Direct filesystem is the simplest pattern. Run cd ~/vault && claude and Claude reads and writes your .md files directly. Use this if you want zero setup and are comfortable in the terminal.
MCP bridge connects Claude Code to Obsidian through a WebSocket. The obsidian-mcp server by StevenStavrakis gives you structured tools for reading, writing, and searching notes. Use this if you want tool-level access without opening Obsidian.
Embedded (Claudian plugin) runs Claude Code as a sidebar inside Obsidian's UI. You get full agentic capabilities without leaving your editor. Use this if you prefer staying inside Obsidian for everything.