smartcontractkit · ejacquier · Apr 7, 2026 · Apr 24, 2026 · Apr 27, 2026
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+kind: starter-template
+id: prediction-market-data-streams-ts
+projectDir: .
+title: "Prediction Market (Data Streams)"
+description: "Full prediction market lifecycle: create, resolve, and dispute binary markets using Chainlink Data Streams."
+language: typescript
+category: workflow
+capabilities:
+  - cron
+  - log-trigger
+  - chain-read
+  - chain-write
+  - http
+tags:
+  - prediction-market
+  - data-streams
+  - defi
+workflows:
+  - dir: market-creation
+  - dir: market-resolution
+  - dir: market-dispute
+postInit: |
+  A demo PredictionMarket contract is pre-deployed on Sepolia. See README.md for details.
+  This template uses Chainlink Data Streams (off-chain) instead of Data Feeds (on-chain).
+  You will need Data Streams API credentials — see README.md.
+  Run `cd market-creation && bun install && cd ..` for each workflow, then simulate.
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+*.env
+.cre_build_tmp.js
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+# Prediction Market Template (Data Streams)
+
+A CRE starter template implementing a full prediction market lifecycle with three workflows: **Market Creation**, **Market Resolution**, and **Dispute Management**. All three workflows share a single `PredictionMarket` smart contract. Price resolution uses **Chainlink Data Streams** — an off-chain, low-latency price feed accessed via the Data Streams REST API.
+
+> **Data Feeds vs Data Streams:** This template fetches prices from the [Data Streams REST API](https://docs.chain.link/data-streams) using HMAC-authenticated HTTP requests. For the on-chain Data Feeds variant, see the sibling `prediction-market-ts` template.
+
+**⚠️ DISCLAIMER**
+
+This template is an educational example to demonstrate how to interact with Chainlink systems, products, and services. It is provided **"AS IS"** and **"AS AVAILABLE"** without warranties of any kind, has **not** been audited, and may omit checks or error handling for clarity. **Do not use this code in production** without performing your own audits and applying best practices. Neither Chainlink Labs, the Chainlink Foundation, nor Chainlink node operators are responsible for unintended outputs generated due to errors in code.
+
+---
+
+## Architecture
+
+```
+┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
+│  1. CREATION     │────>│  2. RESOLUTION   │────>│  3. DISPUTE      │
+│                  │     │                  │     │                  │
+│  Cron trigger    │     │  Cron trigger    │     │  LogTrigger      │
+│  Creates new     │     │  Checks expired  │     │  (DisputeRaised) │
+│  markets         │     │  markets, calls  │     │  Calls Data      │
+│                  │     │  Data Streams    │     │  Streams API,    │
+│                  │     │  API, resolves   │     │  resolves dispute│
+└─────────────────┘     └─────────────────┘     └─────────────────┘
+        │                        │                        │
+        └────────────────────────┼────────────────────────┘
+                                 │
+                    ┌────────────▼────────────┐
+                    │   PredictionMarket.sol   │
+                    │   (shared contract)      │
+                    │                          │
+                    │  - createMarket()        │
+                    │  - resolveMarket()       │
+                    │  - resolveDispute()      │
+                    │  - raiseDispute()        │
+                    └────────────┬────────────┘
+                                 │
+                    ┌────────────▼────────────┐
+                    │  Chainlink Data Streams  │
+                    │  REST API (off-chain)    │
+                    │  HMAC-SHA256 auth        │
+                    └─────────────────────────┘
+```
+
+## Project Structure
+
+```
+prediction-market-data-streams-ts/
+├── .cre/template.yaml          # Template metadata
+├── project.yaml                # CRE project settings (RPCs)
+├── secrets.yaml                # Secrets for Data Streams API credentials
+├── .env                        # Private key + API credentials (local)
+├── README.md
+├── contracts/                  # Shared contracts and bindings
+│   ├── package.json
+│   ├── abi/                    # Human-readable ABI (viem parseAbi)
+│   └── evm/
+│       ├── src/                # Solidity source + ABI JSON
+│       │   ├── PredictionMarket.sol
+│       │   ├── ReceiverTemplate.sol
+│       │   ├── IReceiver.sol
+│       │   ├── IERC165.sol
+│       │   └── abi/            # Compiled ABI JSON files
+│       └── ts/generated/       # Generated TypeScript bindings
+├── data-streams/               # Shared Data Streams API client
+│   └── client.ts               # HMAC auth, report decoding, price fetch
+├── market-creation/            # Workflow 1: Create markets
+│   ├── main.ts
+│   ├── workflow.ts
+│   ├── workflow.test.ts
+│   ├── workflow.yaml
+│   ├── config.staging.json
+│   └── config.production.json
+├── market-resolution/          # Workflow 2: Resolve expired markets
+│   ├── main.ts
+│   ├── workflow.ts
+│   ├── workflow.test.ts
+│   ├── workflow.yaml
+│   ├── config.staging.json
+│   └── config.production.json
+└── market-dispute/             # Workflow 3: Handle disputes
+    ├── main.ts
+    ├── workflow.ts
+    ├── workflow.test.ts
+    ├── workflow.yaml
+    ├── config.staging.json
+    └── config.production.json
+```
+
+---
+
+## Quick Start
+
+### Prerequisites
+
+- [Bun](https://bun.sh/) (v1.2.21+)
+- [CRE CLI](https://docs.chain.link/cre/getting-started)
+- Chainlink Data Streams API credentials ([request access](https://chain.link/data-streams))
+
+### 1. Set Up API Credentials
+
+Edit `.env` with your Data Streams credentials:
+
+```bash
+CRE_ETH_PRIVATE_KEY=<your-private-key>
+DATA_STREAMS_API_KEY=<your-api-key>
+DATA_STREAMS_API_SECRET=<your-api-secret>
+```
+
+### 2. Install Dependencies
+
+```bash
+cd market-creation && bun install && cd ..
+cd market-resolution && bun install && cd ..
+cd market-dispute && bun install && cd ..
+```
+
+### 3. Run Tests
+
+```bash
+cd market-creation && bun test && cd ..
+cd market-resolution && bun test && cd ..
+cd market-dispute && bun test && cd ..
+```
+
+### 4. Simulate
+
+```bash
+# Create a market
+cre workflow simulate market-creation --target staging-settings
+
+# Resolve expired markets (requires Data Streams API credentials)
+cre workflow simulate market-resolution --target staging-settings
+
+# Handle a dispute (triggered by on-chain DisputeRaised event)
+cre workflow simulate market-dispute --target staging-settings
+```
+
+### 5. Broadcast (Sepolia Testnet)
+
+```bash
+cre workflow broadcast market-creation --target staging-settings
+cre workflow broadcast market-resolution --target staging-settings
+cre workflow broadcast market-dispute --target staging-settings
+```
+
+---
+
+## Workflows
+
+### 1. Market Creation (Cron Trigger)
+
+Creates a new binary prediction market every hour. The market asks: "Will BTC be above $100,000 by {date}?"
+
+**Config** (`market-creation/config.staging.json`):
+- `schedule`: Cron expression (default: hourly)
+- `evms[].predictionMarketAddress`: Deployed PredictionMarket contract
+- `marketDefaults.question`: Market question template; `{expirationDate}` is replaced at creation
+- `marketDefaults.strikePriceUsd`: Price threshold in USD
+- `marketDefaults.durationSeconds`: Market duration (default: 24h)
+
+**How it works:**
+1. Reads `getNextMarketId()` from the contract
+2. Computes strike price in 8 decimal places
+3. Encodes a `CREATE` action and writes it on-chain via CRE report
+
+### 2. Market Resolution (Cron Trigger + Data Streams)
+
+Checks markets every 10 minutes. For each resolvable market, fetches the latest BTC/USD price from Chainlink Data Streams and resolves the market.
+
+**Config** (`market-resolution/config.staging.json`):
+- `schedule`: Cron expression (default: every 10 min)
+- `dataStreams.apiUrl`: Data Streams REST API base URL
+- `dataStreams.feedId`: The Data Streams feed ID (BTC/USD)
+- `marketIdsToCheck`: Array of market IDs to monitor
+
+**How it works:**
+1. Calls `isResolvable(marketId)` on the contract
+2. Fetches the latest report from the Data Streams REST API with HMAC authentication
+3. Decodes the v3 (Crypto Advanced) report to extract the benchmark `price`
+4. Converts from 18 decimal places (Data Streams) to 8 decimal places (on-chain)
+5. Encodes a `RESOLVE` action and writes it on-chain via CRE report
+
+### 3. Dispute Management (Log Trigger + Data Streams)
+
+Listens for `DisputeRaised` events. When triggered, fetches a fresh price from Data Streams and re-resolves the market.
+
+**Config** (`market-dispute/config.staging.json`):
+- `dataStreams.apiUrl`: Data Streams REST API base URL
+- `dataStreams.feedId`: The Data Streams feed ID (BTC/USD)
+
+**How it works:**
+1. Decodes `DisputeRaised` event (marketId, disputor, reason)
+2. Verifies the market is in `Disputed` status
+3. Fetches a fresh price from Data Streams
+4. Encodes a `RESOLVE_DISPUTE` action and writes it on-chain
+
+---
+
+## Data Streams Integration
+
+### Authentication
+
+The Data Streams REST API requires HMAC-SHA256 authentication. Three headers are sent with every request:
+
+| Header | Description |
+|--------|-------------|
+| `Authorization` | Your API key (UUID) |
+| `X-Authorization-Timestamp` | Current timestamp in milliseconds |
+| `X-Authorization-Signature-SHA256` | HMAC-SHA256 signature of the request |
+
+The HMAC signature is computed over: `METHOD PATH BODY_HASH API_KEY TIMESTAMP`
+
+See [`data-streams/client.ts`](./data-streams/client.ts) for the full implementation.
+
+### Report Schema (v3 — Crypto Advanced)
+
+Data Streams returns a `fullReport` blob that is ABI-decoded in two steps:
+
+1. **Outer wrapper**: `(bytes32[3] reportContext, bytes reportData, bytes32[] rawRs, bytes32[] rawSs, bytes32 rawVs)`
+2. **Report body (v3)**: `(bytes32 feedId, uint32 validFromTimestamp, uint32 observationsTimestamp, uint192 nativeFee, uint192 linkFee, uint32 expiresAt, int192 price, int192 bid, int192 ask)`
+
+The `price` field uses **18 decimal places** for crypto feeds. This template converts to 8 decimals to match the on-chain PredictionMarket contract's strike price format.
+
+### Feed IDs
+
+| Feed | Testnet Feed ID | Network |
+|------|----------------|---------|
+| BTC/USD | `0x00027bbaff688c906a3e20a34fe951715d1018d262a5b66e38edd64e0fdd0d00` | Sepolia |
+
+Find more feed IDs at [docs.chain.link/data-streams](https://docs.chain.link/data-streams).
+
+### API Endpoints
+
+| Environment | Base URL |
+|------------|----------|
+| Testnet | `https://api.testnet-dataengine.chain.link` |
+| Mainnet | `https://api.dataengine.chain.link` |
+
+---
+
+## Smart Contract
+
+The template uses the same `PredictionMarket.sol` contract as the Data Feeds variant. The contract is agnostic to the price source — it receives prices via CRE reports regardless of whether the workflow reads them from on-chain Data Feeds or the off-chain Data Streams API.
+
+### Pre-deployed Contract (Sepolia)
+
+| Component | Address |
+|-----------|---------|
+| PredictionMarket | `0xEb792aF46AB2c2f1389A774AB806423DB43aA425` |
+| MockKeystoneForwarder | `0x15fc6ae953e024d975e77382eeec56a9101f9f88` |
+
+### Constructor Arguments
+
+| Argument | Value (Sepolia) | Description |
+|----------|----------------|-------------|
+| `forwarder` | `0x15fc6ae953e024d975e77382eeec56a9101f9f88` | MockKeystoneForwarder |
+| `_priceFeed` | `0x1b44F3514812d835EB1BDB0acB33d3fA3351Ee43` | BTC/USD feed (stored for reference) |
+| `_disputeWindow` | `86400` | 24-hour dispute window |
+
+---
+
+## Differences from Data Feeds Template
+
+| Aspect | Data Feeds (`prediction-market-ts`) | Data Streams (this template) |
+|--------|-------------------------------------|------------------------------|
+| Price source | On-chain `PriceFeedAggregator` contract | Off-chain Data Streams REST API |
+| Price read | `priceFeed.latestAnswer(runtime)` | HTTP GET + HMAC auth + ABI decode |
+| Decimals | 8 (native) | 18 → converted to 8 |
+| Latency | Block-finality dependent | Sub-second updates |
+| Auth | None (public on-chain read) | HMAC-SHA256 with API key/secret |
+| Capabilities | `chain-read`, `chain-write`, `cron`, `log-trigger` | + `http` |
+| Secrets | None | `DATA_STREAMS_API_KEY`, `DATA_STREAMS_API_SECRET` |
+
+---
+
+## Customization
+
+### Different asset
+Change `dataStreams.feedId` in the config files and update the market question and strike price accordingly.
+
+### Different duration
+Adjust `marketDefaults.durationSeconds` in market-creation config.
+
+### Different resolution frequency
+Modify the `schedule` cron expression in market-resolution config.
+
+### Different dispute window
+Redeploy the contract with a different `_disputeWindow` constructor argument.
+
+---
+
+## Security Notes
+
+- **Forwarder Validation**: The contract validates that only the trusted Chainlink Forwarder can call `onReport()`
+- **HMAC Authentication**: Data Streams API access is secured with HMAC-SHA256 signatures
+- **Secrets Management**: API credentials are stored as CRE secrets, never hardcoded in workflow code
+- **Consensus**: CRE nodes reach consensus on the HTTP response before writing on-chain
+- **Dispute Window**: Prevents disputes after `expirationTime + disputeWindow`
+
+## Known Limitations
+
+- **Spot-price resolution**: Markets resolve using the latest price at resolution time (not historical high/low)
+- **Single feed**: All markets use the same BTC/USD feed
+- **No betting**: This contract does not implement token deposits or payouts
+- **API access required**: Data Streams requires approved API credentials
+
+---
+
+## Alternative Patterns
+
+- **On-chain Data Feeds**: Use the sibling `prediction-market-ts` template for simpler zero-setup price resolution
+- **HTTP trigger**: Replace the Cron trigger with an HTTP trigger for on-demand market creation/resolution
+- **WebSocket**: For real-time price monitoring, Data Streams also offers a WebSocket API
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+import { parseAbi } from "viem"
+
+export const PredictionMarketAbi = parseAbi([
+  "function getMarket(uint256 marketId) view returns ((uint256 marketId, string question, uint256 strikePrice, uint256 expirationTime, uint256 disputeDeadline, uint8 status, uint8 outcome, int256 resolutionPrice, uint256 resolvedAt))",
+  "function getMarketStatus(uint256 marketId) view returns (uint8)",
+  "function getNextMarketId() view returns (uint256)",
+  "function isExpired(uint256 marketId) view returns (bool)",
+  "function isResolvable(uint256 marketId) view returns (bool)",
+  "function priceFeed() view returns (address)",
+  "function disputeWindow() view returns (uint256)",
+  "event MarketCreated(uint256 indexed marketId, string question, uint256 strikePrice, uint256 expirationTime, uint256 disputeDeadline)",
+  "event MarketResolved(uint256 indexed marketId, uint8 outcome, int256 resolutionPrice, uint256 resolvedAt)",
+  "event DisputeRaised(uint256 indexed marketId, address indexed disputor, string reason)",
+  "event DisputeResolved(uint256 indexed marketId, uint8 outcome, int256 newPrice, bool overturned)",
+])
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+export { PredictionMarketAbi } from "./PredictionMarket"
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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.4.0) (utils/introspection/IERC165.sol)
+
+pragma solidity >=0.4.16;
+
+/**
+ * @dev Interface of the ERC-165 standard, as defined in the
+ * https://eips.ethereum.org/EIPS/eip-165[ERC].
+ *
+ * Implementers can declare support of contract interfaces, which can then be
+ * queried by others ({ERC165Checker}).
+ *
+ * For an implementation, see {ERC165}.
+ */
+interface IERC165 {
+  /**
+   * @dev Returns true if this contract implements the interface defined by
+   * `interfaceId`. See the corresponding
+   * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[ERC section]
+   * to learn more about how these ids are created.
+   *
+   * This function call must use less than 30 000 gas.
+   */
+  function supportsInterface(
+    bytes4 interfaceId
+  ) external view returns (bool);
+}
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		export { PredictionMarketAbi } from "./PredictionMarket"