Three steps from work-done to money-in.
1. Generate: /billing → pick client → "Generate invoice". Pulls all un-invoiced time + events + the monthly retainer into one draft invoice.
2. Send: click "Email →" on the invoice row. Enter the recipient (defaults to the client's contact email). They get a clean branded email with a "View invoice" button and (if Stripe is configured) a "Pay now" button.
3. Collect: if you've connected Stripe, click "Create pay link" — that opens a hosted Stripe Checkout page. When they pay, the webhook marks the invoice as paid automatically.
Manual payment: if they pay by bank transfer or cheque, click "Mark paid" on the invoice row.
Customer view: every invoice has a public URL at /invoices/[id] that's print-friendly. Recipients with the link can save it as PDF (Cmd-P → Save as PDF) — but they cannot see anything else in your workspace.