chore: updated AGENTS (#1270)

Updated this with opencode + Kimi-K2.6's suggestion, guided and modified
a bit.

:robot: Assisted-by: OpenCode:Kimi-K2.6

---------

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: henryiii

AGENTS.md

@@ -1,89 +1,65 @@
-# AI Instructions
-
-## Overview
-
-**scikit-build-core**: Python 3.8+ adaptor for CMake 3.15+ to be used with
-Python package builds.
-
----
-
-## Core Commands
-
-### Setup
-
-If `uv`, `nox`, and `prek` commands are not available, they can be installed
-from PyPI:
-
-```bash
-pip install uv prek nox
-```
-
-### Test & Lint
-
-```bash
-uv run pytest        # run tests
-prek -a              # run all lint/format hooks
-```
-
-### Build
-
-```bash
-uv build
-```
-
-### Docs (only if needed)
-
-```bash
-nox -s docs
-```
-
-### Other things
-
-```bash
-nox -s pylint          # A bit slower than the normal lints
-nox -t gen             # Several generation steps, like parts of the README
-nox -s tests -- --cov  # A way to run coverage
-```
-
----
-
----
-
-## Development Workflow
-
-1. Run baseline if needed:
-
-   ```bash
-   uv run pytest
-   prek -a
-   ```
-
-2. Make changes
-
-3. Validate:
-
-   ```bash
-   prek -a
-   uv run pytest
-   ```
-
-4. If API/docs changed:
-
-   ```bash
-   nox -s docs
-   ```
-
----
-
-## PR Requirements
-
-- Tests pass: `uv run pytest`
-- Lint passes: `prek -a`
-
----
-
-## Key Notes
-
-- Python ≥3.8 (uses modern syntax)
-- Pre-commit handles formatting, linting, typing
-- Tests are a bit slow
+# AGENTS.md
+
+## Project
+
+`scikit-build-core` is a PEP 517 build backend for CMake-based Python packages.
+It is built with **hatchling** and stored under `src/scikit_build_core/`.
+
+## Running things
+
+- Prefer `uv run` over bare Python invocations. There is a `uv.lock` checked in.
+- Use `uv sync` for a local dev install. `uv run` does this for you.
+- `nox` is the task runner.
+  - `nox -s tests` — run tests with xdist (`-n auto`).
+  - `nox -s tests -- -k test_foo` — single test runner.
+  - `nox -s docs` — build Sphinx docs (serve with `nox -s docs -- serve`;
+    non-interactive with `nox -s docs -- --non-interactive`).
+  - `nox -t gen` — run all code generators (cog for README + schema + config
+    reference + API docs).
+  - `nox -s minimums` — lowest-direct dependency tests.
+- For linting, `prek -a --quiet` is preferred.
+
+## Testing
+
+- Tests live in `tests/`. Sample packages are in `tests/packages/` but **must
+  not be recursed into** by pytest (`norecursedirs = ["tests/packages/**"]`).
+- `tests/utils` is on `pythonpath` for test utilities.
+- Many tests need a virtualenv (fixtures: `isolated`, `virtualenv`). These are
+  auto-marked as `virtualenv` and `isolated` by `conftest.py`.
+- Important pytest markers: `compile`, `configure`, `fortran`, `integration`,
+  `isolated`, `network`, `setuptools`, `upstream`, `virtualenv`.
+- `pytest -n auto` is the default parallelism. Some platforms retry on PyPy.
+
+## Code quality
+
+- **Ruff** handles linting and formatting. Do not import banned modules directly
+  (e.g. use `scikit_build_core._compat.tomllib` instead of `tomli`/`tomllib`,
+  `scikit_build_core._compat.typing.Self` instead of `typing.Self`). See
+  `pyproject.toml` `tool.ruff.lint.flake8-tidy-imports.banned-api`.
+- **mypy** is strict for `scikit_build_core.*`, less strict for tests. Config in
+  `pyproject.toml`.
+- **pylint** is sometimes run separately in CI (`nox -s pylint`).
+- pre-commit includes `check-sdist`, `validate-pyproject`, JSON schema checks,
+  typos, shellcheck, and `sp-repo-review`.
+
+## Generated files
+
+- `README.md` and `docs/reference/configs.md` contain cog-generated sections.
+- `src/scikit_build_core/resources/scikit-build.schema.json` is generated from
+  the Pydantic-style model.
+- Run `nox -t gen` after changing any of these sources, then verify
+  `git diff --exit-code` in CI.
+
+## Architecture notes
+
+- `src/scikit_build_core/build/` — PEP 517 entry points.
+- `src/scikit_build_core/settings/` — configuration system,
+  TOML/env/config-settings reading.
+- `src/scikit_build_core/cmake.py` / `src/scikit_build_core/builder/` — CMake
+  invocation and builders.
+- `src/scikit_build_core/file_api/` — CMake File API reader.
+- `src/scikit_build_core/_compat/` — backports (typing, tomllib, importlib).
+  Ruff enforces their use.
+- `src/scikit_build_core/_vendor/` — vendored `pyproject_metadata`. Do not lint.
+- Experimental interfaces (setuptools, hatchling) will likely be split into
+  separate packages.