Contexts, stores, and scenarios

Context modules

Export class Context from routes/_.context.ts or a nested _.context.ts. Routes use the nearest context as $.context. Constructors receive helpers; import the generated Context$ type from the corresponding types/_.context.js file.

Store module

Export class Store from <basePath>/_.store.ts. Counterfact creates one store per simulator and supplies it to contexts across API groups. Routes, middleware, and scenarios access shared behavior through contexts; their $ argument has no direct store member.

The store survives hot reload and stop/start on the same simulator. reset() reconstructs it. See shared store for supported reload behavior.

Scenario modules

Export named functions from files under scenarios/. A scenario receives context, loadContext, route, and routes on its $ argument. An exported startup function in scenarios/index.ts runs during startup and reset, once per group. Named scenarios transform current state; compose focused changes rather than implicitly replacing the entire world.

See scenario scripts for function selection and additional helper arguments, and simulator lifecycle for reset behavior.

Middleware

Export middleware from a route subtree’s _.middleware.ts, using its generated Middleware type. Its signature is async ($, respondTo) => response. Return an early response or call and await respondTo($) to continue through the subtree. See middleware.