# Deftlet `deft/stdext/deftlet` is the panel-app module contract. It separates module loading from instantiation: a panel file imports deftlet, declares `implements Deftlet`, and exports `get-panel` (plus optional `get-menu` / `get-margins`). Importing it also opts the panel into the debug-attach protocol.

import "deft/stdext/deftlet"

## Contract | Method | Signature | Description | |---|---|---| | `get-panel` | `{||}` | Return the Panel value to mount (build state, spawn coroutines here) | | `get-menu` | `{||}` | Return the app's menu map (optional) | | `get-margins` | `{||}` | `%{ left right top bottom }` margins (optional) |

import "deft/stdext/deftlet"

def get-panel {||
    # init state, spawn coroutines…
    %MyView{ label "My App" }
}

Every shipping app in the tree is written this way — see the App Platform chapter for the panel model and the Editor help for a large real example. ## Debug Attach Importing deftlet transitively imports debug-host and subscribes the panel to `debug-attach-request` and `debug-detach`, forwarding to the real handlers. The result: any deftlet-based panel can be attached to by the shell/editor debugger without extra wiring — the shell publishes an attach request with the target panel id, the panel starts a debug server, and announces its port. ## See Also - App Platform — workspaces and panel apps - Debugging — the attach protocol, client and host - Debug server — the JSON-RPC protocol