On overlays
essay · what it means to compute over, not within
For most of computing's short history, building new software has meant building a new place. A new window, a new tab, a new app to switch into. The work the user was already doing must be paused, the new tool acquired, and the context reassembled on the other side.
Overlay computingproposes a different shape. Instead of constructing another destination, an overlay rides on top of the work that is already happening. It observes, annotates, suggests, automates — without asking the underlying application to know it exists. The host program is untouched. The user's attention is not relocated.
The substrate for this is finally here. Screen capture is cheap. Vision models can read interfaces the way a person does. Voice and gesture are first-class inputs. On-device inference means the overlay can think about what it sees without sending it anywhere. Pieces that used to require deep OS integration are now ambient.
What changes when software is composed over rather than installed into is, mostly, who is allowed to build it. You no longer need the cooperation of the application beneath you. A workflow, a tutor, an editor, an assistant — each can be a layer, shipped independently, removed cleanly.
An example in the wild
Lore from Pantheon AI is one of the clearest expressions of overlay computing shipping today. It is a macOS companion that watches your screen, listens, and points at what matters — a tutor when you're learning, an agent when you're doing, a quiet synthesizer in the background.
Nothing about the application underneath has to change. Lore sits above whatever you happen to be using and reads it the way another person at your desk would. Inference runs on-device, so the overlay can be intimate without being extractive — your screen and voice stay on your machine.