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Koyd Apps

Turn an idea into a saved tool with its own interface, persistent data, optional server backend, and private AI assistant.

What a Koyd app is

A Koyd app has a browser interface and can include a TypeScript backend on your Koyd Server. It can be a small visualization, a project tool, or a more substantial interface. Backend code and durable records belong to the server; the app window is a client.

Create an app

  1. Ask an agent to build the tool you need in a project session. Koyd includes the koyd-apps-builder skill and authoring documentation.
  2. Preview the result and inspect its source. If it has a backend, enable the preview’s exact source revision before trying server features.
  3. Save the app with a name and description so it appears in Apps.
  4. For a saved app with a backend, enable the saved version in Apps. Preview and saved versions have separate execution approvals and backend identities.

Good to know · Changing source requires backend activation again. Imported source does not silently receive approval to execute. Client SDK capabilities are supplied by Koyd; the separate backend activation is not a per-action permission prompt.

Open your saved apps

  1. Open Apps in the workspace and select a saved tool. Selecting it shows its details and runtime controls without launching its interface.
  2. Choose Open app for a separate desktop window when supported, or Open here to run it inside Koyd.
  3. On phones, tablets, narrow screens, and when a window cannot open, Koyd uses the in-app view automatically.
  4. Choose Back to Koyd or press Escape in the in-app view to return to the existing chat and draft.

Browser tabs and installed PWAs use the same paired server connection. App windows stay attached to the instance they were opened from. Server features require that instance to remain running and reachable.

Edit, import, and share

Use /apps in a chat to load a saved app for editing. Loading restores its saved source snapshot; Koyd keeps the previous source folder in koyd-apps/.backups for recovery. The Apps library supports search, rename, import, and deletion. Resource exports share app source, not its runtime data or execution approvals.

Download app shortcut provides a link to the saved app on your current client. It still needs the correct server connection and browser pairing; it does not bundle the backend or install a standalone offline program.

Client and backend APIs

Apps use the supported Koyd app APIs for their interface and runtime features. A backend declares handlers and optional MCP tools with defineServer; the client calls those handlers through createServerClient. Backend source is excluded from the browser document. The built-in authoring guides cover the full SDK; a backend entry is server.ts or server/index.ts.

Private app AI has its own conversations and receives the app’s declared tools. It shares configured provider authentication through Koyd, but does not create ordinary project sessions or receive the entire coding toolset by default.

Client-only apps

An app can remain entirely in the browser when it does not need backend execution. Use server features when you need durable server work, backend dependencies, or private AI. A client-only preview should not be described as a persistent headless service.

Start, stop, and inspect

The app window and its tools attach to the same backend. Start headless keeps an app running without a window. Stop prevents automatic MCP restarts until you start it again. Inspect logs and restart controls in the app’s runtime controls.

Idle backends without windows, MCP consumers, or active work stop after five minutes. Stop running app backends and app AI work before a server update can restart the instance.

Use app tools in sessions

  1. Save an app with declared backend tools, enable its saved backend, and turn on Use tools in sessions.
  2. Select the app by name in /mcp, an agent’s configuration, or always-on MCP settings.
  3. Koyd can start the approved backend for tool use without opening its app window. The app interface and session tools use the same saved app backend and data.

Data and trust

App runtime data lives on the selected server. Preview and saved versions have separate backend data and AI histories. The legacy key-value storage API retains its shared storage ID. Resource exports include source, not local execution grants or runtime data. Removing an app revokes execution and stops its backend; durable runtime data remains on disk.

Good to know · An enabled Node backend can execute code on the server. Review untrusted app source and dependencies before enabling it.