When this page is relevant
Use compile-time diagnostics to catch singleton-to-scoped and singleton-to-transient lifetime mismatches before stale state or thread-safety bugs ship.
Problem guide
Find Captive Dependencies In ASP.NET Core
This page is for teams searching for captive dependency detection in ASP.NET Core, worker services, and generic-host apps.
Recommended install command
dotnet add package DependencyInjection.Lifetime.Analyzers --version 3.7.8Relevant diagnostics
The rules that cover this failure mode
DI003
Captive Dependency
Singleton services capturing scoped or transient dependencies, including constructor injection, `IEnumerable<T>` collection captures, known scoped framework services such as `IOptionsSnapshot<T>`, typed HTTP clients registered with `AddHttpClient<TClient>()` / `AddHttpClient<TClient,TImplementation>()`, EF Core contexts and `DbContextOptions<TContext>` registrations from `AddDbContext(...)`, `AddDbContextFactory(...)`, `AddDbContextPool(...)`, and `AddPooledDbContextFactory(...)` including service/implementation overload self-registrations, and high-confidence factory paths such as inline delegates, stable local delegate factories, method-group factories, `GetServices<T>()`, keyed resolutions, and `ActivatorUtilities.CreateInstance(...)` calls where DI still resolves a scoped or transient constructor parameter. A factory that creates and provably disposes its own scope (`using var scope = sp.CreateScope();`) stays quiet for resolutions through that scope when only derived values flow into the product — one-time scoped setup is not a captive — while an escaping resolved instance or an undisposed factory scope still reports.
DI009
Open Generic Captive Dependency
Open generic singleton registrations that depend on shorter-lived services, including common registration-shape variants such as `TryAddSingleton(...)`, `ServiceDescriptor.Singleton(...)`, keyed open-generic singleton registrations, and `IEnumerable<T>` constructor captures where the element service is shorter-lived.