diff --git a/.github/release-drafter.yml b/.github/release-drafter.yml
index 7a04410..95d0cb5 100644
--- a/.github/release-drafter.yml
+++ b/.github/release-drafter.yml
@@ -1,3 +1,9 @@
+---
+name-template: "v$RESOLVED_VERSION"
+tag-template: "v$RESOLVED_VERSION"
+change-template: "- $TITLE @$AUTHOR (#$NUMBER)"
+sort-direction: ascending
+
 categories:
   - title: ":boom: Breaking Changes"
     label: "breaking"
diff --git a/.github/workflows/release-drafter.yml b/.github/workflows/release-drafter.yml
index 999a42a..980626b 100644
--- a/.github/workflows/release-drafter.yml
+++ b/.github/workflows/release-drafter.yml
@@ -1,14 +1,42 @@
+---
 name: Draft a release note
+
+# yamllint disable-line rule:truthy
 on:
   push:
     branches:
       - main
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
 jobs:
   draft_release:
     name: Release Drafter
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: read
     steps:
-      - name: Run release-drafter
-        uses: release-drafter/release-drafter@v7.7.0
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: ⤵️ Check out code from GitHub
+        uses: actions/checkout@v7
+        with:
+          # Full history so that all existing tags are available
+          fetch-depth: 0
+          persist-credentials: false
+
+      # Release Drafter's version resolver only understands SemVer, so the next
+      # CalVer version (YYYY.M.N) is computed by scripts/release.py and passed in.
+      - name: 📅 Calculate next CalVer version
+        id: calver
+        run: |
+          version="$(python3 scripts/release.py --next-version)"
+          echo "Calculated next CalVer: ${version}"
+          echo "version=${version}" >> "$GITHUB_OUTPUT"
+
+      - name: 🚀 Run release-drafter
+        uses: release-drafter/release-drafter@v7
+        with:
+          version: ${{ steps.calver.outputs.version }}
+          token: ${{ github.token }}
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
new file mode 100644
index 0000000..3e3554e
--- /dev/null
+++ b/.github/workflows/release.yaml
@@ -0,0 +1,71 @@
+---
+name: Release
+
+# yamllint disable-line rule:truthy
+on:
+  release:
+    types:
+      - published
+  workflow_dispatch:
+    inputs:
+      tag_name:
+        description: "Release tag to publish (e.g. v2026.10.1)"
+        required: true
+        type: string
+
+env:
+  DEFAULT_PYTHON: "3.13"
+
+permissions:
+  contents: read
+
+jobs:
+  release:
+    name: Releasing to PyPI
+    runs-on: ubuntu-latest
+    environment:
+      name: release
+      url: https://pypi.org/p/python-hilo
+    permissions:
+      attestations: write
+      contents: read
+      id-token: write
+    steps:
+      - name: ⤵️ Check out code from GitHub
+        uses: actions/checkout@v7
+        with:
+          ref: ${{ github.event.release.tag_name || inputs.tag_name }}
+          persist-credentials: false
+
+      - name: 🏗 Set up Python ${{ env.DEFAULT_PYTHON }}
+        id: python
+        uses: actions/setup-python@v7.0.0
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+
+      - name: 🏗 Install uv
+        uses: astral-sh/setup-uv@v10.2.0
+
+      - name: 🧪 Run tests
+        run: |
+          uv sync --group test
+          uv run pytest
+
+      - name: 🏗 Set package version
+        env:
+          RELEASE_TAG: ${{ github.event.release.tag_name || inputs.tag_name }}
+        run: |
+          if [ -z "${RELEASE_TAG}" ]; then
+            echo "Error: No release tag found or provided."
+            exit 1
+          fi
+          python3 scripts/release.py --set-version "${RELEASE_TAG}"
+
+      - name: 🏗 Build package
+        run: uv build
+
+      - name: 🚀 Publish to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          verbose: true
+          print-hash: true
diff --git a/scripts/release.py b/scripts/release.py
new file mode 100644
index 0000000..5207819
--- /dev/null
+++ b/scripts/release.py
@@ -0,0 +1,121 @@
+#!/usr/bin/env python3
+"""Manage release versioning and packaging for python-hilo."""
+
+from __future__ import annotations
+
+import argparse
+from datetime import datetime, timezone
+from pathlib import Path
+import re
+import subprocess
+import sys
+
+# Pattern for Calendar Versioning: YYYY.M.N (e.g. 2026.10.1)
+# with an optional pre-release suffix (e.g. 2026.10.1b1).
+VERSION_PATTERN = re.compile(r"^[0-9]{4}\.[0-9]{1,2}\.[0-9]+(b[0-9]+)?$")
+ROOT = Path(__file__).resolve().parent.parent
+
+
+def clean_version_from_tag(tag: str) -> str:
+    """Validate a release tag and strip the leading 'v' prefix.
+
+    Raises ValueError if the tag does not follow the expected CalVer format.
+    """
+    version = tag.removeprefix("v")
+    if not VERSION_PATTERN.match(version):
+        raise ValueError(
+            f"Release tag '{tag}' must match version format vYYYY.M.N "
+            "(e.g. v2026.10.1 or v2026.10.1b1)"
+        )
+    return version
+
+
+def get_next_version(reference_date: datetime | None = None) -> str:
+    """Calculate the next version name (YYYY.M.N) from existing git tags.
+
+    Inspects git tags for the current UTC year and month. If tags exist, increments
+    the highest patch number; otherwise starts at patch 1 (e.g. 2026.10.1).
+    """
+    now = reference_date or datetime.now(timezone.utc)
+    prefix = f"{now.year}.{now.month}"
+
+    try:
+        output = subprocess.check_output(
+            ["git", "tag", "--list", f"v{prefix}.*", f"{prefix}.*"],
+            cwd=ROOT,
+            text=True,
+        )
+        tags = output.splitlines()
+    except (subprocess.SubprocessError, FileNotFoundError):
+        tags = []
+
+    # Only match final/stable releases so pre-releases (e.g. v2026.10.1b1)
+    # do not consume the stable patch number for draft releases.
+    pattern = re.compile(rf"^v?{re.escape(prefix)}\.([0-9]+)$")
+    patches = [int(m.group(1)) for tag in tags if (m := pattern.match(tag.strip()))]
+    next_patch = max(patches, default=0) + 1
+    return f"{prefix}.{next_patch}"
+
+
+def set_package_version(tag_or_version: str, root_dir: Path = ROOT) -> str:
+    """Validate and update the version in pyproject.toml and pyhilo/const.py."""
+    version = clean_version_from_tag(tag_or_version)
+
+    pyproject_path = root_dir / "pyproject.toml"
+    if not pyproject_path.is_file():
+        raise FileNotFoundError(f"Missing {pyproject_path}")
+    content = pyproject_path.read_text(encoding="utf-8")
+    new_content, count = re.subn(
+        r'(?m)^version = "[^"]*"',
+        f'version = "{version}"',
+        content,
+        count=1,
+    )
+    if count == 0:
+        raise ValueError(f"Could not find 'version' field in {pyproject_path}")
+    pyproject_path.write_text(new_content, encoding="utf-8")
+
+    const_path = root_dir / "pyhilo" / "const.py"
+    if not const_path.is_file():
+        raise FileNotFoundError(f"Missing {const_path}")
+    content = const_path.read_text(encoding="utf-8")
+    new_content, count = re.subn(
+        r'PYHILO_VERSION: Final = "[^"]*"',
+        f'PYHILO_VERSION: Final = "{version}"',
+        content,
+    )
+    if count == 0:
+        raise ValueError(f"Could not find 'PYHILO_VERSION' constant in {const_path}")
+    const_path.write_text(new_content, encoding="utf-8")
+
+    return version
+
+
+def main(argv: list[str] | None = None) -> None:
+    """CLI entrypoint for release automation."""
+    parser = argparse.ArgumentParser(
+        description="Manage release versions for python-hilo."
+    )
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument(
+        "--next-version",
+        action="store_true",
+        help="Calculate the next CalVer version from git tags",
+    )
+    group.add_argument(
+        "--set-version",
+        metavar="TAG",
+        help="Set package version in pyproject.toml and pyhilo/const.py",
+    )
+
+    args = parser.parse_args(argv)
+
+    if args.next_version:
+        sys.stdout.write(f"{get_next_version()}\n")
+    elif args.set_version:
+        version = set_package_version(args.set_version)
+        sys.stdout.write(f"Updated package version to {version}\n")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tests/test_release.py b/tests/test_release.py
new file mode 100644
index 0000000..412618e
--- /dev/null
+++ b/tests/test_release.py
@@ -0,0 +1,111 @@
+"""Unit tests for scripts/release.py."""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+from scripts.release import (
+    clean_version_from_tag,
+    get_next_version,
+    main,
+    set_package_version,
+)
+
+
+@pytest.mark.parametrize(
+    ("tag", "expected"),
+    [
+        ("v2026.10.1", "2026.10.1"),
+        ("2026.10.1", "2026.10.1"),
+        ("v2026.10.1b2", "2026.10.1b2"),
+        ("v2025.5.12", "2025.5.12"),
+    ],
+)
+def test_clean_version_from_tag_valid(tag: str, expected: str) -> None:
+    """Test valid version tags are parsed correctly."""
+    assert clean_version_from_tag(tag) == expected
+
+
+@pytest.mark.parametrize(
+    "invalid_tag",
+    [
+        "v1.0.0",
+        "invalid",
+        "v2026.10",
+        "v2026.10.",
+        "v2026.10.1rc1",
+        "v2026.10.1-beta",
+    ],
+)
+def test_clean_version_from_tag_invalid(invalid_tag: str) -> None:
+    """Test invalid version tags raise ValueError."""
+    with pytest.raises(ValueError, match="must match version format"):
+        clean_version_from_tag(invalid_tag)
+
+
+@pytest.mark.parametrize(
+    ("existing_tags", "expected_version"),
+    [
+        ("", "2026.10.1"),
+        ("v2026.10.1\n", "2026.10.2"),
+        ("v2026.10.1\nv2026.10.2\n", "2026.10.3"),
+        ("v2026.10.1b1\n", "2026.10.1"),
+        ("v2026.10.1\nv2026.10.2b1\n", "2026.10.2"),
+        ("v2026.9.5\n", "2026.10.1"),
+    ],
+)
+def test_get_next_version(existing_tags: str, expected_version: str) -> None:
+    """Test next version calculation with various existing tag states."""
+    ref_date = datetime(2026, 10, 15, tzinfo=timezone.utc)
+    with patch("subprocess.check_output", return_value=existing_tags):
+        assert get_next_version(reference_date=ref_date) == expected_version
+
+
+def test_set_package_version_success(tmp_path: Path) -> None:
+    """Test successfully updating pyproject.toml and pyhilo/const.py versions."""
+    pyproject = tmp_path / "pyproject.toml"
+    pyproject.write_text(
+        '[project]\nname = "python-hilo"\nversion = "2026.9.1"\n', encoding="utf-8"
+    )
+
+    const_dir = tmp_path / "pyhilo"
+    const_dir.mkdir()
+    const_file = const_dir / "const.py"
+    const_file.write_text('PYHILO_VERSION: Final = "2026.9.01"\n', encoding="utf-8")
+
+    version = set_package_version("v2026.10.1", root_dir=tmp_path)
+    assert version == "2026.10.1"
+    assert 'version = "2026.10.1"' in pyproject.read_text(encoding="utf-8")
+    assert 'PYHILO_VERSION: Final = "2026.10.1"' in const_file.read_text(
+        encoding="utf-8"
+    )
+
+
+def test_set_package_version_missing_files(tmp_path: Path) -> None:
+    """Test that missing target files raise FileNotFoundError."""
+    with pytest.raises(FileNotFoundError, match="Missing"):
+        set_package_version("v2026.10.1", root_dir=tmp_path)
+
+
+def test_set_package_version_missing_pattern(tmp_path: Path) -> None:
+    """Test that unmatched version patterns raise ValueError."""
+    pyproject = tmp_path / "pyproject.toml"
+    pyproject.write_text('[project]\nname = "python-hilo"\n', encoding="utf-8")
+
+    with pytest.raises(ValueError, match="Could not find 'version' field"):
+        set_package_version("v2026.10.1", root_dir=tmp_path)
+
+
+def test_main_cli(capsys: pytest.CaptureFixture[str]) -> None:
+    """Test main CLI entrypoint flags."""
+    with patch("scripts.release.get_next_version", return_value="2026.10.1"):
+        main(["--next-version"])
+        assert capsys.readouterr().out == "2026.10.1\n"
+
+    with patch("scripts.release.set_package_version", return_value="2026.10.1"):
+        main(["--set-version", "v2026.10.1"])
+        assert capsys.readouterr().out == "Updated package version to 2026.10.1\n"