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Use the built-in source-generated validation for synchronous, attribute-expressible rules in ASP.NET Core 11; reach for FluentValidation when you need async rules, complex cross-field logic, or validation kept out of your domain models.

The Cursor SDK already persists agent state to disk so Agent.resume() can pick a conversation back up after a crash. This walks the SqliteLocalAgentStore default, the JsonlLocalAgentStore you can commit to git, and how to implement the LocalAgentStore interface for Postgres, Redis, or an in-memory CI store.

EF Core 11 Preview 5 ships the EF1004 analyzer. It flags ToAsyncEnumerable() on an IQueryable so you do not accidentally enumerate a database query synchronously inside an await foreach.

Pass local.customTools to a Cursor SDK agent and the model calls your in-process functions through the built-in custom-user-tools MCP server. No stdio handshake, no separate process, no transport bugs. Local agents only: cloud agents throw ConfigurationError.

This crash means a WidgetRef was used after its widget left the tree, usually in an async callback. Read what you need before the await, then guard with a mounted check.

This crash means you called context.of() after the widget left the tree, usually in an async callback or dispose(). Capture the value before the await, or in didChangeDependencies().

Default to HybridCache for new caching code in .NET 11. Reach for IMemoryCache only when you need raw single-server speed with no serialization, and IDistributedCache only as a backing store. Here is the decision matrix.

.NET 11 Preview 5 adds a first-class X25519DiffieHellman type to System.Security.Cryptography, so you can do Curve25519 key exchange without BouncyCastle or NSec.

The inner AuthenticationException tells you the real cause: an untrusted chain, a name mismatch, or a TLS version gap. Trust the cert, fix the host name, or align protocols. Do not blanket-disable validation.

Use Quartz.NET when an LLM job must run on a real cron and never overlap itself, Hangfire when each run must survive a restart and retry on rate limits, and a plain BackgroundService only for a loose in-process loop. A decision matrix with the cron and concurrency gotchas that pick for you.