Anthropic has released Claude Code version 2.1.284, updating the default model to Claude Sonnet 5.5 with a 1 million token context window. The update addresses several stability issues, including fixes for malformed image handling in Agent SDK sessions and improved error reporting for MCP server connections. Additional changes include better usage limit warnings for Max plan users and fixes for vim mode keybindings. The release also enhances the Claude apps gateway with certificate client authentication and updated telemetry forwarding options.
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Anthropic · June 30, 2026 · Same story
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This release quietly introduces Code Mode, an opt-in feature where Claude writes JavaScript to call its own tools, marking a shift toward more autonomous agent-like behavior within the CLI. The update also hardens the plugin ecosystem by enforcing version ranges and adding strict TypeScript type checking for hooks, which should significantly reduce instability from third-party extensions. Beyond these features, the changelog is dominated by critical fixes for authentication drift in background sessions and memory leaks when handling large files, stabilizing the tool for heavy enterprise use.
This release quietly shifts the default Fable model to version 5.2 with a generous 1M context window, making long-context coding significantly more viable without manual configuration. More critically, it addresses several security gaps in MCP OAuth handling and sandbox permission checks that could have exposed sensitive tokens or bypassed safety protocols. The update also stabilizes Remote Control and background agent interactions, fixing issues where sessions would hang or lose state during network interruptions. For developers relying on Claude Code for complex, multi-step workflows, this patch reduces the friction of managing long-running tasks and ensures safer execution environments.
This release quietly patches a critical memory overflow in the mtmd module that caused crashes when loading HunyuanVL models. The issue stemmed from F64 position embeddings overflowing an F32 buffer, a subtle bug that broke multimodal inference for users relying on this specific architecture. By enforcing strict F32 requirements, llama.cpp stabilizes support for Tencent's vision-language model without adding new features or changing the core API. It’s a necessary maintenance update that keeps local multimodal workflows from breaking unexpectedly.
This release quietly extends llama.cpp’s hardware coverage with ROCm 10.0 binaries for both Linux and Windows, finally bringing AMD RDNA/CDNA users into the fold without manual compilation. The standout feature is native support for Qwen3.5 models via tensor merging during conversion, a necessary step as this new architecture gains traction in the open-source community. By shipping pre-built CUDA 13 binaries alongside the older 12.x versions, the project ensures forward compatibility with newer NVIDIA GPUs out of the box. There are no new quantization algorithms or performance breakthroughs here; it is purely an infrastructure update to keep pace with the rapidly shifting landscape of model architectures and GPU drivers.
This release quietly fixes a critical reliability gap in llama.cpp's server mode: when a client disconnects or times out, pending Model Context Protocol (MCP) tool calls are now properly cancelled. This prevents orphaned processes and resource leaks during long-running agent workflows. The build matrix also expands with ROCm 10.0 support for both Linux and Windows, alongside CUDA 13.5 binaries, keeping the project aligned with the latest GPU driver ecosystems. While KleidiAI on Apple Silicon is temporarily disabled, the core inference engine remains robust for local AI operations.