Fix the Lint job, which is failing on main

.github/workflows/pr_code_changes.yaml

@@ -16,7 +16,7 @@ jobs:
         uses: astral-sh/setup-uv@v8.1.0
       - name: Install relevant dependencies
         run: |
-          uv pip install "ruff>=0.9.0" --system
+          uv pip install "ruff>=0.16.0,<0.17.0" --system
       - name: Check code formatting
         run: make check-format
 

changelog.d/lint-on-main.fixed.md

@@ -0,0 +1 @@
+The Lint job no longer fails on an untouched checkout: documentation prose is excluded from the formatter, and the ruff version is bounded so a future release cannot silently change what the job checks.

pyproject.toml

@@ -35,7 +35,7 @@ dependencies = [
 dev = [
     "pytest>=8.0.0,<10.0.0",
     "pytest-cov>=6.0.0,<8.0.0",
-    "ruff>=0.9.0",
+    "ruff>=0.16.0,<0.17.0",
     "mypy>=1.2.3,<2.0.0",
     "build>=1.2.0,<2.0.0",
     "towncrier>=24.8.0",
@@ -101,3 +101,9 @@ showcontent = true
 directory = "removed"
 name = "Removed"
 showcontent = true
+
+[tool.ruff]
+# Documentation is prose, not a lint surface. ruff 0.16.0 began formatting
+# Python inside markdown code blocks, which reformatted five docs files that
+# nobody had edited and turned the Lint job red on an untouched checkout.
+extend-exclude = ["docs/**/*.md"]