Wallet & Credits

Philosophy

Mu is a tool, not a destination. Like Google Search in 2000 — you arrive with intent, get what you need, and leave.

Credits are a straightforward way to pay for what you use. No dark patterns, no pressure to upgrade, no “unlimited” tiers that incentivize us to maximize your engagement.

• Free tier: 10 AI queries/day - enough for casual utility use
• Pay-as-you-go: Deposit crypto, use credits when you need more
• Self-host: Run your own instance for free, forever

We charge because LLMs and APIs cost money. Here’s our actual cost breakdown — we’re not extracting margin, just covering infrastructure.

How It Works

Credits

• 1 credit = £0.01 GBP (1 penny)
• Credits stored as integers to avoid floating-point issues
• Top up via crypto deposit (Ethereum, Base, Arbitrum, Optimism)
• Credits never expire

Daily Free Quota

Every registered user gets 10 free AI queries per day:

• Resets at midnight UTC
• Covers news search, video search, and chat AI queries
• No payment required

This should be enough if you’re using Mu as a utility. If you need more, pay-as-you-go.

Credit Costs

Note: Internal messages (user-to-user within Mu) are free. Only external email (to addresses outside Mu) costs credits.

Who Pays What

Why No “Unlimited” Tier?

Unlimited tiers create misaligned incentives. If you pay a flat fee for unlimited usage, we’re incentivized to make you use Mu more to feel you’re getting value. That’s the seed of engagement optimization.

Pay-as-you-go keeps us honest: we want to build efficient tools that solve your problem quickly, not sticky products that maximize your screen time.

If you want truly unlimited and free — self-host. The code is open source.

Crypto Deposits

How It Works

1. Go to /wallet/deposit
2. Select your network (Ethereum, Base, Arbitrum, or Optimism)
3. You’ll see your unique deposit address and QR code
4. Send ETH, USDC, or any ERC-20 token
5. Deposits are detected automatically (~30 seconds)
6. Credits added based on current exchange rate

Supported Networks

• Ethereum - Mainnet
• Base - Coinbase L2
• Arbitrum - Arbitrum One
• Optimism - OP Mainnet

Same address works on all networks.

Supported Tokens

• ETH - Native token
• USDC - USD Coin
• ERC-20 - Any token on supported networks

Important

• Select the correct network before sending
• Your address is the same on all networks
• Minimum deposit: ~$1 equivalent
• Deposits typically confirm within 1-2 minutes

Why Crypto?

• No credit cards, no KYC forms, no payment processor gatekeeping
• Works globally without bank restrictions
• You control your funds until you deposit
• Aligns with Mu philosophy: decentralized, no middlemen

Data Model

Wallet

type Wallet struct {
    UserID    string    `json:"user_id"`
    Balance   int       `json:"balance"`    // Credits (pennies)
    Currency  string    `json:"currency"`   // "GBP"
    UpdatedAt time.Time `json:"updated_at"`
}

Transaction

type Transaction struct {
    ID        string                 `json:"id"`
    UserID    string                 `json:"user_id"`
    Type      string                 `json:"type"`      // "topup", "spend", "refund"
    Amount    int                    `json:"amount"`    // Positive for topup, negative for spend
    Balance   int                    `json:"balance"`   // Balance after transaction
    Operation string                 `json:"operation"` // e.g., "news_search", "topup"
    Metadata  map[string]interface{} `json:"metadata"`
    CreatedAt time.Time              `json:"created_at"`
}

Daily Usage

type DailyUsage struct {
    UserID   string `json:"user_id"`
    Date     string `json:"date"`     // "2006-01-02"
    Searches int    `json:"searches"` // Free queries used today
}

Crypto Wallet

type CryptoWallet struct {
    UserID       string    `json:"user_id"`
    AddressIndex uint32    `json:"address_index"` // BIP32 derivation index
    Address      string    `json:"address"`       // Derived ETH address
    CreatedAt    time.Time `json:"created_at"`
}

API Endpoints

Environment Variables

# Crypto Wallet (optional)
# If not set, seed is auto-generated and saved to ~/.mu/keys/wallet.seed
WALLET_SEED="24 word mnemonic phrase"

# Base RPC endpoint (optional)
BASE_RPC_URL="https://mainnet.base.org"

# Quota (optional - these are defaults)
FREE_DAILY_SEARCHES="10"
CREDIT_COST_NEWS="1"
CREDIT_COST_NEWS_SUMMARY="1"
CREDIT_COST_VIDEO="2"
CREDIT_COST_VIDEO_WATCH="0"
CREDIT_COST_CHAT="3"

Implementation

HD Wallet

Mu uses an HD (Hierarchical Deterministic) wallet to derive unique deposit addresses per user:

• Master seed stored in ~/.mu/keys/wallet.seed (or WALLET_SEED env var)
• BIP44 derivation path: m/44'/60'/0'/0/{index}
• Index 0 = treasury address
• Each user gets a deterministic index based on their user ID

Quota Check Flow

1. User initiates search/chat
2. Check if admin → allow (no charge)
3. Check daily free quota → allow if available, decrement
4. Check wallet balance → allow if sufficient, deduct credits
5. Otherwise → show “quota exceeded” with options

Deposit Detection (Coming Soon)

1. Poll Base RPC for incoming transactions to user addresses
2. Detect ETH transfers and ERC-20 Transfer events
3. Fetch current token price from price oracle
4. Calculate credits and add to wallet
5. Record transaction with tx hash

Security

• Wallet seed file has 0600 permissions (owner read/write only)
• Never log seed or private keys
• Full transaction audit trail
• Never allow negative balance
• Deposit addresses derived deterministically (no key storage per user)