Migrate to pyproject.toml and towncrier fragments

.github/bump_version.py

@@ -0,0 +1,79 @@
+"""Infer semver bump from towncrier fragment types and update version."""
+
+import re
+import sys
+from pathlib import Path
+
+
+def get_current_version(pyproject_path: Path) -> str:
+    text = pyproject_path.read_text()
+    match = re.search(r'^version\s*=\s*"(\d+\.\d+\.\d+)"', text, re.MULTILINE)
+    if not match:
+        print(
+            "Could not find version in pyproject.toml",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+    return match.group(1)
+
+
+def infer_bump(changelog_dir: Path) -> str:
+    fragments = [
+        f
+        for f in changelog_dir.iterdir()
+        if f.is_file() and f.name != ".gitkeep"
+    ]
+    if not fragments:
+        print("No changelog fragments found", file=sys.stderr)
+        sys.exit(1)
+
+    categories = {f.suffix.lstrip(".") for f in fragments}
+    for f in fragments:
+        parts = f.stem.split(".")
+        if len(parts) >= 2:
+            categories.add(parts[-1])
+
+    if "breaking" in categories:
+        return "major"
+    if "added" in categories or "removed" in categories:
+        return "minor"
+    return "patch"
+
+
+def bump_version(version: str, bump: str) -> str:
+    major, minor, patch = (int(x) for x in version.split("."))
+    if bump == "major":
+        return f"{major + 1}.0.0"
+    elif bump == "minor":
+        return f"{major}.{minor + 1}.0"
+    else:
+        return f"{major}.{minor}.{patch + 1}"
+
+
+def update_file(path: Path, old_version: str, new_version: str):
+    text = path.read_text()
+    updated = text.replace(
+        f'version = "{old_version}"',
+        f'version = "{new_version}"',
+    )
+    if updated != text:
+        path.write_text(updated)
+        print(f"  Updated {path}")
+
+
+def main():
+    root = Path(__file__).resolve().parent.parent
+    pyproject = root / "pyproject.toml"
+    changelog_dir = root / "changelog.d"
+
+    current = get_current_version(pyproject)
+    bump = infer_bump(changelog_dir)
+    new = bump_version(current, bump)
+
+    print(f"Version: {current} -> {new} ({bump})")
+
+    update_file(pyproject, current, new)
+
+
+if __name__ == "__main__":
+    main()

.github/workflows/pr.yaml

@@ -11,25 +11,20 @@ jobs:
         uses: "lgeiger/black-action@master"
         with:
           args: ". -l 79 --check"
-  check-version:
-    name: Check version
+  check-changelog:
+    name: Check changelog fragment
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.event.pull_request.head.ref }}
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: 3.12
-      - name: Build changelog
-        run: pip install yaml-changelog>=0.1.7 && make changelog
-      - name: Preview changelog update
-        run: ".github/get-changelog-diff.sh"
-      - name: Check version number has been properly updated
-        run: .github/is-version-number-acceptable.sh
+      - name: Check for changelog fragment
+        run: |
+          FRAGMENTS=$(find changelog.d -type f ! -name '.gitkeep' | wc -l)
+          if [ "$FRAGMENTS" -eq 0 ]; then
+            echo "::error::No changelog fragment found in changelog.d/"
+            echo "Add one with: echo 'Description.' > changelog.d/\$(git branch --show-current).<type>.md"
+            echo "Types: added, changed, fixed, removed, breaking"
+            exit 1
+          fi
   Test:
     runs-on: ${{ matrix.os }}
     strategy:
@@ -48,6 +43,6 @@ jobs:
         run: make install
       - name: Run tests
         run: make test
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
       - name: Build package
         run: make build

.github/workflows/push.yaml

@@ -24,15 +24,16 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@v4
         with:
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.event.pull_request.head.ref }}
           token: ${{ secrets.POLICYENGINE_GITHUB }}
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.14
+          python-version: "3.14"
       - name: Build changelog
-        run: pip install yaml-changelog && make changelog
+        run: |
+          pip install towncrier
+          python .github/bump_version.py
+          towncrier build --yes --version $(python -c "import re; print(re.search(r'version = \"(.+?)\"', open('pyproject.toml').read()).group(1))")
       - name: Preview changelog update
         run: ".github/get-changelog-diff.sh"
       - name: Update changelog
@@ -56,12 +57,12 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.14
+          python-version: "3.14"
       - name: Install package
         run: make install
       - name: Run tests
         run: make test
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
   Publish:
     runs-on: ubuntu-latest
     if: |
@@ -73,7 +74,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.14
+          python-version: "3.14"
       - name: Publish a git tag
         run: ".github/publish-git-tag.sh || true"
       - name: Install package
@@ -97,13 +98,11 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@v4
         with:
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.event.pull_request.head.ref }}
           token: ${{ secrets.POLICYENGINE_GITHUB }}
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.14
+          python-version: "3.14"
       - name: Install Wheel and Pytest
         run: pip3 install wheel setuptools pytest==5.4.3
       - name: Install package

Makefile

@@ -13,11 +13,8 @@ test:
 	policyengine-core test policyengine_ng/tests -c policyengine_ng
 
 build:
-	python setup.py sdist bdist_wheel
+	python -m build
 
 changelog:
-	build-changelog changelog.yaml --output changelog.yaml --update-last-date --start-from 0.0.1 --append-file changelog_entry.yaml
-	build-changelog changelog.yaml --org PolicyEngine --repo policyengine-ng --output CHANGELOG.md --template .github/changelog_template.md
-	bump-version changelog.yaml setup.py docs/requirements.txt
-	rm changelog_entry.yaml || true
-	touch changelog_entry.yaml
+	python .github/bump_version.py
+	towncrier build --yes --version $$(python -c "import re; print(re.search(r'version = \"(.+?)\"', open('pyproject.toml').read()).group(1))")

changelog.d/migrate-to-towncrier.changed.md

@@ -0,0 +1 @@
+Migrated from changelog_entry.yaml to towncrier fragments to eliminate merge conflicts.

pyproject.toml

@@ -0,0 +1,77 @@
+[project]
+name = "policyengine-ng"
+version = "0.5.1"
+description = "Core microsimulation engine enabling country-specific policy models."
+readme = "README.md"
+authors = [
+    { name = "PolicyEngine", email = "hello@policyengine.org" }
+]
+requires-python = ">=3.10"
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "License :: OSI Approved :: GNU Affero General Public License v3",
+    "Operating System :: POSIX",
+    "Programming Language :: Python",
+    "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Topic :: Scientific/Engineering :: Information Analysis",
+]
+dependencies = [
+    "numpy",
+    "policyengine-core",
+]
+
+[project.optional-dependencies]
+dev = [
+    "build",
+    "jupyter-book>=1.0.4",
+    "mystmd>=1.3.17",
+    "towncrier>=24.8.0",
+]
+
+[project.scripts]
+policyengine-core = "policyengine_core.scripts.policyengine_command:main"
+
+[project.urls]
+Homepage = "https://github.com/policyengine/policyengine-core"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["policyengine_ng"]
+
+[tool.towncrier]
+package = "policyengine_ng"
+directory = "changelog.d"
+filename = "CHANGELOG.md"
+title_format = "## [{version}] - {project_date}"
+issue_format = ""
+underlines = ["", "", ""]
+
+[[tool.towncrier.type]]
+directory = "breaking"
+name = "Breaking changes"
+showcontent = true
+
+[[tool.towncrier.type]]
+directory = "added"
+name = "Added"
+showcontent = true
+
+[[tool.towncrier.type]]
+directory = "changed"
+name = "Changed"
+showcontent = true
+
+[[tool.towncrier.type]]
+directory = "fixed"
+name = "Fixed"
+showcontent = true
+
+[[tool.towncrier.type]]
+directory = "removed"
+name = "Removed"
+showcontent = true