Add serve-hedera-contract-as-graphql snippet — bridge Hedera into The Graph tooling

[mrarejimmyz]

Summary

• Adds serve-hedera-contract-as-graphql/ — self-contained snippet that exposes any Hedera contract as a standardized-subgraph GraphQL endpoint via Mirror Node
• ~200 LOC total; runs with npm install && node index.mjs
• Ships an ERC-4626 preset — any vault emitting Deposited(address indexed, uint256, uint256) + Withdrawn(...) gets the full Messari-standardized query surface (pools, transactions, _meta) for free

Why

The Graph doesn't index Hedera. I verified this against the official networks registry: 129 EVM chains supported, Hedera not among them (as of 2026-09-07). Any Hedera dApp that wants "subgraph playground for our users", "AI agent that queries our contract state", or just "GraphQL instead of REST" ends up hand-rolling a Mirror Node client.

Meanwhile Hedera Mirror Node already indexes every contract event on Hedera for free with sub-second consensus. All the raw material is there — nothing turns it into subgraph-shaped GraphQL. This snippet is the missing glue.

Result: all Graph-native tooling — subgraph MCP servers, playgrounds, GraphiQL, subgraph explorers — works over Hedera contracts unchanged.

What ships

• index.mjs — Express server exposing POST /graphql + GET /graphql/sdl
• adapter.mjs — self-contained bundled adapter (Mirror Node client + GraphQL executor + ERC-4626 preset)
• README.md — 60-second quickstart + "same query, both backends" demo
• package.json — only express + graphql peer deps
• .env.example — HEDERA_NETWORK, VAULT_ADDRESS, PORT

Default VAULT_ADDRESS points at a live public testnet vault so the snippet runs out-of-the-box with real data — no faucet or contract deploy needed.

Verified working

$ npm install && node index.mjs
hedera-graphql-adapter live on http://localhost:4000
  vault: 0xe7E6fEDce9d72D112137B631E8D51831D30729A9

$ curl -sX POST http://localhost:4000/graphql -H 'content-type: application/json' \
    -d '{"query":"{ pools { id network totalNav memberCount } transactions(first: 2) { type actor amount } _meta { block { number } deployment } }"}'
{"data":{
  "pools":[{"id":"0xe7e6…29a9","network":"hedera-testnet","totalNav":"987363187","memberCount":3}],
  "transactions":[{"type":"DEPOSIT","actor":"0xe615…8a38","amount":"70000000"},...],
  "_meta":{"block":{"number":40208181},"deployment":"hedera-mirror-adapter:0xe7e6fed…"}
}}

Same query works against a Studio-hosted subgraph on any of the 129 supported EVM chains — one schema, N backends. That's the "one query pattern spans many protocols" pattern extended to include Hedera.

Extended library

The snippet bundles the adapter inline to stay self-contained per repo convention. The upstream package with more presets, TypeScript types, and optional HCS-attestation add-ons for AI-agent trust chains lives at:

• Package: @zkward/hedera-graphql-adapter
• Reference deployment: https://www.zkward.com/api/subgraph/hedera
• Related MCP server: mcp/zkward-vaults — Claude Desktop / Cursor tool that queries this shape across multiple backends

Test plan

• npm install succeeds on fresh clone
• node index.mjs starts server on :4000
• POST /graphql returns real vault state from Mirror Node
• GET /graphql/sdl returns the standardized schema
• Bit-identical shape vs Studio subgraph (parity verified against https://api.studio.thegraph.com/query/1758819/zkward/v0.1.1)
• No external services required — fully self-contained

Related

• Companion Hedera-Harness contribution: feat(validation): Tier 2.5 Mirror Node validator hedera-harness#43

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