feat: brainstorm sessions, PDF document Q&A, embedding fixes, and UI improvements

- Add brainstorm feature with collaborative canvas, AI idea generation, live cursors, playback, and export
- Add PDF upload/extraction/ingestion pipeline with pgvector document search (RAG)
- Add document Q&A overlay with streaming chat and PDF preview
- Add note attachments UI with status polling, grid layout, and auto-scroll
- Add task extraction AI tool and agent executor improvements
- Fix NoteEmbedding missing updatedAt column, re-index 66 notes with 1536-dim embeddings
- Fix brainstorm 'Create Note' button: add success toast and redirect to created note
- Fix memory echo notification infinite polling
- Fix chat route to always include document_search tool
- Add brainstorm i18n keys across all 14 locales
- Add socket server for real-time brainstorm collaboration
- Add hierarchical notebook selector and organize notebook dialog improvements
- Add sidebar brainstorm section with session management
- Update prisma schema with brainstorm tables, attachments, and document chunks

memento-note/app/api/brainstorm/join/route.ts

@@ -0,0 +1,85 @@
+import { NextRequest, NextResponse } from 'next/server'
+import prisma from '@/lib/prisma'
+import { auth } from '@/auth'
+import { z } from 'zod'
+import { logActivity } from '@/lib/brainstorm-collab'
+
+const joinSchema = z.object({
+  token: z.string().min(1),
+})
+
+export async function POST(request: NextRequest) {
+  const session = await auth()
+  if (!session?.user?.id) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
+
+  try {
+    const body = await request.json()
+    const { token } = joinSchema.parse(body)
+
+    const brainstormSession = await prisma.brainstormSession.findFirst({
+      where: { inviteToken: token },
+      select: { id: true, inviteExpiry: true, userId: true, seedIdea: true },
+    })
+
+    if (!brainstormSession) {
+      return NextResponse.json({ error: 'Invalid invite token' }, { status: 404 })
+    }
+
+    if (brainstormSession.inviteExpiry && brainstormSession.inviteExpiry < new Date()) {
+      return NextResponse.json({ error: 'Invite expired' }, { status: 410 })
+    }
+
+    const existing = await prisma.brainstormParticipant.findFirst({
+      where: { sessionId: brainstormSession.id, userId: session.user.id },
+    })
+
+    if (existing) {
+      return NextResponse.json({
+        success: true,
+        sessionId: brainstormSession.id,
+        role: existing.role,
+      })
+    }
+
+    const participant = await prisma.brainstormParticipant.create({
+      data: {
+        sessionId: brainstormSession.id,
+        userId: session.user.id,
+        role: 'editor',
+      },
+    })
+
+    await logActivity(brainstormSession.id, 'joined', session.user.id)
+
+    try {
+      const joinerName = session.user.name || 'Someone'
+      const seedPreview = brainstormSession.seedIdea.length > 40
+        ? brainstormSession.seedIdea.substring(0, 40) + '…'
+        : brainstormSession.seedIdea
+      await prisma.notification.create({
+        data: {
+          userId: brainstormSession.userId,
+          type: 'brainstorm_joined',
+          title: `${joinerName} joined your brainstorm`,
+          message: seedPreview,
+          actionUrl: `/brainstorm?session=${brainstormSession.id}`,
+          relatedId: brainstormSession.id,
+        },
+      })
+    } catch {}
+
+    return NextResponse.json({
+      success: true,
+      sessionId: brainstormSession.id,
+      role: participant.role,
+    }, { status: 201 })
+  } catch (error: any) {
+    if (error instanceof z.ZodError) {
+      return NextResponse.json({ error: error.issues }, { status: 400 })
+    }
+    console.error('Error joining brainstorm:', error)
+    return NextResponse.json({ error: 'Failed to join' }, { status: 500 })
+  }
+}