Title: I gave myself 30 minutes to ship a deterministic grounding gate—5 tests, standard library only

Title: I gave myself 30 minutes to ship a deterministic grounding gate—5 tests, standard library only

I wanted to finish one small engineering task instead of opening another oversized AI project.

I built a two-file Python “grounding gate” that validates LLM-shaped JSON before another system accepts it. It checks:

• nonempty answers
• recognized evidence IDs
• confidence bounded from 0.0–1.0
• verified claims requiring evidence
• unverified claims reporting exactly 0.0 confidence

I used Codex for implementation, but defined the contract, scope and acceptance tests first. No API, framework, UI, network calls or dependencies.

Final result:

Ran 5 tests in 0.002s
OK

The runtime is not the interesting part—the project is tiny. The useful lesson was making the workflow deterministic:

contract → implementation → independent test → stop

That felt like a healthier version of vibe coding: AI can write quickly, but executable tests decide whether the work is actually finished.

What is the smallest verification gate you use in AI-assisted development?