2 min lesson
Anchor on their stack, never a clean-room toy
Answer "Why is demoing on a 15-year Java monolith more persuasive than a clean Next.js scaffold, even though the scaffold demo runs more smoothly?" Use one lesson detail to support it.
Step 1 of 2
Anchor on THEIR stack, never a clean-room toythe single biggest credibility lever
Demo on a fresh Next.js scaffold and every senior in the room mentally files it under "toy," then stops listening. The repo you drive must look like their world: a 15-year Java monolith, a Spring app with a 4,000-line service class, a nine-minute build, a test suite that fails intermittently on integration. Messy is the point. The harder and uglier the repo, the more the audience leans in, because that's the codebase they actually have to live in on Monday.
A real, gnarly monolith. Ideally a fork of their repo (under their security review) or a faithful analog if that's not possible in time.
Legacy patterns the seniors will recognize: god classes, no tests on the path you touch, a module boundary nobody can explain.
Their ticketing system, their CI, their PR template.
A todo app, a fresh create-react-app, anything green-field.
A repo you've secretly pre-warmed so the agent comes out suspiciously perfect.
Anything where the audience can't recognize their own pain.
"I'm not going to scaffold a todo app and call it a revolution. Let's open the ugliest 15-year-old service in your monolith and do real work in it - because that's the codebase your engineers actually wake up to."
Pre-warming the repo so the agent looks flawless is the fastest way to lose a senior engineer's trust. They can smell a rehearsed-to-perfection run.
If you cannot get their repo in time, say so explicitly and use the closest public analog - never pretend an analog is theirs.