You are helping me build the following AI agent workflow.

## Goal
Evaluate Support Ticket Classifier: Runs support ticket test cases through the classifier to measure exact match accuracy against known labels.

## Specification
- What it does: Measure your support ticket classifier's accuracy by running test cases against known labels to find exactly where it makes mistakes. You get precise performance scores using n8n and OpenAI Chat Model to validate how well the system predicts correct answers.
- Trigger: Run manually (Manual · on demand)
- Autonomy: You stay in control
- Expected setup effort: about an afternoon
- Tools/services involved:
  - n8n: Workflow orchestration and evaluation trigger
  - OpenAI Chat Model: Classifying tickets by category and urgency
  - Evaluation Node: Scoring AI predictions against expected labels

## Known pitfalls, handle each one explicitly in your implementation
1. The OpenAI model may output extra text like 'The answer is' which breaks exact match evaluation, so add a post-processing step to strip non-label characters.
2. Evaluation nodes in n8n can fail silently if input data types mismatch, so ensure the expected label field is always a string and not null.
3. Hardcoded category names in the prompt may drift from your actual database labels, so use dynamic variables to inject the current list of valid categories into the system prompt.

## Reference implementation
https://n8n.io/workflows/15133 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/evaluate-support-ticket-classifier/ via usecasesforagents.com