Polymarket Cross-Chain Setup

Configure cross-chain bridging and SFP outcome token minting for Polymarket-style prediction markets

Cross-chain support allows bridging and SFP outcome token minting on L2s (e.g. Base, Polygon) for Polymarket-style prediction markets. When CROSS_CHAIN_ENABLED=true, the bridge API and outcome token contract can be used by BridgeService and related APIs (see roadmap).

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1. Overview

Component	Role
CROSS_CHAIN_ENABLED	Master switch for cross-chain bridge and outcome token features
POLYMARKET_BRIDGE_API_URL	Bridge/relay API for cross-chain transfers
OUTCOME_TOKEN_CHAIN_ID	Chain ID where SFP outcome tokens are minted (e.g. Base 8453, Polygon 137)
SFP_OUTCOME_TOKEN_CONTRACT	ERC-1155 contract address for SFP outcome tokens on that chain

Code: CrossChainTransaction model (app/db/models.py) and migration a1c2d3e4f5b6_add_cross_chain_transactions. When implemented: BridgeService, blockchain_service.mint_outcome_token, GET /cross-chain/transactions, GET /bridge/status, POST /outcome-tokens/mint. Config: app/core/config.py.

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2. Configuration

Variable	Description	Default
CROSS_CHAIN_ENABLED	Enable cross-chain bridge and outcome token minting	false
POLYMARKET_BRIDGE_API_URL	Bridge API base URL for cross-chain transfers (Polymarket bridge or custom relay)	—
OUTCOME_TOKEN_CHAIN_ID	Chain ID for outcome tokens (e.g. Base=8453, Polygon=137)	—
SFP_OUTCOME_TOKEN_CONTRACT	ERC-1155 SFP outcome token contract on OUTCOME_TOKEN_CHAIN_ID	—

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3. CrossChainTransaction model

Column	Type	Description
user_id	FK users	Initiator
source_chain_id	int	e.g. 137 Polygon
dest_chain_id	int	e.g. 8453 Base
bridge_external_id	str, nullable	Id from bridge API
status	str	pending, submitted, completed, failed
amount	Numeric, nullable	Amount transferred
token_address	str, nullable	Token on source/dest
market_event_id	FK market_events, nullable	Optional SFP market
outcome_token_id	str, nullable	Outcome token id
dest_tx_hash	str, nullable	Tx hash on destination chain
extra_data	JSONB, nullable	Extra payload from bridge
created_at, updated_at	DateTime

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4. Chain IDs (examples)

Network	Chain ID
Ethereum mainnet	1
Polygon	137
Base	8453
Base Sepolia	84532
Polygon Amoy	80002

Set OUTCOME_TOKEN_CHAIN_ID to the chain where the SFP outcome token contract is deployed. RPC for that chain must be available (e.g. via X402_NETWORK_RPC_URL when that is the active network, or a dedicated RPC if the app supports it).

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5. Bridge API

POLYMARKET_BRIDGE_API_URL should point to an API that supports at least:

• Status: GET {base}/bridge/status/{bridge_id} — BridgeService.get_bridge_status(bridge_id) calls this. Returns JSON with at least status (and optionally dest_tx_hash, bridge_id, etc.).
• Submit: POST {base}/bridge/submit — BridgeService.submit_bridge(...) sends JSON: source_chain_id, dest_chain_id, amount, token_address, sender_address, and optionally market_event_id, outcome_token_id, receiver_address, extra. The API should return e.g. { "bridge_id": "...", "status": "submitted" }.

Exact request/response shapes depend on the Polymarket bridge or your custom relay. BridgeService (app/services/bridge_service.py) implements the above; adapt the service or base URL path if your relay uses different conventions.

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6. SFP Outcome Token (ERC-1155)

SFPOutcomeToken.sol (contracts/contracts/SFPOutcomeToken.sol) is an ERC-1155 with mint(to, outcomeTokenId, amount, data) and mintBatch (owner-only). Deploy it on OUTCOME_TOKEN_CHAIN_ID and set SFP_OUTCOME_TOKEN_CONTRACT.

blockchain_service.mint_outcome_token(recipient_address, outcome_token_id, amount, data) calls mint; it requires CROSS_CHAIN_ENABLED, SFP_OUTCOME_TOKEN_CONTRACT, and BLOCKCHAIN_DEPLOYER_PRIVATE_KEY (or deployer from BLOCKCHAIN_AUTO_DEPLOY). The Web3 RPC is X402_NETWORK_RPC_URL—use the node for OUTCOME_TOKEN_CHAIN_ID when minting.

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7. Example .env

CROSS_CHAIN_ENABLED=true
POLYMARKET_BRIDGE_API_URL=https://bridge.example.com
OUTCOME_TOKEN_CHAIN_ID=8453
SFP_OUTCOME_TOKEN_CONTRACT=0x...

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8. Related

• Polymarket (SFP markets): POLYMARKET_ENABLED, POLYMARKET_API_URL, POLYMARKET_GAMMA_API_URL, etc. — for internal SFP prediction markets and optional Gamma/CLOB. See dev/POLYMARKET_CONFIGURATION_GUIDE.md or .env.example if present.
• Polymarket Surveillance: Polymarket Surveillance Signals — POLYMARKET_DATA_API_URL, POLYMARKET_SURVEILLANCE_ENABLED.
• Blockchain / RPC: X402_NETWORK_RPC_URL, BLOCKCHAIN_DEPLOYER_PRIVATE_KEY — used for on-chain calls including outcome token minting when wired.