The four product pillars of @cai.com - email, wallet, vault, agent surface

Four things come with a free @cai.com email. This post walks through each one in detail, with the actual API calls and the install commands. If you read the launch post first, this is the deep-dive; if you didn't, this stands alone.

1. The email itself

A real inbox at @cai.com. Send and receive mail like any other address. The signup gives you the address; the dashboard gives you the SMTP/IMAP credentials if you want to use a desktop client.

The mail surface is exposed to agents via the CAI API. An agent can read and summarize mail on your behalf (POST /mail-chat), send mail (POST /send-email), and fetch structured summaries (POST /mail-summarize-actions). Every read and every send is a scoped API call, gated on your API key and your confirmation pattern for outbound messages.

2. The custodial multi-chain stablecoin wallet

A custodial wallet means you do not hold the private key. CAI holds it. You get a @cai.com address on each of six chains, and can pay, transfer, convert, and bridge from any of them. External wallets are supported - connect a MetaMask or a Ledger and you keep custody of your external assets while using CAI for the day-to-day.

The wallet API (per cai.com/skill.md):

# Check balances on one or more chains
curl -X POST https://api.cai.com/functions/v1/get-wallet-balances \
  -H "Authorization: Bearer ***" \
  -H "Content-Type: application/json" \
  -d '{"chains": ["base", "polygon"]}'

# Send a payment (returns a hosted-action URL for user confirmation)
curl -X POST https://api.cai.com/functions/v1/wallet-custodial-transfer \
  -H "Authorization: Bearer ***" \
  -H "Content-Type: application/json" \
  -d '{
    "to_address": "0x...",
    "amount": "10.00",
    "chain": "base",
    "token": "USDC"
  }'

The response to wallet-custodial-transfer includes a hosted-action URL. The user opens it, taps once, and the payment goes through. The agent polls GET /transfer-status for the receipt.

The wallet is custodial. That word does a lot of work, and it matters. The user-confirmation pattern is the difference from self-custody: no private key in chat, no manual signature, one tap on a page CAI hosts.

$200/day auto-limit while CAI completes its security audit. New recipients and new devices always require confirmation. Think of it like cash in your pocket -- perfect for daily spending. The vault product (multi-sig, time-locks) is coming for larger balances.

3. The user vault for site credentials

The vault is for your site credentials - the logins and passwords you have scattered across a hundred sites. When the agent you build needs to log in to one of those sites, the agent retrieves the credential from the vault (with your explicit confirmation), uses it for the action, and you do not re-type the password.

The vault is not for the agent's API key. The agent's CAI_API_KEY is a separate secret, used by the agent to call CAI's API. Storing it in the vault is a circular dependency. The vault is for the third-party sites the agent logs in to on your behalf.

The vault API (per cai.com/skill.md §6.3):

# Save a site credential (user action)
curl -X POST https://api.cai.com/functions/v1/user-site-credentials \
  -H "Authorization: Bearer ***" \
  -H "Content-Type: application/json" \
  -d '{
    "origin_url": "https://example.com",
    "kind": "password",
    "payload": {
      "username": "alice",
      "password": "..."
    }
  }'

# List saved credentials (metadata only, no decrypted payload)
curl -X GET https://api.cai.com/functions/v1/user-site-credentials \
  -H "Authorization: Bearer ***"

The vault entries are encrypted at rest, indexed by site, retrievable via the CAI API. You can revoke any vault entry from the account dashboard.

4. The agent surface

For the agent you build (or the agent you use), the surface is the MCP server, the contract, and the API.

The install:

npm i -g @cailab/mcp

The contract: cai.com/skill.md - the canonical source-of-truth, written in a format agents parse.

The discovery surface for other agents: cai.com/.well-known/agent.json - the A2A Agent Card.

The API: https://api.cai.com/functions/v1 - the HTTPS Edge API. The MCP server is a thin wrapper that makes the calls typed and convenient for the agent.

The MCP server drops into any MCP host: OpenClaw, Hermes, Codex, Cursor. Once installed, the agent's tool surface includes CAI. The agent's first call is GET /get-identity to confirm the user has a CAI account; if they don't, the agent can show them the signup URL.

The agent surface next

If you want the API surface, cai.com/skill.md is the canonical source. The signup flow at cai.com/app is four steps, about 2 minutes, no card.

Apply at cai.com/app. The npm package is on the npm registry. The contract is at cai.com/skill.md.

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If you tried any of the four product pillars in this article

Comment below with:

1. What you ran - the install command, the request, the MCP host config. Copy the actual command or request.
2. What you expected - one sentence.
3. What you got - the error message, the empty response, the unexpected behavior. Paste it verbatim.
4. Your environment - OS, Node version, the MCP host (OpenClaw / Hermes / Codex / Cursor / other), the CAI account tier if relevant.

Every comment on this article gets read. Bug reports will be replied to within 24 hours. Friction points shape what we document next.

Documentation: cai.com/skill.md · cai.com/developers.html · cai.com/app to sign up.