I wrote a bit about this the other day: https://simonwillison.net/2025/Jun/27/context-engineering/ Drew Breunig has been doing some fantastic writing on this subject - coincidentally at the same time as the "context engineering" buzzword appeared but actually unrelated to that meme. How Long Contexts Fail - https://www.dbreunig.com/2025/06/22/how-contexts-fail-and-ho... - talks about the various ways in which longer…
Those issues are considered artifacts of the current crop of LLMs in academic circles; there is already research allowing LLMs to use millions of different tools at the same time, and stable long contexts, likely reducing the amount of agents to one for most use cases outside interfacing different providers. Anyone basing their future agentic systems on current LLMs would likely face LangChain fate - built for GPT-3,…
The new skill in AI is not prompting, it's context engineering
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Re: The new skill in AI is not prompting, it's context engineering
#52That's when I understood that vibe coding is real and context is the biggest hurdle.
That said, most of the context could not be pulled from the codebase directly but came from me after asking the AI to check/confirm certain things that I suspected could be the problem.
I think vibe coding can be very powerful in the hands of a senior developer because if you're the kind of person who can clearly explain their intuitions with words, it's exactly the missing piece that the AI needs to solve the problem... And you still need to do code review aspect which is also something which senior devs are generally good at. Sometimes it makes mistakes/incorrect assumptions.
I'm feeling positive about LLMs. I was always complaining about other people's ugly code before... I HATE over-modularized, poorly abstracted code where I have to jump across 5+ different files to figure out what a function is doing; with AI, I can just ask it to read all the relevant code across all the files and tell me WTF the spaghetti is doing... Then it generates new code which 'follows' existing 'conventions' (same level of mess). The AI basically automates the most horrible aspect of the work; making sense of the complexity and churning out more complexity that works. I love it.
That said, in the long run, to build sustainable projects, I think it will require following good coding conventions and minimal 'low code' coding... Because the codebase could explode in complexity if not used carefully. Code quality can only drop as the project grows. Poor abstractions tend to stick around and have negative flow-on effects which impact just about everything.
Re: The new skill in AI is not prompting, it's context engineering
#53I'm trying to figure out how to build a "Context Management System" (as compared to a Content Management System) for all of my prompts. I completely agree with the premise of this article, if you aren't managing your context, you are losing all of the context you create every time you create a new conversation. I want to collect all of the reusable blocks from every conversation I have, as well as from my research and reading around the internet. Something like a mashup of Obsidian with some custom Python scripts.
The ideal inner loop I'm envisioning is to create a "Project" document that uses Jinja templating to allow transclusion of a bunch of other context objects like code files, documentation, articles, and then also my own other prompt fragments, and then to compose them in a master document that I can "compile" into a "superprompt" that has the precise context that I want for every prompt.
Since with the chat interfaces they are always already just sending the entire previous conversation message history anyway, I don't even really want to use a chat style interface as much as just "one shotting" the next step in development.
It's almost a turn based game: I'll fiddle with the code and the prompts, and then run "end turn" and now it is the llm's turn. On the llm's turn, it compiles the prompt and runs inference and outputs the changes. With Aider it can actually apply those changes itself. I'll then review the code using diffs and make changes and then that's a full turn of the game of AI-assisted code.
I love that I can just brain dump into speech to text, and llms don't really care that much about grammar and syntax. I can curate fragments of documentation and specifications for features, and then just kind of rant and rave about what I want for a while, and then paste that into the chat and with my current LLM of choice being Claude, it seems to work really quite well.
My Django work feels like it's been supercharged with just this workflow, and my context management engine isn't even really that polished.
If you aren't getting high quality output from llms, definitely consider how you are supplying context.
Re: The new skill in AI is not prompting, it's context engineering
#54Re: The new skill in AI is not prompting, it's context engineering
#55Which is funny because everyone is already looking at AI as: I have 30 TB of shit that is basically "my company". Can I dump that into your AI and have another, magical, all-konwning, co-worker?
Re: The new skill in AI is not prompting, it's context engineering
#56> Conclusion Building powerful and reliable AI Agents is becoming less about finding a magic prompt or model updates. It is about the engineering of context and providing the right information and tools, in the right format, at the right time. It’s a cross-functional challenge that involves understanding your business use case, defining your outputs, and structuring all the necessary information so that an LLM can “a…
(X-Y problem, for example.)
Re: The new skill in AI is not prompting, it's context engineering
#57I’m curious how this applies to systems like ChatGPT, which now have two kinds of memory: user-configurable memory (a list of facts or preferences) and an opaque chat history memory. If context is the core unit of interaction, it seems important to give users more control or at least visibility into both. I know context engineering is critical for agents, but I wonder if it's also useful for shaping personality and i…
If I'm debugging something with ChatGPT and I hit an error loop, my fix is to start a new conversation.
Now I can't be sure ChatGPT won't include notes from that previous conversation's context that I was trying to get rid of!
Thankfully you can turn the new memory thing off, but it's on by default.
I wrote more about that here: https://simonwillison.net/2025/May/21/chatgpt-new-memory/
Re: The new skill in AI is not prompting, it's context engineering
#58It is wrong. The new/old skill is reverse engineering. If the majority of the code is generated by AI, you'll still need people with technical expertise to make sense of it.
Ultimately humans will never need to look at most AI-generated code, any more than we have to look at the machine language emitted by a C compiler. We're a long way from that state of affairs -- as anyone who struggled with code-generation bugs in the first few generations of compilers will agree -- but we'll get there.
Re: The new skill in AI is not prompting, it's context engineering
#59> Conclusion Building powerful and reliable AI Agents is becoming less about finding a magic prompt or model updates. It is about the engineering of context and providing the right information and tools, in the right format, at the right time. It’s a cross-functional challenge that involves understanding your business use case, defining your outputs, and structuring all the necessary information so that an LLM can “a…
Re: The new skill in AI is not prompting, it's context engineering
#60"Wow, AI will replace programming languages by allowing us to code in natural language!" "Actually, you need to engineer the prompt to be very precise about what you want to AI to do." "Actually, you also need to add in a bunch of "context" so it can disambiguate your intent." "Actually English isn't a good way to express intent and requirements, so we have introduced protocols to structure your prompt, and various k…