feat: add immutable level template lifecycle

server/index.ts

@@ -23,6 +23,9 @@ const levels = createLevelRepository(pool, editingEnabled)
 function wantsEdit(req: express.Request) {
   return editingEnabled && req.query.edit === '1'
 }
+function slug(value: unknown, fallback: string) {
+  return String(value || fallback).trim().toLowerCase().replace(/[^a-z0-9-]+/g, '-').replace(/^-+|-+$/g, '')
+}
 
 export const app = express()
 app.disable('x-powered-by')
@@ -41,14 +44,36 @@ app.get('/api/levels', async (_req, res, next) => {
   try { res.json(await levels.listLevels()) }
   catch (error) { next(error) }
 })
+app.get('/api/templates', async (_req, res, next) => {
+  try { res.json(await levels.listTemplates()) }
+  catch (error) { next(error) }
+})
+app.post('/api/templates/:slug/levels', async (req, res, next) => {
+  try {
+    if (!wantsEdit(req)) return res.status(403).json({ error: 'Level editing is disabled' })
+    const title = String(req.body?.title || '').trim() || undefined
+    const levelSlug = slug(req.body?.id, `${req.params.slug}-${Date.now()}`)
+    const level = await levels.instantiateTemplate(req.params.slug, { id: levelSlug, title, version: req.body?.version })
+    level ? res.status(201).json(level) : res.status(404).json({ error: 'Template version not found' })
+  } catch (error) { next(error) }
+})
 app.post('/api/levels', async (req, res, next) => {
   try {
     if (!editingEnabled) return res.status(403).json({ error: 'Level editing is disabled' })
     const title = String(req.body?.title || 'Untitled Investigation').trim()
-    const id = String(req.body?.id || `level-${Date.now()}`).trim().toLowerCase().replace(/[^a-z0-9-]+/g, '-')
+    const id = slug(req.body?.id, `level-${Date.now()}`)
     res.status(201).json(await levels.createLevel({ id, title, subtitle: String(req.body?.subtitle || '') }))
   } catch (error) { next(error) }
 })
+app.post('/api/levels/:id/templates', async (req, res, next) => {
+  try {
+    if (!wantsEdit(req)) return res.status(403).json({ error: 'Level editing is disabled' })
+    const name = String(req.body?.name || 'Untitled Template').trim()
+    const templateSlug = slug(req.body?.slug, name)
+    const template = await levels.saveLevelAsTemplate(req.params.id, { slug: templateSlug, name })
+    template ? res.status(201).json(template) : res.status(404).json({ error: 'Level not found' })
+  } catch (error) { next(error) }
+})
 app.get('/api/assets/:id', async (req, res, next) => {
   try {
     const asset = await levels.getAsset(req.params.id)