Product thesis01 / 10

Agent-initiated commerce

A one-cent reservation, built for a machine buyer.

LuxArb Reserve is a headless supplier endpoint where an AI procurement agent pays 0.01 USDC to hold scarce inventory for 15 minutes—without a cart, login, or human checkout.

Open buyer workspace See the payment flow

Price0.01 USDC

Hold15 minutes

Replay ruleSettle once

Source: Agentic Commerce Stack · pp. 3, 21–24, 29; Why Solana for Agentic Commerce · pp. 9–17

The problem02 / 10

Autonomous buyers cannot depend on human checkout.

Scarce inventory needs a paid hold while an agent completes a larger decision. Card rails add identity, UI, fixed fees, and retry risk to a transaction worth one cent.

01Human identity

Cards assume an account holder and an interactive approval surface.

02Wrong economics

A one-cent hold is below the practical floor of card processing.

03Retry ambiguity

A timeout can make a safe retry look like a second purchase.

04Inventory trust

The supplier needs payment proof, not faith in the agent's identity.

Source: Agentic Commerce Stack · pp. 3, 21–24, 29; Why Solana for Agentic Commerce · pp. 9–17

Agentic commerce03 / 10

The endpoint becomes the store.

The buyer agent discovers terms, accepts a machine-readable price, signs within policy, and receives the resource. The reservation API replaces product page, cart, and checkout.

Source: Agentic Commerce Stack · pp. 3, 21–24, 29

HTTP 402 + x40204 / 10

Quote → challenge → pay → reserve → replay.

Payment is part of the HTTP resource contract. A facilitator verifies the signed payload and submits settlement; the supplier never receives the buyer private key.

01Gemini

Authorize or stop

google/gemini-3-flash returns reserve, review, or decline. Only reserve reaches the supplier.

02Buyer

Request quote

Ask for one inventory hold with a stable idempotency key.

03Supplier

Price and challenge

Bind inventory, expiry, amount, and recipient, then return x402 requirements as HTTP 402.

04Buyer

Sign and retry

Authorize the exact SVM payload from the funded agent wallet.

05Facilitator

Verify and settle

Validate the payload, submit settlement, and return its signature.

06Supplier

Reserve and replay

Create one hold; duplicate commits return the same reservation.

Source: Agentic Commerce Stack · pp. 3, 21–24, 29

Trust boundaries05 / 10

Strict contracts outside. Pure invariants inside.

Apps own HTTP and mutable state. Shared packages own wire shapes, reservation rules, and the payment boundary without importing from either app.

Decisiongoogle/gemini-3-flash via the Vercel AI Gateway, parsed against a strict schemaagent

BuyerNext.js procurement workspace and quote → 402 → paid retry orchestratoragent

ContractsStrict Zod wire schemas shared by both applicationsshared

SupplierAuthoritative inventory, quote, payment gate, and replay statemerchant

DomainPure fingerprints, proof validation, and legal state transitionsshared

Paymentsx402 buyer signer plus facilitator verification and settlement boundaryrail

Source: Repository architecture and test suite

Why on-chain06 / 10

Machine cash needs machine-scale economics.

Scheme: exact
Network: Solana devnet
Asset: USDC
Amount: 10000 atomic
Human price: 0.01 USDC
Challenge: HTTP 402

Fast, inexpensive, always-on settlement makes a one-cent inventory hold economically coherent—and independently auditable.

Source: Why Solana for Agentic Commerce · pp. 9–17

Proof, not posture07 / 10

We separate code, tests, and live proof.

Fixture mode proves the workflow deterministically. Devnet code proves integration shape. Only a real explorer signature proves settlement—and that final artifact is still required.

A typed Gemini decision gates every paymentgoogle/gemini-3-flash structured output, re-parsed before any supplier callverified

A broken or absent model call never authorizes a transferGateway faults fail closed; no credential yields a labelled fallbackverified

Quote → 402 → proof retry → reservation → replayFixture flow executes through real HTTP routesverified

Duplicate requests cannot double-payConcurrent and delayed settlement regression testsverified

Payment data remains bound to the quoteStrict contracts and domain proof validationverified

The buyer can sign and the supplier can settle on devnetx402 exact-SVM adapters and mocked boundary testsimplemented

A real devnet USDC transfer settledNo explorer transaction is captured in this repositorymissing

Source: Repository tests and executable routes

Judging criteria08 / 10

A direct fit—with two honest gaps.

Novel UXStrong

The endpoint is the store: no product page, cart, login, or human checkout.

Agent autonomyStrong

After wallet funding, payment executes inside exact quote terms without another approval.

Solana paymentNeeds live trace

x402, exact SVM, devnet USDC, wallet signing, and facilitator settlement are implemented.

Google AIStrong

google/gemini-3-flash returns the typed reserve decision that unlocks the 402 retry.

Source: Hackathon Intro Deck · pp. 3, 5

Google Cloud path09 / 10

The production path is explicit, not implied.

Gemini 3 Flash and Vercel hosting are integrated. Buyer and supplier run on Vercel; Gemini gates decisions via the AI Gateway before fixture-mode payment.

Today · Decision, live

google/gemini-3-flash

Structured decision, confidence, rationale, and risk flags. Anything but reserve returns 409.

Next evidence →

Today · Credentials, zero-secret

Vercel OIDC

Vercel injects VERCEL_OIDC_TOKEN in production, so no gateway key is stored. AI_GATEWAY_API_KEY overrides it locally.

Next evidence →

Today · Runtime, two projects

Buyer and supplier on Vercel

One repository, two root directories, independent scaling, one live URL per service. Supplier state is still process-local.

Next evidence →

Source: Vibe Coding on Google Cloud · pp. 12–15; Vercel AI Gateway + OIDC

Under three minutes10 / 10

Show the transaction. Then show it cannot repeat.

The strongest demo is one live devnet settlement followed by an identical commit that returns the same reservation without a second settlement.

0:00ProblemExplain why one-cent, time-boxed inventory holds need machine cash.

0:20DecisionShow the Gemini reserve call with its confidence, rationale, and source.

0:40QuoteShow the bound amount, asset, recipient, network, and expiry.

0:55402 + payRun the buyer agent and expose the signed retry in the activity log.

1:40On-chain proofOpen the real devnet transaction in Solana Explorer.

2:15ReplayRepeat the commit and prove the same reservation returns without settlement.

Run the buyer flow

Source: Hackathon Intro Deck · pp. 3, 5; repository demo flow