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docs/CONTRIBUTING.md

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+# Contributing to Nadir
+
+Thanks for considering contributing to Nadir. This project is deliberately small and human-driven. Every line of code must be understood by its author. Please read this guide and the [README](../README.md) before opening a pull request.
+
+## AI use policy
+
+AI assistance is allowed, but it must stay **minimal**
+
+Please stick to the following rules if you plan to use AI in your contributions:
+- The majority of the code must be authored by a human. Use AI as a tutor or reviewer if you need help.
+- Never paste large AI-generated chunks into the tree.
+- You are responsible for every committed line.
+- Everything must be documented. Committed code, human or AI-authored, must be well documented. Undocumented code WILL be regected.
+- Attribution is not welcome, it's required. If a commit contains meaningful AI-assisted work, add a `Co-Authored-By:` trailer in the PR description.
+
+## Ground rules
+
+- Never commit generated artifacts: `*.o`, `*.a`, `*.elf`, `*.bin`, `*.iso`, `*.img`, `build/` (see `.gitignore`).
+- Every change must still build and boot in QEMU.
+
+## Code style
+
+- C11 or C17, plus NASM/GAS assembly.
+- Compile-clean discipline: `-Wall -Wextra -Werror`.
+- Match the surrounding style.
+
+## Documentation
+
+- Every function, type, and file gets a doc comment explaining its purpose and, when relevant, the *why*.
+- Every privileged primitive (GDT, IDT, paging, context switch) must document the Ring / CPL it operates in and its fault behavior.
+
+## Building and running
+
+Build from the repository root. See the [README](../README.md).
+
+## License
+
+By contributing, you agree that your contributions are licensed under the project's license. See [LICENSE](../LICENSE).