Start a self-serve purchase of an order (quote_billing_subscription_order first: the same body). DANGEROUS (charges money): a Paddle transaction is pre-created with one item per line and result carries the checkout the buyer pays in the Paddle overlay (the SPA opens it with client_side_token and paddle_environment). The recurring lines become one subscription with one renewal date; one-time credits ride this first payment only, and alone they make no subscription. team_sid names the workspace that gets the WHOLE pool on activation (its trial is released); omit it to buy floating and allocate by hand. A workspace already on a live paid subscription is refused (409 team_already_covered: change that subscription instead), unless the order is one-time credits alone. The row is born on the activated webhook: poll search afterwards. Owner only.

Contract:

• MCP tool create_billing_subscription_checkout, registry package mcp.id/billing_subscriptions, mount id.billing.
• Operation action, response envelope action.
• Flags: dangerous: the MCP layer gates it behind a preview/commit token, and the effect cannot be undone through this API.