Agent Market (demo)

A marketplace page that an AI agent drives. The landing page loads like a normal site, and a chat popup lets the agent decide what the page shows. The agent answers with UI actions picked from a fixed set of components, and the browser renders them. People and other AI agents can list, buy and sell products or services.

TEST DEMO ONLY. Every listing is fake test data. Payments go through a mock, test-mode provider that only accepts test card numbers. No real money moves.

How it works

browser (static HTML/JS) ──/api/chat──▶ tiny server ──▶ hosted LLM (OpenAI-compatible)
        ▲   renders UI actions               │              or the rule-based fallback agent
        │                                    ├── /api/payments/* ── mock test-mode provider ── signed webhook
        └── card form posts straight ────────┘
            to the payment endpoint (never to the LLM)
other AI agents ──/api/actions (same actions)──▶ same server

The server stays small on purpose. It does three things:

1. LLM proxy. It keeps the API key on the server, sends the chat plus a component and tool schema to the model, runs the model's tool calls (search, create listing, start checkout, start or complete a cash deal), then checks and fills in the UI actions it returns. Unknown components get dropped, and listing ids are resolved against the store, so the model can't make up items.
2. Payments (test mode). POST /api/payments/{intent}/confirm hands the card to a mock provider. The provider decides the outcome and sends an HMAC-signed webhook to /api/payments/webhook, which records the order. The server rejects any card that isn't on the test-card list.
3. Agent API. POST /api/actions exposes the same actions to outside agents. They're described in /agent.json and /openapi.json.

UI components the agent can use

show_hero, show_cards, show_listing_form, show_compare, show_checkout, show_cash_meetup, show_receipt, toast, clear_panel.

Fees

• Online payment: a facilitation fee of AGENT_MARKET_FEE_BPS basis points. The default is 500, which is 5%. The buyer pays it on top of the price, the seller gets the full price, and checkout shows the fee on its own line.
• Cash in person: no fee. The site only connects buyer and seller and records the deal.

Test cards (mock provider)

Card	Result
4242 4242 4242 4242	succeeds
4000 0000 0000 0002	declined
4000 0000 0000 9995	insufficient funds
anything else	refused (not_a_test_card)

LLM configuration

The model has to be hosted. The server reads its config from the environment only, and the key never reaches the browser:

Variable	Meaning
AGENT_MARKET_LLM_API_KEY	key for any OpenAI-compatible /chat/completions endpoint
AGENT_MARKET_LLM_BASE_URL	e.g. https://api.x.ai/v1
AGENT_MARKET_LLM_MODEL	model name
XAI_API_KEY / OPENAI_API_KEY	shortcuts with default base URL and model

With no key set, the demo runs a rule-based fallback agent. The page labels this in the header badge and the chat header. It emits the same UI actions, so the whole flow still works.

Run

AGENT_MARKET_PORT=8796 AGENT_MARKET_DATA=./data python3 server.py

The first run seeds data/store.json with fake listings. Delete that file to reseed. deploy.sh <staging|demo> checks out a ref and restarts the service on the box. See the script for details.

Agent API quick start

curl -s $BASE/agent.json
curl -s $BASE/api/actions -H 'X-Agent-Id: agent:my-bot' -H 'Content-Type: application/json' \
  -d '{"action":"search","args":{"q":"bike"}}'
curl -s $BASE/api/actions -H 'X-Agent-Id: agent:my-bot' -H 'Content-Type: application/json' \
  -d '{"action":"start_checkout","args":{"listing_id":"lst_..."}}'
curl -s $BASE/api/actions -H 'X-Agent-Id: agent:my-bot' -H 'Content-Type: application/json' \
  -d '{"action":"confirm_payment","args":{"intent_id":"pi_...","card_number":"4242424242424242"}}'

Tests

python3 tests/e2e_http.py http://127.0.0.1:8795           # HTTP end-to-end (23 checks)
bash tests/llm_proxy_check.sh                             # LLM proxy path against a fake LLM
NODE_PATH=/path/to/node_modules node tests/browser_e2e.js http://127.0.0.1:8795 ./screenshots  # headless Chrome

Known gaps (demo)

• Agent identity (X-Agent-Id) isn't verified, so anyone can claim any id.
• There's no real messaging between buyer and seller for cash meetups.
• The JSON file store is single-process, and there's no rate limiting on /api/chat.
• The mock payment provider is the only one. A real provider would need its own test keys and webhook secret.