ci(deps): add dependency floor checks

Author: harryswift01

.github/workflows/dependency-floors.yaml

@@ -0,0 +1,54 @@
+name: Dependency Floors
+
+on:
+  pull_request:
+    paths:
+      - pyproject.toml
+      - .github/workflows/dependency-floors.yaml
+  schedule:
+    - cron: '0 8 * * 1'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: dependency-floors-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lowest:
+    name: Lowest dependencies (${{ matrix.os }}, py${{ matrix.python-version }})
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 30
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-26.04, macos-26, windows-2025-vs2026]
+        python-version: ["3.12", "3.13", "3.14"]
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install uv
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install uv
+
+      - name: Resolve lowest dependencies as wheels
+        run: |
+          uv pip compile pyproject.toml --resolution lowest-direct --only-binary :all: --output-file lowest.txt
+          cat lowest.txt
+
+      - name: Install lowest dependencies
+        run: uv pip install --system --resolution lowest-direct -e ".[testing]"
+
+      - name: Run unit tests
+        run: python -m pytest tests/unit

docs/developer_guide.rst

@@ -167,9 +167,30 @@ Weekly workflows:
 
 - Full regression suite including slow tests
 - Documentation build across all Python versions
+- Dependency floor checks (see :ref:`dependency-policy`)
 
 CI also caches regression datasets to improve performance.
 
+.. _dependency-policy:
+
+Dependency Policy
+-----------------
+
+Runtime dependencies in ``pyproject.toml`` are declared as ranges. The lower
+bound (floor) is the oldest release CodeEntropy is known to work with, so that it
+stays installable alongside other scientific packages. Floors are only raised
+when the code needs a newer release. Upper bounds are widened by Renovate.
+
+The ``dependency-floors.yaml`` workflow checks this on pull requests that change
+``pyproject.toml`` and weekly. It checks that the lowest allowed versions resolve
+to installable wheels on each platform and Python version, and that the unit tests
+pass with them installed.
+
+Run the same checks locally with `uv <https://docs.astral.sh/uv/>`_::
+
+    uv pip install --resolution lowest-direct -e ".[testing]"
+    python -m pytest tests/unit
+
 Building Documentation
 ----------------------