Introduction

Redstart is a multi-file language for authoring The Graph subgraphs.

A subgraph today is three loosely-coupled artifacts — schema.graphql, subgraph.yaml, and AssemblyScript mappings — stitched together by stringly-typed names and a manual graph codegen step. Drift between them is the dominant source of “it compiled but failed at runtime, three hours into a sync.”

Redstart unifies all three into one language, split across as many .red modules as you like (mod/use, just like Rust). It type-checks them against each other and transpiles to readable AssemblyScript that the canonical graph build toolchain compiles unmodified.

abi ERC20 from "./abis/ERC20.json"

entity Account {
  id: Id<Bytes>
  balance: BigInt
  label: Option<String>          // nullability is always explicit — there is no `null`
}

source Token {
  abi: ERC20
  network: mainnet
  address: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
  startBlock: 6082465
}

handler on Token.Transfer(event) {
  let receiver = Account.loadOrCreate(event.params.to, { balance: BigInt.zero })
  receiver.balance = receiver.balance + event.params.value
  // auto-saved at handler end — forgetting `.save()` can't happen
}

redstart build turns that into schema.graphql + subgraph.yaml + mappings.ts. The event signature in the manifest is derived from the ABI by reference — rename the event and it’s a compile error, not a runtime one.

Try it now — the playground runs the real compiler in your browser: write .red, watch the generated AssemblyScript, schema, and manifest update as you type.

Why a language?

The killer feature is unification, not syntax. A single source of truth makes manifest/schema/handler drift impossible. The whole class of AssemblyScript footguns — nullable-arithmetic miscompiles, ==/=== inversion, reverted-call aborts, array prefill, forgotten .save() — becomes unrepresentable by construction.

The eject path (see How it works) means abandoning Redstart costs nothing but the generated code, which keeps working. Redstart does not make indexing faster; it makes staying on The Graph’s decentralized network pleasant. It is scoped as a Graph-Foundation-grant public good in the lineage of Matchstick, not a venture bet.