Open Brain: Your AI-Readable Memory Infrastructure

How Open Brain Works

One database at the center. Everything that can write to it can also read from it. Slack, Telegram, WhatsApp, Claude, ChatGPT, Cursor - they all go both ways. Everything connects through Supabase Edge Functions and MCP. Nothing running on your machine.

What You Need

--- OPEN BRAIN CREDENTIALS (fill as you go) ---

Supabase Project ref:         [Step 1 - from dashboard URL]
Supabase Database password:   [Step 1 - generated during setup]
Supabase Project URL:         [Step 3 - Settings > API]
Supabase Service role key:    [Step 3 - Settings > API]
OpenRouter API key:           [Step 4 - openrouter.ai/keys]
Capture Channel/Group ID:     [Step 5 - platform-specific [if using Slack/Telegram/WhatsApp]]
Bot Token / Bot API Key:      [Step 6 - platform-specific [if using Slack/Telegram/WhatsApp]]
Edge Function URL:            [Step 7 - after deploy]
MCP Access Key:               [Step 10 - generated random hex]
MCP Server URL:               [Step 11 - after deploy]

Supabase is your database. It stores raw text, vector embeddings, and structured metadata. It also gives you a REST API and Edge Functions runtime automatically.

1. Go to supabase.com and sign up (GitHub login is fastest)
2. Click New Project in the dashboard
3. Pick your organization (default is fine)
4. Project name: open-brain
5. Generate a strong database password - paste into credential tracker NOW
6. Pick the Region closest to you
7. Click Create new project and wait 1-2 minutes

Three SQL commands, pasted one at a time. Creates your storage table, search function, and security policy.

A. Enable the Vector Extension

In the left sidebar: Database → Extensions → search for "vector" → flip pgvector ON.

B. Create the Thoughts Table

Left sidebar: SQL Editor → New query → paste and Run:

create table thoughts (
  id          bigint generated always as identity primary key,
  content     text not null,
  embedding   vector(1536),
  metadata    jsonb default '{}'::jsonb,
  created_at  timestamptz default now(),
  updated_at  timestamptz default now()
);

C. Create the Search Function

New query → paste and Run:

create or replace function match_thoughts (
  query_embedding vector(1536),
  match_threshold float default 0.5,
  match_count     int default 10
)
returns table (
  id         bigint,
  content    text,
  metadata   jsonb,
  similarity float,
  created_at timestamptz
)
language sql stable
as $$
  select
    thoughts.id,
    thoughts.content,
    thoughts.metadata,
    1 - (thoughts.embedding <=> query_embedding) as similarity,
    thoughts.created_at
  from thoughts
  where 1 - (thoughts.embedding <=> query_embedding) > match_threshold
  order by thoughts.embedding <=> query_embedding
  limit match_count;
$$;

D. Lock Down Security

One more new query:

-- Enable Row Level Security
alter table thoughts enable row level security;

-- Service role full access only
create policy "Service role full access"
  on thoughts
  for all
  using (auth.role() = 'service_role');

In the left sidebar: Settings (gear icon) → API. Copy into your credential tracker:

1. Project URL - listed at the top as "URL"
2. Service role key - under "Project API keys" → click reveal

OpenRouter is a universal AI gateway. One key gives you access to every major model. We use it for embeddings (text-embedding-3-small at $0.13/M tokens) and metadata extraction (gpt-4o-mini).

1. Go to openrouter.ai and sign up
2. Go to openrouter.ai/keys
3. Click Create Key, name it open-brain
4. Copy the key into your credential tracker immediately
5. Add $5 in credits under Credits (lasts months at this usage)

This is the bridge between your platform and your database.

This is the brains of the operation. One function receives messages from your platform, generates an embedding, extracts metadata, stores everything, and replies with a confirmation.

A. Install the Supabase CLI

brew install supabase/tap/supabase

npm install -g supabase

If you don't have npm, install Node.js from nodejs.org first - npm comes with it.

B. Log In and Link

supabase login
supabase link --project-ref YOUR_PROJECT_REF

C. Create the Function

supabase functions new ingest-thought

Open supabase/functions/ingest-thought/index.ts in any text editor and replace its entire contents with the Edge Function code from the companion Substack guide.

D. Set Your Secrets

supabase secrets set OPENROUTER_API_KEY=your-openrouter-key
supabase secrets set SLACK_BOT_TOKEN=xoxb-your-slack-bot-token
supabase secrets set SLACK_CAPTURE_CHANNEL=C0your-channel-id

supabase secrets set OPENROUTER_API_KEY=your-openrouter-key
supabase secrets set TELEGRAM_BOT_TOKEN=your-bot-token-from-botfather
supabase secrets set TELEGRAM_CHAT_ID=-your-chat-id

supabase secrets set OPENROUTER_API_KEY=your-openrouter-key
supabase secrets set WHATSAPP_ACCESS_TOKEN=your-access-token
supabase secrets set WHATSAPP_PHONE_ID=your-phone-id
supabase secrets set WHATSAPP_VERIFY_TOKEN=random-verify-token

SUPABASE_URL and SUPABASE_SERVICE_ROLE_KEY are automatically available inside Edge Functions - you don't set them.

E. Deploy

supabase functions deploy ingest-thought --no-verify-jwt

Go to your capture channel / group and type:

Sarah mentioned she's thinking about leaving her job to start a consulting business

Wait 5-10 seconds. You should see a confirmation:

Captured as person_note -- career, consulting
People: Sarah
Action items: Check in with Sarah about consulting plans

Then open Supabase dashboard → Table Editor → thoughts. You should see one row with your message, an embedding, and metadata.

Your MCP server will be a public URL. Generate a simple access key for authentication.

openssl rand -hex 32

-join ((1..32) | ForEach-Object { '{0:x2}' -f (Get-Random -Maximum 256) })

Copy the 64-character output into your credential tracker. Then set it as a Supabase secret:

supabase secrets set MCP_ACCESS_KEY=your-generated-key-here

One Edge Function. Four tools: semantic search, browse recent, remember frameworks, and stats.

A. Create the Function

supabase functions new open-brain-mcp

B. Add Dependencies

Create supabase/functions/open-brain-mcp/deno.json:

{
  "imports": {
    "@hono/mcp":                    "npm:@hono/mcp@0.1.1",
    "@modelcontextprotocol/sdk":      "npm:@modelcontextprotocol/sdk@1.24.3",
    "hono":                           "npm:hono@4.9.2",
    "zod":                            "npm:zod@4.1.13",
    "@supabase/supabase-js":          "npm:@supabase/supabase-js@2.47.10"
  }
}

C. Write the Server

Open supabase/functions/open-brain-mcp/index.ts and replace with the MCP server code from the companion guide.

D. Deploy

supabase functions deploy open-brain-mcp --no-verify-jwt

Your MCP server is live at:

https://YOUR_PROJECT_REF.supabase.co/functions/v1/open-brain-mcp

Paste the full URL into your credential tracker as the MCP Server URL.

You need two things from your credential tracker: the MCP Server URL (Step 11) and the access key (Step 10).

Claude Desktop

Settings → Developer → Edit Config:

{
  "mcpServers": {
    "open-brain": {
      "type": "http",
      "url": "https://YOUR_PROJECT_REF.supabase.co/functions/v1/open-brain-mcp",
      "headers": {
        "x-brain-key": "your-access-key-from-step-10"
      }
    }
  }
}

Restart Claude Desktop. "open-brain" should appear in the MCP tools indicator.

Claude Code

claude mcp add open-brain \
  --transport http \
  --url https://YOUR_PROJECT_REF.supabase.co/functions/v1/open-brain-mcp \
  --header "x-brain-key: your-access-key-from-step-10"

Other Clients

Cursor, VS Code Copilot, ChatGPT Desktop, Windsurf - every MCP-compatible client follows the same pattern: point it at the URL with the x-brain-key header. Check their MCP docs for where to add remote HTTP servers with custom headers.

Use any connected platform naturally. Chat apps use slash commands, AI clients pick the right MCP tool automatically.

Making It Compound

The system is infrastructure. These prompts are the habits that make it compound. Use them in order the first week, then keep the weekly review as your Friday ritual.

Five Capture Templates

Type these into your chat apps or say them naturally in AI conversations. Each is structured to trigger the right classification in your processing pipeline.

If Something Goes Wrong

The Supabase dashboard has a built-in AI assistant (chat icon, bottom-right). It has access to all Supabase docs and can help with every Supabase-specific step.

Key Takeaways