Here's why AI starts going wrong mid-build.
You start a project, things are going well, and then somewhere around week two the AI starts contradicting itself. It forgets the schema it wrote. It suggests an approach that breaks something you already built. You paste context back in, it works for a bit, then drifts again.
This isn't a model problem. It's a context problem. The longer a session gets, the more the model is holding in memory — and the more it starts filling gaps with guesses instead of facts. That's hallucination. Not stupidity, just overload.
The fix is simple. Before you touch any code, you create three files. A PRD.md, a DESIGN.md, and a TASKS.md. Every serious project I've shipped has these. Every project I've regretted skipping them on has shown it.
your-project/ ├── PRD.md # The "What" and "Why" ├── DESIGN.md # The "How" (Architecture) └── TASKS.md # The "Step-by-Step" (Roadmap)
The PRD File
PRD stands for Product Requirements Document. Forget the corporate name — it's just a markdown file that captures everything about what you're building. The problem you're solving, who it's for, every feature with enough description that someone who's never seen your product could understand what it does, and the key user flows.
This is what you paste at the start of every new AI session. It gets the model up to speed in 30 seconds so it's never guessing about your product.
PRD.md
Product RequirementsProblem[What breaks without this? One paragraph.]User[Specific. Not "developers" — "solo founders building SaaS who use AI coding tools."]Features
Feature A: [what it actually does]
Feature B: [same — be specific]
User Flows
Lands on homepage → sees value prop → clicks Get Started
Onboarding → [step by step]
Core loop → [the thing they come back for]Keep it honest and updated. If a feature changes, update the PRD. It's your source of truth and the AI should always be working from it.
The Design File
This is the technical blueprint. Not what you're building — how. Folder structure, database schemas, the stack you're using, API conventions, and any architectural decisions with a quick note on why you made them.
That last part matters more than people think. AI will often "fix" something that wasn't broken if it doesn't understand why you built it that way. A one-line comment saves you from undoing 20 minutes of work.
DESIGN.md
Design DocumentStack
Frontend: Next.js (App Router)
Backend: Express + BullMQ + Redis
Database: Supabase / PostgreSQL
Storage: AWS S3
Auth: ClerkUpdate this file every time the architecture changes. A stale design file is worse than no design file — the AI will build confidently on top of something that no longer exists.
The Task File
This is the one most people skip. It's also the most important one.
The task file breaks your entire build into small, specific, completable chunks. Not "build auth." More like: "set up Clerk, protect the dashboard route, redirect unauthenticated users to login." One task should fit in one session comfortably.
When a task is done, you check it off. Next session, you paste the PRD, the Design file, and point at the next unchecked task. The AI has exactly what it needs and nothing extra clogging the context window.
TASKS.md
Task ListPhase 1: Foundation
[x] Init project with TypeScript
[x] Set up Supabase, run migrations
[ ] Configure Clerk, protect routes
[ ] Set up Express + BullMQ
Phase 2: Core Features
[ ] Job queue for AI processing
[ ] Upload flow to S3
[ ] AI provider abstraction layer
Phase 3: Shipping
[ ] Error boundaries
[ ] Rate limiting on API routes
[ ] Webhook signature verificationThe task file also forces you to actually plan the build before you start. That alone cuts wasted sessions in half. You stop building randomly and start building deliberately.
“Small tasks, fresh context every time. That's how you keep AI sharp from day one to launch.”
The actual workflow
Every session looks the same. Efficiency comes from consistency. No long sprawling conversations, no re-explaining your whole project every time something goes wrong.
01
Fresh Context
Open a fresh conversation. Paste your PRD.md and DESIGN.md immediately.
02
Define Task
Say: "We're working on Task X from TASKS.md" and paste the task description.
03
Build & Verify
Build the feature. Once done, verify it works as expected.
04
Update & Close
Check the task off in TASKS.md. Update DESIGN.md if you added new tables/routes. Close the session.
Commit all three files to your repo from day one. They're not just AI scaffolding — they're living documentation. When you come back to a project after two weeks, you'll know exactly where you left off.
I've shipped multiple products with this setup. It's the simplest system I've found that actually holds up through a full build. Three files, every project, no exceptions.
