Claude for Cheap bulk LLM automation

I'm building a production LLM task. Help me draft the prompt and an eval set.

Task description:
"""
{{describe the task: input, expected output format, what 'correct' means}}
"""

Output, in this order:

1. **System prompt** — the production prompt that will run on every input. Strict output format. No conversational hedging.
2. **30-row eval set** — table of {input, expected output, why}. Cover the easy cases, the edge cases, and 5 deliberately adversarial inputs.
3. **Eval rubric** — exactly how I'll score outputs against the expected outputs. Define partial credit if useful.
4. **Smoke test plan** — the 3 minimum-viable runs I should do before sending real volume to a cheaper model.

The point of all this: I'm going to run the prompt on 100k inputs/month via DeepSeek's API. I want a prompt that survives the swap from Claude (where I'm authoring it) to DeepSeek (where it'll run).