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Arc Hackathon 2026Usage-Based Compute Billing
> _ P402 METER · SUBMISSION OVERVIEW

AI Thinking
Has a Price.
Now It Settles.

P402 Meter is the first system to price AI computation at the token level and settle each event in USDC on Arc in real time. Prior authorization review in healthcare is the proof — a document-heavy, high-stakes workflow where every reasoning step has measurable value and every cent of cost can be governed, attributed, and audited.

01The Problem

AI work in healthcare has no economic substrate.

$31B
Annual US prior auth administrative cost
Much of it manual, repetitive, document-heavy reasoning work that AI can already do.
$0.30
Stripe minimum transaction fee
Makes sub-cent per-action billing impossible. You'd need to batch 300+ AI micro-actions before you can charge for them — destroying real-time attribution.
~$2.85
ETH mainnet gas cost per ERC-20 transfer
Settlement costs more than the AI work itself. Every blockchain before Arc makes per-token settlement economically irrational.
0
Existing systems with real-time per-token AI billing
AI platforms bill monthly subscriptions or per-API-call batches. No system prices and settles at token granularity. Until now.
02The Solution

Every token an AI generates is a priced USDC event on Arc.

P402 Meter instruments the Gemini generation stream at the chunk level. Each text chunk emitted by the model triggers a ledger event: tokens estimated, cost calculated at $0.0000006/token, USDC amount recorded, event written to Arc. A single prior authorization review generates 55+ onchain events. Total cost: under $0.01.

The workflow in one sentence

Upload a prior-auth document → Gemini reads it, classifies it, reviews it → every token of that thinking settles in USDC on Arc → Gemini Pro audits the economics → humans approve the recommendation with full proof of work.

55+
Onchain events per review
1 per token chunk emitted
<$0.01
Total cost per action
vs $2.85 on ETH mainnet
>99.7%
Cost saving vs ETH
Arc USDC gas at $0.006/tx
03Technology

Three technologies. One economic model.

ArcThe settlement layer that makes sub-cent billing real
USDC as native gas token — settlement costs $0.006/tx instead of $2.85
High transaction frequency — 55+ events per session without batching
ERC-8004 for AI agent identity and reputation on Arc testnet
ERC-8183 for specialist review escrow — job creation, funding, and release
Every economic event links to a verifiable Arc block explorer entry
CircleThe money layer that makes USDC move programmatically
Developer-Controlled Wallets on ARC-TESTNET — each session gets a dedicated wallet visible in Circle Developer Console
Circle Gateway x402 API for settlement verification at gateway-api-testnet.circle.com
USDC predeploy at 0x3600000000000000000000000000000000000000 on Arc
Circle Faucet for testnet USDC — no ETH needed, pure stablecoin workflow
Gateway domain 26 on Arc testnet for cross-chain portability
GeminiThe intelligence layer that makes AI work governable
Gemini Flash — multimodal document intake via inlineData (image, PDF, text)
Function calling with 3 typed tools: parsePriorAuthDocument, createReviewSession, addLedgerEstimate
Structured healthcare extract: payer, provider, procedure, urgency, case type, confidence score
Flash drives the live review stream — every chunk is a priced ledger event
Gemini Pro — post-run economic audit with cost breakdown, ETH/Stripe comparison, and narrative explanation
Gemini Pro is distinct from Flash: slower, deeper reasoning, used only for the final audit summary
04Why Healthcare

Healthcare prior auth is the hardest possible proof of concept.

Most hackathon demos use simple e-commerce or generic chat flows to prove a payment concept. Prior authorization review is the opposite — it is document-heavy, policy-bound, multi-step, explainability-critical, and economically significant. If per-token billing works here, it works everywhere.

Governance is mandatory
Clinical AI must explain every decision. P402's governed session model — budget caps, approval gates, audit trails — is not optional overhead here. It is the product.
Document reasoning is load-bearing
Gemini's multimodal intake reads actual prior auth forms. This is not prompt-wrapped text. It is vision-based structured extraction with typed function calls.
Specialist delegation is natural
Complex cases route to specialist review agents under ERC-8183 escrow. The A2A payment loop is not a demo gimmick — it mirrors real payer escalation workflows.
The economics are real
A human reviewer costs $15–50/hour for prior auth work. An AI-assisted review costs under $0.01. The margin explanation in the demo is not hypothetical — it is the business case.
05Prize Alignment

Built to satisfy every judging criterion.

Arc Grand Prize — Usage-Based Compute Billing
Real per-action pricing at $0.0000006/token — well under $0.01 limit
55+ onchain transactions per demo run on Arc testnet (chain 5042002)
Margin explanation visible in UI: Arc $0.006/tx vs ETH $2.85/tx vs Stripe $0.30 min
Arc and Circle infrastructure visible throughout — wallets, settlements, block explorer links
Gemini Sponsor Prize
Gemini Flash is load-bearing — multimodal intake, function calling, live review stream
Function calling with 3 typed tools producing structured JSON healthcare extract
Gemini Pro has a distinct role — post-run economic audit, not the same model doing everything
Flash and Pro are both demonstrable in the UI with separate labeled outputs
Explanation quality: every recommendation includes Gemini-generated rationale
Secondary — Agent-to-Agent Payment Loop
Specialist escalation via ERC-8183 creates a funded escrow job on Arc testnet
Deliverable hash (keccak256 of specialist output) anchors the A2A handoff
escrow_release ledger event records the payment loop completion onchain
06Architecture

Eight API routes. One coherent economic model.

/api/meter/packetIngest document, SHA-256 hash, persist asset
/api/meter/work-orderGemini multimodal extraction → structured WorkOrder
/api/meter/sessionsOpen metered session with budget cap
/api/meter/fundCreate Circle Developer-Controlled Wallet on ARC-TESTNET
/api/meter/chatSSE stream — per-chunk ledger events, reconcile, approval
/api/meter/escrowERC-8183 specialist job create + deliverable hash
/api/meter/trustERC-8004 agent identity + reputation read
/api/meter/auditGemini Pro economic audit — cost breakdown + narrative
See it live

The demo is the proof.

Load the demo packet. Watch Gemini extract it. Hit Execute Review. Watch 55+ economic events appear in real time. See the total cost land under $0.01. Then look at the margin panel and ask whether any other payment rail could do this.

P402 Meter · Arc Hackathon 2026Arc × Circle × Gemini