Host it your way
Put the weights in Hedera contract bytecode, keep them off-chain on IPFS or HTTPS with their SHA-256 on-chain, or serve the model from any OpenAI-compatible endpoint (vLLM, Ollama, hosted LLMs).
Submission · Hedera Scaffold-HBAR Template Bounty (opens in a new tab)Hedera On-Chain AI Service (HOCA)
Sell inference from your own AI model on Hedera, and let anyone check every output.
HOCA is a Scaffold-HBAR template by ColdAI. Bring your own model and host it on Hedera, off-chain or behind your own endpoint; take HBAR at a USD price or any HTS token; sell public or private sessions, delivered by the buyer or by your provider worker with escrow and refunds. Ivy Ink 1, deployed on Hedera, is the worked example.
Start your own in one command
npm create scaffold-hbar@latest -- --template shayansal/scaffold-hbar-onchain-aiSee the example project: Medusa Poets at coldai.org/poets, 500 poets writing with Ivy Ink 1. The model itself is deployed on Hedera: testnet 0.0.10765083 (opens in a new tab) and mainnet 0.0.10893786 (opens in a new tab).
- 3
- model hosting modes
- 3
- USD oracle sources
- Any
- HTS token as payment
- 2
- privacy modes
- 59
- Foundry tests
- +2
- fork tests on live testnet
- 54
- app tests (Vitest)
- 39
- worker tests
01How it works
Configure your own AI market
Pick how your model is hosted, how buyers pay, whether sessions are private, who delivers the answer and how long it can be. The diagram, the flow and the settings follow. The Ivy Ink 1 / Medusa Poets example is just the first preset.
Build
Bring your own model
Train → quantize → export → EQTY manifest
Host
Your model on Hedera
Integer weights stored as contract bytecode
Anyone replays it through the mirror node
Set up
HTS NFT collection (optional revenue share)
Holders earn a share of every payment
Set up
HCS provenance topic + EQTY manifest
Manifest CID and weight hashes anchored
Buy
Buyer
Pays with HBAR at a USD price or an HTS token
Sends the prompt in the clear
Pay
HTS tokens
INK, USDC or any token at a fixed price
Price
Oracles
Chainlink + Supra (+ optional Pyth)
Median with a deviation guard
Sell
InferenceMarket
Ticket with a PRNG seed (0x169)
Pricing, revenue split, pause switch
Run
Buyer runs it
Browser runtime or free mirror-node calls
Publish
Anthology (public)
Output text stored; ticket redeemed once
Inline in one transaction
Verify
Mirror node (verify)
Anyone replays the seed for free
Weights checked against the EQTY manifest
Your model lives in Hedera contract bytecode. Buyers pay in HBAR priced in USD by the oracle median or an HTS token at a fixed price; the buyer runs it with the ticket's seed; the answer is published to the Anthology for anyone to re-check.
config
# packages/foundry: yarn foundry:deploy --network hedera_testnet withMODEL_HOSTING=hedera# IVY_MODEL=0x0…0 deploys your own model contractsORACLES=chainlink,supra PRICE_USD_MICROS=10000# add pyth + PYTH_API_KEY for a third source # then accept a token (the HTS association runs on Hedera)yarn foundry:accept-token --token 0.0.x --price <smallest units> # owner switches at any timesetPaused(true)# stops new sales; refunds and deliveries still work02Features
Customise every part, keep every guarantee
Bring your own model
The model/ pipeline trains, quantizes and exports a model and signs its lineage with EQTY. Swap in your own model; the market, payments and provenance stay the same.
Pay in any token
HBAR or any HTS token through its ERC-20 facade, each at its own price. The market associates itself with each token via the HTS system contract 0x167; the UI lists whatever it accepts.
Your oracle mix
Price HBAR in US dollars from Chainlink and Supra, plus Pyth if you want it. Every feed must be fresh and within a 2% band, and the market uses the median, so one bad feed cannot misprice a sale.
Public or private
Private sessions seal inputs and outputs with X25519 + AES-256-GCM to the buyer and the model creator. The seed mixes the PRNG with the buyer's secret: still unbiased, known only to them. The creator decrypts for their own use.
Inputs and outputs of any length
Payloads bigger than one transaction travel as chunked events. The contract completes them only when the byte count and a rolling keccak hash both match.
Provider-served, with escrow
The provider worker fulfils paid tickets and publishes the answer. Payment waits in escrow until delivery, and the buyer is refunded if nothing arrives in the delivery window. The worker ships with 39 tests.
Pause and key rotation
The owner can pause sales while paid tickets can still be delivered or refunded, and the provider can rotate its encryption key, all without redeploying the market.
Unbiased seeds
Each ticket's seed comes from Hedera's PRNG (0x169, HIP-351). Buyers cannot pick a seed, and each ticket is redeemed once, so every published output is one paid draw.
Optional revenue share
Tie each model variant to an HTS NFT and its holder earns a share of every payment. Anyone withdraws their own balance, including from an ECDSA alias via HIP-632.
EQTY provenance on HCS
A signed EQTY manifest covers corpus, code, checkpoint and weights. Its CID is anchored on an HCS topic, and the app re-hashes what is deployed against it.
Tested, with CI and a scaffold gate
CI runs lint, Foundry, Vitest, the build and EQTY verification. A daily job scaffolds a new project from the latest CLI, the same way the bounty gate does. A Hedera Harness (opens in a new tab) recipe lets coding agents extend it safely.
The worked example: Ivy Ink 1
The template ships with Ivy Ink 1, a 235k-parameter poetry model deployed on Hedera: its int8 weights are the bytecode of 12 data contracts, and a GRU in Solidity reads them with EXTCODECOPY. Python, Solidity and TypeScript are bit-exact, so the browser, the contract and the reference all write the same poem.
- weights in bytecode
- bit-exact in Python, Solidity, TypeScript
- 1.85M gas per character
- 7 characters per free mirror call
03Hedera technology
Ten Hedera services, each doing real work
| Service | Where | What it does here |
|---|---|---|
| Smart Contracts (EVM) | IvyInk1, 12 data contracts, InferenceMarket, Anthology | The model itself runs in the EVM: an int8 GRU with SWAR matrix-vector products and lookup-table activations |
| HTS, non-fungible | Poets collection | The poet serial is the model's conditioning record; holders earn a revenue share (ownerOf through the ERC-721 facade) |
| HTS, fungible | INK demo token, USDC or any token | Payment through the ERC-20 facade; the market associates itself through the HTS system contract 0x167 |
| Consensus Service (HCS) | Provenance topic | Anchors the EQTY manifest CID, the weights' SHA-256 and each chunk's SHA-256 |
| PRNG system contract (HIP-351) | 0x169 | An unbiased seed for every ticket |
| Account service (HIP-632) | 0x16a | Maps an ECDSA EVM alias to the long-zero account HTS reports as the NFT owner |
| Mirror Node | App, verifier, provider worker | Free model execution (/contracts/call), weight bytecode, Anthology logs, HCS messages |
| JSON-RPC relay (Hashio) | Wallets, Foundry | Deploys, fork tests and every wallet transaction |
| Hiero SDK | Setup and provider scripts | Creates the Poets NFT, the INK token and the provenance topic, and anchors the manifest |
| Sourcify verification | yarn foundry:verify:testnet | Verified source, shown on HashScan |
04Integrations
Built with the ecosystem
Every integration carries weight: remove one and a guarantee goes with it.
Hedera (opens in a new tab)
The networkContracts, tokens, topics, randomness and the mirror node. Load-bearing: with Hedera hosting, the model, payment, seeds and provenance all live on-chain, so nothing else needs to be trusted.
Chainlink (opens in a new tab)
HBAR/USD push feedThe default USD price source, with no keys to manage. Load-bearing: half of the cross-check. If Chainlink and Supra disagree by more than the band, the market stops selling rather than guess.
Supra (opens in a new tab)
HBAR/USDT push oracle, pair 75A second, independent source. Load-bearing: with Chainlink it forms the deviation guard, and the deviation bound also caps how far USDT can drift from USD.
Pyth (opens in a new tab)
Optional HBAR/USD pull feedA third source for the median. Load-bearing: Hermes needs an API key since 2026-08-26, so the app fetches signed updates server-side with PYTH_API_KEY and never exposes it; the market pays the update fee from the transaction.
EQTY Lab (opens in a new tab)
Integrity Manifest (eqty_sdk)Signed, content-addressed lineage from training corpus to quantized weights. Load-bearing: the export runs inside a recorded EQTY computation, and the manifest's hashes are checked against the bytecode deployed on Hedera.
IPFS (opens in a new tab)
Off-chain weight hostingWhere the weights live when the model is not hosted on Hedera. Load-bearing: the market stores the blob's SHA-256, so the app refuses any file that does not match, while payment, seeds and provenance stay on Hedera.
05Live on testnet
Check it yourself on HashScan
The template's app talks to this deployment by default. Every contract, token, topic and transaction is in EVIDENCE.md (opens in a new tab).
| Contract | Hedera ID | EVM address | Deploy |
|---|---|---|---|
| InferenceMarket Pricing, tickets with PRNG seeds, escrow and refunds, revenue | 0.0.10780285 (opens in a new tab) | 0x9E0337…7d5779 | 0x7f198ec3… (opens in a new tab) |
| Anthology One published output per ticket | 0.0.10780288 (opens in a new tab) | 0xdaEc96…27ad5e | 0x724c4620… (opens in a new tab) |
| ChainlinkHbarUsd adapter HBAR/USD push feed | 0.0.10780292 (opens in a new tab) | 0x4F1D6f…0aBc38 | 0x407d4319… (opens in a new tab) |
| SupraHbarUsd adapter HBAR/USDT push feed, pair 75 | 0.0.10780294 (opens in a new tab) | 0x264720…bB10fb | 0x8f90ed0a… (opens in a new tab) |
| IvyInk1 (the model) Public deployment, reused by every market | 0.0.10765083 (opens in a new tab) | 0x93CA12…C6993f | reused |
| Weight contracts (12) The model's int8 weights as bytecode | 0.0.10765038 (opens in a new tab) to 0.0.10765080 (opens in a new tab), poet registry 0.0.10765081 (opens in a new tab) | ||
| Native resource | ID |
|---|---|
| Poets NFT collection HTS non-fungible, 5 example poets | 0.0.10778530 (opens in a new tab) |
| INK payment token HTS fungible, 2 decimals | 0.0.10778532 (opens in a new tab) |
| Provenance topic HCS, EQTY manifest anchor (message #3) | 0.0.10778533 (opens in a new tab) |
| Oracle | Address |
|---|---|
| Chainlink HBAR/USD | 0x59bC15…c92B4a (opens in a new tab) |
| Supra push oracle (pair 75) | 0x6Cd598…6Fb917 (opens in a new tab) |
| Pyth (optional) | 0xA2aa50…5B5729 (opens in a new tab) |
| Owner | 0.0.5215457 (opens in a new tab) |
06Why it fits the bounty
Against the judging criteria
Ecosystem integration
- Chainlink and Supra cross-checked, Pyth optional, all behind one adapter interface.
- EQTY Lab lineage anchored on HCS; IPFS for off-chain hosting.
- An example project: Medusa Poets at coldai.org/poets, 500 poets writing with Ivy Ink 1, the model deployed on Hedera.
Documentation
- README (opens in a new tab): quick start, deploy steps, every setting, private inference, limits.
- AGENTS.md (opens in a new tab) for coding agents: mental model, file map, Hedera rules that bite, recipes.
- EVIDENCE.md (opens in a new tab) with every testnet contract and transaction, and these docs.
Code quality
- 59 Foundry tests, plus 2 fork tests against the live testnet oracles and the deployed model.
- 54 app tests (Vitest) and 39 provider-worker tests; the model is bit-exact across Python, Solidity and TypeScript.
- CI with lint, types and build, plus a daily fresh-scaffold gate.
Hedera service depth
- EVM, HTS (NFT and fungible), HCS, PRNG, the HIP-632 alias service and the mirror node, each doing real work.
- Hiero SDK for native setup, Hashio for the relay, Sourcify for verification.
- Handles Hedera specifics: tinybar units, HTS association, long-zero addresses, the 15M gas cap.
07What's next
Soon powering SFAI
HOCA will power verifiable, private AI inference on SFAI, the ColdAI intelligence exchange, and on its NATDAQ indexes: paid on Hedera, sealed to buyer and provider, and checkable by anyone.
Run your own model on Hedera with HOCA
Scaffold it, start the app against the live testnet deployment, and write a free poem in minutes.
npm create scaffold-hbar@latest -- --template shayansal/scaffold-hbar-onchain-aiMIT licenceBuilt by ColdAISource on GitHub (opens in a new tab)DocumentationExample project: Medusa PoetsThe bounty (opens in a new tab)Hedera (opens in a new tab)