contrib: allow all AI-generated code in general (#26012)

CONTRIBUTING.md

@@ -9,27 +9,36 @@ The project differentiates between 3 levels of contributors:
 # AI Usage Policy
 
 > [!IMPORTANT]
-> This project does **not** accept pull requests that are fully or predominantly AI-generated. AI tools may be utilized solely in an assistive capacity.
 >
-> Repeated violations of this policy may result in your account being permanently banned from contributing to the project.
+> AI-generated code is allowed. You are 100% responsible for every line, however it was produced.
 >
 > Detailed information regarding permissible and restricted uses of AI can be found in the [AGENTS.md](AGENTS.md) file.
 
-Code that is initially generated by AI and subsequently edited will still be considered AI-generated. AI assistance is permissible only when the majority of the code is authored by a human contributor, with AI employed exclusively for corrections or to expand on verbose modifications that the contributor has already conceptualized (e.g., generating repeated lines with minor variations).
-
 If AI is used to generate any portion of the code, contributors must adhere to the following requirements:
 
 1. Explicitly disclose the manner in which AI was employed.
-2. Perform a comprehensive manual review prior to submitting the pull request.
-3. Be prepared to explain every line of code they submitted when asked about it by a maintainer.
-4. It is strictly prohibited to use AI to write your posts for you (bug reports, feature requests, pull request descriptions, Github discussions, responding to humans, ...).
+2. Check for an existing PR addressing the same change; if one exists, comment there to work with its author instead of opening a duplicate.
+3. Perform a comprehensive manual review prior to submitting the pull request.
+4. Be prepared to explain every line of code they submitted when asked about it by a maintainer.
+5. It is strictly prohibited to use AI to write your posts for you (bug reports, feature requests, pull request descriptions, Github discussions, responding to humans, ...).
 
 For more info, please refer to the [AGENTS.md](AGENTS.md) file.
 
 # Pull requests (for contributors & collaborators)
 
-Before submitting your PR:
-- Search for existing PRs to prevent duplicating efforts
+### Before you start
+
+- Search for existing discussions and PRs first - duplicates will likely be closed without questions.
+- Features must begin with an issue, not a PR - let interest accumulate before writing code; niche features may only land as an example/tool, or on a private fork.
+- Bug-fix PRs must include a reproducible issue and a regression test that fails before your change and passes after. Fixes without a test may be closed without review.
+- New CLI or public API additions carry a **higher bar** than internal changes - justify why an existing mechanism doesn't suffice.
+- Meeting all of the above still doesn't guarantee a merge - see [Pull requests (for maintainers)](#pull-requests-for-maintainers).
+- If you are a new contributor
+    - Limit your open PRs to 1
+    - Do not submit trivial fixes (e.g. typos, formatting changes)
+
+### Preparing your PR
+
 - llama.cpp uses the ggml tensor library for model evaluation. If you are unfamiliar with ggml, consider taking a look at the [examples in the ggml repository](https://github.com/ggml-org/ggml/tree/master/examples/). [simple](https://github.com/ggml-org/ggml/tree/master/examples/simple) shows the bare minimum for using ggml. [gpt-2](https://github.com/ggml-org/ggml/tree/master/examples/gpt-2) has minimal implementations for language model inference using GPT-2. [mnist](https://github.com/ggml-org/ggml/tree/master/examples/mnist) demonstrates how to train and evaluate a simple image classifier
 - Test your changes:
   - Execute [the full CI locally on your machine](ci/README.md) before publishing
@@ -38,7 +47,6 @@ Before submitting your PR:
   - If you modified a `ggml` operator or added a new one, add the corresponding test cases to `test-backend-ops`
 - Create separate PRs for each feature or fix:
   - Avoid combining unrelated changes in a single PR
-  - For intricate features, consider opening a feature request first to discuss and align expectations
   - When adding support for a new model or feature, focus on **CPU support only** in the initial PR unless you have a good reason not to. Add support for other backends like CUDA in follow-up PRs
   - In particular, adding new data types (extension of the `ggml_type` enum) carries with it a disproportionate maintenance burden. As such, to add a new quantization type you will need to meet the following *additional* criteria *at minimum*:
     - convert a small model to GGUF using the new type and upload it to HuggingFace
@@ -46,11 +54,9 @@ Before submitting your PR:
     - provide KL divergence data calculated vs. the FP16/BF16 (whichever is the native precision) version for both the new type as well as types of similar size
     - provide [performance data](https://github.com/ggml-org/llama.cpp/tree/master/tools/llama-bench) for the new type in comparison to types of similar size on pure CPU
 - Consider allowing write access to your branch for faster reviews, as reviewers can push commits directly
-- If you are a new contributor
-    - Limit your open PRs to 1
-    - Do not submit trivial fixes (e.g. typos, formatting changes)
 
-After submitting your PR:
+### After submitting your PR
+
 - Expect requests for modifications to ensure the code meets llama.cpp's standards for quality and long-term maintainability
 - Maintainers will rely on your insights and approval when making a final decision to approve and merge a PR
 - If your PR becomes stale, rebase it on top of latest `master` to get maintainers attention
@@ -70,6 +76,7 @@ Maintainers reserve the right to decline review or close pull requests for any r
 - The proposed change is already mentioned in the roadmap or an existing issue, and it has been assigned to someone.
 - The pull request duplicates an existing one.
 - The contributor fails to adhere to this contributing guide or the AI policy.
+- The change doesn't fit the existing architecture, or is too complex to justify its benefit.
 
 # Coding guidelines