Cels

Cels are floating glass notes for macOS 26. Each one is a small pane of Liquid Glass that lives above your windows: drag it anywhere, pin it across Spaces, or stick it to a terminal window and let it follow. And because Cels listens to a local inbox, your tools can write to a note while you work — a terminal posting its working directory, an agent posting what it just finished.

What's in the app

• Liquid Glass notes. True macOS 26 glass — translucent, edge-lit, refracting whatever is underneath. Not a yellow rectangle pretending to be paper.
• One hotkey. A global shortcut conjures a new Cel at your cursor. Type, click away, done.
• Three-axis presence. Always-on-top is universal. Fading when unfocused and appearing on every Space are independent per-note toggles, so each Cel behaves the way that note needs to.
• Window attachment. Stick a Cel to another app's window and it follows, with motion fades that keep the tracking calm. Attachment health is managed automatically; stale attachments get cleaned up.
• Terminal-aware. Attached to a Ghostty window, a Cel knows the session, title, and working directory it's riding along with.
• A local inbox for your tools. The celsctl CLI and an optional zsh hook post structured updates — titles, fields, notes — straight onto a Cel. Terminals and AI agents become note-writers.
• Position memory that survives display changes. Cels remember which display they live on and restore to the right relative position when your setup changes.
• Menu bar quiet. No Dock icon. Cels stays out of the way, which is the entire point.

Why the studio built this

Sticky-note apps treat notes as documents. The studio wanted something closer to a heads-up display: small, glanceable surfaces that hold what you're juggling right now — and that your tools can write to. The breakthrough use is agentic work. When a terminal or an AI agent runs something long, a Cel attached to that window becomes its status surface: what's running, where, what just finished. The note stops being a thing you maintain and becomes a thing that maintains itself.

How it was made

Native SwiftUI and SwiftData on macOS 26, Swift 6.2 with strict concurrency, windows hosted as borderless floating panels. The glass is the platform's own glassEffect, not a custom shader. Window attachment rides the accessibility system with a reconciliation engine for terminal metadata. Notes persist locally; the schema carries field-level timestamps so sync can ship later without a migration — and it ships only when it meets a zero-data-loss bar. The inbox protocol is plain JSON files in a local folder: inspectable, scriptable, and entirely on your machine.

Frequently asked

What is a Cel?

A small translucent note window made of macOS 26 Liquid Glass. It floats above your other windows, you drag it where you want it, and it stays. Plain text, smart links, no formatting ceremony.

How do Cels stick to other windows?

Through the macOS accessibility system. An attached Cel follows its window with soft motion fades so the tracking feels physical. Terminal attachment goes deepest: a Cel on a Ghostty window knows the session, its title, and its working directory.

What is the local inbox protocol?

Cels watches a local folder for small JSON updates. The bundled celsctl tool and an optional zsh hook write to it, so your terminal or an AI agent can post structured status onto a Cel in real time. Everything stays on your Mac.

Does Cels sync between Macs?

Not yet. Notes persist locally in SwiftData today. The data model was designed for sync from day one, and iCloud sync ships only when it passes the studio's zero-data-loss bar. Cels does remember positions per display, so notes restore correctly across multi-display setups.

Is Cels available now?

Cels is in beta on macOS 26. Request an invite with the form above; you'll get one email, nothing else.