CHANGELOG entry: null

## **Related issues**

Fixes:

[MMQA-1523](https://consensyssoftware.atlassian.net/browse/MMQA-1523)

## **Manual testing steps**

```gherkin
Feature: Create Bug Skill Root Cause Analysis

  Scenario: user runs /create-bug and opts into root cause investigation
    Given user has Claude Code open in the metamask-mobile repo

    When user runs /create-bug and files a bug report
    And user opts into root cause investigation
    Then Claude performs root cause investigation (6a)
    And Claude identifies regression PRs by comparing release branches (6b)
    And Claude performs scope analysis to find same pattern elsewhere (6c)
    And Claude posts a comment with summary, regression PRs, error flow, scope of impact, key files, suggested fix, and related bug links
```

## **Screenshots/Recordings**

### **Before**

N/A

### **After**

Run `/create-bug` in Claude Code terminal and opt into root cause
investigation to see the full 3-phase workflow.

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

[MMQA-1523]:
https://consensyssoftware.atlassian.net/browse/MMQA-1523?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: chrisleewilcox

.claude/commands/create-bug.md

@@ -124,15 +124,43 @@ For `render: shell` fields, wrap the value in a code fence:
 - Output the issue URL so the user can view it
 - Ask the user: "Would you like me to investigate the codebase for the possible root cause? (yes/no)"
 - Default is **no** — only proceed if the user explicitly says yes
-- If yes, investigate the codebase (research only — no code changes) and add a comment using:
+- If yes, perform the full **Root Cause Analysis** (Step 6)
+
+## Step 6: Root Cause Analysis
+
+When the user opts in, perform all three phases below and post a single comment on the issue with the combined findings.
+
+### 6a: Investigate the root cause
+
+- Trace the bug through the code to identify the exact files, lines, and logic causing the issue
+- Research only — no code changes
+
+### 6b: Identify regression PRs
+
+- Check `git log` history of affected files, comparing the release branch against the previous release branch
+- Identify which PRs introduced or surfaced the bug (new code, removed compensating mechanisms, refactors, etc.)
+- Note whether the issue is a new regression or pre-existing
+
+### 6c: Scope analysis
+
+- Search the codebase for the same pattern, function, or anti-pattern causing the bug
+- Identify all affected areas beyond the originally reported bug
+- If other features are impacted, file separate bug issues for each and link them
+
+### Comment format
+
+Post findings as a comment using:
 
 ```bash
 gh issue comment <issue-number> --repo MetaMask/metamask-mobile --body "..."
 ```
 
 The comment should include:
 
-- A summary of the possible root cause
-- The error flow with relevant file paths and line numbers
-- Key files table (file, line(s), description)
-- A suggested fix approach
+- **Summary** of the root cause
+- **Likely Regression PR(s)** — PR numbers, titles, authors, and explanation of what changed (or note if pre-existing)
+- **Error flow** with relevant file paths and line numbers
+- **Full scope of impact** — all affected files, hooks, and components beyond the reported bug
+- **Key files table** (file, line(s), description)
+- **Suggested fix approach**
+- **Links to related bugs** filed from the scope analysis