diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..11d4bf6
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,44 @@
+name: CI
+
+on:
+  push:
+    branches: [master, prerelease]
+  pull_request:
+    branches: [master, prerelease]
+
+jobs:
+  build-and-test:
+    name: Python ${{ matrix.python-version }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Set up conda (Miniforge)
+        uses: conda-incubator/setup-miniconda@v3
+        with:
+          python-version: ${{ matrix.python-version }}
+          miniforge-variant: Miniforge3
+          use-mamba: true
+          auto-activate-base: false
+          activate-environment: test-env
+
+      - name: Install llvm-openmp (macOS)
+        if: runner.os == 'macOS'
+        shell: bash -el {0}
+        run: conda install -y -c conda-forge llvm-openmp
+
+      - name: Install svmbir with dev dependencies
+        shell: bash -el {0}
+        run: pip install -e ".[dev]"
+
+      - name: Run tests
+        shell: bash -el {0}
+        run: pytest svmbir/tests/ -v
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..065ddef
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,40 @@
+name: Build and Release Wheels
+
+on:
+  push:
+    tags:
+      - "v*"
+
+jobs:
+  create-draft-release:
+    name: Create draft release
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: softprops/action-gh-release@v2
+        with:
+          draft: true
+          generate_release_notes: true
+
+  build-linux:
+    name: Linux wheels and sdist
+    runs-on: ubuntu-latest
+    needs: create-draft-release
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Build wheels
+        uses: pypa/cibuildwheel@v2.22.0
+
+      - name: Build sdist
+        run: pipx run build --sdist
+
+      - name: Upload to draft release
+        run: gh release upload ${{ github.ref_name }} wheelhouse/*.whl dist/*.tar.gz --clobber
+        env:
+          GH_TOKEN: ${{ github.token }}
diff --git a/.gitignore b/.gitignore
index 8d903b2..54bc4df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,4 +22,6 @@ sftp-config.json
 *.DS_Store
 
 # Pycharm idea folder
-.idea/
\ No newline at end of file
+.idea/
+# cibuildwheel output
+wheelhouse/
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 7766dfa..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,93 +0,0 @@
-os: linux
-
-language: python
-
-python:
-  - "3.6"
-  - "3.7"
-  - "3.8"
-
-#matrix:
-#  include:
-#  - os: osx
-#    osx_image: xcode12.2
-#    language: generic
-#    env:
-#      - MATRIX_EVAL="brew install gcc@10 &&CC=gcc-10 && CXX=g++-10"
-#      - PYTHON=3.8
-#      - SO_COMPILER=gcc
-#
-#  - os: osx
-#    osx_image: xcode12.2
-#    language: generic
-#    env:
-#      - MATRIX_EVAL="curl https://mac.r-project.org/openmp/openmp-11.0.1-darwin20-Release.tar.gz | tar -xz&& sudo cp usr/local/lib/* /usr/local/lib/ &&  sudo cp usr/local/include/* /usr/local/include/ &&CC=clang "
-#      - PYTHON=3.8
-#      - SO_COMPILER=clang
-notifications:
-  email: false
-
-addons:
-  apt:
-    packages:
-    - libfftw3-dev
-    - libatlas-dev
-    - libatlas-base-dev
-    - liblapack-dev
-    - libblas-dev
-    - gfortran
-
-before_install:
-    - export URLROOT=https://repo.continuum.io/miniconda/;
-      if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-         brew update;
-         brew upgrade;
-         brew install fftw;
-         export MCINST=Miniconda3-latest-MacOSX-x86_64.sh;
-      else
-         if [[ "$TRAVIS_PYTHON_VERSION" == "2.7" ]]; then
-           export MCINST=Miniconda2-latest-Linux-x86_64.sh;
-         else
-           export MCINST=Miniconda3-latest-Linux-x86_64.sh;
-         fi
-      fi;
-      export MCURL=$URLROOT$MCINST;
-      wget $MCURL -O miniconda.sh
-    - bash miniconda.sh -b -p $HOME/miniconda
-    - export PATH="$HOME/miniconda/bin:$PATH"
-    - hash -r
-    - conda config --set always_yes yes --set changeps1 no
-    - conda update -q conda
-    - conda info -a
-#    - eval "${MATRIX_EVAL}"
-
-install:
-    - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-         export PYTHON_VERSION=3.8;
-      else
-         export PYTHON_VERSION=$TRAVIS_PYTHON_VERSION;
-      fi;
-      conda create --yes -q -n test-env python=$PYTHON_VERSION
-    - source activate test-env
-    - pip install -r requirements.txt
-    - if [[ "$TRAVIS_OS_NAME" != "osx" && "$TRAVIS_PYTHON_VERSION" == "3.8" ]]; then
-         conda install -c conda-forge codecov;
-      fi
-    - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-          if [[ "$SO_COMPILER" == "gcc" ]]; then
-              CC=gcc-10 python setup.py build_ext --inplace;
-          else
-              CC=clang python setup.py build_ext --inplace;
-          fi;
-      else
-          python setup.py build_ext --inplace;
-      fi;
-
-
-script:
-    - pytest
-
-after_success:
-    - if [[ "$TRAVIS_OS_NAME" != "osx" && "$TRAVIS_PYTHON_VERSION" == "3.8" ]]; then
-        codecov;
-      fi
diff --git a/dev_scripts/README.md b/dev_scripts/README.md
new file mode 100644
index 0000000..f1a96bd
--- /dev/null
+++ b/dev_scripts/README.md
@@ -0,0 +1,114 @@
+Considerations for package maintenance:
+---------------------------------------
+
+1. Package metadata (requires-python, dependencies in pyproject.toml)
+This declares the minimum you need, not the maximum. The strong community consensus is: never put upper bounds on requires-python or on dependencies in published package metadata. Upper bounds are actively harmful — they prevent users from installing your package alongside other packages that have already moved forward. If numpy>=2.0 breaks something, the right fix is to fix the code, not to block numpy>=2.0. The only exception is when you have a known, tested incompatibility with a specific version.
+
+2. The CI test matrix
+CI (Continuous Integration) is automated testing that runs in the cloud every time code is pushed to the repository or a pull request is opened. For svmbir, this means GitHub automatically installs the package and runs the test suite on Linux across all supported Python versions. The goal is to catch breakage early — before a bug reaches users — and to confirm that changes work correctly across the Python versions the package claims to support. Check https://github.com/cabouman/svmbir/actions for status.
+
+The CI matrix is the list of Python versions CI tests against. The current matrix is under jobs->matrix->python-version in `ci.yml`. When a new Python version comes out in October, add it to the list and see if anything breaks. This is the right place to discover problems early, before users file bugs.
+
+3. The dev environment (install_conda_environment.sh)
+This should pin to a specific recent version for a reproducible daily-driver environment. The version you pick here doesn't limit what users can run — it's just what developers work in. Updating this once a year when a new Python ships is reasonable.
+
+4. The CI workflow (.github/workflows/ci.yml)
+This is the configuration file that tells GitHub how to run CI. It specifies which Python versions to test, which operating system to use (Linux only — see section 5 for macOS), and what commands to run (install the package, run pytest). It fires automatically on every push to `master` or `prerelease`, and on every pull request targeting either branch — no manual action needed.
+
+Updating Python versions (do this ~once a year):
+- **Add a new version**: Each October, Python ships a new release. Add it to the `python-version` list in `ci.yml`, and add the matching `cp3XX-*` entry to the `build` setting in `[tool.cibuildwheel]` in `pyproject.toml` so release wheels are built for it too. Note that Cython may lag a few months behind a new Python release, so if CI fails on the new version due to a Cython build error, simply remove it from both lists and try again after the next Cython release.
+- **Drop an EOL version**: Python versions reach end-of-life roughly 3 years after release (schedule at python.org/downloads). Remove it from the `python-version` list in `ci.yml`, the `build` setting in `pyproject.toml`, and raise `requires-python` in `pyproject.toml` to match.
+
+Updating OS runners:
+- CI runs Linux only (`ubuntu-latest`). macOS is no longer in the CI matrix — macOS compatibility is verified when building and test-installing the release wheels locally (see section 5 below).
+- If a future Linux runner name change is needed, `ubuntu-latest` tracks GitHub's current default and rarely requires manual updates.
+
+5. The release workflow (.github/workflows/release.yml) and local macOS build
+Linux wheels and the source distribution are built automatically by GitHub Actions. macOS arm64 wheels are built locally using `dev_scripts/build_mac_wheels.sh` and uploaded to the same draft release. Intel Mac (x86_64) is no longer supported.
+
+New releases:
+-------------
+
+Each release is staged on the `prerelease` branch and stays as a non-public draft until you explicitly publish it, so you can verify everything before it goes live. The process has two steps: test first, then release.
+
+Both scripts are run from the `prerelease` branch. The typical sequence after your feature branch PR has been merged into `prerelease`:
+
+   ```
+   git checkout prerelease && git pull
+   ./test_release.sh      # dry run — verify the pipeline works
+   ./cut_release.sh       # real release
+   ```
+
+`test_release.sh` warns (but does not exit) if you are not on `prerelease`, so it can also be used from a feature branch to debug a workflow problem.
+
+Note that the scripts need to be run as `./<script>.sh` rather than `source <script>.sh`. 
+
+Step A — Test the release workflow (run before every release):
+`./test_release.sh` automates a complete dry run of the release process using a throwaway tag. It:
+- Creates and pushes a test tag of the form `v<current_version>-bump-test` (e.g. `v0.4.0-bump-test`), based on the current version in `pyproject.toml`. The wheels built during the test will carry the current version number — this is expected. The real release will update `pyproject.toml` to the new version before building.
+- Triggers GitHub Actions to create a draft release and build Linux wheels
+- Builds the macOS arm64 wheels locally and uploads them to the same draft release
+- Pauses for you to verify that all wheels appear correctly on the GitHub Releases page
+- Cleans up the test tag and draft release automatically when you confirm success
+
+Step B — Cut the real release:
+Once the test in Step A passes, `./cut_release.sh` does the real release. It:
+- Shows the current version and the latest published release, and prompts for the new version
+- Validates the new version is greater than the existing one
+- Updates `pyproject.toml`, commits, pushes, and creates the version tag
+- Triggers GitHub Actions to create a draft release and build Linux wheels
+- Builds the macOS arm64 wheels locally and uploads them
+- Prints the remaining manual steps: verify the draft release, open the prerelease→master PR, and publish
+
+Prerequisites: `cibuildwheel` and `gh` (the GitHub CLI) are installed automatically by `install_conda_environment.sh`. `gh` is GitHub's official command-line tool — it talks to the GitHub API to create releases and upload wheel files on your behalf, separate from your normal `git` push access. Both scripts detect whether `gh` is authenticated and run `gh auth login` for you if needed (opens a browser to log in to your GitHub account).
+
+Manual steps (for reference or recovery if a script fails partway through):
+1. On the `prerelease` branch, update the version in `pyproject.toml` to the new version (e.g. `0.4.X`). This is the single source of truth — `__init__.py` reads it at runtime via `importlib.metadata`.
+2. Commit and push the version bump: `git commit -m "Release v0.4.X" && git push`
+3. Tag the commit and push the tag: `git tag v0.4.X && git push --tags`
+   GitHub Actions immediately creates a draft release, then builds Linux wheels and the source distribution and uploads them.
+4. Build and upload the macOS arm64 wheels: `cd dev_scripts && ./build_mac_wheels.sh v0.4.X`
+5. Go to the repo's Releases page on GitHub and confirm both Linux and macOS wheels are attached.
+6. Merge `prerelease` → `master` via a pull request: `gh pr create --base master --title "Release v0.4.X"`
+7. After the PR merges, publish the draft release on GitHub.
+
+Updating the release workflow over time:
+- **Python versions**: keep the `build` setting in `[tool.cibuildwheel]` in `pyproject.toml` in sync with the CI matrix in `ci.yml` and `requires-python`. All three should agree.
+- **cibuildwheel version**: `pypa/cibuildwheel@v2.22.0` in `release.yml` is pinned for reproducibility. When a new Python version requires a newer cibuildwheel release, bump the pin here and also update the version in `install_conda_environment.sh` so local builds stay in sync.
+
+Adding PyPI distribution later:
+When ready to publish to PyPI, add a final job to `release.yml` after `create-draft-release`:
+1. Set up PyPI Trusted Publishing in your PyPI project settings (links the GitHub repo without needing a stored API token).
+2. Add a `publish-to-pypi` job that downloads the `dist/` artifacts and runs `pypa/gh-action-pypi-publish`.
+
+
+Development workflow: prerelease → master
+-----------------------------------------
+
+The standard workflow for this repo is: feature branch → PR to `prerelease` → PR from `prerelease` to `master`. CI runs automatically at both gates.
+
+When working on a feature branch:
+1. Push your branch to GitHub: `git push -u origin <branch-name>`
+2. Open a pull request to `prerelease`: `gh pr create --base prerelease`
+3. GitHub automatically runs CI. Go to the PR page and click the "Checks" tab, or visit https://github.com/cabouman/svmbir/actions, to watch the jobs run (one per Python version on Linux).
+4. If a job fails, click into it to read the log, fix the issue, push another commit to the branch, and CI re-runs automatically.
+5. Once CI passes, merge the PR into `prerelease`.
+6. When ready to release, run `./test_release.sh` then `./cut_release.sh` from dev_scripts/ on the `prerelease` branch.
+7. Open a PR from `prerelease` to `master` and merge after CI passes.
+8. Publish the draft release on GitHub.
+
+
+Keeping current over time — the practical options:
+--------------------------------------------------
+
+1. Dependabot (built into GitHub): opens automated PRs when dependencies release new versions. Very low friction — it just creates a PR, and your CI tells you if it breaks anything. This is the right tool for routine package bumps.
+
+2. Manual annual review: less automated but sufficient for a project that doesn't change often. When a new Python or NumPy ships, run the test suite against it and fix what breaks.
+
+3. pip-compile / lock files: great for applications that need exact reproducibility, but not the right tool for a library — it over-constrains what users can install alongside you.
+
+For this project specifically, Cython + C extensions have two real compatibility risks:
+
+1. New Python versions: Cython generates standard CPython API code, so new Pythons almost always Just Work once Cython itself is updated. The main friction is that Cython needs to release a version supporting the new Python's ABI before you can build wheels for it.
+
+2. NumPy major versions: NumPy 2.0 changed the C API in breaking ways. We already added NPY_NO_DEPRECATED_API which is the right first step, but a runtime test against NumPy 2.x is worth adding to the CI matrix.
diff --git a/dev_scripts/build_mac_wheels.sh b/dev_scripts/build_mac_wheels.sh
new file mode 100755
index 0000000..f7b4a5b
--- /dev/null
+++ b/dev_scripts/build_mac_wheels.sh
@@ -0,0 +1,82 @@
+#!/bin/bash
+# Build macOS arm64 wheels locally and upload them to the draft GitHub Release
+# for the given tag.
+#
+# Prerequisites:
+#   pip install cibuildwheel   (once; any Python environment)
+#   gh auth login              (once; authenticates the gh CLI)
+#
+# Usage (run from dev_scripts/):
+#   ./build_mac_wheels.sh v0.4.1
+
+set -euo pipefail
+
+TAG=${1:?"Usage: build_mac_wheels.sh <tag>  e.g.  ./build_mac_wheels.sh v0.4.1"}
+
+# Always work from the repo root regardless of where the script is called from.
+cd "$(dirname "$0")/.."
+
+# Fetch tags from remote so we can verify the tag exists.
+echo "Fetching tags ..."
+git fetch --tags --quiet
+
+# Verify the tag exists.
+git rev-parse "$TAG" >/dev/null 2>&1 || {
+    echo "ERROR: Tag $TAG not found on remote. Push the tag first:"
+    echo "  git tag $TAG && git push --tags"
+    exit 1
+}
+
+# Verify HEAD matches the tag so the wheel is built from the correct commit.
+HEAD_COMMIT=$(git rev-parse HEAD)
+TAG_COMMIT=$(git rev-parse "$TAG")
+if [ "$HEAD_COMMIT" != "$TAG_COMMIT" ]; then
+    echo "ERROR: HEAD does not match tag $TAG."
+    echo "Check out the tagged commit first:"
+    echo "  git checkout $TAG"
+    exit 1
+fi
+
+# Verify the working tree is clean.
+if ! git diff --quiet || ! git diff --cached --quiet; then
+    echo "ERROR: Working tree has uncommitted changes."
+    echo "Commit or stash all changes before building a release wheel."
+    exit 1
+fi
+
+# Verify the git submodule is initialized.
+if ! ls svmbir/sv-mbirct/src/*.c >/dev/null 2>&1; then
+    echo "ERROR: C source files not found — git submodule not initialized."
+    echo "Run:  git submodule update --init --recursive"
+    exit 1
+fi
+
+# Verify cibuildwheel is available.
+if ! command -v cibuildwheel &>/dev/null; then
+    echo "ERROR: cibuildwheel not found."
+    echo "Install it with:  pip install cibuildwheel"
+    exit 1
+fi
+
+# Verify the gh CLI is authenticated; offer to log in if not.
+if ! gh auth status &>/dev/null; then
+    echo "gh CLI not authenticated — launching 'gh auth login' now ..."
+    echo "(This is a one-time step. Follow the prompts to log in via browser.)"
+    gh auth login
+    if ! gh auth status &>/dev/null; then
+        echo "ERROR: gh auth login did not succeed. Re-run this script to try again."
+        exit 1
+    fi
+fi
+
+echo "Building macOS arm64 wheels for $TAG ..."
+cibuildwheel --platform macos
+
+echo "Uploading wheels to draft release $TAG ..."
+gh release upload "$TAG" wheelhouse/*.whl --clobber
+
+echo ""
+echo "macOS wheels uploaded. Check that the Linux wheels are also attached, then"
+echo "publish the release at:"
+REPO=$(gh repo view --json nameWithOwner -q .nameWithOwner)
+echo "  https://github.com/$REPO/releases/tag/$TAG"
diff --git a/dev_scripts/clean_svmbir.sh b/dev_scripts/clean_svmbir.sh
index 4de201b..5760f15 100644
--- a/dev_scripts/clean_svmbir.sh
+++ b/dev_scripts/clean_svmbir.sh
@@ -8,5 +8,5 @@ cd ..
 /bin/rm -r dist
 /bin/rm -r svmbir.egg-info
 
-pip uninstall svmbir
+pip uninstall -y svmbir
 cd dev_scripts
diff --git a/dev_scripts/cut_release.sh b/dev_scripts/cut_release.sh
new file mode 100755
index 0000000..8c4fbcf
--- /dev/null
+++ b/dev_scripts/cut_release.sh
@@ -0,0 +1,238 @@
+#!/bin/bash
+set -euo pipefail
+#
+# Interactive release script for svmbir.
+#
+# Verifies preconditions, bumps the version, commits, tags, triggers the
+# GitHub Actions draft release, builds macOS arm64 wheels locally, and
+# prints the remaining manual steps.
+#
+# Usage (run from dev_scripts/):
+#   ./cut_release.sh
+
+# Always work from the repo root regardless of where the script is called from.
+cd "$(dirname "$0")/.."
+
+echo "=== svmbir release script ==="
+echo ""
+
+# ---------------------------------------------------------------------------
+# Preflight checks
+# ---------------------------------------------------------------------------
+
+echo "Preflight checks:"
+
+# Branch must be prerelease.
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [ "$BRANCH" != "prerelease" ]; then
+    echo "  FAIL  branch is '$BRANCH' (must be 'prerelease')"
+    echo "        Switch with:  git checkout prerelease"
+    exit 1
+fi
+echo "  OK    branch is prerelease"
+
+# Fetch latest state from remote (also needed for tag checks later).
+git fetch --tags --quiet
+echo "  OK    fetched from remote"
+
+# Local branch must not be behind remote.
+LOCAL=$(git rev-parse HEAD)
+REMOTE=$(git rev-parse "@{u}" 2>/dev/null || true)
+if [ -n "$REMOTE" ] && [ "$LOCAL" != "$REMOTE" ]; then
+    echo "  FAIL  local branch is behind remote"
+    echo "        Run:  git pull"
+    exit 1
+fi
+echo "  OK    up to date with remote"
+
+# Working tree must be clean.
+if ! git diff --quiet || ! git diff --cached --quiet; then
+    echo "  FAIL  working tree has uncommitted changes"
+    echo "        Commit or stash all changes before cutting a release."
+    exit 1
+fi
+echo "  OK    working tree is clean"
+
+# Git submodule must be initialized.
+if ! ls svmbir/sv-mbirct/src/*.c >/dev/null 2>&1; then
+    echo "  FAIL  git submodule not initialized"
+    echo "        Run:  git submodule update --init --recursive"
+    exit 1
+fi
+echo "  OK    git submodule initialized"
+
+# gh CLI must be authenticated.
+if ! gh auth status &>/dev/null; then
+    echo "  gh CLI not authenticated — launching 'gh auth login' now ..."
+    echo "  (This is a one-time step. Follow the prompts to log in via browser.)"
+    gh auth login
+    if ! gh auth status &>/dev/null; then
+        echo "  FAIL  gh auth login did not succeed. Re-run this script to try again."
+        exit 1
+    fi
+fi
+echo "  OK    gh CLI authenticated"
+
+# cibuildwheel must be installed.
+if ! command -v cibuildwheel &>/dev/null; then
+    echo "  FAIL  cibuildwheel not found"
+    echo "        Run:  pip install cibuildwheel"
+    exit 1
+fi
+echo "  OK    cibuildwheel available"
+
+echo ""
+
+# ---------------------------------------------------------------------------
+# Version selection
+# ---------------------------------------------------------------------------
+
+# Read current version from pyproject.toml.
+CURRENT=$(python3 -c "
+import re, sys
+m = re.search(r'^version = \"(.+)\"', open('pyproject.toml').read(), re.MULTILINE)
+sys.exit(1) if not m else print(m.group(1))
+")
+
+# Read latest published release (strips leading 'v').
+LATEST_TAG=$(gh release list --exclude-drafts --limit 1 --json tagName \
+             -q '.[0].tagName' 2>/dev/null || true)
+LATEST="${LATEST_TAG#v}"
+[ -z "$LATEST" ] && LATEST_DISPLAY="(none)" || LATEST_DISPLAY="$LATEST"
+
+echo "Current version in pyproject.toml : $CURRENT"
+echo "Latest published GitHub release   : $LATEST_DISPLAY"
+echo ""
+read -rp "New version (X.Y.Z): " NEW_VERSION
+
+# Must be valid semver.
+if ! echo "$NEW_VERSION" | grep -qE '^[0-9]+\.[0-9]+\.[0-9]+$'; then
+    echo "ERROR: '$NEW_VERSION' is not valid semver (expected X.Y.Z)."
+    exit 1
+fi
+
+# Must differ from the current pyproject.toml version.
+if [ "$NEW_VERSION" = "$CURRENT" ]; then
+    echo "ERROR: $NEW_VERSION is already the version in pyproject.toml."
+    exit 1
+fi
+
+# Must differ from the latest published release.
+if [ -n "$LATEST" ] && [ "$NEW_VERSION" = "$LATEST" ]; then
+    echo "ERROR: $NEW_VERSION is already the latest published release."
+    exit 1
+fi
+
+# Must be strictly greater than the latest published release.
+if [ -n "$LATEST" ]; then
+    IS_GREATER=$(python3 -c "
+a = tuple(int(x) for x in '$NEW_VERSION'.split('.'))
+b = tuple(int(x) for x in '$LATEST'.split('.'))
+print('yes' if a > b else 'no')
+")
+    if [ "$IS_GREATER" != "yes" ]; then
+        echo "ERROR: $NEW_VERSION is not greater than the latest release ($LATEST)."
+        exit 1
+    fi
+fi
+
+TAG="v$NEW_VERSION"
+
+# ---------------------------------------------------------------------------
+# Confirmation
+# ---------------------------------------------------------------------------
+
+echo ""
+echo "About to:"
+echo "  1. Set version to $NEW_VERSION in pyproject.toml"
+echo "  2. Commit: \"Release $TAG\""
+echo "  3. Push commit to prerelease"
+echo "  4. Create and push tag $TAG"
+echo "     (GitHub Actions will create a draft release and build Linux wheels)"
+echo "  5. Build macOS arm64 wheels locally and upload to the draft release"
+echo ""
+read -rp "Proceed? [yes/N]: " CONFIRM
+[ "$CONFIRM" = "yes" ] || { echo "Aborted."; exit 0; }
+echo ""
+
+# Print a helpful message if anything fails from here on.
+trap 'echo ""; echo "Script failed at the step above. The remaining steps can be run manually — see dev_scripts/README.md."' ERR
+
+# ---------------------------------------------------------------------------
+# Step 1/5 — Update pyproject.toml
+# ---------------------------------------------------------------------------
+
+echo "--- 1/5  Updating pyproject.toml ---"
+python3 - <<PYEOF
+import re
+path = 'pyproject.toml'
+txt = open(path).read()
+new_txt = re.sub(
+    r'^version = ".+"',
+    'version = "$NEW_VERSION"',
+    txt, count=1, flags=re.MULTILINE
+)
+assert new_txt != txt, "Version substitution had no effect — check pyproject.toml format."
+open(path, 'w').write(new_txt)
+PYEOF
+echo "     version = \"$NEW_VERSION\""
+
+# ---------------------------------------------------------------------------
+# Step 2/5 — Commit
+# ---------------------------------------------------------------------------
+
+echo ""
+echo "--- 2/5  Committing ---"
+git add pyproject.toml
+git commit -m "Release $TAG"
+
+# ---------------------------------------------------------------------------
+# Step 3/5 — Push commit
+# ---------------------------------------------------------------------------
+
+echo ""
+echo "--- 3/5  Pushing commit to prerelease ---"
+git push
+
+# ---------------------------------------------------------------------------
+# Step 4/5 — Tag and push
+# ---------------------------------------------------------------------------
+
+echo ""
+echo "--- 4/5  Tagging and pushing $TAG ---"
+git tag "$TAG"
+git push origin "$TAG"
+echo "     GitHub Actions is creating the draft release and building Linux wheels."
+
+# ---------------------------------------------------------------------------
+# Step 5/5 — Build macOS wheels locally
+# ---------------------------------------------------------------------------
+
+echo ""
+echo "--- 5/5  Building macOS arm64 wheels ---"
+dev_scripts/build_mac_wheels.sh "$TAG"
+
+# ---------------------------------------------------------------------------
+# Handoff
+# ---------------------------------------------------------------------------
+
+trap - ERR
+
+REPO=$(gh repo view --json nameWithOwner -q .nameWithOwner)
+
+echo ""
+echo "============================================================"
+echo "  Release $TAG is ready to review"
+echo "============================================================"
+echo ""
+echo "Remaining steps:"
+echo ""
+echo "  1. Confirm all wheels are attached to the draft release"
+echo "     (Linux + macOS arm64, all three Python versions):"
+echo "     https://github.com/$REPO/releases/tag/$TAG"
+echo ""
+echo "  2. Open a pull request from prerelease to master:"
+echo "     gh pr create --base master --title \"Release $TAG\""
+echo ""
+echo "  3. After the PR merges, publish the draft release on GitHub."
+echo ""
diff --git a/dev_scripts/install_conda_environment.sh b/dev_scripts/install_conda_environment.sh
index f5df8d9..d423741 100644
--- a/dev_scripts/install_conda_environment.sh
+++ b/dev_scripts/install_conda_environment.sh
@@ -1,11 +1,37 @@
 #!/bin/bash
 # This script destroys the conda environment named "svmbir" and reinstall it.
 
+# On macOS, Xcode Command Line Tools are required for clang, git, and SDK headers.
+if [[ "$(uname)" == "Darwin" ]]; then
+    if ! xcode-select -p &>/dev/null; then
+        echo ""
+        echo "ERROR: Xcode Command Line Tools are not installed."
+        echo "Run the following command and follow the prompts, then retry:"
+        echo ""
+        echo "    xcode-select --install"
+        echo ""
+        return 1
+    fi
+fi
+
 # Create and activate new conda environment
 cd ..
 conda deactivate
-conda remove env --name svmbir --all
-conda create --name svmbir python=3.10
+conda remove -y --name svmbir --all
+conda create -y --name svmbir python=3.12
 conda activate svmbir
+
+# macOS: llvm-openmp is required for OpenMP support with Apple Clang.
+if [[ "$(uname)" == "Darwin" ]]; then
+    conda install -n svmbir -y -c conda-forge llvm-openmp
+fi
+
+# gh (GitHub CLI) — used by cut_release.sh and build_mac_wheels.sh to create
+# and upload to GitHub Releases. 'gh auth login' must be run once after install.
+conda install -n svmbir -y -c conda-forge gh
+
+# cibuildwheel — used by build_mac_wheels.sh to build macOS wheels locally.
+pip install cibuildwheel==2.22.0
+
 cd dev_scripts
 
diff --git a/dev_scripts/install_svmbir.sh b/dev_scripts/install_svmbir.sh
index 58861f9..b07fa22 100644
--- a/dev_scripts/install_svmbir.sh
+++ b/dev_scripts/install_svmbir.sh
@@ -1,11 +1,8 @@
 #!/bin/bash
-# This script just installs svmbir along with requirements of svmbir, demos, and documation.. 
-# However, it does not remove the existing installation of svmbir.
+# Install svmbir in editable mode together with all dev, docs, and demo dependencies.
+# Does not remove an existing installation — run clean_svmbir.sh first if needed.
 
 cd ..
-pip install -r requirements.txt
-pip install .
-pip install -r demo/requirements_demo.txt
-pip install -r docs/requirements.txt 
+git submodule update --init --recursive
+pip install -e ".[dev,docs,demo]"
 cd dev_scripts
-
diff --git a/dev_scripts/test_release.sh b/dev_scripts/test_release.sh
new file mode 100755
index 0000000..2e4b322
--- /dev/null
+++ b/dev_scripts/test_release.sh
@@ -0,0 +1,183 @@
+#!/bin/bash
+set -euo pipefail
+#
+# Test the release workflow end-to-end using a throwaway tag.
+# Run this before ./cut_release.sh to verify that GitHub Actions builds
+# the Linux wheels correctly and the local macOS build works.
+#
+# The script creates a test tag (e.g. v0.4.1-test) based on the current
+# version in pyproject.toml, triggers the GitHub Actions release workflow,
+# builds the macOS wheels locally, then cleans everything up after you
+# confirm it all looks right.
+#
+# Usage (run from dev_scripts/):
+#   ./test_release.sh
+
+cd "$(dirname "$0")/.."
+
+echo "=== svmbir release workflow test ==="
+echo ""
+
+# ---------------------------------------------------------------------------
+# Preflight checks
+# ---------------------------------------------------------------------------
+
+echo "Preflight checks:"
+
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [ "$BRANCH" != "prerelease" ]; then
+    echo "  WARN  branch is '$BRANCH', not 'prerelease'"
+    echo "        For a pre-release test, run this from the prerelease branch."
+    echo "        Continuing anyway (useful for debugging workflow issues)."
+else
+    echo "  OK    branch is prerelease"
+fi
+
+git fetch --tags --quiet
+echo "  OK    fetched from remote"
+
+if ! git diff --quiet || ! git diff --cached --quiet; then
+    echo "  FAIL  working tree has uncommitted changes"
+    echo "        Commit or stash changes before testing."
+    exit 1
+fi
+echo "  OK    working tree is clean"
+
+if ! ls svmbir/sv-mbirct/src/*.c >/dev/null 2>&1; then
+    echo "  FAIL  git submodule not initialized"
+    echo "        Run:  git submodule update --init --recursive"
+    exit 1
+fi
+echo "  OK    git submodule initialized"
+
+if ! gh auth status &>/dev/null; then
+    echo "  gh CLI not authenticated — launching 'gh auth login' now ..."
+    echo "  (This is a one-time step. Follow the prompts to log in via browser.)"
+    gh auth login
+    if ! gh auth status &>/dev/null; then
+        echo "  FAIL  gh auth login did not succeed. Re-run this script to try again."
+        exit 1
+    fi
+fi
+echo "  OK    gh CLI authenticated"
+
+if ! command -v cibuildwheel &>/dev/null; then
+    echo "  FAIL  cibuildwheel not found"
+    echo "        Run:  pip install cibuildwheel==2.22.0"
+    exit 1
+fi
+echo "  OK    cibuildwheel available"
+
+REPO=$(gh repo view --json nameWithOwner -q .nameWithOwner)
+echo ""
+
+# ---------------------------------------------------------------------------
+# Determine test tag
+# ---------------------------------------------------------------------------
+
+CURRENT=$(python3 -c "
+import re, sys
+m = re.search(r'^version = \"(.+)\"', open('pyproject.toml').read(), re.MULTILINE)
+sys.exit(1) if not m else print(m.group(1))
+")
+TEST_TAG="v${CURRENT}-bump-test"
+
+echo "Current version in pyproject.toml : $CURRENT"
+echo "Test tag                          : $TEST_TAG"
+echo "(Wheels will carry version $CURRENT — expected for a test run."
+echo " The real release will update pyproject.toml to the new version before building.)"
+echo ""
+
+# If the test tag already exists, offer to remove it and start fresh.
+if git rev-parse "$TEST_TAG" >/dev/null 2>&1; then
+    echo "WARNING: tag $TEST_TAG already exists."
+    read -rp "Delete it and start fresh? [yes/N]: " REDO
+    if [ "$REDO" = "yes" ]; then
+        gh release delete "$TEST_TAG" --yes 2>/dev/null && echo "  deleted existing draft release" || true
+        git push --delete origin "$TEST_TAG" 2>/dev/null && echo "  deleted remote tag" || true
+        git tag -d "$TEST_TAG" 2>/dev/null && echo "  deleted local tag" || true
+        echo ""
+    else
+        echo "Aborted."
+        exit 0
+    fi
+fi
+
+# ---------------------------------------------------------------------------
+# Confirmation
+# ---------------------------------------------------------------------------
+
+echo "About to:"
+echo "  1. Create and push test tag $TEST_TAG"
+echo "     (GitHub Actions will create a draft release and build Linux wheels)"
+echo "  2. Build macOS arm64 wheels locally and upload to the draft release"
+echo "  3. Pause for you to verify the draft release on GitHub"
+echo "  4. Delete the test tag and draft release"
+echo ""
+read -rp "Proceed? [yes/N]: " CONFIRM
+[ "$CONFIRM" = "yes" ] || { echo "Aborted."; exit 0; }
+echo ""
+
+# Print cleanup instructions if anything fails from here on.
+trap '
+echo ""
+echo "Script failed. The test tag may still exist — clean up with:"
+echo "  gh release delete '"$TEST_TAG"' --yes"
+echo "  git push --delete origin '"$TEST_TAG"'"
+echo "  git tag -d '"$TEST_TAG"'"
+' ERR
+
+# ---------------------------------------------------------------------------
+# Step 1/3 — Create and push test tag
+# ---------------------------------------------------------------------------
+
+echo "--- 1/3  Creating and pushing test tag $TEST_TAG ---"
+git tag "$TEST_TAG"
+git push origin "$TEST_TAG"
+echo ""
+echo "     GitHub Actions is now creating the draft release and building"
+echo "     Linux wheels. Watch progress at:"
+echo "     https://github.com/$REPO/actions"
+echo ""
+
+# ---------------------------------------------------------------------------
+# Step 2/3 — Build macOS wheels locally
+# ---------------------------------------------------------------------------
+
+echo "--- 2/3  Building macOS arm64 wheels locally ---"
+dev_scripts/build_mac_wheels.sh "$TEST_TAG"
+echo ""
+
+# ---------------------------------------------------------------------------
+# Step 3/3 — Verify
+# ---------------------------------------------------------------------------
+
+echo "--- 3/3  Verify the draft release ---"
+echo ""
+echo "Once the GitHub Actions Linux build finishes, confirm that all wheels"
+echo "(Linux + macOS arm64, all Python versions) and the source distribution"
+echo "are attached at:"
+echo "  https://github.com/$REPO/releases/tag/$TEST_TAG"
+echo ""
+echo "Optional: test-install a wheel to confirm it works:"
+echo "  pip install <URL copied from the release page>"
+echo ""
+read -rp "Did everything look correct? [yes/N]: " VERIFIED
+
+trap - ERR
+
+echo ""
+if [ "$VERIFIED" = "yes" ]; then
+    echo "Cleaning up ..."
+    gh release delete "$TEST_TAG" --yes 2>/dev/null && echo "  deleted draft release" || true
+    git push --delete origin "$TEST_TAG" 2>/dev/null && echo "  deleted remote tag" || true
+    git tag -d "$TEST_TAG" 2>/dev/null && echo "  deleted local tag" || true
+    echo ""
+    echo "Release workflow verified. Run ./cut_release.sh when ready for the real release."
+else
+    echo "Leaving the draft release in place for investigation."
+    echo "When done, clean up manually:"
+    echo "  gh release delete $TEST_TAG --yes"
+    echo "  git push --delete origin $TEST_TAG"
+    echo "  git tag -d $TEST_TAG"
+fi
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 83228ed..da073d3 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -12,7 +12,7 @@
 #
 import os
 import sys
-from ast import parse
+from importlib.metadata import version as _version
 import sphinx_rtd_theme
 
 if os.environ.get('SVMBIR_BUILD_DOCS') =='true':
@@ -25,12 +25,7 @@
 copyright = '2020-2022, SVMBIR Development Team'
 author = 'SVMBIR Development Team'
 
-# The full version, including alpha/beta/rc tags
-#version = '0.2'
-#release = '0.2'
-# Retrieve the version number from svmbir/__init__.py
-with open(os.path.join("../..",project,"__init__.py")) as f:
-    release = parse(next(filter(lambda line: line.startswith("__version__"), f))).body[0].value.s
+release = _version("svmbir")
 
 
 # -- General configuration ---------------------------------------------------
@@ -102,7 +97,6 @@
 #
 #html_theme = 'bizstyle'
 html_theme = 'sphinx_rtd_theme'
-html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 
 html_theme_options = {
     'style_nav_header_background': '#4f8fb8ff',
diff --git a/pyproject.toml b/pyproject.toml
index 4385f60..1c42a31 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,42 @@
 [build-system]
 requires = ["setuptools", "wheel", "numpy>=1.26.0", "Cython"]
 build-backend = "setuptools.build_meta"
+
+[project]
+# Keep version in sync with svmbir/__init__.py
+name = "svmbir"
+version = "0.4.0"
+description = "Python code for fast parallel-beam MBIR (Model Based Iterative Reconstruction)"
+readme = "README.md"
+license = "BSD-3-Clause"
+requires-python = ">=3.10"
+maintainers = [{name = "Charles A. Bouman", email = "charles.bouman@gmail.edu"}]
+dependencies = [
+    "numpy>=1.26.0",
+    "psutil>=5.8",
+    "Pillow>=9.0",
+]
+
+[project.optional-dependencies]
+dev  = ["pytest", "ruamel.yaml", "Cython"]
+docs = ["sphinx", "sphinx-rtd-theme", "sphinxcontrib-bibtex", "ipython>=6.3.1"]
+demo = ["matplotlib"]
+
+[project.urls]
+Homepage = "https://github.com/cabouman/svmbir"
+
+[tool.setuptools.packages.find]
+where     = ["."]
+include   = ["svmbir*"]
+
+[tool.cibuildwheel]
+# Build CPython 3.10–3.12 only; skip musl Linux (Alpine) and PyPy.
+build = "cp310-* cp311-* cp312-* cp313-* cp314-*"
+skip  = "*-musllinux_*"
+
+[tool.cibuildwheel.macos]
+# arm64 only — Intel Mac support has been dropped.
+# Install libomp before each build so setup.py's brew fallback finds it.
+# delocate (run automatically by cibuildwheel) then bundles it into the wheel.
+archs = ["arm64"]
+before-build = "brew install libomp"
diff --git a/requirements.txt b/requirements.txt
index b0a8a61..a223b64 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,4 @@
-numpy>=1.26.0
-psutil>=5.8
-Pillow<=10.1.0
-Cython
-ruamel.yaml
-pytest
+# Runtime and development dependencies are declared in pyproject.toml.
+# To install svmbir with all development, docs, and demo dependencies run:
+#
+#   pip install -e ".[dev,docs,demo]"
diff --git a/setup.py b/setup.py
index 0366fb7..0a9447c 100644
--- a/setup.py
+++ b/setup.py
@@ -1,107 +1,155 @@
 import os
 import sys
-from ast import parse
 import numpy as np
 from setuptools import setup, Extension
 from Cython.Distutils import build_ext
 
-with open("README.md", "r") as fh:
-    long_description = fh.read()
-
-name = 'svmbir'
-#version number set in svmbir/__init__.py
-with open(os.path.join(name,"__init__.py")) as f:
-    version = parse(next(filter(lambda line: line.startswith("__version__"), f))).body[0].value.s
-description="Python code for fast parallel-beam MBIR (Model Based Iterative Reconstruction) "
-long_description_content_type="text/markdown"
-url="https://github.com/cabouman/svmbir"
-maintainer="Charles A. Bouman"
-maintainer_email="charles.bouman@gmail.edu"
-license="BSD-3-Clause"
-
-packages_dir = 'svmbir'
-packages = [packages_dir]
-src_dir = packages_dir + "/sv-mbirct/src/"
-
-# Dependencies for running svmbir. Dependencies for build/installation are in pyproject.toml
-# 1/7/23: Pillow 10.2.0 (latest on this date) is missing a library libXau, that chokes on import PIL.Image
-install_requires=['numpy>=1.26.0','psutil>=5.8','Pillow<=10.1.0']
-
+src_dir = "svmbir/sv-mbirct/src/"
 
 # Set up install for Cython or Command line interface
 if os.environ.get('CLIB') != 'CMD_LINE':
 
-    # Check for compiler env variable. If not set, assume it's a gcc build (linux & macOS only).
-    if os.environ.get('CC') is None:
-        os.environ['CC']='gcc'
-
-    if os.environ.get('CC') not in ['icc','clang','msvc']:
-        extra_compile_args=["-std=c11","-O3","-fopenmp","-Wno-unknown-pragmas"]
-        extra_link_args=["-lm","-fopenmp"]
-
-    if os.environ.get('CC') =='icc':
+    # Fail fast: Xcode Command Line Tools provide clang, git, and SDK headers on macOS.
+    if sys.platform == 'darwin':
+        import subprocess as _sp
+        _xcode = _sp.run(['xcode-select', '-p'], capture_output=True)
+        if _xcode.returncode != 0:
+            sys.exit(
+                "\nERROR: Xcode Command Line Tools are not installed.\n"
+                "Run the following command and follow the prompts, then retry:\n\n"
+                "    xcode-select --install\n"
+            )
+
+    # Fail fast: submodule must be initialized before compilation can proceed.
+    import glob as _glob
+    if not _glob.glob(src_dir + '*.c'):
+        sys.exit(
+            "\nERROR: C source files not found in " + src_dir + "\n"
+            "The git submodule has not been initialized. Run:\n\n"
+            "    git submodule update --init --recursive\n"
+        )
+
+    # On macOS, force clang unless the user explicitly chose something other than gcc.
+    # Homebrew GCC at /usr/local is Intel-only and silently produces x86_64 binaries
+    # on arm64 machines. We override both the unset case and the generic 'gcc' default
+    # (which conda activation sometimes injects into the environment).
+    if sys.platform == 'darwin':
+        if os.environ.get('CC') in (None, 'gcc'):
+            os.environ['CC'] = 'clang'
+    elif os.environ.get('CC') is None:
+        os.environ['CC'] = 'gcc'
+
+    # Fail fast: verify the selected compiler is actually on PATH.
+    import shutil as _shutil
+    _cc = os.environ['CC']
+    if _cc != 'msvc' and _shutil.which(_cc) is None:
+        sys.exit(
+            f"\nERROR: Compiler '{_cc}' not found in PATH.\n"
+            "Set the CC environment variable to a compiler that is installed,\n"
+            "e.g.:  CC=gcc pip install .   or   CC=clang pip install .\n"
+        )
+
+    if os.environ.get('CC') not in ['icc', 'clang', 'msvc']:
+        extra_compile_args = ["-std=c11", "-O3", "-fopenmp", "-Wno-unknown-pragmas"]
+        extra_link_args = ["-lm", "-fopenmp"]
+
+    if os.environ.get('CC') == 'icc':
         if sys.platform == 'linux':
             os.environ['LDSHARED'] = 'icc -shared'
-        extra_compile_args=["-O3","-DICC","-qopenmp","-no-prec-div","-restrict","-inline-calloc","-qopt-calloc",
-                            "-no-ansi-alias","-xCORE-AVX2"]
-        extra_link_args=["-lm","-qopenmp"]
-
-    if os.environ.get('CC') =='clang':
-        extra_compile_args=["-O3","-Xclang", "-fopenmp","-Wno-unknown-pragmas"]
-        extra_link_args=["-lm","-lomp"]
-
-    # build for Windows using MS Visual C++
-    if os.environ.get('CC') =='msvc':
-        extra_compile_args=["/std:c11","/O2","/openmp","/DMSVC"]
-        extra_link_args=["-lm"]
-
-    c_extension = Extension(packages_dir + ".interface_cy_c",
+        extra_compile_args = ["-O3", "-DICC", "-qopenmp", "-no-prec-div", "-restrict",
+                              "-inline-calloc", "-qopt-calloc", "-no-ansi-alias", "-xCORE-AVX2"]
+        extra_link_args = ["-lm", "-qopenmp"]
+
+    if os.environ.get('CC') == 'clang':
+        import subprocess
+        # Search for arm64 libomp in order of preference:
+        #   1. CONDA_PREFIX — the active conda env, inherited even inside pip's
+        #      build-isolation subprocess, so this works for both direct builds
+        #      and `pip install`.
+        #   2. sys.prefix — the Python env running this script (same as CONDA_PREFIX
+        #      for direct invocations, different for pip build isolation).
+        #   3. brew --prefix libomp — last resort; only reliable on native arm64
+        #      Homebrew (/opt/homebrew). The Intel Homebrew at /usr/local ships an
+        #      x86_64-only libomp that silently disables OpenMP at runtime on arm64.
+        libomp_prefix = None
+        for _candidate in filter(None, [
+            os.environ.get('CONDA_PREFIX'),
+            sys.prefix,
+        ]):
+            if os.path.exists(os.path.join(_candidate, 'lib', 'libomp.dylib')):
+                libomp_prefix = _candidate
+                break
+        if libomp_prefix is None:
+            try:
+                _brew = subprocess.check_output(['brew', '--prefix', 'libomp'],
+                                                text=True).strip()
+                _dylib = os.path.join(_brew, 'lib', 'libomp.dylib')
+                if os.path.exists(_dylib):
+                    # Verify the library matches this machine's architecture.
+                    # Intel Homebrew at /usr/local ships x86_64-only libomp; linking
+                    # it into an arm64 build silently disables OpenMP at runtime.
+                    import platform as _platform
+                    _machine = _platform.machine()  # 'arm64' or 'x86_64'
+                    _file_out = subprocess.run(['file', _dylib],
+                                               capture_output=True, text=True).stdout
+                    if _machine in _file_out:
+                        libomp_prefix = _brew
+            except Exception:
+                pass
+        # Fail fast: libomp is required on macOS; silent absence causes a dlopen crash.
+        if libomp_prefix is None:
+            sys.exit(
+                "\nERROR: libomp not found. OpenMP is required on macOS.\n"
+                "Install it into your active conda environment (recommended):\n\n"
+                "    conda install -c conda-forge llvm-openmp\n\n"
+                "Or, if using native arm64 Homebrew (/opt/homebrew):\n\n"
+                "    brew install libomp\n"
+            )
+        extra_compile_args = ["-O3", "-Xclang", "-fopenmp", "-Wno-unknown-pragmas"]
+        extra_link_args = ["-lm", "-lomp"]
+        extra_compile_args += [f"-I{libomp_prefix}/include"]
+        extra_link_args += [f"-L{libomp_prefix}/lib", f"-Wl,-rpath,{libomp_prefix}/lib"]
+
+    if os.environ.get('CC') == 'msvc':
+        extra_compile_args = ["/std:c11", "/O2", "/openmp", "/DMSVC"]
+        extra_link_args = ["-lm"]
+
+    c_extension = Extension("svmbir.interface_cy_c",
                             [src_dir + "A_comp.c", src_dir + "allocate.c", src_dir + "heap.c",
                              src_dir + "icd3d.c", src_dir + "initialize.c", src_dir + "MBIRModularUtils.c",
-                             src_dir + "recon3d.c", packages_dir + "/interface_cy_c.pyx"],
+                             src_dir + "recon3d.c", "svmbir/interface_cy_c.pyx"],
                             libraries=[],
                             include_dirs=[np.get_include()],
+                            define_macros=[('NPY_NO_DEPRECATED_API', 'NPY_1_7_API_VERSION')],
                             extra_compile_args=extra_compile_args,
                             extra_link_args=extra_link_args)
 
-    package_data={}
+    package_data = {}
     cmdclass = {"build_ext": build_ext}
     ext_modules = [c_extension]
 
-    # set cython language level for all .pyx modules to Python 3
+    # Set cython language level for all .pyx modules to Python 3.
     for e in ext_modules:
         e.cython_directives = {'language_level': "3"}
 
 else:
-    # Command-line interface install
-
-    # Check for compiled executable
+    # Command-line interface install — requires a pre-compiled mbir_ct binary.
     if os.path.exists('svmbir/sv-mbirct/bin/mbir_ct'):
         exec_file = 'sv-mbirct/bin/mbir_ct'
     elif os.path.exists('svmbir/sv-mbirct/bin/mbir_ct.exe'):
         exec_file = 'sv-mbirct/bin/mbir_ct.exe'
     else:
-        exec_file = None
-        raise Exception("Compiled executable not present in 'svmbir/sv-mbirct/bin/' . Need to compile the binary executable first.")
-
-    package_data={'svmbir': [exec_file]}
-    install_requires.append('ruamel.yaml')
+        raise Exception(
+            "Compiled executable not present in 'svmbir/sv-mbirct/bin/'. "
+            "Compile the binary first."
+        )
+    package_data = {'svmbir': [exec_file]}
     cmdclass = {}
     ext_modules = None
 
 
-setup(name=name,
-      version=version,
-      description=description,
-      long_description=long_description,
-      long_description_content_type=long_description_content_type,
-      url=url,
-      maintainer=maintainer,
-      maintainer_email=maintainer_email,
-      license=license,
-      packages=packages,
-      install_requires=install_requires,
-      package_data=package_data,
-      cmdclass=cmdclass,
-      ext_modules=ext_modules)
-
+setup(
+    package_data=package_data,
+    cmdclass=cmdclass,
+    ext_modules=ext_modules,
+)
diff --git a/svmbir/__init__.py b/svmbir/__init__.py
index b18d6e9..ef3f374 100644
--- a/svmbir/__init__.py
+++ b/svmbir/__init__.py
@@ -1,4 +1,8 @@
-__version__ = '0.4.0'
+from importlib.metadata import version as _version, PackageNotFoundError as _PackageNotFoundError
+try:
+    __version__ = _version("svmbir")
+except _PackageNotFoundError:
+    __version__ = "unknown"
 from .svmbir import *
 from .phantom import *
 __all__ = ['recon','project','backproject','sino_sort','calc_weights','auto_sigma_x','auto_sigma_y','auto_sigma_p','_clear_cache','_svmbir_lib_path']
diff --git a/svmbir/interface_cy_c.pyx b/svmbir/interface_cy_c.pyx
index 509eedd..1293a0e 100644
--- a/svmbir/interface_cy_c.pyx
+++ b/svmbir/interface_cy_c.pyx
@@ -431,7 +431,7 @@ def multires_recon(sino, angles, weights, weight_type, init_image, prox_image, i
     #cdef cnp.ndarray[float, ndim=3, mode="c"] py_image
     cdef cnp.ndarray[char, ndim=1, mode="c"] Amatrix_fname
 
-    if 'py_image' not in locals():
+    if not go_to_lower_resolution:
         if np.isscalar(init_image):
             py_image = np.zeros((num_slices, nrows, ncols), dtype=ctypes.c_float) + init_image
         else: