Proposal — Minting an Interactive Software Artwork on Ethereum

Prepared for John Provencher

1. Artwork Contents

File	Un‑minified size	Role	Notes
`index.html` (includes inlined `<script>` tag)	≈ 44 KB (2 KB HTML + 42 KB JS)	Self‑contained interactive piece	After minification & dead‑code elimination we expect ≈ 28 – 32 KB total. Compression isn’t available on‑chain.
`image.json` (one per edition)	100-200 KB	Token‑specific parameters	Lives off‑chain (IPFS) in the hybrid design.

2. Technical Constraints

EIP‑170 size ceiling: 24 576 bytes of runtime byte‑code per contract.
- Current contract (FeralfileExhibitionV4) uses ~21 KB, leaving ~3 KB free.
Gas cost of on‑chain storage
- Direct SSTORE writes are expensive and mutable.
- SSTORE2 embeds immutable data as contract byte‑code; one‑time cost ≈ 200–300 gas/byte, reads are free.

Because the flattened HTML (~30 KB) cannot fit inside the main contract, we either:

Store it in a separate data‑contract via SSTORE2 (hybrid), or
Keep everything on IPFS (off‑chain).

3. Implementation Paths

	Hybrid (HTML on‑chain, JSON off‑chain)	All off‑chain (current)
HTML + JS	Stored in an SSTORE2 data‑contract; main contract stores a pointer.	Inside an IPFS folder.
`image.json`	IPFS; contract holds `mapping(tokenId ⇒ CID)`.	Same.
Contract changes	• New `bytes dataPtr` (address of data‑contract).• `tokenURI()` assembles metadata JSON with in‑contract HTML.	None.
Gas / cost	One‑time deployment ~0.09 ETH* for 30 KB at 10 gwei.	Minimal (CID writes).
Permanence	Executable art is fully on‑chain.	Depends on IPFS pinning.
Engineering effort	Medium (≈ 2–3 days Solidity + backend update).	None – ready today.

* Assumes 10 gwei gas and 1 ETH ≈ USD 3 000.

4. `tokenURI()` Example (Hybrid)

function tokenURI(uint256 tokenId) public view override returns (string memory) {
    // 1 – Load the single HTML+JS blob
    bytes memory html = SSTORE2.read(dataPtr); // immutable, ~30 KB

    // 2 – Fetch the edition-specific JSON CID
    string memory imgCid = _imageCid[tokenId];

    // 3 – Patch the placeholder {{IMAGE_JSON}} inside the HTML
    bytes memory patched = _replacePlaceholder(html, "{{IMAGE_JSON}}", imgCid);

    // 4 – Wrap everything in on-chain metadata
    bytes memory metadata = abi.encodePacked(
        '{"animation_url":"data:text/html;base64,',
        Base64.encode(patched),
        '","image":"ipfs://', imgCid, '"}'
    );

    return string(
        abi.encodePacked(
            "data:application/json;base64,",
            Base64.encode(metadata)
        )
    );
}

Similarity

Use this contract FeralfileArtworkV3_1.sol as a reference.

5. Artist Deliverables

Step	Deliverable	Purpose
A. 64 edition folders	Directories `0/` … `63/`, each containing:• `image.json` (token parameters)• `thumbnail.jpg` or `thumbnail.png` (≤ 1 MB recommended), `index.html` and `script.js`	Per‑token variation & preview.
B. Testing	Verify each edition renders correctly after the `{{IMAGE_JSON}}` substitution.	Ensures deterministic behaviour.

6. Recommendation

Criterion	Hybrid (HTML on‑chain)	All off‑chain (IPFS)
Launch speed	Slower – additional 2–3 days to implement, test and integrate Solidity + backend changes.	Fast – approach is already battle‑tested in previous exhibitions.
Collector appeal	Higher – code is provably on‑chain; stronger decentralization narrative.	Standard – relies on external IPFS pinning but accepted by most marketplaces.
Permanence	Guaranteed – Ethereum full nodes retain the byte‑code forever.	Requires ongoing IPFS pinning; risk if pins are lost.
Deployment cost	One‑time gas expense (~0.09 ETH for 30 KB via SSTORE2).	Negligible – only storing a few CIDs.
Maintenance	Slightly higher – must track the data‑contract address when upgrading.	Minimal – same workflow we use today.
Engineering risk	Medium – custom logic needs additional audits and QA.	Very low – contracts and backend remain unchanged.

Guidance

Choose Hybrid if the artistic concept benefits from being truly “on‑chain” and you wish to highlight decentralization to collectors. Choose All off‑chain if a quick launch is the priority and on‑chain storage is not critical.

jollyjoker992/software-artwork-minting-proposal.md