Every AI agent I have built has the same disease. It remembers everything and learns nothing. The chat history grows, the context window overflows, the vector database fills up, and yet on the next task it starts from zero again, asking the same questions, making the same mistakes. If that sounds familiar, this article is for you.
I spent months fighting this problem in production. I tried bigger context windows, better embedding models, more sophisticated retrieval pipelines. None of it worked, because I was solving the wrong problem. The problem is not storage. The problem is learning. This article explains the mental shift that finally fixed it, and the complete four layer memory methodology I now use with every agent I build. It is open source, zero dependency, and you can apply it today.
The Warehouse Problem
Most agent memory systems work like a warehouse. One event happens, you record one entry. One conversation ends, you save one snippet. One bug is fixed, you drop one log. Over time the warehouse gets fuller, and the useful things get buried deeper.
Here is what actually happens after six months of this pattern. Your agent has ten thousand memory entries. Retrieval becomes fishing with a needle. You know the answer is in there somewhere, but the search returns noise. The agent ends up redoing work it already did, because the record of how it solved the problem last time is buried under nine thousand nine hundred entries about nothing.
I call this hoarding, not memory. A warehouse of facts is not the same as a learned skill. You can store a thousand deployment logs and still deploy wrong the next time, because none of those logs taught the agent a rule. Stored a lot, never really learned.
Why Vector Databases Do Not Fix This
Let me be direct. Vector databases, embeddings, RAG pipelines, these are retrieval infrastructure, not learning systems. They answer the question of how to find something. They do not answer the question of what deserves to be kept, or how raw facts become reusable judgment.
I built a system with a vector store, semantic search, everything shiny. It was fast and it was useless. Why. Because I was still recording everything, so retrieval was still noisy. Because I was still treating each record as a standalone fact, so no patterns ever emerged. Because nothing in the pipeline ever promoted a repeated lesson into a rule.
The infrastructure was excellent. The methodology was missing. That is the gap this article is about.
The Shift: Memory Is Training Data, Not Inventory
Here is the one sentence that changed everything for me.
A piece of information that cannot improve future judgment does not deserve long term retention.
Think of it that way and the whole design changes. Memory is not a place to keep things. Memory is training data. Its only job is to make the next decision better. If a record does not make the agent faster, more accurate, or more careful next time, it should not be in long term memory.
This leads to a second principle that matters just as much.
What can be promoted into a skill should not stay at log level.
Logs are raw ore. Skills are the refined weapon. The goal of a memory system is not to accumulate ore. The goal is to keep refining ore into weapons. When you see it this way, the entire architecture of your agent memory changes, and the four layer design below is the result.
The Four Layer Architecture
I organize long term memory into four layers. The higher the layer, the closer to learned. The whole job of the system is to keep pushing facts upward.
Layer one, world facts. These are the stable background facts of the collaboration. Who the user is and how they prefer to work. Where the project directory lives. What the deployment conventions are. What the current product direction is. This layer does not change often, but every task needs it. It lives in a single file called MEMORY.md.
Layer two, experience facts. These are traces of real actions. What changed in this round. How a problem was located. Which version was synced where. Which pipeline was verified working. This layer lives in daily logs named by date, for example 2026-08-14.md, and it is the raw material for everything above it.
Layer three, observations. These are patterns distilled from repeated facts. Why a certain type of problem keeps recurring. Where a certain testing convention tends to misjudge. How a certain type of requirement converges most reliably. This layer is where memory starts to become intelligence, because it is no longer about one event, it is about the rule behind many events.
Layer four, skills and mental models. This is the highest value layer. When a pattern is stable enough and will be used repeatedly, it stops being a memory and becomes a skill. It gets condensed into a skill pack, a standard operating procedure, a checklist, a judgment standard. From now on the agent calls the skill instead of searching the archives.
A real example makes this concrete. Early in my work I hit a frontend bug where several buttons on a page all stopped responding at the same time. I recorded it as an experience fact. A few weeks later it happened again, same symptom, different page. Now I had two facts, so I could form an observation. When multiple touchpoints fail at once on the frontend, check for a JavaScript syntax error first, because one broken script can take down every handler on the page. That observation became a layer four skill. Today my agent checks JavaScript syntax first whenever multiple UI elements fail together. It never has to rediscover that lesson again.
The Four Elements Every Memory Needs
Once you accept that memory is training data, the next question is what a well formed memory looks like. I require four elements in every effective memory entry, and I reject entries that lack them.
Time. When it happened. A date, a version, a milestone. Without time you cannot tell old facts from new facts, and stale information quietly poisons decisions.
Context. In what task or environment it happened. Deployment stage, testing phase, which project. Without context a fact is a floating island that nothing can connect to.
Conclusion. What the fact is and how it was solved. This is the part that actually carries value. If an entry only describes a symptom without a solution, it is not a memory, it is a complaint.
Next step. How to reuse it and what to watch out for later. This is the element that most people skip, and it is the one that turns a record into training. A deployment entry that ends with the rule, all long running processes must be started in background mode with nohup so they survive the session, is worth ten entries that just say, deployment failed today.
The Five Quality Gates
Before writing anything to long term memory, I run it through five gates. All five must pass, or the entry does not get written.
Reusable. Will this be needed again. If it is a one off fact with no future use, it does not belong in long term memory.
Has a conclusion. Is there a clear conclusion or solution. An entry that only describes what happened, with no lesson, fails this gate.
Has boundaries. Are the applicable conditions and risks stated. Mindless rules like always do this are dangerous. The rule needs to say when it holds and when it does not.
Retrievable. Can it be found later. If the entry has no context and no keywords, it will never be retrieved, so it might as well not exist.
Timely. Is the time or version marked. Old and new information mixed together creates false confidence.
The five gates have a beautiful side effect. They force the agent to think before writing. Most bad memory systems fail not because retrieval is bad, but because the writing gate is wide open and everything floods in. Close the gate and the whole system gets cleaner.
The Lifecycle: Write, Retrieve, Reflect, Promote, Clean
Memory is not write once and keep forever. It has a full lifecycle with five stages.
Write. Record per the four element rules, through the five quality gates.
Retrieve. Actually use it in later tasks. A memory that is never retrieved is decoration.
Reflect. After multiple uses, distill the stable pattern underneath.
Promote. When the pattern is stable, upgrade it into a skill or an SOP.
Clean. Expired, merged, or skill covered records get archived or deleted.
I run this on a cadence. Daily, at the end of the day, scan today's log and mark items that can be promoted. Weekly, summarize observation type memories and merge duplicates. Monthly, formally promote the stable patterns into skill packs. The cadence matters because promotion is not automatic, it is a discipline.
Three Layer Retrieval
Retrieval follows a strict order, and the order is the point.
Layer one, call the corresponding skill first if one exists. Skills are refined weapons. If a skill covers this type of task, use it. Do not go digging through raw history first.
Layer two, search recent memory, the MEMORY.md file and recent logs.
Layer three, only as a last resort, read raw logs and historical conversations.
The order must not be reversed. Most agents search raw history first, which is exactly why they drown in noise. The skill layer exists so the agent does not have to re derive the lesson every single time. And when retrieval fails, the system does not give up. It searches with synonyms, it expands from daily log to weekly log to special report, and if it still finds nothing, that is a signal the memory was poorly recorded, and it writes an observation about the retrieval blind spot so the system improves itself.
Four Common Mistakes
After using this system for months, I have a list of the mistakes that kill agent memory, and every one of them is a behavior, not a technical problem.
Mistake one, record everything. The belief that more records mean better memory. The result is bloat, slow retrieval, and useful information drowned in noise. The fix is the five quality gates.
Mistake two, record but never act. Entries are written and never reviewed, never promoted, so memory stays loose logs forever. The fix is the daily, weekly, monthly cadence.
Mistake three, record but never retrieve. The next task starts from zero anyway, so the memory is a museum. The fix is making retrieval a default action, check skills and memory first every time a task starts.
Mistake four, keep everything forever. The belief that deleting memory is a loss. In reality expired memory only interferes with judgment. The fix is cleaning on schedule and keeping the memory lean.
How to Start Today
You do not need a vector database to start. You need a file and a discipline.
Step one, create a MEMORY.md file with the stable facts about your project and your user. This is your layer one.
Step two, keep a daily log named by date, and write every experience fact with the four elements. Time, context, conclusion, next step.
Step three, at the end of each week, look at the daily logs and ask one question. What pattern showed up more than once. That pattern becomes an observation, and the observation is the seed of a skill.
That is the whole system in its simplest form. The full version in the open source project adds the writing rules, the retrieval techniques, the lifecycle management, the five quality criteria, the memory templates, and the common pitfalls, all formatted so you can install it directly as an agent skill.
Get Fenglei Memory
The methodology is called Fenglei Memory, and its motto is learn, don't store. It is open source, free, and MIT licensed.
https://github.com/Kim-FengLei/fenglei-memory
The repository contains the complete SKILL.md file that you can install directly into your agent, plus a full README with the architecture, the workflow, and the quick start. Star it if it helps you, fork it if you want to adapt it, and share it with anyone whose agent keeps forgetting.
Your agent already stores everything. It is time to teach it to learn.
Built by KIM, Founder of FENGLEI YI, 风雷益, 天施地生，其益无方. Technical exchange, kimsunjian@vip.qq.com.
