PredictMarket

An autonomous, self-resolving binary prediction market on Ritual Chain. (PLC version)

Create a market like "Will ETH/USD be above $4,000 when this market resolves?", stake native RITUAL on YES or NO, and watch it settle on its own. When the betting window closes, no button press and no backend cron is needed. The Ritual Scheduler wakes the contract at a pre-determined block; the contract calls the HTTP precompile to fetch the oracle URL, extracts one number with the jq precompile, compares it to the target, and settles. Winners pull their proportional share.

---

Architecture

                createMarket()                     ????????????????????????????
  user  ???????????????????????????????????????????  PredictMarket.sol        ?
  user  ???????????? bet(id, YES|NO) ??????????????                           ?
                                                  ?  markets, stakes, claims  ?
                                    schedule() ????                           ?
                                                  ????????????????????????????
   ???????????????????????????????                      ?             ?
   ? Scheduler  0x56e7?D58B      ?  onScheduledResolve  ?             ? deposit()
   ? system contract             ????????????????????????             ?
   ? fires at resolveBlock,      ?                        ??????????????????????????
   ? 3 attempts, 200 blocks apart?                        ? RitualWallet 0x532F?   ?
   ???????????????????????????????                        ? prepaid execution fees ?
                                                          ??????????????????????????
                       inside that one scheduled transaction:

  TEEServiceRegistry 0x9644?  ??pickServiceByCapability(HTTP_CALL)???  executor address
  HTTP precompile    0x0801   ??GET oracleUrl (in a TEE)?????????????  oracle endpoint
  jq  precompile     0x0803   ??jsonPath, outputType=uint256??????????  observed value
                                         ?
                                         ?
                       observed ? target  ?  Settled(YES|NO)
                       failed 3?          ?  Refunded (everyone reclaims stake)

---

Design highlights

Block-number deadlines only. Human durations (in seconds) are converted to blocks at deployment using the measured blockTimeMs. Nothing reads block.timestamp.

Typed failure codes. Every resolution attempt records an AttemptCode enum value (NoExecutor, HttpFailure, BadStatus, OracleError, BadValue) alongside a string detail, making failures indexable and auditable without parsing free-form strings.

Separate claim paths. Winners call claimWinnings; losers from failed markets call claimRefund. The cancelled or refunded status covers both exhausted-retries and creator-initiated cancellation.

Paginated market reads. getMarkets(offset, limit) returns a bounded page, suitable for frontends and scripts that need discovery without an unpaginated full scan.

A failed oracle read is never a NO. HTTP errors, non-2xx responses, malformed envelopes, executor error messages, and unparseable jq output are all recorded as failures, not outcomes.

---

Prerequisites

• Node.js 20+ and pnpm
• A wallet with testnet RITUAL from https://faucet.ritualfoundation.org

Setup

cd hardhat
pnpm install
cp .env.example .env

---

Commands

npx hardhat test                                # local safety checks (no chain needed)
npx hardhat build                               # compile

npx hardhat run scripts/block-time.ts           # measure live block time
npx hardhat run scripts/deploy.ts               # deploy to Ritual Chain
PREDICT_ADDRESS=0x... npx hardhat run scripts/status.ts
PREDICT_ADDRESS=0x... npx hardhat run scripts/fund.ts

---

Error Encountered and Solution

1. decodeHttpResponse External Call Context with try/catch

During the contract compilation and test suite integration, Solidity threw a compiler error when invoking the response decoder:

TypeError: Try-catch statements are only allowed for external function calls and contract creation calls.

Cause: In PredictMarket.sol, _readOracle was originally trying to call decodeHttpResponse(response) directly as an internal helper inside a try ... catch block. Solidity strictly requires try/catch targets to be external calls (this.decodeHttpResponse(...)) so that ABI-decoding reverts can be safely intercepted at the EVM call boundary without rolling back the parent resolution transaction.

Solution:

1. Declared decodeHttpResponse as external pure.
2. Invoked it via this.decodeHttpResponse(response) in _readOracle.
3. Validated that malformed payloads or unfinalized simulation outputs are caught cleanly as AttemptCode.BadValue rather than reverting the Scheduler's scheduled callback.

2. TypeScript Extensions in Hardhat Scripts

When executing Hardhat helper scripts (deploy.ts, status.ts), TypeScript reported:

TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.

Solution: Updated hardhat/tsconfig.json to enable "allowImportingTsExtensions": true, allowing seamless ESM .ts imports for shared utilities like ./ritual.ts across all deployment and query scripts.

---

Reference

• Ritual Chain docs ? https://docs.ritualfoundation.org
• dApp skills ? https://github.com/ritual-foundation/ritual-dapp-skills
• Explorer ? https://explorer.ritualfoundation.org ? Faucet ? https://faucet.ritualfoundation.org