SITCH — Backend

Pay-per-query startup intelligence agent. PitchBook-level research for the people priced out: founders, students, small funds. No subscription. No API key. Pay per query in USDC on Base via x402.

Hackathon: Microsoft × Coinbase × Tavily Agentic Commerce Hackathon, 2026. Scope: backend only. Frontend lives elsewhere.

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What this backend does

1. Accept a natural-language query ("top Series A edtech startups 2025").
2. Return HTTP 402 Payment Required with x402 payment terms.
3. Verify USDC payment on Base via x402 facilitator.
4. Run Tavily multi-source search (Crunchbase, TechCrunch, SEC EDGAR, LinkedIn, open web).
5. Synthesize results into a structured one-page brief via Azure OpenAI (OpenAI direct as fallback).
6. Return JSON brief.

Total latency target: <10s. Cost per query: ~$0.005 USDC.

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Architecture

┌──────────────┐       POST /query (no payment)        ┌────────────────┐
│ Caller       │ ─────────────────────────────────────▶│  /query route  │
│ (agent or    │                                       │   (Express)    │
│  human via   │ ◀────  402 Payment Required ──────────│                │
│  frontend)   │       (x-payment-required hdr)        └────────────────┘
└──────┬───────┘                                                │
       │                                                        │
       │  POST /query  +  X-PAYMENT header                      │
       │  (signed USDC transfer on Base)                        │
       ▼                                                        ▼
┌────────────────────────┐         ┌──────────────────────────────────┐
│  x402-express          │ ───────▶│  Orchestrator                    │
│  middleware:           │         │  - validate query                │
│  - parse X-PAYMENT     │         │  - dispatch Tavily search        │
│  - verify via          │         │  - dispatch OpenAI synthesis     │
│    facilitator         │         │  - return structured brief       │
│  - settle on Base      │         └────────┬─────────────────────────┘
└────────────────────────┘                  │
                                            ├──▶ Tavily Search SDK
                                            ├──▶ Azure OpenAI (gpt-4o-mini; OpenAI fallback)
                                            └──▶ Postgres (query log, briefs cache)

Caller wallet:  Coinbase CDP Agentic Wallet (autonomously signs the X-PAYMENT)
Server wallet:  Coinbase CDP wallet (receives settled USDC on Base)

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Tech stack

Layer	Choice
Runtime	Node 20 + TypeScript
HTTP	Express (x402 middleware compat)
Search	Tavily SDK (@tavily/core)
LLM	Azure OpenAI (gpt-4o-mini, primary) — OpenAI direct as fallback via env
Wallet (caller side, demo)	Coinbase CDP Agentic Wallets (launch ref)
Wallet (server side)	Coinbase CDP wallet — receives settled USDC
Payments	x402-express middleware, USDC on Base Sepolia (demo) / Base mainnet (prod)
DB	Postgres (Neon) — query log, brief cache
Host	Azure Container Apps (Microsoft sponsor credits)
Local chain	Anvil (Foundry) optional, for offline x402 dev

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Repo layout

sitch-backend/
├── README.md
├── package.json
├── tsconfig.json
├── .env.example                # template only — never commit .env
├── .gitignore
├── src/
│   ├── index.ts                # Express app entry
│   ├── routes/
│   │   └── query.ts            # POST /query — main paid endpoint
│   ├── x402/
│   │   └── middleware.ts       # x402-express config + pricing
│   ├── orchestrator/
│   │   └── orchestrator.ts     # query → search → synthesis pipeline
│   ├── tavily/
│   │   └── search.ts           # Tavily multi-source search
│   ├── synthesis/
│   │   └── brief.ts            # OpenAI tool-use → structured brief
│   ├── wallet/
│   │   └── cdp.ts              # Coinbase CDP server wallet
│   ├── agents/
│   │   └── (reserved for future multi-agent expansion)
│   └── db/
│       └── client.ts           # Postgres client + migrations
├── tests/
└── scripts/
    └── seed.ts                 # seed demo data

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API

POST /query

First call (no payment):

POST /query
Content-Type: application/json

{ "query": "top Series A AI startups in healthcare 2025" }

Response:

HTTP/1.1 402 Payment Required
X-Payment-Required: { chain: "base-sepolia", asset: "USDC", amount: "5000", recipient: "0x..." }

Second call (with payment header):

POST /query
X-Payment: <base64-signed-usdc-transfer>
Content-Type: application/json

{ "query": "top Series A AI startups in healthcare 2025" }

Response (200):

{
  "query": "top Series A AI startups in healthcare 2025",
  "brief": {
    "summary": "...",
    "key_companies": [
      { "name": "...", "stage": "Series A", "amount_raised_usd": 25000000, "lead_investors": [...], "source_urls": [...] }
    ],
    "market_trends": [...],
    "content_angles": [...]
  },
  "sources": [...],
  "payment": { "tx_hash": "0x...", "amount_usdc": "0.005", "settled_at": "..." },
  "latency_ms": 7421
}

GET /healthz

Liveness probe. No payment required.

GET /pricing

Returns current per-query pricing in USDC. No payment required.

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Branching

Solo build. Branches kept for organized commits + clean PR history (judges look at repo activity).

Branch	Purpose
main	Demo-ready. Scaffold + merged features.
feature/x402-middleware	x402-express setup + pricing config
feature/tavily-search	Tavily search wrapper + source filtering
feature/agentkit-wallet	Coinbase Agentic Wallet (awal) + x402 signing
feature/synthesis-agent	Azure OpenAI synthesis → structured brief (OpenAI fallback)
feature/orchestrator	Pipeline glue: search → synth → return

PR rule: feature → main, squash merge. No direct commits to main after scaffold.

Postgres/DB deferred to v0.2. v0 uses in-memory query log only. Judges don't need persistence for a 60-sec demo.

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Environment

See .env.example. Required vars:

• AZURE_OPENAI_ENDPOINT, AZURE_OPENAI_API_KEY, AZURE_OPENAI_DEPLOYMENT, AZURE_OPENAI_API_VERSION (synthesis; primary)
• OPENAI_API_KEY (fallback; only used if Azure vars unset)
• TAVILY_API_KEY (search)
• CDP_API_KEY_NAME, CDP_API_KEY_PRIVATE_KEY (Coinbase Developer Platform — NOT the coinbase.com exchange key)
• X402_FACILITATOR_URL, X402_RECEIVING_ADDRESS, X402_NETWORK, X402_PRICE_USDC
• BASE_RPC_URL
• PORT (default 8787)

Never commit .env. It is in .gitignore. Per project security rules, no secrets in repo.

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Local dev

npm install
cp .env.example .env  # fill in your keys locally
npm run dev           # tsx watch on :8787

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Build plan (hackathon)

Hour	Branch	Deliverable
0–1	main	Scaffold + README + env template (this commit)
1–3	feature/x402-middleware	x402-express wired, returns 402 with correct pricing
3–5	feature/tavily-search	Tavily multi-source search, returns normalized hits
5–7	feature/synthesis-agent	OpenAI tool-use → structured brief JSON
7–8	feature/agentkit-wallet	CDP wallet receiving + (optional) caller-side demo signer
8–10	feature/orchestrator	End-to-end pipeline + Postgres logging
10–11	main	Merge all PRs, deploy to Azure Container Apps
11–12	—	Demo script: query → 402 → pay → brief in <10s

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Out of scope (v0)

• Frontend (separate repo).
• Brief caching dedup beyond exact-query match.
• Multi-language (English only).
• Streaming responses (return full JSON, no SSE for v0).
• Non-USDC payment paths.
• Crunchbase / PitchBook direct API integration (Tavily covers public web).

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Why this fits every sponsor

• Tavily: real-time multi-source web search is the data layer.
• Coinbase: x402 protocol + CDP Agentic Wallets handle autonomous payment.
• Microsoft: Azure Container Apps hosts the agent runtime; Azure OpenAI powers synthesis.
• x402: every paid call uses HTTP 402 + USDC settlement on Base.