Fix AI prompt wiring, asset generation flow, and signup trigger

app/api/ai/headlines/route.ts

@@ -1,6 +1,6 @@
 import { createClient } from '@/lib/supabase/server'
 import { getSupabaseAdmin } from '@/lib/supabase/admin'
-import { generateHeadlines } from '@/lib/ai/claude'
+import { brandProfileToMetadataConfig, generateHeadlines } from '@/lib/ai/claude'
 import { checkUsage, incrementUsage } from '@/lib/utils/rate-limit'
 import {
   handleApiError,
@@ -32,12 +32,23 @@ export async function POST(request: Request) {
       throw new UsageLimitError('AI 헤드라인', usage.limit)
     }
 
+    const promptConfig = body.promptConfig ?? (
+      body.brandStyleDirection || body.brandKeywords?.length
+        ? brandProfileToMetadataConfig({
+            platform: body.platform,
+            styleDirection: body.brandStyleDirection,
+            keywords: body.brandKeywords,
+          })
+        : undefined
+    )
+
     const result = await generateHeadlines({
       projectName: body.projectName,
       description: body.description,
       platform: body.platform,
       brandKeywords: body.brandKeywords,
       brandStyleDirection: body.brandStyleDirection,
+      promptConfig,
     })
 
     await incrementUsage(getSupabaseAdmin(), user.id, 'ai_headlines_used_this_month')

app/api/assets/generate/route.ts

@@ -46,6 +46,37 @@ export async function POST(request: Request) {
 
     const project = projectData as Project
 
+    const { data: startedProject, error: startError } = await supabase
+      .from('projects')
+      .update({ status: 'generating', pipeline_stage: 'icon_resolve' })
+      .eq('id', projectId)
+      .eq('user_id', user.id)
+      .neq('status', 'generating')
+      .select('id')
+      .maybeSingle()
+
+    if (startError) {
+      throw new AppError(
+        startError.message,
+        'ASSET_GENERATION_START_FAILED',
+        500,
+        '에셋 생성을 시작하지 못했습니다. 잠시 후 다시 시도해주세요.'
+      )
+    }
+
+    if (!startedProject) {
+      return Response.json(
+        {
+          success: false,
+          error: {
+            code: 'ASSET_GENERATION_IN_PROGRESS',
+            message: '이미 에셋 생성이 진행 중입니다.',
+          },
+        },
+        { status: 409 }
+      )
+    }
+
     let brandProfile: BrandProfile | null = null
     if (project.brand_profile_id) {
       const { data: brandData } = await supabase
@@ -68,11 +99,6 @@ export async function POST(request: Request) {
 
     const stylePreset = presetData as StylePreset
 
-    await supabase
-      .from('projects')
-      .update({ status: 'generating', pipeline_stage: 'icon_resolve' })
-      .eq('id', projectId)
-
     try {
       const startedAt = Date.now()
       const { storageUrl, warnings } = await runAssetPipeline({

components/wizard/step-5-preview.tsx

@@ -168,7 +168,7 @@ export function Step5Preview({
     document.body.removeChild(link)
   }
 
-  if (status === 'generating' || status === 'idle') {
+  if (status === 'generating') {
     return <GeneratingState progress={progress} stage={stage} />
   }
 

components/wizard/wizard-shell.tsx

@@ -106,7 +106,6 @@ export function WizardShell({ brandProfiles, stylePresets, user }: WizardShellPr
       })
 
       setProjectId(project.id)
-      store.reset()
       nextStep()
     } catch {
       setSaveError(tErrors('projectSaveUnknownError'))