What a solver does for a swap order

A solver builds a proposed execution that satisfies users' signed trading constraints. It can search pools, compare dealer quotes, match compatible orders and combine those ingredients into a settlement. A solver's job is broader than simply relaying a message.

What the solver contributes

Imagine several hypothetical orders in one opportunity set. One user sells A for B, another sells B for A, and a third wants C. A solver can test direct matching, external routes and combined plans. The chosen proposal must fit the protocol's constraints and available liquidity.

CoW's solver documentation describes independent participants constructing settlement solutions. Its current auction documentation explains a competition involving individual and batched bids. The generic term solver does not imply one universal auction design.

Search and enforcement remain separate

The solver proposes a path, but the settlement system verifies the applicable signed conditions. In CoW's documented architecture, users grant token permission to protocol contracts rather than directly granting arbitrary token access to each solver.

That separation is useful: the entity choosing execution need not receive unlimited discretion over the user's assets. The precise guarantees still depend on the actual contracts and authorization mechanism.

A solver is not automatically the liquidity owner

Some fulfillment can use the solver's own inventory; other fulfillment can consume external AMMs or market-maker offers. Owning inventory and computing a route are different functions that one participant may combine.

Competition rules also determine how proposals are selected and rewarded. A protocol may evaluate surplus, feasibility and additional constraints rather than simply choosing whichever response arrives first. Avoid generalizing a single protocol's scoring rule to all intent systems.

For users, the relevant result is a valid settled outcome. For evaluating the system, separate three questions: what execution alternatives solvers can access, how the competition selects proposals, and what the settlement contracts enforce.

Competition can contain routing

A routing algorithm searches execution paths for a specified objective. A solver competition compares fulfillment proposals under auction rules. These layers can nest: each solver may run its own router, query aggregators or combine routing with internal order matching. Selecting a winning proposal therefore does not eliminate the route-search problem; it creates a market in which participants solve it in different ways.