aspire

# .NET Aspire

## Trigger On

- `Aspire.AppHost.Sdk`, `Aspire.Hosting.*`, `DistributedApplication.CreateBuilder`, `WithReference`, `WaitFor`, `AddProject`, `AddRedis`, `AddPostgres`, `aspire run`, `aspire init`, `aspire add`, or `aspire update`
- `Aspire.Hosting.Testing`, `DistributedApplicationTestingBuilder`, or a test harness that mixes an Aspire AppHost with `WebApplicationFactory`
- orchestrating multiple services and resources with an AppHost for local development or cloud deployment
- setting up `ServiceDefaults`, service discovery, OpenTelemetry, health checks, or the Aspire Dashboard
- choosing between official first-party Aspire integrations and `CommunityToolkit/Aspire`
- upgrading older 8.x or 9.x Aspire solutions to the current CLI and AppHost SDK model
- wiring polyglot services into an Aspire topology, especially when Go, Java, Python, or extra dev-time tools enter the picture

## Workflow

1. Classify the task first: new AppHost creation, existing-solution enlistment, integration wiring, testing and observability, deployment, or version upgrade.
2. Prefer the current Aspire toolchain. For greenfield or modernized work, use the Aspire CLI and current AppHost SDK instead of writing new guidance around the deprecated legacy workload.
3. Treat 13.3.x releases as servicing and feature updates for the current CLI-first app model, not a topology rewrite. Keep the Aspire CLI, `Aspire.AppHost.Sdk`, and closely coupled hosting or testing packages on the same line, then rerun the AppHost and deployment checks after `aspire update`.
4. Keep the AppHost code-first and topology-focused. Model services, resources, dependencies, endpoints, lifetimes, and parameters there; keep business logic out.
5. Keep `ServiceDefaults` narrow. It exists for telemetry, health checks, resilience, and service discovery, not shared domain models or general utility code.
6. Prefer official first-party Aspire integrations when they cover the requirement. Use `CommunityToolkit/Aspire` only when the capability gap is real: unsupported language hosts, extra dev infrastructure, or extension packages the official project does not provide.
7. Validate the whole distributed system, not one project in isolation. Local success means the AppHost starts cleanly, dependencies resolve through `WithReference`, the dashboard shows the expected resource graph, and end-to-end tests can exercise the topology.
8. For integration tests, keep one shared AppHost fixture per test session. Use `Aspire.Hosting.Testing` to boot the distributed app, create `HttpClient` or SignalR clients from the AppHost, and layer `WebApplicationFactory` on top only when tests need direct Host DI, grains, or runtime services.
9. When publishing, switch from local containers or emulators to managed resources deliberately and verify which services truly need external endpoints.

## Architecture

```mermaid
flowchart LR
  A["Distributed-app task"] --> B{"Need code-first orchestration?"}
  B -->|No| C["Stay in service-level skills such as ASP.NET Core, Worker, or Orleans"]
  B -->|Yes| D["Create or update the AppHost"]
  D --> E["Model resources and services with `WithReference` and `WaitFor`"]
  E --> F{"Official Aspire integration exists?"}
  F -->|Yes| G["Use first-party Aspire integration"]
  F -->|No or gap remains| H["Evaluate `CommunityToolkit/Aspire`"]
  G --> I["Apply `ServiceDefaults`, dashboard, and tests"]
  H --> I
  I --> J{"Publishing now?"}
  J -->|No| K["Run locally with `aspire run` or the AppHost project"]
  J -->|Yes| L["Choose `azd`, App Service, or the CLI deploy/publish pipeline"]
```

## Current Guidance

- AppHost shape: prefer current SDK-style AppHost projects using `Aspire.AppHost.Sdk/<version>` or a file-based AppHost when that repo intentionally uses the single-file model. Recognize both as valid current patterns.
- CLI entry points: use `aspire new` for starter projects, `aspire init` to add Aspire support to an existing solution or create a single-file AppHost, `aspire add` to add integrations or starter pieces, `aspire run` for local orchestration, `aspire start`/`aspire stop`/`aspire ps` for detached lifecycle management, `aspire describe` for live resource inspection, `aspire doctor` for environment diagnostics, `aspire secret` for user secrets, `aspire docs` for terminal documentation lookup, `aspire agent` for AI agent integration, `aspire deploy` for the current CLI deploy pipeline, `aspire restore` for AppHost and TypeScript resource refresh, and `aspire update` for version-aware upgrades. `aspire publish` still exists for explicit artifact-generation flows and remains preview-sensitive.
- Patch posture: Aspire `13.2.2` is the current baseline release in the 13.2 line. Treat it as a current CLI and AppHost refresh, not a new topology model; align package versions, rerun `aspire update`, then revalidate local orchestration and the chosen deployment path.
- App model wiring: use `WithReference(...)` for dependency and configuration flow, and `WaitFor(...)` for startup ordering. Use `WithExternalHttpEndpoints()` only when the resource truly needs an externally reachable endpoint for the chosen runtime or publish target.
- ServiceDefaults boundaries: `AddServiceDefaults()` should stay focused on OpenTelemetry, health endpoints, service discovery, `HttpClient` resilience, and related cross-cutting infrastructure.
- Testing model: prefer Aspire closed-box testing when you need to run the distributed application as a system. Use `DistributedApplicationTestingBuilder` plus a shared fixture for AppHost lifecycle, `App.CreateHttpClient(...)` for resource-bound clients, and a `WebApplicationFactory<TEntryPoint>` wrapper only when the test must resolve DI services or in-process runtime state from the hosted app. For UI flows, initialize Playwright once in the shared fixture, create a fresh browser context per test, and capture failure artifacts.
- Dashboard usage: treat the Aspire Dashboard as the development observability su