Building a Base Runtime

Clock, logging, random, GUID, and environment-variable access are explicit services. FsFlow.Services.Core provides a BaseRuntime record that groups the standard services most hosts need:

type BaseRuntime =
    { Clock: IClock
      Log: ILog
      Random: IRandom
      Guid: IGuid
      EnvironmentVariables: IEnvironmentVariables }

BaseRuntime implements IHas<'service> for each service, so helpers such as Clock.now and EnvironmentVariable.get work against it directly.

Live Runtime

Use BaseRuntime.liveValue when you already want a concrete value:

let result =
    (Clock.now).RunSynchronously(BaseRuntime.liveValue)

Use BaseRuntime.live when composing with layers:

let runnable =
    workflow
    |> Flow.provide BaseRuntime.live

Provider-Backed Runtime

Use BaseRuntime.fromServiceProvider when a .NET host container owns the service implementations and you want typed startup validation.

let runnable =
    workflow
    |> Flow.provide BaseRuntime.fromServiceProvider

The provider must contain IClock, ILog, IRandom, IGuid, and IEnvironmentVariables. Missing registrations are reported as BaseRuntimeError.MissingService.

Custom Runtime

Tests can construct a deterministic base runtime directly:

let testRuntime =
    { Clock = Clock.fromValue fixedNow
      Log = Log.live
      Random = Random.fromValue 4
      Guid = Guid.fromValue fixedGuid
      EnvironmentVariables = EnvironmentVariables.fromPairs [ "MODE", "test" ] }

No override API is required. The override is just the environment value passed to the flow.