Wiki Phase 3: internal links, backlinks, and tags

Connectivity phase of the wiki upgrade (see WIKI_UPGRADE.md).

Schema (additive new tables): wiki_tags, wiki_page_tags, wiki_links.

Internal links & backlinks:
- new wiki.links.js parses a saved body for /wiki/<slug> (and data-wiki-slug)
  targets; wiki_links is rebuilt on every save
- article shows a "Linked from" section (published backlinks) and renders
  links to non-existent pages as red links (server returns missing_links)
- editor gains an internal-link picker listing existing pages

Tags:
- pages accept a tags[] array; tags upsert on save, page tag-set is replaced,
  and orphaned tags are auto-pruned (on save and delete)
- public/admin list filter by ?tag=; /wiki/tags lists tags with published counts
- article shows tag chips; the index has a flat tag-filtered view; editor has a
  comma-separated tags field

Verified end-to-end: A->B backlink appears, red link detected, link index
rebuilds on edit, tag filtering + chips + pruning all work.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/src/model/wiki/wiki.model.js

@@ -1,45 +1,97 @@
 const wikiDb = require('./wiki.db')
 const { cleanBody } = require('../../utils/sanitizeHtml')
+const { extractTargets } = require('./wiki.links')
+
+function slugifyTag(label) {
+  return String(label)
+    .toLowerCase()
+    .trim()
+    .replace(/[^a-z0-9]+/g, '-')
+    .replace(/(^-|-$)/g, '')
+}
+
+// Upsert each label into wiki_tags and set the page's tag set exactly.
+async function syncTags(pageId, tags) {
+  const ids = []
+  const seen = new Set()
+  for (const raw of tags) {
+    const label = String(raw).trim()
+    if (!label) continue
+    const slug = slugifyTag(label)
+    if (!slug || seen.has(slug)) continue
+    seen.add(slug)
+    ids.push(await wikiDb.upsertTag(slug, label))
+  }
+  await wikiDb.setPageTags(pageId, ids)
+  await wikiDb.deleteOrphanTags()
+}
+
+// Rebuild the page's outgoing internal-link rows from its (sanitized) body.
+async function rebuildLinks(pageId, html) {
+  await wikiDb.clearLinks(pageId)
+  for (const target of extractTargets(html)) {
+    await wikiDb.insertLink(pageId, target)
+  }
+}
 
 // ── Pages ──────────────────────────────────────────────────────────────
-async function listPublished(categoryId = null) {
-  return wikiDb.listPublishedSummaries(categoryId)
+async function listPublished(filters = {}) {
+  return wikiDb.listPublishedSummaries(filters)
 }
 
 async function listAll(filters = {}) {
   return wikiDb.listAllSummaries(filters)
 }
 
+// Admin detail: page + its tags.
 async function getBySlug(slug) {
-  return wikiDb.findBySlug(slug)
+  const page = await wikiDb.findBySlug(slug)
+  if (!page) return null
+  page.tags = await wikiDb.getTagsForPage(page.id)
+  return page
 }
 
+// Public detail: page + tags + backlinks + missing (red) link targets.
 async function getPublishedBySlug(slug) {
-  return wikiDb.findPublishedBySlug(slug)
+  const page = await wikiDb.findPublishedBySlug(slug)
+  if (!page) return null
+  page.tags = await wikiDb.getTagsForPage(page.id)
+  page.backlinks = await wikiDb.getBacklinks(slug, { publishedOnly: true })
+  const targets = extractTargets(page.body)
+  const existing = await wikiDb.getExistingSlugs(targets)
+  page.missing_links = targets.filter((t) => !existing.has(t))
+  return page
 }
 
-async function create({ slug, title, body, excerpt, categoryId, published, updatedBy }) {
+async function create({ slug, title, body, excerpt, categoryId, published, updatedBy, tags }) {
+  const clean = cleanBody(body)
   await wikiDb.insert({
     slug,
     title,
-    body: cleanBody(body),
+    body: clean,
     excerpt: excerpt || null,
     categoryId: categoryId ?? null,
-    published: published !== false, // default published unless explicitly false
+    published: published !== false,
     updatedBy,
   })
-  return wikiDb.findBySlug(slug)
+  const page = await wikiDb.findBySlug(slug)
+  if (Array.isArray(tags)) await syncTags(page.id, tags)
+  await rebuildLinks(page.id, clean)
+  return getBySlug(slug)
 }
 
-// Partial update — only keys present in `input` are written. Body is sanitized;
-// published_at is stamped the first time a page goes live.
+// Partial update — only keys present in `input` are written.
 async function update(slug, input) {
   const current = await wikiDb.findBySlug(slug)
   if (!current) return null
 
   const fields = { updated_by: input.updatedBy ?? null }
+  let cleanForLinks = null
   if ('title' in input) fields.title = input.title
-  if ('body' in input) fields.body = cleanBody(input.body)
+  if ('body' in input) {
+    fields.body = cleanBody(input.body)
+    cleanForLinks = fields.body
+  }
   if ('excerpt' in input) fields.excerpt = input.excerpt || null
   if ('categoryId' in input) fields.category_id = input.categoryId ?? null
   if ('published' in input) {
@@ -48,7 +100,9 @@ async function update(slug, input) {
   }
 
   await wikiDb.updateBySlug(slug, fields)
-  return wikiDb.findBySlug(slug)
+  if (Array.isArray(input.tags)) await syncTags(current.id, input.tags)
+  if (cleanForLinks != null) await rebuildLinks(current.id, cleanForLinks)
+  return getBySlug(slug)
 }
 
 async function setPublished(slug, published) {
@@ -57,11 +111,22 @@ async function setPublished(slug, published) {
   const fields = { published: published ? 1 : 0 }
   if (published && !current.published_at) fields.published_at = new Date()
   await wikiDb.updateBySlug(slug, fields)
-  return wikiDb.findBySlug(slug)
+  return getBySlug(slug)
 }
 
 async function remove(slug) {
-  return wikiDb.deleteBySlug(slug)
+  const res = await wikiDb.deleteBySlug(slug)
+  await wikiDb.deleteOrphanTags() // page_tags cascade on delete; drop now-empty tags
+  return res
+}
+
+// ── Tags ───────────────────────────────────────────────────────────────
+async function listTags() {
+  return wikiDb.listTags()
+}
+
+async function getTagBySlug(slug) {
+  return wikiDb.findTagBySlug(slug)
 }
 
 // ── Categories ─────────────────────────────────────────────────────────
@@ -97,7 +162,6 @@ async function removeCategory(id) {
 }
 
 module.exports = {
-  list: listPublished, // back-compat alias (old callers expected published list)
   listPublished,
   listAll,
   getBySlug,
@@ -106,6 +170,8 @@ module.exports = {
   update,
   setPublished,
   remove,
+  listTags,
+  getTagBySlug,
   listCategories,
   getCategoryBySlug,
   getCategoryById,