feat(web-api): add recipient_team_id and recipient_user_id to chat.startStream method (#2377)

Author: mwbrooks

packages/web-api/src/types/request/chat.ts

@@ -223,7 +223,18 @@ export interface ChatStartStreamArguments
     Channel,
     Partial<ThreadTS>,
     Partial<MarkdownText>,
-    Unfurls {}
+    Unfurls {
+  /**
+   * @description The ID of the team that is associated with `recipient_user_id`.
+   * This is required when starting a streaming conversation outside of a DM.
+   */
+  recipient_team_id?: string;
+  /**
+   * @description The ID of the user to receive the streaming conversation messages.
+   * This is required when starting a streaming conversation outside of a DM.
+   */
+  recipient_user_id?: string;
+}
 
 export type ChatStopStreamArguments = TokenOverridable &
   ChannelAndTS &

packages/web-api/test/types/methods/chat.test-d.ts

@@ -608,6 +608,16 @@ expectAssignable<Parameters<typeof web.chat.startStream>>([
     unfurl_media: false,
   },
 ]);
+expectAssignable<Parameters<typeof web.chat.startStream>>([
+  {
+    channel: 'C1234',
+    markdown_text: 'hello',
+    unfurl_links: true,
+    unfurl_media: false,
+    recipient_team_id: 'T1234',
+    recipient_user_id: 'U1234',
+  },
+]);
 
 // chat.stopStream
 // -- sad path