feat: introduce webxdc.isAppSender and webxdc.isBroadcast

This allows apps to behave differently, dependeing on the sending context.

Author: hpk42

src-docs/spec/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [1.4] - 2026-04-16
+
+### New APIs
+
+- add `webxdc.isAppSender` and `webxdc.isBroadcast` to allow apps to determine
+  their role and if they are in a broadcast chat
+
 ## [1.3] - 2026-02-11
 
 ### Other changes

src-docs/spec/messenger.md

@@ -54,6 +54,9 @@ When starting a web view for a webxdc app to run, messenger implementors
 
 - MUST support `<meta name="viewport" ...>` is useful especially as webviews from different platforms have different defaults
 
+- MUST support `window.webxdc.isAppSender` and `window.webxdc.isBroadcast`
+  to allow apps to determine their role and if they are in a broadcast chat.
+
 - MUST support `<input type="file">` to allow importing of files;
   see [`sendToChat()`](../spec/sendToChat.md) for a way to export files. 
 

src-docs/spec/selfAddr_and_selfName.md

@@ -32,6 +32,24 @@ Note that `selfAddr`
 - should not be shown in the user interface of the webxdc application
   (use `selfName` instead). 
 
+## isAppSender
+
+```js
+window.webxdc.isAppSender
+```
+
+`isAppSender` is a boolean value that is `true` if the local user is the one
+who initially shared the webxdc application in the chat.
+If it is `false`, the user is a receiver.
+
+## isBroadcast
+
+```js
+window.webxdc.isBroadcast
+```
+
+`isBroadcast` is a boolean value that is `true` if the webxdc
+application is shared in a broadcast chat context.
 
 
 ## Example using selfAddr and selfName

src-docs/webxdc.d.ts

@@ -72,6 +72,10 @@ interface Webxdc<T> {
   selfAddr: string;
   /** Returns the peer's own name. This is name chosen by the user in their settings, if there is nothing set, that defaults to the peer's address. */
   selfName: string;
+  /** True if the current user is the sender of this webxdc app. */
+  isAppSender: boolean;
+  /** True if the current user is in a broadcast chat. */
+  isBroadcast: boolean;
   /**
    * set a listener for new status updates.
    * The "serial" specifies the last serial that you know about (defaults to 0).