Rework category labels, slug validation, and task-list checkboxes

- Remove the section-header ➕ "add landing page" button; landing pages are
  now created via the page editor pen.
- Treat saving a page with empty (after stripping) Markdown as deleting it:
  childless nodes are removed, nodes with children become content-less labels.
- Restrict server-side slugs to [a-z0-9_-] with no leading underscore or dot;
  drop the reserved-filename blacklist.
- Render placeholder pages for content-less category labels and link them to
  their first published child in the navigation.
- Make task-list checkboxes live, non-disabled inputs: toggling updates the
  Markdown source, updates the open CodeMirror document when the page editor is
  open, and persists to the server when no editor is open. Errors revert the UI.
- Update docs and AGENTS.md conventions accordingly.

frontend/src/PageEditor.vue

@@ -120,8 +120,10 @@ function openPath(p) {
   send({ type: 'open', path: p })
 }
 
-function setDocument(text) {
-  view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: text } })
+function setDocument(text, preserveSelection = false) {
+  const tr = { changes: { from: 0, to: view.state.doc.length, insert: text } }
+  if (preserveSelection) tr.selection = view.state.selection
+  view.dispatch(tr)
 }
 
 function onHashChange() {
@@ -272,6 +274,11 @@ onMounted(() => {
     parent: editorEl.value,
   })
   view.scrollDOM.addEventListener('scroll', syncScroll)
+  window.__pageritePageEditor = {
+    getMarkdown: () => view.state.doc.toString(),
+    setMarkdown: (text) => setDocument(text, true),
+    path: () => path.value,
+  }
   if (props.standalone) addEventListener('hashchange', onHashChange)
   addEventListener('keydown', onKeydown)
 })
@@ -283,6 +290,7 @@ onUnmounted(() => {
     ws.close()
   }
   view?.destroy()
+  delete window.__pageritePageEditor
   if (props.standalone) removeEventListener('hashchange', onHashChange)
   removeEventListener('keydown', onKeydown)
 })

frontend/src/SiteEditor.vue

@@ -8,8 +8,8 @@
 //
 // The tree comes from the server nested (GET /_/api/pages); every node is
 // real — a label with a title and slug, with content (landing page) or
-// without (category redirecting to its first child). The front page is a
-// top-level row with an empty slug, not the parent of the others.
+// without (category whose URL renders a placeholder page). The front page
+// is a top-level row with an empty slug, not the parent of the others.
 import { computed, onMounted, onUnmounted, provide, ref } from 'vue'
 import StructureTree from './StructureTree.vue'
 import { EditorView, basicSetup } from 'codemirror'
@@ -125,8 +125,8 @@ async function loadPlain(p) {
     const res = await fetch(finalUrl)
     const type = res.headers.get('content-type') || ''
     if (!type.includes('text/html')) return
-    // Category URLs redirect to their first child; reflect that. A 404
-    // layout is fine too (new pages are created by editing them).
+    // Category and missing URLs render a placeholder 404 page — fine to
+    // swap in (new pages are created by editing them).
     if (res.redirected) finalUrl = res.url
     doc = new DOMParser().parseFromString(await res.text(), 'text/html')
   } catch { return }
@@ -239,22 +239,6 @@ async function commitPending() {
   navigate(newPath)
 }
 
-// Give a content-less category a landing page (empty page at its path).
-async function addContent(node) {
-  const res = await fetch(`/_/api/pages/${node.path}`, {
-    method: 'PUT',
-    headers: { 'content-type': 'application/json' },
-    body: JSON.stringify({ title: node.title, markdown: '', published: node.published }),
-  })
-  if (res.ok) {
-    saveError.value = ''
-    await refreshPages()
-    navigate(node.path)
-  } else {
-    saveError.value = '⚠️ changes could not be saved'
-  }
-}
-
 // --- Site-wide brand (header link + <title> suffix) ----------------------
 // Edits apply to the live page immediately and save while typing. An
 // empty brand removes the header link and the title suffix entirely.
@@ -330,8 +314,8 @@ async function removePage(node) {
     refreshPages()
     const p = node.path
     if (p === path.value || (p && path.value.startsWith(`${p}/`))) {
-      // The current page was deleted — or reduced to a category that now
-      // redirects to its first child. Either way, re-render from the server.
+      // The current page was deleted — or reduced to a category, which now
+      // renders a placeholder page. Either way, re-render from the server.
       if (node.children.length) loadPlain(path.value)
       else navigate('')
     } else {
@@ -429,7 +413,6 @@ provide('structureHandlers', {
   reorder: onReorder,
   titleInput: onTitleInput,
   commitSlug,
-  addContent,
   commitPending,
   discardPending,
   newPage,

frontend/src/StructureTree.vue

@@ -5,8 +5,8 @@
 // Every node is real: a label whose title and slug are always editable
 // inline — the title saves while typing (and focusing it opens the page),
 // the slug commits on blur/Enter since it renames the path, moving the
-// whole subtree. Nodes without content are category labels that redirect
-// to their first child; the ➕ on their row gives them a landing page.
+// whole subtree. Nodes without content are category labels whose URL
+// renders a placeholder page; the ➕ on their row gives them a landing page.
 // Every non-empty list (and the root list) ends with a ➕ footer row:
 // clicking it adds a *pending* row (a local-only item persisted to the
 // server only on commit, ✓/Enter, Esc discards) at the end of that list,
@@ -140,13 +140,6 @@ function onEnd() {
             />
             <span class="acts">
               <span v-if="!element.published" class="draft">draft</span>
-              <button
-                v-if="!element.has_content"
-                type="button"
-                class="act"
-                title="add a landing page (currently redirects to the first child)"
-                @click="handlers.addContent(element)"
-              >➕</button>
               <button
                 type="button"
                 class="act del"

frontend/src/assets/style.css

@@ -316,11 +316,17 @@ article ul ul ul li::before {
   content: "🔹";
 }
 
-/* Task lists render emoji checkmarks (see markdown.py), no diamond. */
+/* Task lists: real checkboxes (not emoji), clickable in the public page. */
 article .task-list-item::before {
   content: none;
 }
 
+article .task-list-item-checkbox {
+  cursor: pointer;
+  margin-inline-end: 0.35em;
+  vertical-align: middle;
+}
+
 article {
   position: relative;
 }

frontend/src/pagerite.js

@@ -169,7 +169,7 @@ import "./assets/style.css";
       const res = await fetch(url);
       const type = res.headers.get("content-type") || "";
       if (!res.ok || !type.includes("text/html")) throw new Error("not a page");
-      // Section URLs redirect to their first child; reflect that.
+      // Reflect any redirect the server issued.
       if (res.redirected) finalUrl = res.url;
       doc = new DOMParser().parseFromString(await res.text(), "text/html");
     } catch {
@@ -255,5 +255,41 @@ import "./assets/style.css";
 
   addEventListener("popstate", () => load(location.href, false, true));
 
+  // --- Task-list checkboxes ------------------------------------------------
+  // Checkboxes in the rendered article are live: toggling them edits the
+  // Markdown source. If the page editor is open, its CodeMirror document is
+  // updated directly; otherwise the server copy is toggled and saved.
+  async function toggleTask(checkbox, index) {
+    const editor = window.__pageritePageEditor;
+    const pagePath = editor ? editor.path() : currentPath;
+    const path = pagePath.replace(/^\/+|\/+$/g, "");
+    const originalChecked = !checkbox.checked;
+    try {
+      const body = { path, index };
+      if (editor) body.markdown = editor.getMarkdown();
+      const res = await fetch("/_/api/toggle-task", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(body),
+      });
+      if (!res.ok) {
+        const detail = await res.json().catch(() => ({}));
+        throw new Error(detail.detail || res.statusText);
+      }
+      const { markdown } = await res.json();
+      if (editor) editor.setMarkdown(markdown);
+    } catch {
+      checkbox.checked = originalChecked;
+    }
+  }
+
+  addEventListener("change", (ev) => {
+    const checkbox = ev.target.closest(".task-list-item-checkbox");
+    if (!checkbox) return;
+    const index = Number(checkbox.dataset.taskIndex);
+    if (Number.isNaN(index)) return;
+    toggleTask(checkbox, index);
+  });
+
   applyEffects();
 })();