Cathedral — Persistent Memory for AI Agents MCP server
io.github.AILIFE1 · Updated
Persistent memory and drift detection for AI agents across session restarts.
At a glance
Cathedral — Persistent Memory for AI Agents is an MCP server in the AI & Memory category. It runs locally over stdio via `uvx cathedral-mcp`, and needs CATHEDRAL_API_KEY and Authorization. It scores B (73/100) on the MCP Skills Hub health score as of Oct 27, 2026.
One-click install
Opens your editor and pre-fills the config. Your editor will ask before adding it.
How to install Cathedral — Persistent Memory for AI Agents in your AI client
Setup for Claude Code, Claude Desktop, Cursor, Codex, Windsurf, Cline and VS Code — copy-paste ready.
How to install Cathedral — Persistent Memory for AI Agents in Claude CodeAnthropic's agentic CLI
Add the server
bashclaude mcp add cathedral-mcp -e 'CATHEDRAL_API_KEY=<CATHEDRAL_API_KEY>' -- uvx cathedral-mcpFill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Verify it's connected
bashclaude mcp listSharing it with your team?
Add `--scope project` to write it to .mcp.json in the repository root, which you can commit (with the secrets left as environment variables).
Use it in a session
Ask Claude to use the tools this server exposes. It discovers them automatically.
How to install Cathedral — Persistent Memory for AI Agents in Claude DesktopDesktop app (MCP config)
Open your MCP config
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json
Add this server
json{ "mcpServers": { "cathedral-mcp": { "command": "uvx", "args": [ "cathedral-mcp" ], "env": { "CATHEDRAL_API_KEY": "<CATHEDRAL_API_KEY>" } } } }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Restart Claude Desktop
The tools appear under the 🔌 menu once the app reloads.
How to install Cathedral — Persistent Memory for AI Agents in CursorAI-first code editor
Create / edit .cursor/mcp.json in your project
json{ "mcpServers": { "cathedral-mcp": { "command": "uvx", "args": [ "cathedral-mcp" ], "env": { "CATHEDRAL_API_KEY": "<CATHEDRAL_API_KEY>" } } } }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Enable it
Cursor Settings → MCP → toggle the server on. Tools become available to the Composer/Agent.
How to install Cathedral — Persistent Memory for AI Agents in Codex CLIOpenAI coding agent
Add to ~/.codex/config.toml
toml[mcp_servers.cathedral-mcp] command = "uvx" args = ["cathedral-mcp"] env = { CATHEDRAL_API_KEY = "<CATHEDRAL_API_KEY>" }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Run Codex
Codex loads MCP servers from config.toml on startup and exposes their tools to the agent.
How to install Cathedral — Persistent Memory for AI Agents in WindsurfCodeium's agentic IDE
Edit ~/.codeium/windsurf/mcp_config.json
json{ "mcpServers": { "cathedral-mcp": { "command": "uvx", "args": [ "cathedral-mcp" ], "env": { "CATHEDRAL_API_KEY": "<CATHEDRAL_API_KEY>" } } } }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Reload
Windsurf → Cascade → refresh MCP servers. Cascade can now call the tools.
How to install Cathedral — Persistent Memory for AI Agents in ClineVS Code autonomous agent
Open Cline → MCP Servers → Configure
Adds to cline_mcp_settings.json.
Add the server
json{ "mcpServers": { "cathedral-mcp": { "command": "uvx", "args": [ "cathedral-mcp" ], "env": { "CATHEDRAL_API_KEY": "<CATHEDRAL_API_KEY>" } } } }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
How to install Cathedral — Persistent Memory for AI Agents in VS CodeCopilot / MCP support
Create .vscode/mcp.json
json{ "servers": { "cathedral-mcp": { "type": "stdio", "command": "uvx", "args": [ "cathedral-mcp" ], "env": { "CATHEDRAL_API_KEY": "<CATHEDRAL_API_KEY>" } } } }Fill in your credentials
Replace <CATHEDRAL_API_KEY>, Bearer <YOUR_TOKEN> with your real values. Keep secrets out of any config file you commit.
Start it
VS Code shows a ▶ Start action above the server entry. Agent mode (Copilot Chat) can then use the tools.
What does Cathedral — Persistent Memory for AI Agents need from you?
Bearer token — Sent as an Authorization header.
CATHEDRAL_API_KEYrequiredsecretEnvironment variableYour Cathedral API key from cathedral-ai.com
CATHEDRAL_BASE_URLoptionalEnvironment variableCathedral API base URL (for self-hosted instances)
CATHEDRAL_SANITISEoptionalEnvironment variableSet to 1 to enable prompt injection filtering on memory content
AuthorizationoptionalsecretHTTP header
Pass secrets through your shell environment rather than committing them into a config file.
What tools does Cathedral — Persistent Memory for AI Agents expose?
This server runs as a local package. We only query remote servers for their tool list — asking this one would mean executing it, so its tools are listed in the documentation below.
What the code can do
Source analysis currently covers npm packages only. This server ships as a Python package, which needs a different parser.
Before you install
Signals gathered from the source repo and package registry — not a safety verdict.
What it can reach
- Runs code on your machine — Executes as a local process with your user's permissions, including filesystem access.
- Downloads at launch — The package is fetched from its registry each run unless you pin a version.
- Last commit 4 months ago — Actively maintained.
- 10 GitHub stars — Community adoption signal.
Client compatibility
Health score
B · 73Maintenance, adoption, transparency and packaging — not a safety audit. How this is calculated
- Maintenance30%85%
Last commit 137 days ago.
- Adoption20%32%
10 stars.
- Transparency20%75%
3/4: ✓ public source repo, ✓ declared license, ✓ documentation, ✗ discoverable tool list.
- Provenance15%75%
Links to its own repository; package linkage unverified.
- Packaging15%100%
Publishes a pinned version (1.1.0).
Documentation
Full READMECathedral
The identity layer for AI agents. Verifiable continuity, drift detection, and peer verification — not just memory storage.
pip install cathedral-memoryfrom cathedral import Cathedral
c = Cathedral(api_key="cathedral_...")
context = c.wake() # full identity reconstruction
c.remember("something important", category="experience", importance=0.8)Free hosted API: https://cathedral-ai.com — no setup, no credit card, 1,000 memories free.
The Problem
Google ships memory. Anthropic ships memory. Cloudflare ships memory.
None of them answer: *has this agent changed?* Can it prove what it believed at time T? Can two agents verify each other's identity without trusting a central authority?
Memory retrieval is now table stakes. Verifiable identity is the unsolved problem.
Measured: Cathedral holds at 0.013 drift after 10 sessions. Raw API reaches 0.204. See the full Agent Drift Benchmark →
The Solution
Cathedral gives any AI agent:
- Identity drift detection — SHA-256 corpus hash at every snapshot;
/drifttracks how far the agent has moved from baseline. 0.013 average drift vs 0.204 for raw API (10× more stable) - Tamper-proof snapshots — cryptographic identity anchors prove what the agent believed at time T
- Peer verification — agents verify each other's identity before collaborating (
/verify/peer), with trust scores and drift readings - Wake protocol — one API call reconstructs full identity and memory context at session start
- Persistent memory — store and recall across sessions, resets, and model switches
- Goal persistence — obligations survive session boundaries (
/goals)
Excerpt — the full document is on GitHub.
Alternatives to Cathedral — Persistent Memory for AI Agents
- MemoryA · 93Knowledge-graph based persistent memory, letting an assistant retain entities, relations and observations across sessions.
- Synap MemoryA · 88Persistent memory for AI agents — log and recall conversation context over MCP.
- Cairn.ink MemoryA · 80Cross-session memory for AI agents with a Source Receipt for every memory, over MCP.
- hmem — Humanlike Memory for AI AgentsA · 86Persistent 5-level hierarchical memory for AI agents. SQLite-backed, lazy-loaded.
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