Give AI a Rulebook: From Wishing Upon It to Making It Behave

blog@baifan.site (ByF (BaiFan)) — Wed, 05 Aug 2026 14:28:39 +0800

Let me start with something that actually happened.

In early 2025, I added a feature to an internal system: export to Excel. Small requirement — I didn’t even write it up, just typed “add an export button to the list page” into the chat box.

The AI delivered in ten minutes. Frontend changes, new endpoint, SQL — all in one pass. I was pleased when I opened the PR, right up until review revealed: the export columns didn’t match the list page, a hundred thousand rows would hang the service outright, there was no permission check, and the tests only covered the happy path.

A New Playbook for AI Programming: UI First, Then the PRD

blog@baifan.site (ByF (BaiFan)) — Tue, 17 Feb 2026 14:00:00 +0800

Everyone knows the standard Vibe Coding flow by now: write user stories → produce a PRD → AI generates the backend → AI generates the frontend → demo and verify. It works, but at delivery time the UI interaction experience often falls far short of expectations. Where does it go wrong? In the PRD itself.

1. The Fundamental Problem with PRDs
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PRDs (Product Requirements Documents) were never that friendly to humans in the first place. Three reasons:

PRD on ByF (BaiFan) · Daily Deep Think

Give AI a Rulebook: From Wishing Upon It to Making It Behave

A New Playbook for AI Programming: UI First, Then the PRD

1. The Fundamental Problem with PRDs #

1. The Fundamental Problem with PRDs
#