How do I install Cosmos?

Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.

Does Cosmos need an API key?

The publisher lists these environment variables: COSMOS_TOKEN.

What transport does Cosmos use?

Cosmos runs locally over stdio.

When was Cosmos last checked?

Last checked 2026-11-10. Personal knowledge graph every MCP client reads from and writes to. Portable across agents.

Cosmos MCP server

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Add to Cursor Add to VS Code Run on PlugMCP

Host a copy with our keys and logs.

Local command

npx -y @polarity-lab/[email protected]

Credentials from the publisher

COSMOS_TOKEN — pmk_ key from https://cosmos.polarity-lab.com/connectors. Optional on macOS once the system keychain is provisioned via `npx -y @polarity-lab/cosmos-mcp provision pmk_...`.

Claude Code has no install link for a local command. Copy the command below and run it in a terminal.

shClaude Code

1COSMOS_TOKEN=<secret> claude mcp add io.github.teampolarity-cosmos-mcp -- npx -y @polarity-lab/cosmos-mcp@0.7.1

Run in a terminal.

jsonClaude Desktop

1{2  "mcpServers": {3    "io.github.teampolarity-cosmos-mcp": {4      "command": "npx",5      "args": [6        "-y",7        "@polarity-lab/[email protected]"8      ],9      "env": {10        "COSMOS_TOKEN": "<secret>"11      }12    }13  }14}

claude_desktop_config.json

Local · npmPublisher installStep-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

Server facts

Local

Transport: stdio
Version: 0.7.1
API key

Tools

No tool list yet. Remote servers get one after the first health check.

FAQ

Questions

Every AI you use is building its own private graph of you. Claude has one. ChatGPT has one. Cursor has one. None of them talk to each other, and none of them are yours.

Cosmos inverts that. Your knowledge graph lives in one place, and any MCP-capable client (Claude Code, Claude Desktop, Cursor, Codex, Zed, Continue) reads and writes to the same one. When an agent notices something durable about you, it lands in the graph. When you switch tools, the graph follows. The user, not the platform, owns the integration layer.

The thing you carry is a .polarity file. Yours.

One-line install

curl -fsSL https://mcp.polarity-lab.com/install.sh | sh

On macOS this installs the MCP server, registers cosmos-mcp://, wires Claude Desktop, Claude Code, Cursor, Codex, Zed, and Continue, then installs Cosmos Sync.app so iMessage, browser history, calendar, Claude Desktop transcripts, and shell history can sync in the background. On linux and windows it installs the MCP server path only.

If you want to inspect before changing anything:

curl -fsSL https://mcp.polarity-lab.com/install.sh -o install.sh
bash install.sh --dry-run
bash install.sh

Provisioning

There are two ways to get a pmk_… key onto your Mac.

Automatic. Sign in at cosmos.polarity-lab.com/connectors, tap "open in cosmos-mcp." The OS opens a one-shot handler that writes the key into your system keychain. You never see the raw key.

For that deep link to work, register the URL scheme once:

npx -y @polarity-lab/cosmos-mcp install-handler

This drops a tiny .app into ~/Library/Application Support/cosmos-mcp/ and registers cosmos-mcp:// with Launch Services. macOS-only.

Manual. If you already have a pmk_… key, or you do not want to install the handler:

npx -y @polarity-lab/cosmos-mcp provision pmk_xxx

The CLI validates the key against cosmos, then stores it in the macOS system keychain under service cosmos-mcp-key. Subsequent imessage sync, browser sync, calendar sync calls read from the keychain. No env var needed.

Confirm iMessage access.

npx -y @polarity-lab/cosmos-mcp imessage probe

Verifies Full Disk Access is granted and reports how many chats are visible. If you see an EACCES message, open System Settings, Privacy & Security, Full Disk Access, and add Terminal (or whichever app runs the CLI).

CI. Set COSMOS_TOKEN=pmk_… in env. It takes precedence over the keychain, so existing pipelines keep working untouched.

Manual MCP config

The installer handles this for common clients. If you want to wire a client by hand, point it at the package.

npx -y @polarity-lab/cosmos-mcp init

This opens your browser. Sign in at cosmos.polarity-lab.com, approve a per-user key, and the token lands at ~/.config/cosmos-mcp/token (0600). Then point any MCP client at it:

{
  "mcpServers": {
    "cosmos": {
      "command": "npx",
      "args": ["-y", "@polarity-lab/cosmos-mcp"]
    }
  }
}

That config drops into ~/Library/Application Support/Claude/claude_desktop_config.json for Claude Desktop, your .cursor/mcp.json for Cursor, the equivalent for whichever client.

What you get

Eleven tools, four read, seven write.

Read

Tool	Calls	What it returns
`polarity_whoami`	`GET /api/polarity/whoami`	Bound user + scopes. Cheap probe.
`polarity_export`	`POST /api/polarity/export`	Full personal graph as `polarity/v1` JSON.
`polarity_get_graph`	`GET /api/polarity`	Graph view, scoped by entity (`user`, `cosmos`, `polarity`).
`polarity_ask`	`POST /api/polarity/ask`	NL question synthesized over the graph.

Write

Tool	Calls	What it does
`polarity_observe`	`POST /api/polarity/observe`	Freeform observation. Cosmos extracts.
`polarity_record_event`	`POST /api/polarity/observe` (kind=event)	Something happened at a point in time.
`polarity_record_preference`	`POST /api/polarity/observe` (kind=preference)	A like, dislike, working-style rule.
`polarity_capture_turn`	`POST /api/polarity/capture-turn`	Hand a whole user/assistant exchange to cosmos. Pulls every durable observation in one call. Prefer over multiple `polarity_observe` calls.
`polarity_reconstruct_hours`	`POST /api/polarity/reconstruct-hours`	Persist life-hour receipts onto the skill-map sky (per user only). Use from Cursor/Cosmos IDE after substantive work.
`polarity_dump`	`POST /api/polarity/dump`	Location-anchored short message.
`polarity_checkin`	`POST /api/polarity/checkin`	Check-in at a waypoint. Triggers co-presence detection.
`polarity_declare`	`POST /api/polarity/declare`	Declare future presence at a waypoint.

Sources

The MCP server is one way to write to the graph. Cosmos accepts source pages from anywhere you keep notes, and the MCP read tools see all of it through the same view.

Source	How it connects	What lands
iMessage	Local CLI: `npx -y @polarity-lab/cosmos-mcp imessage sync`. Mac only. Grant Terminal Full Disk Access first.	Conversational turns from `chat.db`, with text content. People appear as person nodes in your graph, sized by conversation weight, named via your local AddressBook, dated by your real message timestamps.
Claude Desktop	Local CLI: `npx -y @polarity-lab/cosmos-mcp claude-desktop sync`. Reads Claude Code session transcripts at `~/.claude/projects/`.	Every Claude Code session becomes a thread node; user and assistant turns land in `conversation_turns` with full text. Tool-use plumbing is stripped client-side.
Shell history	Local CLI: `npx -y @polarity-lab/cosmos-mcp shell-history sync`. Reads `~/.zsh_history` (falls back to bash/fish) with a byte-offset watermark.	Each sync window lands as one `source_page` keyed by `shell-history:<sync-iso>`, body = newline-joined commands. Trivial commands (`ls`, `cd ..`, single chars) and consecutive duplicates are filtered client-side.
Notion	OAuth at cosmos.polarity-lab.com/connectors. Pick the pages and databases you want shared.	Each Notion page becomes a `source_page` node, keyed by Notion id, kept fresh by a daily sync.
Obsidian	Community plugin: polarity-lab/obsidian-cosmos. Paste your `pmk_` key, point at your vault.	Each note becomes a `source_page` node keyed by vault-relative path. Tags and wikilinks resolve into edges.
MCP clients	This package.	Observations, events, preferences, location dumps, check-ins, declarations.
Direct API	`POST /api/polarity/observe` with your key.	Anything you can express as an observation.

Unchanged pages are skipped server-side, so re-syncing a quiet vault or stable Notion workspace costs almost nothing. The iMessage sync is incremental too, watermarked on the last successful run, so re-running it is a no-op until new messages arrive.

iMessage sync

cosmos-mcp ships an imessage subcommand that reads your local Messages database and lands every conversation in your graph.

# default: incremental sync, 90-day window on first run
npx -y @polarity-lab/cosmos-mcp imessage sync

# re-sync the original 90-day window regardless of watermark
npx -y @polarity-lab/cosmos-mcp imessage sync --backfill

# pull everything since a specific date
npx -y @polarity-lab/cosmos-mcp imessage sync --since 2024-01-01

# check what the last run did
npx -y @polarity-lab/cosmos-mcp imessage status

A three-rule slop filter (no-reply senders, short-code numbers, low-volume contacts) keeps the graph clean. Your AddressBook resolves phone numbers and emails into real contact names. The reading is local to your Mac; only the extracted, normalized turns go into your cosmos graph, which is your account.

Claude Desktop sync

cosmos-mcp ships a claude-desktop subcommand that watches Claude Code session transcripts and lands each turn in your graph. The desktop chat surface itself stores conversations server-side, so the live, watchable on-disk source is ~/.claude/projects/<encoded-cwd>/<session-id>.jsonl.

# default: incremental, watermarked per session
npx -y @polarity-lab/cosmos-mcp claude-desktop sync

# limit to recent activity
npx -y @polarity-lab/cosmos-mcp claude-desktop sync --since 2026-05-01

# scan and report without shipping
npx -y @polarity-lab/cosmos-mcp claude-desktop sync --dry-run

# see what the last run did
npx -y @polarity-lab/cosmos-mcp claude-desktop status

Tool-use blocks, hook plumbing, and sub-agent (sidechain) turns are stripped client-side; only the visible text the user and the assistant exchanged is shipped. Each session id becomes its own thread node, keyed by (user_id, "claude-desktop", session_id).

Background sync (macOS)

cosmos-mcp daemon install drops a LaunchAgent that ticks every four hours and runs the browser, iMessage, calendar, claude-desktop, and shell-history syncs back-to-back. The agent fires a signed, notarized Cosmos Sync.app bundle that ships inside the npm package and gets copied into ~/Applications/Cosmos Sync.app at install time.

npx -y @polarity-lab/cosmos-mcp daemon install

After install, grant the bundle Full Disk Access once:

open System Settings → Privacy & Security → Full Disk Access
click +, then drag ~/Applications/Cosmos Sync.app into the list
make sure the checkbox next to it is on
run cosmos-mcp daemon kick to fire a tick now

Browser sync works without that step. iMessage and Calendar need it because they read TCC-protected SQLite databases on the user side. cosmos-mcp daemon status reports the signing team id, the plist + runner paths, and whether launchd has the agent loaded. cosmos-mcp daemon uninstall removes the plist, runner, and ~/Applications/Cosmos Sync.app.

Configuration

Env var	Default	When you set it
`COSMOS_URL`	`https://cosmos.polarity-lab.com`	Override the cosmos API endpoint.
`COSMOS_TOKEN`	(from keychain)	`pmk_...` per-user key for CLI subcommands. Takes precedence over the macOS keychain entry. Set this in CI.
`COSMOS_MCP_KEY`	(from token file)	`pmk_...` per-user key. Honored for back-compat.
`COSMOS_USER_ID`	(from token file)	Polarity user id.
`COSMOS_SYSTEM_KEY`	(unset)	Single-tenant mode. Sends `X-System-Key` instead of `X-MCP-Key`. Requires `COSMOS_USER_ID`. For internal testing before per-user keys are deployed.

The pitch in three lines

Your AI tools each know fragments of you. They are not allowed to share. Cosmos is the layer that lets them. You hold the key. The graph is portable. When you leave, you take the understanding with you.

License

MIT.

Add this server

Host a copy with our keys and logs.

Server facts

Tools

Questions

How do I install Cosmos?

Does Cosmos need an API key?

What transport does Cosmos use?

When was Cosmos last checked?

Documentation

One-line install

Provisioning

Manual MCP config

What you get

Sources

iMessage sync

Claude Desktop sync

Background sync (macOS)

Configuration

The pitch in three lines

License