Snaps: add snap_getInterfaceContext (#1772)

* Add `snap_getInterfaceContext` method

* Reference `snap_getInterfaceContext` from Custom UI feature page

* Add to what's new

* combine state and context sections

---------

Co-authored-by: Alexandra Tran <[email protected]>

Author: Montoya

docs/whats-new.md

@@ -9,6 +9,11 @@ The latest major MetaMask documentation updates are listed by the month they wer
 For a comprehensive list of recent product changes, visit the "Release Notes" section at the bottom
 of the [MetaMask developer page](https://metamask.io/developer/).
 
+## December 2024
+
+- Documented [`snap_getInterfaceContext`](/snaps/reference/snaps-api/#snap_getinterfacecontext).
+  ([#1772](https://github.com/MetaMask/metamask-docs/pull/1772))
+
 ## November 2024
 
 - Documented [Unichain Sepolia](/services/reference/unichain) support. ([#1725](https://github.com/MetaMask/metamask-docs/pull/1725))

snaps/features/custom-ui/interactive-ui.md

@@ -58,11 +58,13 @@ The following is an example flow:
 5. Custom logic sends the funds.
 6. `snap_updateInterface` is called again, replacing the whole UI with a success message.
 
-## Get an interactive interface's state
+## Get an interactive interface's state and context
 
-At any point you can retrieve an interactive interface's state.
-To do this, call the [`snap_getInterfaceState`](../../reference/snaps-api.md#snap_getinterfacestate)
-method with the ID of the interface.
+At any point, you can retrieve an interactive interface's state and context.
+To retrieve its state, call the [`snap_getInterfaceState`](../../reference/snaps-api.md#snap_getinterfacestate)
+method with the interface ID.
+To retrieve its context, call [`snap_getInterfaceContext`](../../reference/snaps-api.md#snap_getinterfacecontext)
+with the interface ID.
 
 ## Example
 

snaps/reference/snaps-api.md

@@ -986,6 +986,52 @@ console.log(state)
 */
 ```
 
+### `snap_getInterfaceContext`
+
+Gets the context of an interactive interface by its ID.
+For use in [interactive UI](../features/custom-ui/interactive-ui.md).
+
+#### Parameters
+
+- `id` - The ID of the interface.
+
+#### Returns
+
+An object of type `InterfaceContext` if a custom context object was passed when creating or updating the interface, or `null`.
+
+#### Example
+
+```js title="index.js"
+const interfaceId = await snap.request({
+  method: "snap_createInterface",
+  params: {
+    ui: (
+      <Box>
+        <Heading>Hello, world!</Heading>
+        <Text>Welcome to my Snap homepage!</Text>
+      </Box>
+    ),
+    context: { 
+      key: "value"
+    }
+  },
+})
+
+const context = await snap.request({
+  method: "snap_getInterfaceContext",
+  params: {
+    id: interfaceId,
+  },
+})
+
+console.log(context)
+/*
+{
+  "key": "value"
+}
+*/
+```
+
 ### `snap_resolveInterface`
 
 Resolves an interactive interface.