Apps

Apps are small, local-first applications that run inside Tanzanite. They use the window.tanzanite runtime to access the file system, sync peer-to-peer, and run AI on-device — without a server. Open Apps in the sidebar to browse and launch them from the gallery.

The Apps gallery and launcher.

The window.tanzanite runtime

Apps are static single-page apps that talk to a runtime the desktop shell injects:

• window.tanzanite.fs — read and write files in a folder the user grants.
• window.tanzanite.peer — WebRTC signaling for peer-to-peer sync between users in the same room.
• window.tanzanite.ai.local — on-device AI (text generation, and transcription when available) so prompts never leave the machine.

Local-first by design

Apps are built to work offline for a single user and to degrade gracefully when no peers are online. Shared state syncs through CRDTs (Yjs) over encrypted WebRTC data channels, and data at rest is encrypted (AES-GCM). Nothing leaves the machine except encrypted peer-to-peer blobs.

This model powers built-in experiences like the notes/PM workspace, where voice messages are transcribed on-device, summarized, organized into subjects, and shared between teammates — all without a backend.

Building an app

Apps can be created and edited inside Tanzanite with agent assistance. The agent can scaffold the app, wire it to the runtime, and iterate on it with you in a sandboxed preview.

Next steps

• Understand the rules agents follow in the Harness.
• For programmatic control of agents, see the SDK.