add stuff about reasoning

Author: justschen

release-notes/images/1_106/reasoning.png

@@ -235,6 +235,19 @@ Edit Prompt File works with prompts that have an associated file, including user
 
 We changed the default behavior of the agent to no longer automatically open edited files in an editor. If you prefer the previous behavior, you can enable the setting `setting(accessibility.openChatEditedFiles)`.
 
+### Reasoning in Chat (Experimental)
+
+**Setting**: `setting(chat.agent.thinkingStyle)`, `setting(chat.agent.thinking.collapsedTools)`
+
+Last iteration, we added the `setting(chat.agent.thinkingStyle)` setting which enabled displaying thinking tokens in chat. This is now available in more models! As of this release, GPT-5-Codex, GPT-5, GPT-5 mini, and Gemini 2.5 Pro support this.
+
+The `setting(chat.agent.thinkingStyle)` has been adjusted to 3 more common styles, with `fixedScrolling` as the default which will show the most recent chain of thoughts.
+
+An additional setting, `setting(chat.agent.thinking.collapsedTools)` will add tool calls into the collapsible thinking UI.
+
+![Screenshot showing reasoning tokens displayed in chat with interweaved tool cals and reasoning output. This is the UI with `fixedScrolling` and `readOnly` for the respective thinking settings.](images/1_106/reasoning.png)
+
+
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