Simon Willison’s Weblog

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Wednesday, 18th June 2025

That memvid thing that's been going around recently is a trap. It's an embedding store that records the original text that has been embedded in QR codes in a video file. That's an absurd thing to do, and the only purpose of the repo is to make people who uncritically share it look foolish. Don't fall for the trap.

# 4:30 am / jokes

I counted all of the yurts in Mongolia using machine learning (via) Fascinating, detailed account by Monroe Clinton of a geospatial machine learning project. Monroe wanted to count visible yurts in Mongolia using Google Maps satellite view. The resulting project incorporates mercantile for tile calculations, Label Studio for help label the first 10,000 examples, a model trained on top of YOLO11 and a bunch of clever custom Python code to co-ordinate a brute force search across 120 CPU workers running the model.

# 2:11 pm / geospatial, machine-learning, python, ai

I wrote this recently in a conversation about whether coding agents can work as a replacement for human programmers.

The "agentic" coding tools we have right now work like this:

  1. A skilled individual with both deep domain understanding and deep understanding of the capabilities of the agent (including understanding what tools are available to that agent) poses a clear task to it.
  2. The agent writes some code relating to that task. It runs a tool to execute and test that code. It inspects the result, and if there are errors it edits the code and tries again.
  3. It may call other tools as well, for example a search tool to find related code or even to look up API documentation elsewhere (including via web search).
  4. It continues like this until it hits a loosely defined “done” state or gets stuck.
  5. The skilled individual then reviews what it has done and almost always finds that it has not solved the problem to their satisfaction... so they apply their expertise and domain understanding to prompt it again to try and get to that desired state.

Without the skilled individual, the “agent” is useless. It may as well not exist.

# 10:05 pm / coding-agents, ai-assisted-programming, generative-ai, ai-agents, ai, llms

They poison their own context. Maybe you can call it context rot, where as context grows and especially if it grows with lots of distractions and dead ends, the output quality falls off rapidly. Even with good context the rot will start to become apparent around 100k tokens (with Gemini 2.5).

They really need to figure out a way to delete or "forget" prior context, so the user or even the model can go back and prune poisonous tokens.

Right now I work around it by regularly making summaries of instances, and then spinning up a new instance with fresh context and feed in the summary of the previous instance.

Workaccount2 on Hacker News, coining "context rot"

# 11:15 pm / ai, generative-ai, llms, long-context

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