dotpudica-wf-scene-scope

name	dotpudica-wf-scene-scope
description	End-to-end workflow: deliver scene-isolated DI and leave-scene cancellation with SceneContextHost - mount the host, register transient services, create ViewModels from host.Scope, pass Operations tokens to async work, and verify. Use for rooms, matchmaking, or any scene with its own DI boundary and async work that must stop when the player leaves.

dotpudica-wf-scene-scope

Purpose

Take a scene-isolation requirement and deliver it end to end: a SceneContextHost mounted at the scene root, transient scene services registered in the bootstrap, ViewModels created from host.Scope.ViewModels, async work wired to the host's Operations token so leaving the scene cancels it, and verification through build and runtime. This workflow owns the end-to-end task graph; capabilities/dotpudica-di-scope owns the "how" of the host, registration, and scope creation; capabilities/dotpudica-messaging-threading owns the "how" of the cancellation wiring.

Trigger Patterns

Use this workflow when the user says:

• "Build a room / match / level scene" — a scene with its own DI boundary, where services and ViewModels belong to that scene only.
• "Cancel the request when the player leaves" / "stop the operation on exit" — async work (network calls, timers) that must stop when the scene is left.
• "Scene-level short-lived ViewModels/services" — state that must be torn down with the scene and must not leak into other scenes.

Do not use it when the data must survive across pages and scenes (route to dotpudica-wf-shared-data), or when the project has no bootstrap yet (route to dotpudica-wf-project-setup first).

Task graph

Execute the nodes in order; close each node's acceptance point before advancing.

• N1 — Clarify the scene boundary (deliverable: requirement summary; invokes no skill): which scene owns the boundary, which ViewModels and services are scene-level, and which async operations must be cancelled on leaving. Acceptance: the summary names the scene, its scene-scoped services and ViewModels, and the cancellable async work — no open questions.
• N2 — Mount the host (deliverable: host mounted; invokes capabilities/dotpudica-di-scope): attach a SceneContextHost to the scene root — in the editor or at runtime with AddChild — and put the scene's pages in its subtree. Acceptance: AppContext.Initialize completes before the host enters the tree (its _EnterTree builds the scope from AppContext.Current.Services and throws otherwise).
• N3 — Register the scene services (deliverable: registration lines; invokes capabilities/dotpudica-di-scope): services.AddTransient<T>() for the scene-level ViewModels and services in the bootstrap's configureServices. Acceptance: every scene-level type from N1 is registered as AddTransient — never AddSingleton.
• N4 — Create ViewModels through the scope (deliverable: factory method; invokes capabilities/dotpudica-di-scope): the page declares a [ViewModelFactory] that resolves the host from its parent and returns host.Scope.ViewModels.Create<T>(). Acceptance: the page sits in the host's subtree (the GetParent() as SceneContextHost cast resolves) and the factory matches the generator's expected shape.
• N5 — Wire cancellation (deliverable: cancellation wiring; invokes capabilities/dotpudica-messaging-threading): pass host.Operations.Token into the long async calls, and give each individual operation its own CreateLinkedTokenSource() so cancelling one operation does not cancel the whole scene. Acceptance: every long-running call observes a scene-lifetime token and the OperationCanceledException path does not update the UI.
• N6 — Build and runtime check (deliverable: check conclusion; invokes capabilities/dotpudica-verify): dotnet build with zero DOTPUDICA diagnostics, then launch: enter the scene, leave it with async work in flight, and re-enter. Acceptance: entering creates a new scope, leaving cancels the in-flight work, and no state bleeds across visits.

dotnet build

Acceptance criteria

The workflow is complete when all of these hold:

• dotnet build completes with zero DOTPUDICA diagnostics.
• Entering the scene creates a fresh scope each visit; entering and leaving several times leaks nothing — no accumulating duplicate ViewModels.
• Leaving the scene cancels in-flight async work; after leaving, callbacks no longer update the UI.
• No cross-scene bleed — scene A's services and ViewModels never appear in scene B.

Failure branches

Node	Symptom	Fix
N2	Getting the host throws, or the factory's host cast yields null	The page is not under a SceneContextHost subtree (or the host entered the tree before initialization) — mount the host at the scene root and put the page in its subtree.
N4	DOTPUDICA041	The [ViewModelFactory] method is static, has parameters, returns void, or does not return the declared ViewModel type or a derived type — fix the method signature.
N6	Cross-scene bleed (scene A state shows in scene B)	A scene-level service was registered as AddSingleton by mistake — change it to AddTransient so each scene resolves fresh instances.

Any node checkpoint failure returns to capabilities/dotpudica-verify to fix; never roll back and restart the graph from N1.

References

• capabilities/dotpudica-di-scope — N2 (SceneContextHost mount and _EnterTree scope build) and N3/N4 (AddTransient registration, host.Scope.ViewModels.Create<T>(), [ViewModelFactory] contract and failure modes).
• capabilities/dotpudica-messaging-threading — N5 (SceneOperationScope: Token, CreateLinkedTokenSource, dispose-on-exit semantics).
• capabilities/dotpudica-view — related: ViewModel/View shape used by N4's factory and the page lifecycle lines.
• capabilities/dotpudica-verify — N6 (build command, diagnostic loop, runtime checklist).
• dotpudica-route — related: entry point that routes to this workflow; consult it for the next task on this project.