Inject nav-state script centrally

Inject a centralized nav-state script into generated site HTML during Build-Site so first-level menu defaults and persisted fold state are applied for all repositories using Process-PSModule.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

.github/workflows/Build-Site.yml

@@ -179,6 +179,103 @@ jobs:
             if (-not (Test-Path -Path '../../_site')) {
               throw "Expected Zensical output at ../../_site but it was not created."
             }
+
+            $navStateScript = @'
+(() => {
+  const storageKey = "zensical-nav-state-v1";
+  let lastSignature = "";
+
+  const getToggles = () =>
+    Array.from(document.querySelectorAll("input.md-nav__toggle.md-toggle[id]"));
+
+  const getPrimaryList = () =>
+    document.querySelector("nav.md-nav--primary > ul.md-nav__list");
+
+  const applyDefaultTopLevelState = (toggles) => {
+    const primaryList = getPrimaryList();
+    if (!primaryList) {
+      return;
+    }
+
+    const topLevelToggles = Array.from(
+      primaryList.querySelectorAll(
+        ":scope > li > input.md-nav__toggle.md-toggle[id]"
+      )
+    );
+    const topLevelIds = new Set(topLevelToggles.map((toggle) => toggle.id));
+
+    for (const toggle of toggles) {
+      toggle.checked = topLevelIds.has(toggle.id);
+    }
+  };
+
+  const restoreState = (toggles) => {
+    const raw = localStorage.getItem(storageKey);
+    if (!raw) {
+      applyDefaultTopLevelState(toggles);
+      return;
+    }
+
+    try {
+      const state = JSON.parse(raw);
+      for (const toggle of toggles) {
+        if (Object.prototype.hasOwnProperty.call(state, toggle.id)) {
+          toggle.checked = !!state[toggle.id];
+        }
+      }
+    } catch {
+      applyDefaultTopLevelState(toggles);
+    }
+  };
+
+  const persistState = (toggles) => {
+    const state = {};
+    for (const toggle of toggles) {
+      state[toggle.id] = !!toggle.checked;
+    }
+    localStorage.setItem(storageKey, JSON.stringify(state));
+  };
+
+  const initialize = () => {
+    const toggles = getToggles();
+    if (toggles.length === 0) {
+      return;
+    }
+
+    const signature = toggles.map((toggle) => toggle.id).join("|");
+    if (signature === lastSignature) {
+      return;
+    }
+
+    lastSignature = signature;
+    restoreState(toggles);
+    for (const toggle of toggles) {
+      if (toggle.dataset.navStateBound === "true") {
+        continue;
+      }
+
+      toggle.dataset.navStateBound = "true";
+      toggle.addEventListener("change", () => persistState(getToggles()));
+    }
+  };
+
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", initialize, { once: true });
+  } else {
+    initialize();
+  }
+
+  setInterval(initialize, 500);
+})();
+'@
+
+            Get-ChildItem -Path '../../_site' -Filter '*.html' -Recurse | ForEach-Object {
+              $html = Get-Content -Path $_.FullName -Raw
+              if ($html -notmatch 'zensical-nav-state-v1') {
+                $html = $html -replace '</body>', "<script>$navStateScript</script>`n</body>"
+                Set-Content -Path $_.FullName -Value $html -NoNewline
+              }
+            }
           }
 
       - uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0