Wiki Phase 4: full-text search + revision history

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

Schema (additive): wiki_revisions table (per-save content snapshots).
The FULLTEXT index on wiki_pages(title, body) shipped in Phase 1.

Search:
- MATCH ... AGAINST natural-language search over title + body, ordered by
  relevance
- public: GET /public/wiki?q= (published only); admin: GET /admin/wiki?q=
  (all statuses)
- public wiki index gains a search box; admin list gains a search field

Revision history:
- every create/update snapshots the page into wiki_revisions
- admin endpoints: list revisions, get one, and restore (restore overwrites
  the page, rebuilds links, and appends a new revision — history stays
  append-only); logged as wiki.revision.restore
- editor gains a History modal: revision list + word-level diff (jsdiff) of a
  chosen revision against the current page, with one-click restore

Verified end-to-end: search matches body and title; two edits produce three
revisions; diff renders added/removed words; restore reverts and records a new
revision. No console errors.

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

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

@@ -34,6 +34,19 @@ async function rebuildLinks(pageId, html) {
   }
 }
 
+// Snapshot the current content of a page into the revision history.
+async function writeRevision(page, editorId, changeNote = null) {
+  await wikiDb.insertRevision({
+    pageId: page.id,
+    title: page.title,
+    body: page.body,
+    excerpt: page.excerpt,
+    categoryId: page.category_id,
+    editorId,
+    changeNote,
+  })
+}
+
 // ── Pages ──────────────────────────────────────────────────────────────
 async function listPublished(filters = {}) {
   return wikiDb.listPublishedSummaries(filters)
@@ -43,6 +56,10 @@ async function listAll(filters = {}) {
   return wikiDb.listAllSummaries(filters)
 }
 
+async function search(q, opts = {}) {
+  return wikiDb.searchSummaries(q, opts)
+}
+
 // Admin detail: page + its tags.
 async function getBySlug(slug) {
   const page = await wikiDb.findBySlug(slug)
@@ -77,6 +94,7 @@ async function create({ slug, title, body, excerpt, categoryId, published, updat
   const page = await wikiDb.findBySlug(slug)
   if (Array.isArray(tags)) await syncTags(page.id, tags)
   await rebuildLinks(page.id, clean)
+  await writeRevision(page, updatedBy, 'Created')
   return getBySlug(slug)
 }
 
@@ -102,6 +120,8 @@ async function update(slug, input) {
   await wikiDb.updateBySlug(slug, fields)
   if (Array.isArray(input.tags)) await syncTags(current.id, input.tags)
   if (cleanForLinks != null) await rebuildLinks(current.id, cleanForLinks)
+  const page = await wikiDb.findBySlug(slug)
+  await writeRevision(page, input.updatedBy ?? null, input.changeNote || null)
   return getBySlug(slug)
 }
 
@@ -120,6 +140,42 @@ async function remove(slug) {
   return res
 }
 
+// ── Revisions ──────────────────────────────────────────────────────────
+async function listRevisions(slug) {
+  const page = await wikiDb.findBySlug(slug)
+  if (!page) return null
+  return wikiDb.listRevisions(page.id)
+}
+
+async function getRevision(slug, revId) {
+  const page = await wikiDb.findBySlug(slug)
+  if (!page) return null
+  const rev = await wikiDb.findRevision(revId)
+  if (!rev || rev.page_id !== page.id) return null
+  return rev
+}
+
+// Restore an old revision: overwrite the page with the snapshot, rebuild links,
+// then record a new revision (history stays append-only).
+async function restoreRevision(slug, revId, editorId) {
+  const page = await wikiDb.findBySlug(slug)
+  if (!page) return null
+  const rev = await wikiDb.findRevision(revId)
+  if (!rev || rev.page_id !== page.id) return null
+
+  await wikiDb.updateBySlug(slug, {
+    title: rev.title,
+    body: rev.body,
+    excerpt: rev.excerpt,
+    category_id: rev.category_id,
+    updated_by: editorId,
+  })
+  await rebuildLinks(page.id, rev.body)
+  const restored = await wikiDb.findBySlug(slug)
+  await writeRevision(restored, editorId, `Restored from revision #${revId}`)
+  return getBySlug(slug)
+}
+
 // ── Tags ───────────────────────────────────────────────────────────────
 async function listTags() {
   return wikiDb.listTags()
@@ -164,12 +220,16 @@ async function removeCategory(id) {
 module.exports = {
   listPublished,
   listAll,
+  search,
   getBySlug,
   getPublishedBySlug,
   create,
   update,
   setPublished,
   remove,
+  listRevisions,
+  getRevision,
+  restoreRevision,
   listTags,
   getTagBySlug,
   listCategories,