Lesson 01 · spec → eval rubricwhy first?
We extract the spec before writing a single line of UI. Reason: that same spec doubles as the LLM-as-judge rubric in stage 4. One artefact, two jobs.
jobs_to_be_done.functional → judge.criterion[0]
Paste a job-posting URL. WhyC builds a working Next.js preview in under a day — and explains every design choice as the agents make it. Each tooltip is a lesson YC charges 7% equity for.
The agent narrates its own reasoning as it works. Hover a card for the trace span ID.
We extract the spec before writing a single line of UI. Reason: that same spec doubles as the LLM-as-judge rubric in stage 4. One artefact, two jobs.
jobs_to_be_done.functional → judge.criterion[0]
Generating OKLCH design tokens before components means later regenerations stay visually coherent — the loop can rewrite a flow without re-skinning the whole app.
--accent: oklch(72% 0.19 55) // parodic, not trademarked
Cloud Run scale-to-zero matches the spec's usage_frequency: episodic. A founder who pastes a URL once a week shouldn't pay for an idle VM.
The loop targets flows scoring under threshold, not the whole app. This is the difference between self-improvement and thrash — and the reason Phoenix traces matter.
Three takeaways the agent earned by doing — not by reading a Substack.