KotlinLLM, a research prototype for delegating runtime logic to a large language model (LLM) from Kotlin code, is now going open source and public, JetBrains announced.

Revealed July 28, KotlinLLM is an IntelliJ IDEA plugin prototype for experimenting with LLM-driven “Smart macros” in Kotlin, enabling code generation, runtime updates, and hot-reloading. In software engineering, LLMs are commonly used during development for code completion, code generation, and program comprehension, JetBrains noted, but using an LLM at run time of a compiled application is much less common. The existing options for doing this have the following trade-offs, according to JetBrains:

• Direct runtime delegation is slow, non-deterministic, and costly, and makes the application depend on an LLM service at run time.
• External agent workflows keep the generated logic outside the codebase, where it is harder to review, test, and ship.
• Most prior work (byLLM, nightjar, Healer) targets interpreted languages like Python, not a compiled, statically typed language like Kotlin.

KotlinLLM addresses these limitations in three ways, JetBrains said:

• The call site shows that a feature is LLM-backed, so it is visible in code review.
• Generated behavior is saved as an ordinary Kotlin source, not kept only in the runtime session. It can be committed, reviewed, tested, and distributed like any other code.
• Once generated, the code runs as plain Kotlin without the plugin. For scenarios that are already covered, there is no further LLM call, so no added latency or cost, and the result is reproducible.

KotlinLLM is open source under Apache License 2.0. The repository contains the KotlinLLM IntelliJ IDEA plugin, the Smart macro API, and example projects.

Microsoft has released MCP C# SDK v2.0, a major update of the company’s official C# SDK for Model Context Protocol (MCP) servers and clients.

Unveiled July 28, MCP C# SDK v2.0 implements the 2026-07-28 revision of the MCP specification, which Microsoft described as the protocol’s largest revision since its launch. The 2026-07-28 revision makes the MCP protocol stateless by default, standardizes the HTTP surface to allow ordinary HTTP infrastructure to route MCP traffic, and introduces Multi Round-Trip Requests (MRTR) to support interaction without requiring long-lived sessions.

MCP C# SDK 2.0 moves in lockstep with these changes, Microsoft said. The HTTP server transport now runs statelessly by default. Whereas version 1.x of the SDK configured stateful sessions out of the box, in version 2.0 HttpServerTransportOptions.Stateless defaults to true.

MCP C# SDK v2.0 also implements a small set of HTTP headers that the 2026-07-28 MCP revision standardizes. A tools/call now includes Mcp-Method: tools/call and Mcp-Name: get_order_status alongside the JSON-RPC body. With the 2026-07-28 revision, an MCP request becomes a single, self-describing HTTP POST. This means that ordinary HTTP infrastructure such as load balancers, proxies, gateways, and web application firewalls now can act on MCP traffic without deep packet inspection, Microsoft said.

And MCP C# SDK 2.0 adds support for MRTR on the server and on the client. MRTR addresses scenarios in which tools can’t answer in a single round trip, such as when a server wants to confirm with a user before taking a significant action. In previous versions of MCP, these interactions worked only over a live, stateful session. With MRTR, they work with no session at all, because all the continuity travels in the payload, Microsoft said.

With the 2026-07-28 spec compliance landing in MCP C# SDK 2.0, Microsoft said the SDK’s next focus is end-to-end authentication and authorization. The goal is to make secure MCP deployments as “turnkey” as the rest of the stack, building on the closer OAuth and OpenID Connect alignment the spec introduced, Microsoft said.