This is the adaptive counterpart of Program, with the message/command machinery removed. Changeable roots hold the state, derived projections compose it, and the runner forces the frame's projections at the end of every step. There is no 'Msg and no Cmd — handlers write roots directly. Deferred work and subscriptions have adaptive counterparts: systems post unit -> unit work through AdaptiveContext.Intents — post (after this step's Update), postNextFrame (top of the next step), or postTask/postAsync (background work whose completion returns via post) — and external events arrive through AdaptiveSub subscriptions whose callbacks post work.

Both contexts expose the intent queue: Init receives AdaptiveFrameContext and posts through its Intents member (work runs at the startup drain, before the first frame is forced), and Update receives AdaptiveContext with the same surface. The subscription projection receives AdaptiveFrameContext as well and must not post: it runs once per step. The frame builder must not post either: it runs after the post drain.

The Init/Update/Observers slots are the dependency graph (the simulation). The Config/ Renderers/ServiceRegistrations/AssetsBasePath slots are host configuration (the presentation) consumed by the windowed hosts. The headless runner consumes only the simulation slots plus FixedStep.

Example

 let program =
   AdaptiveProgram.mkProgram
     (fun ctx ->
       AdaptiveInit.ofFrameBuilder (Frame.buildFrame cell)
       |> AdaptiveInit.withDisposables [ d1; d2 ])
     (fun ctx gameTime -> Router.step world gameTime)
   |> AdaptiveProgram.withConfig cfg
   |> AdaptiveProgram.withRenderer (fun () -> Renderer2D.create view)

 AdaptiveRaylibGame(program).Run()