diff --git a/.github/workflows/gh-pages.yml b/.github/workflows/gh-pages.yml
index 8f8649b9de..cf88becacc 100644
--- a/.github/workflows/gh-pages.yml
+++ b/.github/workflows/gh-pages.yml
@@ -9,6 +9,9 @@ on:
     branches:
       - main
 
+permissions:
+  contents: read
+
 jobs:
   check-typo:
     runs-on: ubuntu-latest
@@ -57,6 +60,13 @@ jobs:
       # Checkout the repository to access the lychee config file
       - uses: actions/checkout@v7
 
+      # Keep mise.toml as the single source of truth for the lychee version
+      - name: Read lychee version from mise.toml
+        id: lychee-version
+        run: |
+          version="$(python3 -c 'import tomllib; print(tomllib.load(open("mise.toml", "rb"))["tools"]["lychee"])')"
+          echo "version=v${version}" >> "$GITHUB_OUTPUT"
+
       - name: Download Build Artifact
         uses: actions/download-artifact@v8
         with:
@@ -68,13 +78,15 @@ jobs:
         uses: lycheeverse/lychee-action@v2
         with:
           fail: true
-          lycheeVersion: v0.21.0
-          # --root-dir is required to resolve root-relative links (e.g. /talk/...)
-          # in the built HTML; without it lychee silently skips them.
+          lycheeVersion: ${{ steps.lychee-version.outputs.version }}
+          # --root-dir is required since lychee v0.24 to resolve root-relative
+          # links (e.g. /talk/...) in the built HTML; without it lychee errors
+          # out instead of silently skipping them like v0.21 did.
           args: "${{ vars.ARTIFACT_PATH }} --root-dir ${{ github.workspace }}/${{ vars.ARTIFACT_PATH }} --config .lychee/config.toml --exclude-file .lychee/exclude-temporary.txt --exclude-file .lychee/exclude-permanent.txt"
 
   deploy:
-    needs: build
+    needs: [build, check-broken-links]
+    if: (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
 
     steps:
@@ -86,7 +98,6 @@ jobs:
 
       - name: Deploy
         uses: peaceiris/actions-gh-pages@v4
-        if: (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main'
         with:
           deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
           publish_dir: ${{ vars.ARTIFACT_PATH }}
diff --git a/.github/workflows/lychee-prune.yml b/.github/workflows/lychee-prune.yml
index 10ae493f82..8ad4a51a55 100644
--- a/.github/workflows/lychee-prune.yml
+++ b/.github/workflows/lychee-prune.yml
@@ -43,6 +43,14 @@ jobs:
         with:
           token: ${{ steps.app-token.outputs.token }}
 
+      # Keep mise.toml as the single source of truth for the lychee version.
+      # Read it here, before "Prepare prune branch" switches branches.
+      - name: Read lychee version from mise.toml
+        id: lychee-version
+        run: |
+          version="$(python3 -c 'import tomllib; print(tomllib.load(open("mise.toml", "rb"))["tools"]["lychee"])')"
+          echo "version=v${version}" >> "$GITHUB_OUTPUT"
+
       - name: Download Build Artifact
         uses: actions/download-artifact@v8
         with:
@@ -89,7 +97,7 @@ jobs:
         uses: lycheeverse/lychee-action@v2
         with:
           fail: false
-          lycheeVersion: v0.21.0
+          lycheeVersion: ${{ steps.lychee-version.outputs.version }}
           format: json
           output: lychee-excludes.json
           args: "--config .lychee/config.toml lychee-input.txt"
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000000..672cbddb0c
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,33 @@
+name: Test
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "tests/**"
+      - "scripts/**"
+      - ".agents/skills/**"
+      - ".github/workflows/test.yml"
+  pull_request:
+    paths:
+      - "tests/**"
+      - "scripts/**"
+      - ".agents/skills/**"
+      - ".github/workflows/test.yml"
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Setup uv
+        uses: astral-sh/setup-uv@v8.3.2
+
+      - name: Run tests
+        run: uv run --with pytest --with ruamel.yaml pytest tests/ -q
diff --git a/.lychee/exclude-temporary.txt b/.lychee/exclude-temporary.txt
index 1d461767e5..2d78efcf97 100644
--- a/.lychee/exclude-temporary.txt
+++ b/.lychee/exclude-temporary.txt
@@ -23,3 +23,8 @@ confit.atlas.jp
 www.scimagojr.com
 clustrmaps.com
 www.meethawaii.com/convention-center/
+
+# The page is alive (curl returns 200) but lychee >= v0.24 (rustls) cannot
+# complete a TLS handshake because the server only offers legacy TLS cipher
+# suites. Re-check regularly in case the server's TLS config is upgraded.
+book.impress.co.jp
diff --git a/config/_default/hugo.yaml b/config/_default/hugo.yaml
index 8fa5b5c1cb..163eb19834 100644
--- a/config/_default/hugo.yaml
+++ b/config/_default/hugo.yaml
@@ -40,7 +40,7 @@ imaging:
   resampleFilter: Lanczos
   quality: 75
   anchor: Smart
-timeout: 600000
+timeout: "600s"
 taxonomies:
   tag: tags
   category: categories
diff --git a/mise.toml b/mise.toml
index bc91dcebb8..f2c73d481f 100644
--- a/mise.toml
+++ b/mise.toml
@@ -1,5 +1,5 @@
 [tools]
 hugo-extended = "0.136.5"
-lychee = "latest"
+lychee = "0.24.2"
 
 "go:github.com/shunk031/tcardgen" = "latest"