[ADMIN] Adding an MDAnalysis AI tools policy. (#5210)

* Add AI tools policy.

Adds a markdown document that defines MDAnalysis' current stance on AI tools for contributions.

---------

Co-authored-by: Rocco Meli <r.meli@bluemail.ch>
Co-authored-by: Oliver Beckstein <orbeckst@gmail.com>

Author: 3 people

AI_POLICY.md

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+# 🤖 MDAnalysis AI-generated contributions policy 🤖
+
+### Version: 1.0 (2026-02-03)
+
+This document defines the [MDAnalysis organization's](https://github.com/MDAnalysis/) policy regarding AI-generated content. This policy applies to all aspects of the MDAnalysis project, including all the GitHub repositories under the organization.
+
+For the purposes of this document, _content_ is defined as any contribution to the MDAnalysis organization, both code and non-code, including but not limited to:
+- Code submitted for inclusion in MDAnalysis, or other organization-owned repositories
+- Documentation of any kind
+- Communication content (e.g. issues, discussions, pull request descriptions, and reviews)
+
+We recognize that the use of AI in open source software raises many difficult questions and acknowledge that views, approaches, and technical capabilities are rapidly changing. 
+We invite comments and further discussion (via our [discussion channels](https://www.mdanalysis.org/pages/community/)) and expect to periodically review this policy.
+
+## Policy overview
+
+MDAnalysis does not accept any substantial uses of AI-generated content in contributions.
+
+AI tools may be used in limited cases, for example when it is used for small amounts of AI-assisted code (e.g. autocompletion using copilot, cursor, etc...)
+or for language translation purposes. **Such uses must always be declared.**
+
+## Policy details
+
+### 0. AI usage must always be declared
+
+All contributions must be fully transparent about any AI usage. Failure to disclose AI use (e.g. in pull request description details)
+may be queried by other developers and may be considered non-compliance with this policy.
+
+If we suspect that AI tools were used as part of a contribution, MDAnalysis developers may ask you for clarification.
+Please do not take offense if this happens to you, distinguishing between AI-generated and human-authored content is increasingly difficult!
+
+### 1. Fully generated code is not allowed
+
+Fully AI-generated contributions, such as content generated by prompting a large language model (e.g. claude code or chatgpt) or produced by any agentic AI system are not permitted in MDAnalysis.
+
+Some limited exceptions are described in sections #2 and #3 for integrated development environments (IDEs) and language translation.
+
+### 2. Limited AI assistance exemption: IDEs and autocompletion
+
+AI tools are now so deeply integrated into many modern development environments, and it may be impractical to avoid them entirely.
+We recognise that this is particularly true for modern integrated development environments (IDEs), which may use AI to power features like autocompletion.
+
+In these limited cases of code generation, typically ranging from a single variable to a couple of lines of code,
+AI assitance is deemed acceptable. However, if code generation exceeds minimal, sporadic amounts (e.g. repeated or large multi-line blocks),
+it would be considered fully AI-generated and, as defined in section #1, is not acceptable.
+
+As per section #0, it is your responsibility to report the extent of AI assitance you used.
+
+### 3. Limited AI assistance exemption: language translation
+
+MDAnalysis aims to foster an inclusive environment for all contributors and users. We recognise that language barrier can limit participation
+in open-source projects, particularly for non-native English speakers.
+
+Whilst we prefer you communicate with us in your own words (and languages if needed), we acknowledge that AI-based translation tools may sometimes
+be necessary for communicating in issues / discussions. If such tools are used, we ask you to disclose their use and purpose.
+
+### 4. Contributors are responsible authors and must be aware of, and declare, any derivate work
+
+Contributors are responsible for the content and provenance of every aspect of their contribution, including any design decisions.
+Contributors must be aware of whether their work derives from external sources / codebases and must declare any derivative work.
+
+### 5. Human reviewers are required
+
+All code merged into MDAnalysis repositories must be reviewed by a human reviewer. Instructions / suggestions from human reviewers always take precedence over those of non-human reviewers.
+
+### 6. Consequences for failure to comply to this policy
+
+Any failures to comply with this policy should be reported to the MDAnalysis core developers through
+our [standard communications channels](https://www.mdanalysis.org/pages/community/#ask-questions--get-help) or email to mdanalysis@numfocus.org .
+The core developers may enforce this policy through a range of actions, which may include restricting or banning individuals from future contributions.
+
+There is a zero tolerance policy for intentionally failing to disclose or misrepresenting the extent of AI usage.
+
+## Acknowledgements
+
+We acknowledge the [Kornia AI policy](https://github.com/kornia/kornia/blob/main/AI_POLICY.md) and discussions
+within the [Scientific Python Community](https://discuss.scientific-python.org/t/a-policy-on-generative-ai-assisted-contributions/1702/18)
+for providing guidance and insight in shaping this policy.