Document the PyPI release flow and make built artifacts PyPI-valid

.gitignore

@@ -4,6 +4,7 @@ __pycache__/
 *.pyo
 *.pyd
 build/
+dist/
 *.egg-info/
 .pytest_cache/
 .mypy_cache/

README.md

@@ -148,6 +148,7 @@ python -m opencad.cli run examples/hardware_mounting_bracket.py \
 ## Documentation
 
 - [PRODUCTION.md](PRODUCTION.md) — deployment, routes, and verification
+- [RELEASING.md](RELEASING.md) — build and publish OpenCAD to PyPI
 - [ARCHITECTURE.md](ARCHITECTURE.md) — component design and API contracts
 - [TOPOLOGY.md](TOPOLOGY.md) — topology reference stability (open research question)
 - [SECURITY.md](SECURITY.md) — vulnerability reporting and hardening baseline

RELEASING.md

@@ -0,0 +1,77 @@
+# Releasing OpenCAD to PyPI
+
+OpenCAD already uses `setuptools` via `pyproject.toml`, so publishing a release is a
+standard Python packaging flow.
+
+## 1. Prepare the release
+
+- Update `version` in `pyproject.toml`.
+- Make sure `README.md` and any user-facing docs match the release.
+- Run the existing test suite from the repository root:
+
+```bash
+pytest
+```
+
+## 2. Build the distribution artifacts
+
+Install the packaging tools:
+
+```bash
+python -m pip install -U build twine
+```
+
+Build both the source distribution and wheel:
+
+```bash
+python -m build
+```
+
+This writes release artifacts to `dist/`.
+
+## 3. Validate the artifacts locally
+
+Check the generated metadata before uploading:
+
+```bash
+python -m twine check dist/*
+```
+
+Optional smoke test from the built wheel:
+
+```bash
+python -m pip install --force-reinstall dist/opencad-*.whl
+opencad --help
+```
+
+## 4. Upload to PyPI
+
+Create a PyPI API token and either:
+
+- export it for the current shell, or
+- store it in `~/.pypirc`.
+
+Example using an environment variable:
+
+```bash
+export TWINE_USERNAME=__token__
+export TWINE_PASSWORD=pypi-***
+python -m twine upload dist/*
+```
+
+If you want a dry run against TestPyPI first:
+
+```bash
+python -m twine upload --repository testpypi dist/*
+```
+
+## 5. Tag the release
+
+After the upload succeeds, create and push a matching Git tag:
+
+```bash
+git tag vX.Y.Z
+git push origin vX.Y.Z
+```
+
+Replace `X.Y.Z` with the version you released.

pyproject.toml

@@ -1,13 +1,13 @@
 [build-system]
-requires = ["setuptools>=68", "wheel"]
+requires = ["setuptools>=68,<77", "wheel"]
 build-backend = "setuptools.build_meta"
 
 [project]
 name = "opencad"
 version = "0.2.0"
 description = "Modular CAD platform — kernel, solver, feature tree, viewport, and AI agent"
 readme = "README.md"
-license = "MIT"
+license = { text = "MIT" }
 requires-python = ">=3.11"
 dependencies = [
   "pydantic>=2",