Every AI coding tool has the same fatal flaw: it forgets everything between sessions. You can build an entire feature with Claude or GPT, close the tab, and the next conversation starts completely blank. No memory of your project, your architecture, your decisions, or the thing you literally just built together.

The STACK.md method is a dead-simple fix. It's a single file that gives any AI assistant your full project context in 30 seconds. No integrations, no tooling, no vendor lock-in. Just a markdown file and a habit.

What STACK.md Is

STACK.md is a structured project memory file that lives in your project root. It's not a README (that's for humans browsing your repo). It's not documentation (that's for developers joining your team). It's a machine-readable briefing document designed specifically for AI assistants.

When you start a new AI coding session, you paste your STACK.md. The AI immediately knows your project, your tech stack, what's built, what's broken, and what to work on next. The 20-minute re-explanation ritual becomes a 30-second paste.

Here's why it works: AI assistants are extraordinarily good at processing structured context. They just need the right information in the right format. STACK.md is that format.

The Five Essential Sections

Every STACK.md should have these five sections. You can add more, but these are non-negotiable.

1. What This Is

One paragraph describing the project in plain language. What it does, who it's for, and the core value proposition. This orients the AI immediately so every suggestion it makes is grounded in your product's purpose.

2. Currently Working On

The most important section. What are you building right now? What did you finish in the last session? What's the next task? This section changes every session and is the primary handoff mechanism between past-you and present-you (via the AI).

3. Core Features

A bullet list of what's built and working. Not the roadmap. Not the dream. What actually exists in the codebase today. This prevents the AI from suggesting features you already have or building on top of things that don't exist yet.

4. Tech Stack

Framework, language, database, hosting, key libraries. Concrete and specific. The AI needs this to generate code that actually fits your project instead of generic examples from its training data.

5. Known Issues

Bugs, incomplete features, things that are broken or half-done. This is critical — it prevents the AI from building on top of broken foundations and helps it prioritize fixes when you ask "what should I work on next?"

A Real Example

Here's what a STACK.md looks like in practice, using SureStack itself as the example:

# STACK.md — SureStack

## What This Is
SureStack is a productivity tool for solo founders building with AI.
It generates a structured project memory file (STACK.md) from any
codebase, provides AI-driven guidance on what to build next, and
includes a pre-launch audit. Paid product with Stripe integration.

## Currently Working On
- Just finished: Agent Manager v2 dashboard redesign
- In progress: Blog section for marketing site (SEO play)
- Next up: Webhook reliability improvements

## Core Features
- STACK.md generator (analyzes codebase, outputs structured memory)
- Guide mode (AI recommends next high-impact task)
- Launch audit (scores project on security, payments, legal)
- Agent Manager (dashboard for monitoring autonomous AI agents)
- Trial system (7-day free key via email)
- Stripe payments (one-time purchase, two tiers)

## Tech Stack
- Next.js 14 (App Router) + TypeScript
- Postgres via Prisma
- Stripe for payments
- Vercel hosting (app.surestack.dev)
- Marketing site: static HTML on Vercel (surestack.dev)

## Known Issues
- Webhook endpoint occasionally times out on large payloads
- Guide mode suggestions can be generic for very early-stage projects
- Agent Manager doesn't support custom alert thresholds yet

That's 30 lines. It takes 30 seconds to paste and gives the AI a complete picture of the project. No ambiguity, no guessing, no wasted time.

Generate Your First STACK.md in 5 Minutes

You don't have to write your STACK.md from scratch. The fastest way to create one is to ask the AI to do it.

Open a session with your AI tool of choice. Share your codebase (paste key files, or use a tool like Claude Code that can read your project directly). Then send this prompt:

"Analyze this project and generate a STACK.md file with these sections: What This Is, Currently Working On, Core Features, Tech Stack, Known Issues. Be specific and concrete. Focus on current state, not aspirations."

Review the output, make corrections, and save it as STACK.md in your project root. That's it. You now have a project memory file.

The key insight: the AI that builds with you is also the best tool for documenting what you've built. Let it do the work.

The Build Loop: Paste, Build, Update

STACK.md only works if it stays current. Here's the loop that makes it automatic:

Phase 1: Paste. Start every AI session by pasting your STACK.md. The AI now has full context. Tell it what you want to work on.

Phase 2: Build. Code normally. Build features, fix bugs, refactor. The AI has your project context so its suggestions are accurate and grounded.

Phase 3: Update. Before you close the session, send one final prompt: "Update STACK.md with everything we built today. What's now working, what changed, any new issues, and what to tackle next." Save the output over your existing STACK.md.

That's the entire system. Three phases, repeated every session. The memory file accumulates knowledge over time, getting more accurate and more useful with every update.

Works With Any AI Tool

One of the best things about the STACK.md method is that it's completely tool-agnostic. The file is plain markdown. It works with:

If you switch AI tools — which most people do, depending on the task — your project memory travels with you. It's not locked into any platform. It's a file in your repo.

Common Mistakes

Making it too long. If your STACK.md is over 500 lines, it's a documentation file, not a memory file. The AI doesn't need your component API reference. It needs to know what exists, what's broken, and what to build next. Be ruthless about cutting sections that don't help the AI make better decisions.

Not updating it. A stale STACK.md is worse than no STACK.md. If the memory file says your auth system uses JWT but you switched to sessions last week, the AI will generate JWT code. Always run the closing prompt. Always save the update.

Treating it as a README. Your README describes your project to the world. Your STACK.md describes your project's current state to an AI that's about to start coding. Different audiences, different content. Don't merge them.

Including too much code. STACK.md should describe structure and state, not contain code. "Auth routes are in app/api/auth/ using NextAuth" is good. Pasting the entire auth route file is not. The AI can read the actual code when it needs to — the memory file tells it where to look and what to expect.

The STACK.md method isn't revolutionary technology. It's a file and a habit. But it solves the single biggest friction point in AI-assisted development: the blank-slate problem at the start of every session. Start using it today, and you'll never waste 20 minutes re-explaining your project again.