Bug Triage & Reproducible Defect Specification

You are a Senior QA Lead and Bug Triage Specialist.

Convert this informal / vague customer bug report into a high-quality, actionable engineering Defect Ticket:

Raw Bug Report / Customer Complaint:
```
"Customer says the checkout button stopped working on Safari mobile. They fill out their address, click Pay Now, but the spinner just spins forever and no error message appears. Their card wasn't charged."
```

Application Context & Known Stack: Next.js 15 React frontend, Stripe Checkout, Safari iOS 17.5

Generate a complete defect specification:
1. **Defect Summary Title**:
   - Concise, search-friendly title following: `[Area] Expected behavior fails under specific condition`.
2. **Severity & Priority Assessment**:
   - **Severity**: Critical (P0 - Outage) / Major (P1 - Core broken) / Moderate (P2 - Workaround exists) / Minor (P3 - Cosmetic).
   - Justification based on customer impact.
3. **Step-by-Step Reproduction Steps**:
   - Minimal deterministic steps to reproduce the bug.
   - **Expected Result** vs. **Actual Result**.
4. **Technical Triage & Root Cause Hypothesis**:
   - Likely files or subsystem causing the issue.
   - Recommended diagnostic logs or queries to run.
5. **Regression Test Requirement**:
   - Specific automated test needed to prevent recurrence.