Coming from Omen

Audience: teams that already run AI agents trading on Omen and want those same agents to trade on Seer. Goal: explain what changes between the two, with links to the contract code, and describe each Seer market type, so a team can estimate the porting effort. Code links are pinned to commits so the line numbers stay valid:

Seer contracts: seer-pm/demo/contracts/src, pinned at 209c674.
Omen contracts:
- gnosis/conditional-tokens-market-makers (the FPMM)
- gnosis/conditional-tokens-contracts
- RealityETH/reality-eth-monorepo
- The Omen oracle adapter, verified source on Blockscout.

1. TL;DR

Same foundations. Both run on Gnosis Conditional Tokens (CTF) plus Reality.eth. On Gnosis Chain they even share the same CTF contract. The oracle flow, bonds, arbitration and the CTF split/merge/redeem concepts all carry over.
No market maker contract. Omen markets are FPMM contracts: you call buy and sell on the market. Seer markets instead mint one ERC20 per outcome, and those tokens trade on external AMM pools (Swapr/Algebra and Uniswap). Your trade execution, price reading and bet sizing therefore have to be rewritten.
Invalid is a real token, and it wins alone. On Omen an invalid answer pays every outcome equally. On Seer only the SER-INVALID token pays; every other outcome goes to 0.
More market types. Seer adds multi-categorical, scalar, multi-scalar and conditional markets. Each has its own payout rule, so an agent that only outputs p_yes isn’t enough.
Multi-chain. Seer is deployed on Gnosis, Ethereum, Optimism and Base. Omen was deployed on Ethereum mainnet and Gnosis Chain (xDai). Supporting Gnosis first is fine.

2. Concept mapping

Concept	Omen	Seer
Market	One `FixedProductMarketMaker` per market. It is the AMM and also the LP token.	A `Market` clone that only stores metadata. It has no trading logic.
Factory	`FPMMDeterministicFactory.create2FixedProductMarketMaker`	`MarketFactory`. It has one `create*` function per market type.
Outcome tokens	CTF ERC1155 positions, held by the FPMM and by users	CTF ERC1155 positions wrapped as ERC20s through Wrapped1155Factory (`deployERC20Positions`). The last token is always `SER-INVALID`.
Where trades happen	The FPMM itself: `buy` and `sell`	Outcome/collateral pools on Swapr (Algebra) on Gnosis, or Uniswap V3/V4 on other chains. The Lens quoter or `@seer-pm/sdk` picks a route (trading guide).
Fees	FPMM `fee`, set per market and paid to LPs (usually 2%)	No protocol fee. You pay the pool fee of whichever AMM you trade on.
Liquidity	One pool per market (`addFunding` / `removeFunding`)	One pool per outcome token, on the DEX itself. Liquidity can be very uneven across outcomes. Anyone who wants to provide liquidity does it directly on the DEX.
Oracle	Reality.eth v2.1 plus the Omen `RealitioProxy.resolve`. It handles single-select templates (0 and 2) and a nuanced-binary template.	Reality.eth v3.0 plus `RealityProxy.resolve`. It handles templates 1, 2 and 3. Anyone can trigger it with `Market.resolve()`.
Invalid answer	Every outcome pays `1/n` (`getSingleSelectPayouts`)	Only `SER-INVALID` pays (categorical)
Collateral	Any ERC20, chosen per market (wxDAI, sDAI, GNO…)	One collateral per factory: sDAI on Gnosis and Ethereum, sUSDS on Base and Optimism. For conditional markets, the collateral is the parent market’s outcome token.
Split, merge, redeem	Call CTF directly: `splitPosition`, `mergePositions`, `redeemPositions`	Go through the Seer routers, which also wrap and unwrap the ERC20s. `Router` is generic. `GnosisRouter` converts xDAI↔sDAI and `MainnetRouter` converts DAI↔sDAI. `ConditionalRouter` handles child markets.
Market data	Omen subgraph (`fixedProductMarketMakers`, `fpmmTrades`) and the CTF subgraph	The Seer HTTP API (`markets-search`, `get-market`, `get-portfolio`, …), plus the on-chain `MarketView.getMarket`
Chains	Ethereum mainnet and Gnosis Chain (xDai) (omen-exchange README)	Gnosis, Ethereum, Optimism, Base (addresses)

3. The agent loop, step by step

Step	What the agent does on Omen	What the agent does on Seer
1. Discover markets	Query `fixedProductMarketMakers` on the Omen subgraph and filter on open, liquidity > 0, binary.	Use `markets-search` from the Seer API to list and filter markets by type, status and liquidity. Use `get-market` for a single market, with its outcome odds, liquidity and parent or child markets. On-chain, `MarketView.getMarket` returns the core market data in one call (`MarketInfo`).
2. Read prices and probabilities	FPMM balances give `p_i ∝ ∏_{j≠i} balance_j`. `calcBuyAmount` gives exact quotes.	Each outcome token has its own pool price in collateral. `SER-INVALID` usually has no liquidity, so its value is implied: `1 − Σ (prices of the other outcomes)`. This works because a full set of outcome tokens always redeems for exactly 1 collateral. For exact amounts, quote the pool through Lens or the Swapr quoter.
3. Buy	Call `FPMM.buy(investment, outcomeIndex, minTokens)`.	Swap collateral for the outcome ERC20 on the AMM, after approving the DEX router. Alternative: `splitPosition` to mint the full set, then sell the outcomes you don’t want.
4. Sell	Call `FPMM.sell(returnAmount, outcomeIndex, maxTokens)`.	Swap the outcome ERC20 back to collateral. Alternative: buy the complementary outcomes, then `mergePositions`.
5. Size bets	Use closed-form FPMM math with a known fee and a single pool.	Omen closed-form sizing doesn’t transfer. Price impact comes from each outcome’s own concentrated-liquidity pool, so size bets from quotes. Some outcomes may have little or no liquidity.
6. Track positions	CTF subgraph user positions and `fpmmParticipations`.	Read the ERC20 `balanceOf` of each wrapped outcome token, or use the API’s `get-portfolio` and `get-transactions`.
7. Resolution	Once Reality finalizes, someone calls `RealitioProxy.resolve(...)`.	Once Reality finalizes, anyone calls `Market.resolve()`. `RealityProxy` computes type-specific payouts (see §4).
8. Redeem	`CTF.redeemPositions(...)`, then unwrap the collateral.	`GnosisRouter.redeemToBase` pays out xDAI, or use `Router.redeemPositions` for other collaterals. Either way you approve the router for each outcome token first. For child markets, `ConditionalRouter.redeemConditionalToCollateral` redeems all the way to base collateral, provided the parent is a root market.

4. Seer market types

Seer supports the six market types below. Omen only has the first one, and even that one resolves differently on Seer (the Invalid rule above). How payouts work. Payouts are computed in RealityProxy.sol. CTF then normalizes each payout vector by its sum, so a winning token redeems for payout_i / Σ payouts units of collateral.

Type	How it’s created	Outcome tokens	How it pays out
Binary, i.e. categorical Yes/No. The closest to Omen.	`createCategoricalMarket`, with outcomes `[Yes, No]` and Reality template 2	`Yes`, `No`, `SER-INVALID`	The winning outcome gets 1. An invalid answer pays only Invalid (L73-89).
Categorical	Same function as binary, with N outcomes	N outcomes plus Invalid	Exactly one winner, same rule as binary
Multi-categorical	`createMultiCategoricalMarket`, Reality template 3 (multi-select)	N outcomes plus Invalid	The answer is a bitmask, so several outcomes can win. Each winner gets `1/k`, where k is the number of winners. All zeros, or an invalid answer, pays Invalid (L95-121).
Scalar	`createScalarMarket`, Reality template 1 (uint), with `lowerBound` and `upperBound`	`DOWN`, `UP`, `SER-INVALID`	Partial payouts: inside the range, DOWN redeems for `(high−x)/(high−low)` and UP for `(x−low)/(high−low)`. Outside it, one side gets everything (`[1,0]` / `[0,1]`). (L128-150)
Multi-scalar	`createMultiScalarMarket`. It asks one Reality question per outcome (L213-219).	N outcomes plus Invalid	Each outcome’s payout is its raw numeric answer, so token i redeems for `x_i / Σ x_j`. Invalid pays only if every answer is 0 or invalid (L157-190).
Conditional (child). It can be of any type above.	Any `create*` function with `parentMarket` and `parentOutcome` set (`CreateMarketParams`)	Same as the base type, but the collateral is the parent’s outcome token	Same as the base type. If the parent resolves to a different outcome, the whole branch is worth 0.

Futarchy markets (FutarchyFactory) are not covered in this guide. Suggested rollout order, from least to most new work compared with Omen:

Binary and categorical
Conditional
Scalar
Multi-categorical
Multi-scalar

5. Work items for the porting team

The sizes (S/M/L) are rough and assume the team already has a working Omen agent.

#	Item	Size	Notes
1	Trade execution through AMM swaps instead of FPMM `buy` and `sell`	M	Approvals, slippage, routing (Swapr or Uniswap), gas.
2	Pricing and quotes from pools; normalizing probabilities across outcomes	M	Handle pools that don’t exist or are too thin, and derive the implied Invalid price (1 minus the other prices).
3	Market discovery through the Seer API	S	Filter by market type, status, liquidity and parent market.
4	Bet sizing without closed-form FPMM math	M	Size bets from pool quotes, or use fixed-size bets.
5	Forecast outputs for each market type (prompts and output schemas)	M–L	Categorical distributions, independent multi-select probabilities, numeric forecasts for scalar and multi-scalar, conditional framing. This is the largest change on the “AI” side.
6	Position tracking through ERC20 balances or the API	S
7	Resolve and redeem through the Seer routers, including child markets	S–M	Call `Market.resolve()` if nobody has yet, then `redeemToBase` or `ConditionalRouter`.
8	Collateral handling: sDAI (xDAI↔sDAI through `GnosisRouter`), plus parent-token minting for child markets	S
9	Reopened Reality questions (“answered too soon”)	S	Seer resolves with `resultForOnceSettled`, which follows the reopened question. `MarketView.getQuestionId` returns the current question id.
10	Optional: other chains (Ethereum, Optimism, Base)	M	Different collateral and routers (`MainnetRouter` / `Router`), plus Uniswap pools.

6. Pitfalls when coming from Omen

Holding Yes and No is not a hedge against Invalid. Only SER-INVALID pays on an invalid answer. Invalid results are rare but do happen. For example, Romania’s 2024 presidential election was annulled after the first round and rerun in May 2025 with a different set of candidates. The Seer market on the run-off (Georgescu vs Lasconi) resolved to Invalid: both candidate tokens paid 0 and only SER-INVALID paid out.
Multi-categorical outcomes aren’t mutually exclusive. A token can win and still redeem for less than 1, because the payout is shared among all k winners.
Scalar and multi-scalar payouts are fractions, not 0 or 1. Bet-sizing formulas that assume a 0-or-1 payout don’t apply.
Each outcome is a separate pool, so one outcome can be liquid while another has no pool at all. Check every token you plan to trade.
Prices across outcomes can drift apart. Split and merge arbitrage keeps the full set near 1 collateral, but only loosely, so the implied Invalid price can be noisy or even negative.
Conditional markets need the parent’s outcome token as collateral. A child market’s price is a conditional probability, not a joint one.

7. Prior art

prediction-market-agent-tooling runs a single agent pipeline on both Omen and Seer (Gnosis only). It is a useful reference for:

The Omen trading functions: omen_buy_outcome_tx_no_retry and omen_sell_outcome_tx.
Their Seer counterpart, which swaps on Swapr pools: SwapPoolHandler.buy_or_sell_outcome_token.
Reading pool prices: PriceManager.
Minting parent tokens for conditional markets: mint_full_set.

Its Seer support covers binary, categorical, scalar and conditional markets for trading. Its resolution handling is categorical-only and doesn’t cover Invalid, multi-categorical or multi-scalar.

8. References

Seer contracts: https://github.com/seer-pm/demo/tree/main/contracts/src. Addresses per chain are at /developers/contracts/deployed-contracts.
Seer developer docs:
Omen:
- FPMM: https://github.com/gnosis/conditional-tokens-market-makers
- Conditional Tokens: https://github.com/gnosis/conditional-tokens-contracts
- Reality.eth: https://github.com/RealityETH/reality-eth-monorepo
- Omen subgraph: https://github.com/protofire/omen-subgraph
- Frontend: https://github.com/protofire/omen-exchange

Gnosis Chain addresses:

Contract	Omen	Seer
Factory	FPMMDeterministicFactory `0x9083A2B699c0a4AD06F63580BDE2635d26a3eeF0`	MarketFactory `0x83183DA839Ce8228E31Ae41222EaD9EDBb5cDcf1`
Oracle adapter	`0xAB16D643bA051C11962DA645f74632d3130c81E2`	RealityProxy `0xc260ADfAC11f97c001dC143d2a4F45b98e0f2D6C`
Router	None	GnosisRouter `0xeC9048b59b3467415b1a38F63416407eA0c70fB8`
Market reader	None	MarketView `0x95493F3e3F151eD9ee9338a4Fc1f49c00890F59C`
Conditional Tokens	`0xCeAfDD6bc0bEF976fdCd1112955828E00543c0Ce`	The same contract as Omen
Reality.eth	v2.1 `0x79e32aE03fb27B07C89c0c568F80287C01ca2E57`	v3.0 `0xE78996A233895bE74a66F451f1019cA9734205cc`
Collateral	Chosen per market	sDAI `0xaf204776c7245bF4147c2612BF6e5972Ee483701`

Getting started

Guides

HTTP API

Diagrams

Subgraph

Contracts

Coming from Omen

1. TL;DR

2. Concept mapping

3. The agent loop, step by step

4. Seer market types

5. Work items for the porting team

6. Pitfalls when coming from Omen

7. Prior art

8. References

​1. TL;DR

​2. Concept mapping

​3. The agent loop, step by step

​4. Seer market types

​5. Work items for the porting team

​6. Pitfalls when coming from Omen

​7. Prior art

​8. References

1. TL;DR

2. Concept mapping

3. The agent loop, step by step

4. Seer market types

5. Work items for the porting team

6. Pitfalls when coming from Omen

7. Prior art

8. References