Drag a file. Hold Shift. Done.

A letter you don't understand, a receipt for your expenses, a booking to put in your calendar, a PDF in a language you don't read. Each one used to mean another app, another upload, another subscription. With Koi you drag the file, hold Shift, and a wheel opens round your pointer. Drop it on what you want done.

1. Start dragging any file, from Finder or the desktop.
2. While you hold it, press Shift. The wheel opens round the pointer.
3. Move onto a wedge and let go. The middle says which one you're on.

Drop a bill, a contract, a tax letter or test results on Explain. Koi opens a call and tells you, out loud, what it is and what you need to do, with the date or the amount that matters. Then ask anything: “what happens if I pay late?” or “can I complain about this?”. It answers from the file's own words.

The explanation is kept as a page too: the gist, what to do, what to watch out for (a fee, a renewal, a deadline in the small print) and the file's words below. Any date in it is offered for your calendar, to add with a click.

Drop a receipt, an invoice or a bill on Add expense. Koi reads who you paid, the total and how often, and adds it to your expense tracker. A photo of a paper receipt works as well as a PDF: pictures are read on your Mac first.

Drop a flight confirmation, a hotel booking, a ticket or a letter with a deadline on Add to calendar. Koi finds the dates and offers them beside the dock: the flight at its departure time in its own time zone, the hotel's check-in and check-out, a payment due on its day. Pick the ones you want, and they go into Koi's calendar.

Drop a PDF, a Word file, slides or a photo of a page on Translate, and it comes back as a page of Koi's own in your language, a page of the file at a time. Edit it, export it to Word or PDF, or share it.

What it doesn't do, up front: it keeps the paragraphs, lists and headings but not the file's exact layout. A form with boxes and columns comes back as plain text.

Drop anything on Read aloud and your Mac reads it to you, with the best voice installed for its language. A card beside the dock stops it. Nothing is sent anywhere.

• Read aloud: nothing. Your Mac's own voices read it.
• Explain, Translate, Add expense and Add to calendar: the file's words, read on your Mac, go to Koi's AI with your clock and time zone. Never the file itself.
• What comes back is kept only on your Mac: a page, an expense, or dates you add.
• Settings, Koi, Shift wheel for files turns it off.

The Shift wheel is part of Koi, on every plan. Pro is $20 a month, or $192 a year, after a 3-day free trial that needs a card. Lifetime is paid once, from $59. See the plans, or read how to use the Shift wheel step by step.