feat(memory): implement stability stage

Co-authored-by: multica-agent <github@multica.ai>

apps/web/server/api/worlds/generate.post.ts

@@ -1,9 +1,9 @@
 import { CreateWorldRequestSchema, WorldStarterSchema, moderate13Plus } from '@dng/shared'
 import { buildJsonCompletion, parseJsonCompletion } from '../../utils/ai-provider'
-import { requireStageTwoUser } from '../../utils/stage-two-supabase'
+import { requireStageTwoUser, stageSixConsumeAiQuota, stageSixRecordAiUsage } from '../../utils/stage-two-supabase'
 
 export default defineEventHandler(async event => {
-  await requireStageTwoUser(event)
+  const user = await requireStageTwoUser(event)
   const raw = await readBody(event)
   const prompt = typeof raw?.prompt === 'string' ? raw.prompt : ''
   const answers = raw?.answers && typeof raw.answers === 'object' ? raw.answers : {}
@@ -24,15 +24,21 @@ export default defineEventHandler(async event => {
     throw createError({ statusCode: 500, statusMessage: error instanceof Error ? error.message : 'Invalid AI provider configuration.' })
   }
 
+  await stageSixConsumeAiQuota(user.id, null, 'world-preview')
+  const startedAt = Date.now()
   const response = await fetch(completion.endpoint, {
     method: 'POST',
     headers: completion.headers,
     body: JSON.stringify(completion.body),
   })
   if (!response.ok) throw createError({ statusCode: 502, statusMessage: 'The coauthor is temporarily unavailable.' })
+  const payload = await response.json()
+  await stageSixRecordAiUsage({
+    userId: user.id, campaignId: null, requestKind: 'world-preview', completion, payload, latencyMs: Date.now() - startedAt,
+  }).catch(error => console.error('[web] could not record world preview usage:', error))
   let world
   try {
-    world = WorldStarterSchema.parse(parseJsonCompletion(await response.json()))
+    world = WorldStarterSchema.parse(parseJsonCompletion(payload))
   } catch {
     throw createError({ statusCode: 502, statusMessage: 'The coauthor returned an invalid world structure.' })
   }