Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 Want to contribute? Great! First, read this page (including the small print at the end).
 
-### Before you contribute
+## Before you contribute
 **Before we can use your code, you must sign the
 [Google Individual Contributor License Agreement](https://developers.google.com/open-source/cla/individual?csw=1)
 (CLA)**, which you can do online.
@@ -17,11 +17,53 @@ Before you start working on a larger contribution, you should get in touch
 with us first. Use the issue tracker to explain your idea so we can help and
 possibly guide you.
 
-### Code reviews and other contributions.
+## Code Reviews and Contributing PRs
 **All submissions, including submissions by project members, require review.**
-Please follow the instructions in [the contributors documentation](http://bazel.io/contributing.html).
 
-### The small print
+### AI Generated Contributions
+**To ensure maintainability & sustainability of rules_rust in the LLM era, we’re adopting LLVM’s AI tools [policy](https://llvm.org/docs/AIToolPolicy.html).** As a short summary, when contributing to `rules_rust` you are expected to:
+* **Understand and Own the Code**: You may use AI tools, but you are fully accountable for the work. You must thoroughly read, understand, and self-review all content before submitting it for review.
+* **Learn from Feedback**: When maintainers review your work, use their feedback as a human learning opportunity to grow your skills, rather than simply funneling their comments back into an LLM to generate a quick fix.
+* **Be Transparent**: Clearly label any contribution that contains a substantial amount of AI-generated content (e.g., using an Assisted-by commit trailer).
+
+### Public Interface changes
+**If your proposed change affects an existing or adds a public API (e.g new attribute, new build setting), please file an issue explaining the problem space & proposed design first.**
+
+As Rust & Bazel are seeing increased adoption in the industry, we see more and more PRs that add/enhance the public facing interface of rules_rust (e.g new attributes, new rules, new build settings). Sometimes such PRs are near-universally beneficial, other times they address specific/narrow use cases. In its present shape, the core ruleset does not provide a sufficient level of configurability so that the latter use cases can be addressed locally. We will soon start a [redesign](https://github.com/bazelbuild/rules_rust/issues/4049) of the core ruleset that aims to allow for sufficient configurability so that users can address their own needs without expanding the rules_rust API surface.
+
+### Adding New Rules
+**We do not accept new non-core rules to the `rules_rust` repository.**
+
+In its current state, rules_rust contains functionality broader than most rulesets: in addition to a core ruleset, it also contains functionality for automated `BUILD`/`bzl` file generation for crates, IDE integration via `rust-analyzer`, docs generation via `rustdoc`, C++ interop via `bindgen`, Js/Ts interop via `wasm_bindgen` etc.  At present time there are areas that the maintainers don’t have sufficient expertise in, or where there is a single maintainer that can meaningfully act on incoming PRs and issues, making it difficult for interested parties to contribute. To address this, we will be splitting the non-core rulesets into separate repositories. This will allow for additional maintainers to join specific areas. For areas where we don’t find maintainers, we’ll deprecate and retire.
+
+#### Core Rules
+Rules used to compile Rust code.
+* `rust_library`
+* `rust_binary`
+* `rust_test`
+* `rust_static_library`
+* `rust_shared_library`
+* `rust_proc_macro`
+* `cargo_build_script`
+
+### Unowned / Undermaintained / Undertested areas
+There are areas of `rules_rust` that no maintainers currently have expertise in. For these areas, expect some friction during contribution:
+* `prost`
+Best effort maintenance, long term these rules will not live in rules_rust. If you’re interested in taking over maintenance please reach out.
+* `wasm-bindgen`
+Best effort maintenance, long term these rules will not live in rules_rust. If you’re interested in taking over maintenance please reach out.
+* Windows as host
+Best effort maintenance, with no capability / bandwidth to help contributors. Experts willing to help review PRs would be much appreciated!
+* Platforms other than Linux / MacOS / Windows
+Best effort maintenance, no CI testing.
+
+### Testing
+A PR should contain tests for the change where feasible.
+
+### Stale PRs and Issues
+PRs and issues that are in awaiting-response state for more than 90 days will be closed as inactive.
+
+## The small print
 Contributions made by corporations are covered by a different agreement than
 the one above, the
 [Software Grant and Corporate Contributor License Agreement](https://cla.developers.google.com/about/google-corporate).