Covalence – Cross-Client Memory for Claude, Cursor, and MCP (macOS)

I use Claude Desktop, Claude Code, and Cursor daily. They all have memory now, but none of them share it. Something I explained in Claude Desktop doesn't exist when I open Cursor. I got tired of re-explaining my stack, my preferences, and my project context every time I switched tools.

Most solutions I found required Docker, external databases, or cloud accounts - overkill for what's essentially a personal context store. So I built Covalence: a Mac app that bundles an MCP server and a local vector database into a single download. Any MCP client connects to it. Store a memory in Claude, retrieve it from Cursor. Same database, zero config.

The stack: SQLite + sqlite-vec, nomic-embed-text-v1.5 running on-device via CoreML (no API keys, no network calls). Hybrid BM25 + vector search. Everything lives in a single SQLite file. The hard part was concurrency. Multiple Claude sessions writing to the same MCP server would deadlock. SQLite in WAL mode with each MCP client as a separate process solved it - multiple clients read and write simultaneously without blocking. Embeddings run sub-second on Apple Silicon.

A few features that emerged from daily use:

Core Memories - pin facts the AI should always know (your stack, your preferences, standing instructions). They persist across every session and every client. Spaces - separate memory contexts for work, personal, or individual projects. No cross-contamination. Global hotkey capture - store something without switching away from whatever you're doing.

Free, no limits. macOS 15+, ~261MB (mostly the CoreML embedding model). https://covalence.app