Investor-Ready MVPs &
Production SaaS Platforms.

-- Supabase PostgreSQL Multi-Tenant Row Level Security (RLS) Policy
CREATE TABLE workspaces (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  name TEXT NOT NULL,
  created_at TIMESTAMPTZ DEFAULT now()
);

CREATE TABLE workspace_members (
  workspace_id UUID REFERENCES workspaces(id) ON DELETE CASCADE,
  user_id UUID REFERENCES auth.users(id) ON DELETE CASCADE,
  role TEXT CHECK (role IN ('owner', 'admin', 'member')),
  PRIMARY KEY (workspace_id, user_id)
);

-- Enforce Zero Cross-Tenant Data Leaks
ALTER TABLE workspaces ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Tenant isolation: members only" ON workspaces
  FOR ALL
  USING (
    id IN (
      SELECT workspace_id FROM workspace_members
      WHERE user_id = auth.uid()
    )
  );

// Next.js 15 App Router: Cryptographically Verified Stripe Webhook Handler
import { headers } from "next/headers";
import { stripe } from "@/lib/stripe";
import { db } from "@/lib/db";

export async function POST(req: Request) {
  const body = await req.text();
  const sig = (await headers()).get("stripe-signature")!;

  let event;
  try {
    event = stripe.webhooks.constructEvent(body, sig, process.env.STRIPE_WEBHOOK_SECRET!);
  } catch (err) {
    return new Response(`Webhook Error: ${err.message}`, { status: 400 });
  }

  if (event.type === "checkout.session.completed") {
    const session = event.data.object;
    await db.subscription.upsert({
      where: { customerId: session.customer as string },
      update: { status: "active", planTier: "pro" },
      create: { customerId: session.customer as string, planTier: "pro" }
    });
  }
  return new Response(JSON.stringify({ received: true }), { status: 200 });
}

# FastAPI Real-Time Server-Sent Events (SSE) AI Streaming Worker
from fastapi import FastAPI, Depends
from sse_starlette.sse import EventSourceResponse
import anthropic

app = FastAPI()
client = anthropic.AsyncAnthropic()

@app.post("/api/v1/agent/stream")
async def stream_agent_deliberation(prompt: str, user=Depends(verify_jwt)):
    async def event_generator():
        async with client.messages.stream(
            max_tokens=1024,
            messages=[{"role": "user", "content": prompt}],
            model="claude-3-5-sonnet-20241022",
        ) as stream:
            async for text in stream.text_stream:
                yield {"event": "delta", "data": text}
        yield {"event": "done", "data": "[COMPLETED]"}

    return EventSourceResponse(event_generator())