Microsoft just told you to ship it. .NET 11 RC1 landed on September 8 with a go-live support license. Their words, not mine: "you can confidently use this release for your production applications." So read this post differently to the preview posts. This is the stuff you'
Microsoft merged Semantic Kernel and AutoGen into one Agent Framework, shipped it alongside .NET 10, and then buried the good news under docs that assume you already build agent systems for a living. I read those docs so you don't have to. Then I built the thing the
Preview 5 brought the headliners: Runtime Async, unions, vector search. Preview 6 is where they grow up. If my breakdown of .NET 11 Preview 5's features that actually matter was about the ideas, this post is about those ideas taking production shape. Unions now serialize and show up
Every .NET developer has the same reflex. An API wants a Stream, you have a string or a buffer, so you allocate a MemoryStream, copy everything into it, and hand it over. We've done it for twenty years. It's such muscle memory that nobody even registers
Your agent started with a tidy 300-token system prompt. Six months later it's 9,000 tokens. Legal added the compliance rules, Support pasted in the escalation playbook, Finance dropped the entire expense policy on top. I've watched this happen on two projects now. Nobody plans it.
I've deleted more Selenium test suites than I've shipped. Fifteen years of StaleElementReferenceException, Thread.Sleep(3000) landmines all over the codebase, and CI pipelines nobody trusted. A red build meant "re-run it" long before it meant "something's broken". E2E testing
You Committed the Files. Do You Know When They Load? You've set up CLAUDE.md, copilot-instructions.md, path-scoped instructions, prompt files, maybe a custom agent or two. Quick question: which of those files is sitting in your model's context window right now, on this exact request?
Your AI Tools Are Flying Blind Without These Files Every AI coding assistant defaults to generic patterns unless you tell it otherwise. Claude Code reaches for controllers. Copilot suggests IActionResult. Cursor writes synchronous LINQ. The output compiles fine but is architecturally wrong for your project. Every. Single. Time. The fix
Traditional event sourcing asks you to solve five problems independently: concurrency control, aggregate hydration, snapshot management, event persistence, and projection delivery. Five infrastructure concerns, five failure modes, and at least three NuGet packages you'll regret choosing. Orleans already solved every one of those problems. It just solved them
Rate limiting in .NET has always been an afterthought. You either bolted on AspNetCoreRateLimit (which hasn't aged gracefully), hacked together a custom ActionFilter with a ConcurrentDictionary, or shipped without any limiting and hoped nobody would hammer your endpoints. We've all been there. .NET 10's
Your 14-team Angular monolith has a 45-minute build, a 3-hour release train, and one broken import blocks everyone. I've lived this. After running micro frontends in production with Angular 22, I can tell you the situation has genuinely changed. Micro frontends have been oversold for years. Half the
Your job scheduler is probably the oldest pattern in your codebase. Hangfire or Quartz.NET, running in production, doing its thing. It works. But every time you touch the scheduling code, you wince a little. Magic strings mapping to methods. Reflection-based serialization that blows up after a rename. XML config
.NET
EF Core 11's vector search announcement was genuinely exciting, if you're on SQL Server. But according to Stack Overflow's 2024 Developer Survey, PostgreSQL is the most-used database among professional developers at 49%. Half of us watched that announcement and thought: "Cool. Doesn'
.NET
The current AI/RAG stack for .NET developers is architecturally absurd. You've got SQL Server holding your domain data, Pinecone or Qdrant sitting in a separate cloud for vectors, a sync pipeline duct-taped between them to keep embeddings consistent, and a completely different SDK with its own query
dotnet
Microsoft finally killed the "which SDK do I use for agents?" problem. If you've been watching the AI agent space from the .NET sidelines, confused by AutoGen's Python-first research vibe, or frustrated that Semantic Kernel felt awkward for multi-agent scenarios, your wait is over.
You're 40 controllers deep, each with six or more actions, and your project structure looks like a filing cabinet from 1997. Or maybe you went all-in on Minimal APIs and your Program.cs has become a 600-line god file that nobody wants to touch. Either way, you'
.NET
.NET 11 Preview 5: The Features That Actually Matter Every November the .NET release train pulls into the station, and every November the "what's new" posts read like someone piped the changelog through a thesaurus. I've sat through fifteen of these cycles now. Most
.NET
Heads-up on versions: The official MCP C# SDK just went stable -- ModelContextProtocol 1.4.0 shipped in early June 2026, so we're past the preview churn. The code below targets the 1.x API. If you're reading this later, sanity-check the current package version against
AI
I've been using GitHub Copilot since the early preview days. Inline suggestions, Chat panel, slash commands — the whole stack inside VS Code. It's a productivity multiplier. But it has always been confined to one editor window, one context, one conversation at a time. The new GitHub
.NET
If you've shipped a multi-tenant app with EF Core, you already know what I'm about to say. You get one query filter per entity. One. Want tenant isolation AND soft deletes? Mash them into the same lambda and hope nobody ever needs to turn off just
AI
The generic entity pattern I wrote about last time is smart. But smart has a ceiling -- in high-throughput systems and AOT targets, that ceiling is lower than you think. Source generators blow past it. Where the generic pattern starts costing you To be clear: the generic entity service pattern
AI
Every project I join has the same problem. Ten entities, ten controllers, ten services, ten data access classes and all doing the exact same thing. A ProductService that's a copy-paste of CustomerService, which is a copy-paste of OrderService. Nobody questions it. It just grows. I got fed up
AI
I want Gemini in my .NET API without a dependency on whichever SDK is flavour of the month. The official Google .NET SDK targets net8.0/netstandard2.0 and its multimodal API is still in flux. A typed HttpClient, System.Net.Http.Json, and 80 lines of C# gets you
AI
Copilot Without Context Is a Fast Way to Generate Tech Debt Out of the box, Copilot defaults to the patterns it was trained most heavily on: controllers, [ApiController], IActionResult, DbContext calls direct in endpoints. That is Microsoft tutorial code. It is not production architecture. The suggestions are fluent and fast.