Support Ticket Auto-Categorization System Designer

Help me design an automated support ticket categorization and routing system for my team.

**Product/service type:** [e.g., SaaS platform, e-commerce, mobile app]
**Current ticket volume:** [tickets per day/week]
**Support channels:** [e.g., email, chat, in-app, social media]
**Current categories/tags (if any):** [list existing categories]
**Support team structure:** [e.g., Tier 1 general, Tier 2 technical, Tier 3 engineering]
**Helpdesk tool:** [e.g., Zendesk, Intercom, Freshdesk, Help Scout]
**Top 5 most common ticket types:** [list them]
**Current pain points:** [e.g., misrouted tickets, slow first response, inconsistent tagging]

Please provide:
1. **Category taxonomy** — a hierarchical tagging system (primary category → subcategory → issue type) with 15-25 total leaf categories
2. **Priority scoring matrix** — rules for auto-assigning priority (P1-P4) based on keywords, customer tier, sentiment, and issue type
3. **Routing rules** — which team/agent gets each category, with escalation triggers
4. **AI classification prompt** — a ready-to-use prompt template that takes a ticket subject + body and outputs category, priority, sentiment, and suggested first response
5. **Edge case handling** — how to handle ambiguous tickets, multi-issue tickets, and tickets in other languages
6. **Success metrics** — KPIs to track classification accuracy, routing efficiency, and time savings
7. **Implementation roadmap** — phased rollout plan with human-in-the-loop validation