.cursor/rules, Better Codebase Understanding, New Tab Model

Source: Cursor Date: 2025-01-23 URL: https://cursor.com/changelog/0-45-x

Summary

Cursor 0.45.x ships .cursor/rules as a dedicated directory with automatic rule selection by the agent, DeepSeek R1 and DeepSeek V3 support (US self-hosted), a new “Fusion Model” Tab upgrade for extended context and jump handling, and agent access to recent change history between messages. Larger optional context windows added for tagged files on premium models. MCP support and team-configurable blocklists arrive in point releases.

Implications

Agent-IDE feature race. .cursor/rules as a directory with automatic agent selection is Cursor’s answer to Claude Code’s CLAUDE.md — but with multi-file scoping and agent-side retrieval rather than full inclusion. The design choice is significant: Cursor is indexing rules like code, not loading them wholesale. This scales better for large rule sets but trades predictability for efficiency.

Model integration cadence. DeepSeek R1 and V3 US self-hosted is a notable move — Cursor is adding open-weight models behind its own infrastructure, not just routing to provider APIs. This is partly risk management (DeepSeek API reliability concerns) and partly a signal that Cursor will host any model worth integrating. DeepSeek V3’s code performance at lower cost pressures Claude/GPT for routine tasks.

Watch: Whether DeepSeek self-hosting expands to other open-weight models (Qwen, Llama) and whether .cursor/rules directory gains a namespace or tagging system for organizing large rule sets.