fix(web-api): update thread_ts arg to be required for chat.startStream method (#2382)

Author: mwbrooks

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

@@ -218,12 +218,7 @@ export type ChatScheduledMessagesListArguments = OptionalArgument<
     Partial<Channel>
 >;
 
-export interface ChatStartStreamArguments
-  extends TokenOverridable,
-    Channel,
-    Partial<ThreadTS>,
-    Partial<MarkdownText>,
-    Unfurls {
+export interface ChatStartStreamArguments extends TokenOverridable, Channel, Partial<MarkdownText>, ThreadTS, 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.

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

@@ -588,21 +588,34 @@ expectAssignable<Parameters<typeof web.chat.scheduledMessages.list>>([]); // no
 // -- sad path
 expectError(web.chat.startStream()); // lacking argument
 expectError(web.chat.startStream({})); // empty argument
+expectError(
+  web.chat.startStream({
+    channel: 'C1234', // missing thread_ts
+  }),
+);
+expectError(
+  web.chat.startStream({
+    thread_ts: '1234.56', // missing channel
+  }),
+);
 // -- happy path
 expectAssignable<Parameters<typeof web.chat.startStream>>([
   {
     channel: 'C1234',
+    thread_ts: '1234.56',
   },
 ]);
 expectAssignable<Parameters<typeof web.chat.startStream>>([
   {
     channel: 'C1234',
+    thread_ts: '1234.56',
     markdown_text: 'hello',
   },
 ]);
 expectAssignable<Parameters<typeof web.chat.startStream>>([
   {
     channel: 'C1234',
+    thread_ts: '1234.56',
     markdown_text: 'hello',
     unfurl_links: true,
     unfurl_media: false,
@@ -611,6 +624,7 @@ expectAssignable<Parameters<typeof web.chat.startStream>>([
 expectAssignable<Parameters<typeof web.chat.startStream>>([
   {
     channel: 'C1234',
+    thread_ts: '1234.56',
     markdown_text: 'hello',
     unfurl_links: true,
     unfurl_media: false,