Glossary

The stable domain language for BYOS. Every term below is defined here and nowhere else — implementation repos use this vocabulary in issues, ADRs, tests, metric names, and code, and their own CONTEXT.md files define only what is local to them.

If a concept you need is not here, that is a signal. Either you are inventing language the project does not use, or there is a real gap worth flagging.

Source RFP: Bring Your Own Solver (BYOS) · accepted grant application. CoW protocol background: fee collection, slashing policy, auctions, CIPs.

What BYOS is

A bonded CoW solver whose proposed solutions are sourced from a permissionless set of external sub-solvers. Sub-solvers submit signed routing proposals against specific order UIDs, collateralized by an escrow balance held by BYOS. BYOS retains exclusive control over on-chain settlement submission. From the protocol's perspective BYOS is a single, ordinary bonded solver — the sub-solver relationship is entirely internal to BYOS.

v1 targets Ethereum mainnet + Gnosis. Out of scope: a BYOS-operated orderbook, reward pass-through to sub-solvers, cross-chain escrow accounting, and BYOS's own bonding capital.

Two risk classes

The core economic framing. Everything about escrow, penalties, and gatekeeping follows from this split.

	Track A — gas + revert penalty	Track B — EBBO / fairness slash
Determined by	On-chain fact (tx reverted)	Off-chain CIP-52 certificate + DAO
Timing	Seconds to about one accounting week	Days, up to 3 months
Attributable cleanly?	Yes (tx to proposal)	Murky; BYOS chose to settle it
Recoverable from escrow?	Yes	Only if funds are still present; otherwise BYOS eats it
Primary defense	Escrow debit	BYOS pre-settlement gatekeeping

Terms

• Sub-solver — an external, permissionless party that computes a route for a specific order and submits a signed proposal to BYOS. Never holds submission keys; never calls settle. Identified by its address, recovered from its EIP-712 signature; that same address is its escrow key and its Trampoline CREATE2 salt. It is sub_solver, never plain solver — in CoW's vocabulary solver means BYOS itself.

• Proposal — an EIP-712-signed message authorizing BYOS to attempt a settlement of a specific route, and consenting to the associated escrow risk. Immutable: amounts, interactions, expiry, nonce, and signature form one signed unit, so there is no update operation. One proposal commits to exactly one order. Field-level definition is in the design document; the wire shape is in byos-service's crates/byos/openapi.yml.

• Trampoline — the contract that receives a route's sellAmount, executes the sub-solver's interactions as itself, sweeps both trade tokens back to GPv2Settlement, and enforces buyAmount as a floor. Confines sub-solver code to a fund-less context so it cannot reach settlement buffers or plant an exploitable approval. One immutable instance per sub-solver, at a deterministic CREATE2 address, deployed at escrow-deposit time. See the design document.

• Escrow — a per-chain, native-token ERC20 contract holding sub-solver collateral keyed by sub-solver address. Tokens are minted 1:1 with deposited ETH and burned on withdrawal or debit; balanceOf is the single source of truth. The collateral at risk is the only sub-solver capital BYOS ever touches — trade capital flows atomically through GPv2Settlement into the Trampoline and back. See the design document.

• Owner — the secure wallet (multisig or Safe) that owns the Escrow. Receives debited funds, sets the operator, grants and revokes submitters, configures the cooldown. Ownership transfer is two-step.

• Operator — an EOA held by the BYOS service for automated operations: debit, freeze, unfreeze, pause, unpause. Cannot withdraw funds or change configuration. A compromised operator can grief but not steal.

• Submitter — an EOA the BYOS service submits settlements from. Holds the Escrow's SUBMITTER_ROLE; Trampoline.execute requires tx.origin to be one. Covers both the allow-listed solver EOA and the auxiliary accounts of CoW's Solver7702Delegate parallel path, since there the auxiliary account is tx.origin. Rotation is a role change by the Owner, not a redeploy.

• Cooldown — the waiting period between requesting and executing an escrow withdrawal. Withdrawal is all-or-nothing: requesting drops effective balance to zero immediately, so a sub-solver is offline for new proposals for the duration.

• Pause — an operator-triggered global emergency brake blocking all ERC20 transfers and withdrawal executions. Deposits, debits, withdrawal requests and cancellations, and debit sweeps stay operational. The first response to detected malicious transfer activity; should be short-lived, minutes rather than hours.

• Freeze — the operator blocking withdrawal execution and ERC20 transfers, in both directions, for one sub-solver address while a Track B investigation is open. Does not affect effective balance. Deposits to a frozen address are allowed.

• Debit (Track A) — routine, provable recovery of gas + c_l from escrow when a winning settlement carrying a proposal reverts on-chain, misses its deadline, or is abandoned after winning. See the design document.

• Slash / clawback (Track B) — rare passthrough of a CoW EBBO or fairness penalty (CIP-52) to the responsible sub-solver's escrow, mirroring the process CoW runs against BYOS. The service tracks a 5× off-chain reserve against pending claims. See the design document.

• Attribution — mapping a settlement transaction back to the sub-solver whose proposal it contained. Enforced by settling one sub-solver per settlement transaction; the per-sub-solver Trampoline CREATE2 address in the calldata self-evidences which sub-solver's route ran.

• Gatekeeping — BYOS's preventive control: validating each proposal (simulation, hook presence, EBBO baseline price) before settling. Distinct from escrow, which is recovery. Best-effort and non-exculpatory — passing gatekeeping does not absolve a sub-solver.

• Gas cut — what BYOS keeps back to cover submitting a settlement: exactly the estimated gas cost, in the order's sell token, on every solution it bids. Kept rather than reimbursed. Always on, no rate to configure. Say "gas cut", not "fee": the order's signed feeAmount is a different field and is zero on every live order, CoW's protocol fee and network fee are applied by the driver rather than by BYOS, and the percentage-of-sellAmount "BYOS fee" of early drafts never shipped. See the design document.

• c_l — CoW's per-auction lower reward cap, which is the maximum revert penalty: 0.010 ETH on mainnet, 10 xDAI on Gnosis. A BYOS debit per reverted auction is bounded by gas + c_l. See reference/cow-solver-slashing-policy.

• Residue — a retired category. Until 2026-07-22, route output above the signed floor and unconsumed sell tokens stranded in the Trampoline instance and were reclaimable by the sub-solver. execute now sweeps both trade tokens to GPv2Settlement, so that value is BYOS-owned settlement slippage. The term survives only in superseded ADR revisions. See the design document.