prism-framework-patterns

# Prism Framework Patterns Agent implements Prism with modular composition, navigation services, dialogs, event aggregation, and container-backed view-model activation so large MVVM applications stay organized. ## When to Use | Condition | Use | |---|---| | Agent works on a large WPF or MAUI application with many modules or bounded feature areas. | Agent uses this skill. | | Agent needs region navigation, module catalogs, or late-loaded features. | Agent uses this skill. | | Agent needs centralized dialog, navigation, and event aggregation services across many screens. | Agent uses this skill. | | Agent needs a framework-level ViewModelLocator convention. | Agent uses this skill. | ## When Not to Use | Condition | Route | |---|---| | Agent needs lightweight MVVM with generated properties and commands only. | Agent uses `communitytoolkit-mvvm`. | | Agent authors a custom MVVM generator or analyzer package. | Agent uses `roslyn-mvvm-source-generators`. | | Agent works on WinUI 3 without an established Prism stack. | Agent uses `winui3-patterns` or `communitytoolkit-mvvm`. | | Agent edits one small screen with no modular composition needs. | Agent uses the matching platform MVVM skill. | ## Required Inputs | Input | Required | Notes | |---|---|---| | Platform target | Yes | Identify WPF, MAUI, or mixed solution boundaries. | | Module boundaries | Yes | Identify feature packages, shell ownership, and shared services. | | Navigation map | Yes | Identify pages, regions, routes, and dialog entry points. | | Container choice | No | Identify `Prism.DryIoc`, `Prism.Unity`, or the project default. | ## Workflow | Step | Agent Action | Test | Pass | |---|---|---|---| | 1 | Agent maps module boundaries, shell ownership, navigation routes, and dialog entry points. | Review the feature map. | Composition ownership stays explicit. | | 2 | Agent aligns startup with one Prism container path. | Build and inspect startup registration. | Package references and container setup stay coherent. | | 3 | Agent converts touched view models to Prism patterns and locator activation. | Run targeted tests or one screen pass. | View-model activation and command behavior succeed. | | 4 | Agent wires regions, modules, dialogs, and typed events for the touched scope. | Navigate one region path and one dialog path. | Composition and dialog flow behave as designed. | | 5 | Agent verifies module load order and confirmation paths. | Start the shell and leave one dirty screen. | Startup and guarded navigation stay stable. | ## Prism Pattern Matrix | Concern | Pattern | Pass | |---|---|---| | Observable state | `BindableBase` | `SetProperty` updates state and notifications once per change | | Commands | `DelegateCommand` or `DelegateCommand<T>` | Command enablement follows view-model state | | View activation | `ViewModelLocator` and registration conventions | Intended view model activates without code-behind wiring | | Region navigation | Named regions and `IRegionManager` | Region content changes without hard references between views | | Module composition | `IModule` and module catalogs | Views and services load in the intended order | | Dialogs and events | `IDialogService` and typed `PubSubEvent<T>` contracts | Interaction stays explicit, typed, and bounded | ## Module Matrix | Area | Pattern | Pass | |---|---|---| | Module registration | Register services, views, and region targets inside each `IModule`. | Each module loads without startup ordering defects. | | Region naming | Keep region names stable and explicit. | Host and target names match exactly. | | Navigation parameters | Pass compact parameters or IDs. | Target views resolve required state without singleton coupling. | | Confirmation | Wire confirmation into navigation interfaces or dialog services. | User intent stays explicit and state loss stays controlled. | ## Reference Files | File | Purpose | |---|---| | [references/framework-comparison-and-examples.md](references/framework-comparison-and-examples.md) | Package guidance, Prism-versus-CommunityToolkit comparison, examples, platform hooks, MCP hooks, pitfalls, and outputs. | ## Verification Checklist | Item | Test | Pass | |---|---|---| | One container package owns startup. | Inspect startup and package references. | `Prism.DryIoc` or `Prism.Unity` owns registration, not both. | | ViewModelLocator resolves touched views. | Open or resolve one touched view. | The intended view model activates automatically. | | Region names and targets align. | Inspect XAML hosts and navigate once. | Region navigation resolves the expected content. | | Dialog contracts stay explicit. | Trigger one dialog and inspect result handling. | Request and result data stay bounded. | | Event contracts stay typed. | Publish one event path. | Subscribers depend on `PubSubEvent<T>` contracts only. |