feat: caching for link check CI

.github/workflows/link-check-cache.yml

@@ -0,0 +1,39 @@
+# Cache link check results on each commit to main.
+
+name: Lychee Cache Update
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  lychee-cache-update:
+    name: Lychee Link Checking
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Check out repo
+      uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
+
+    - name: Restore Lychee cache
+      id: restore-cache
+      uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+      with:
+        path: .lycheecache
+        key: cache-lychee-${{ github.event.before }}
+        restore-keys: cache-lychee-
+
+    - name: Run Lychee
+      uses: lycheeverse/lychee-action@a8c4c7cb88f0c7386610c35eb25108e448569cb0 # v2.7.0
+      with:
+        fail: false
+        format: markdown
+        jobSummary: true
+        args: >
+          -c lychee.toml --root-dir "$(pwd)" './**/*.mdx'
+
+    - name: Update Lychee cache
+      uses: actions/cache/save@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+      with:
+        path: .lycheecache
+        key: cache-lychee-${{ github.event.after }}

.github/workflows/link-check.yml

@@ -1,7 +1,8 @@
+# Check links on changed MDX files in PRs.
+
 name: Lychee Link Checking
 
 on:
-  # Run on PRs targeting main that change content files.
   pull_request:
     branches: [main]
     paths: ['**/*.mdx?']
@@ -24,8 +25,17 @@ jobs:
         files: |
           **.mdx
 
+    - name: Restore Lychee cache
+      uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+      if: steps.changed-mdx-files.outputs.any_changed == 'true'
+      with:
+        path: .lycheecache
+        key: cache-lychee-${{ github.event.pull_request.base.sha }}
+        restore-keys: cache-lychee-
+
     - name: Run Lychee
       uses: lycheeverse/lychee-action@a8c4c7cb88f0c7386610c35eb25108e448569cb0 # v2.7.0
+      if: steps.changed-mdx-files.outputs.any_changed == 'true'
       with:
         fail: false
         format: markdown
@@ -37,5 +47,6 @@ jobs:
 
     - name: Comment on PR with link check results
       uses: marocchino/sticky-pull-request-comment@773744901bac0e8cbb5a0dc842800d45e9b2b405 # v2.9.4
+      if: steps.changed-mdx-files.outputs.any_changed == 'true'
       with:
         path: lychee/out.md

lychee.toml

@@ -11,9 +11,9 @@ include_verbatim = false   # Don't check links inside code blocks
 exclude_all_private = true # Exclude link local, loopback, and private IPs.
 
 # Cache only successful results to avoid re-checking valid links.
-# TODO: Update GitHub Action to use the cache
 cache = true
 cache_exclude_status = "300.."
+max_cache_age = "7d"
 
 # Set a root dir so Lychee can resolve relative links to URIs, even though we
 # exclude relative links in the actual check.