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The AI Tech Lead Path
The path
2220 min read · 250 XP

Capstone: build an eval harness

Ship the keystone artifact — and your calling card.

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Time to build. Create a reusable, CI-integrated eval harness for one real AI feature. This is the single most valuable artifact you can own as a lead: it makes quality measurable and becomes the standard other teams adopt.

Key ideas

  1. 1

    Done means: a golden dataset, automated scoring, a CI gate that fails on regression, and a score-over-time view — reusable by other teams.

  2. 2

    Ground it in error analysis on real outputs, not generic benchmarks.

  3. 3

    Include cost & latency, not just quality.

  4. 4

    Make it a template others can copy: clear README, swappable dataset and scorers.

Build steps

  • Pick one AI feature and collect 50–100 representative inputs (include edge cases).
  • Do error analysis; define 3–6 checks (assertions, rubric, or calibrated LLM-judge).
  • Implement a runner that scores the dataset and outputs a report (quality, cost, latency).
  • Add a CI job that fails the build when scores drop below a threshold.
  • Write a README so another team can point it at their feature in under an hour.

Stretch goals

  • Pairwise comparison vs a baseline; track win-rate.
  • Pull a sample of production traffic into the dataset automatically.

Watch

Why AI evals are the hottest new skillHusain & Shankar
Building an eval harness (promptfoo / Braintrust)Find it on YouTube →

Do the work

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Test yourself

Question 1 / 2

What makes this harness valuable beyond your own feature?

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