Provide a long-term policy for LLM usage

CONTRIBUTING.md

@@ -19,6 +19,7 @@ These categories of extensions are **highly discouraged**:
  - Very niche extensions. You can write the extension for yourself, then import it as a file instead without needing us to review.
  - Extensions whose primary purpose is monetization. It isn't in the spirit of a free and open source project.
  - Joke extensions. Things that are funny to you are not funny to everyone, especially when we get bug reports about it.
+ - Extensions that were written mostly or entirely by a large language model (ChatGPT, Gemini, Perplexity, Claude, Grok, DeepSeek, etc.)
 
 Some extensions were added before these guidelines existed. We're trying to enforce them moving forward.
 
@@ -40,6 +41,21 @@ This repository contains a custom development server. Extension source code goes
 
 New extensions should be added in a user folder. You can name your folder anything you want; common choices are your GitHub username or your Scratch username. You can largely choose whatever you want. These folders are just for organization; other people are still allowed to edit your extension. Folder name changes are only granted in rare circumstances, so please get it right the first time.
 
+## Some guidelines for content generated by a machine learning model
+### Large language models (LLMs)
+As a rule of thumb, any extension is unlikely to be accepted if:
+ - It would not fulfill its primary goals without the portions which were written by an LLM
+ - The person submitting the extension does not appear to understand the LLM-generated code to a reasonable extent
+ - The person submitting the extension has written the entire extension with an LLM
+
+Some other points to consider:
+ - Visibly faulty code is almost never allowed in new extensions, no matter if an LLM or a human being wrote it
+ - The extension reviewers have the final say on what's okay and what's not, regardless of what these guidelines say
+ - If you spam us with LLM-generated slop and then make something that's really amazing and useful, you might get ignored ([remind you of anything?](https://en.wikipedia.org/wiki/The_Boy_Who_Cried_Wolf))
+ - You do NOT need to write in perfect English when submitting an extension (though this is preferred); worst case, a contributor can edit your post for clarity
+
+### Image generation models
+While there are no rules explicitly prohibiting the use of machine learning models to produce the images used in an extension or to write the extension's description, it does not make you favorable with many of the extension reviewers.
 ## License
 
 **We are not lawyers. This is not legal advice.**