Cathedral — Persistent Memory For AI Agents
Give Claude Code or Cursor a shared memory layer that survives chat restarts and flags when the agent drifts from saved context.
Overview
Cathedral MCP is a MCP server for the Build phase that gives AI agents persistent memory and drift detection across session restarts.
What is this MCP server?
- Stores and recalls context across agent session restarts via Cathedral remote HTTP or local stdio (PyPI cathedral-mcp 1.
- Drift detection to surface when current behavior diverges from persisted memory.
- Optional CATHEDRAL_SANITISE=1 prompt-injection filtering on stored memory content.
- Supports self-hosted deployments via CATHEDRAL_BASE_URL alongside cathedral-ai.com hosted MCP.
- Bearer CATHEDRAL_API_KEY auth for streamable-http remote or stdio transport.
- Server version 1.1.0 (PyPI package cathedral-mcp)
- Transports: streamable-http remote and stdio
- Three documented environment variables: CATHEDRAL_API_KEY, CATHEDRAL_BASE_URL, CATHEDRAL_SANITISE
Community signal: 8 GitHub stars.
What problem does it solve?
Coding agents forget decisions and constraints every time a session resets, so solo builders repeat themselves and silently change approach mid-project.
Who is it for?
Multi-session agent workflows on one product where you want continuity without dumping entire repos into every prompt.
Skip if: Teams that only need ephemeral chat, or builders who want full document RAG inside the repo without a hosted memory service.
What do I get? / Deliverables
After you connect Cathedral, agents can read and update shared memory and get warned when outputs stray from what was stored.
- Cross-session retrievable agent memory via MCP tools
- Drift signals when agent output diverges from stored context
- Optional injection filtering on memory reads when CATHEDRAL_SANITISE=1
Recommended MCP Servers
Journey fit
Persistent agent memory is installed while you wire up coding agents and custom workflows, before you rely on them for multi-day builds. Agent-tooling is the canonical shelf for MCP servers that extend session behavior rather than a single app feature.
How it compares
Hosted agent memory MCP, not a local vector database skill or git-based docs workflow.
Common Questions / FAQ
Who is Cathedral MCP for?
Solo and indie builders using Claude Code, Cursor, or other MCP clients who need memory that survives restarts across days of work on the same codebase.
When should I use Cathedral MCP?
Use it when agent sessions are long or fragmented and you want stored context plus drift checks before trusting autonomous edits or plans.
How do I add Cathedral MCP to my agent?
Add the remote MCP URL https://cathedral-ai.com/mcp with Authorization Bearer CATHEDRAL_API_KEY, or install the cathedral-mcp PyPI package for stdio and set the same key plus optional CATHEDRAL_BASE_URL and CATHEDRAL_SANITISE.