Day 3 at NoteDrop. The Ralph-loop fundamentals from yesterday held — sprints are sized, restarts are cheap — but a new failure mode showed up overnight. Sasha is writing agent prompts the way he writes Slack messages: 'hey can you maybe look at the pgvector thing when you get a sec'. Half of them work. The other half ship features nobody asked for, touch files nobody mentioned, and leave the test suite in a state Sasha calls 'mostly green'. The CEO wants a working demo in 30 hours and Sasha just opened a PR titled 'fix duplicate notes (+small cleanup)'. Today you teach him — and yourself — to write prompts that fail loudly before they fail silently. The discipline is TDD for agents: the failing test first, the named exit, the forbidden scope. A TDD prompt gives the agent a verifier and gives you a kill-switch.
You'll walk out able to
- Spot a vibe-prompt session in under a minute and name what's missing
- Write failing test cases an agent can run as its own verifier
- Pick the TDD-shaped prompt over the polite-email-shaped prompt — and say why
- Phrase a kill-switch tight enough that the agent stops on the first regression
- Use a forbidden-scope clause to block scope-bleed before it happens
- Drive an agent through a failing-test → minimal-fix → green loop in 3 turns
Your first task
Sasha's vibe-prompt session
9:02am. The CEO forwards a Sentry alert — 'duplicate note IDs after rapid create'. Sasha says 'on it' and fires off a prompt before you can read over his shoulder. Eleven minutes later the PR is open. You attach to the pane and scroll back.
What you'll answer
Read the session. What was missing from Sasha's prompt — and what did the agent do because of it?
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