Data, State, And Services

Primary docs:

Dependency Injection Defaults

Register infrastructure and business services in Program.cs
Inject dependencies through constructors by default
Keep scoped services request-bound
Avoid resolving scoped services from singletons
Use keyed or named patterns only when there is a real need for multiple implementations

Use EF Core for common relational data access patterns unless the repository already uses another data layer.

Default guidance:

Use IDbContextFactory<TContext> when the execution model is not request-scoped, such as:

Use IHttpClientFactory for outbound HTTP calls.

Prefer:

Avoid manual new HttpClient() patterns scattered through request handlers.

Use the smallest state mechanism that fits:

query string or route values for transparent request state
form posts for user input
TempData for short-lived redirect-friendly messages
session only when necessary and with an understanding of its server-side and scaling implications

Do not treat session as the primary application data store.

Keep cached data derivable from a durable source
Separate cache shape from persistence shape when it improves safety or performance
Revisit session, in-memory cache, and singleton state when the app scales to multiple instances