ci: debug lychee cache

.github/workflows/netlify-build.yml

@@ -14,15 +14,19 @@ concurrency:
 
 env:
   CARGO_TERM_COLOR: always
+  NOX_DEFAULT_VENV_BACKEND: uv
+  UV_PYTHON: "3.14"
 
 jobs:
   guide-build:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6.0.2
-      - uses: actions/setup-python@v6
+      - uses: astral-sh/setup-uv@v7
         with:
-          python-version: "3.14"
+          # codspeed action needs to be run from within the final Python environment
+          activate-environment: true
+          save-cache: ${{ github.ref == 'refs/heads/main' || contains(github.event.pull_request.labels.*.name, 'CI-save-pr-cache') }}
 
       - uses: dtolnay/rust-toolchain@nightly
 
@@ -47,9 +51,7 @@ jobs:
 
       # This builds the book in target/guide/.
       - name: Build the guide
-        run: |
-          python -m pip install --upgrade pip && pip install nox[uv]
-          nox -s ${{ github.event_name == 'release' && 'build-guide' || 'check-guide' }}
+        run: uvx nox -s ${{ github.event_name == 'release' && 'build-guide' || 'check-guide' }}
         env:
           PYO3_VERSION_TAG: ${{ github.event_name == 'release' && steps.prepare_tag.outputs.tag_name || 'main' }}
           # allows lychee to get better rate limits from github
@@ -79,9 +81,7 @@ jobs:
           echo "PYO3_VERSION=${PYO3_VERSION}" >> $GITHUB_ENV
 
       - name: Build the site
-        run: |
-          python -m pip install --upgrade pip && pip install nox[uv] towncrier requests
-          nox -s build-netlify-site -- ${{ (github.ref != 'refs/heads/main' && '--preview') || '' }}
+        run: uvx --with requests nox -s build-netlify-site -- ${{ (github.ref != 'refs/heads/main' && '--preview') || '' }}
 
       # Upload the built site as an artifact for deploy workflow to consume
       - name: Upload Build Artifact

noxfile.py

@@ -776,6 +776,24 @@ def check_guide(session: nox.Session):
         *session.posargs,
     )
 
+    # We prune connection errors from the cache so that flaky / down sites will be retried
+    # without just causing PRs to fail until the cache expires
+    cache_path = Path(".lycheecache")
+
+    # Cache is a simple CSV of url, status, timestamp; filter out entries without a status code.
+    # (we also have --cache-exclude-status set above)
+    # see also https://github.com/lycheeverse/lychee/issues/2156 for context
+    if cache_path.exists():
+        lines = cache_path.read_text().splitlines()
+        new_lines = []
+        for line in lines:
+            url, status, timestamp = line.split(",", 2)
+            if not status:
+                session.log(f"Pruning lychee cache entry for {url} with empty status")
+                continue
+            new_lines.append(line)
+        cache_path.write_text("\n".join(new_lines) + "\n")
+
     try:
         # check all links in the guide
         _run(