SimpleChatTCRV:DivStreams: Prepared for switching in middle

Missing DivStream caught. Logic ready for a distant future,
where one may allow the chat session to be switched even
if there is a pending ai server / tool call response.

Avoids the unneeded removeChild before calling appendChild.

Also found the reason why sometimes the DivStream was missing
from DivChat. Rather when I switched from the transient <p>
element to the persistant session specific <div> elements,
I had forgotten to convert the flow fully, rather I had
forgotten to replace the elP.remove() with elP.replaceChildren

Also retaining that debug log wrt missing DivStream path, Just
in case for now, to cross check once later, I havent missed
any other path.

tools/server/public_simplechat/readme.md

@@ -467,6 +467,10 @@ The following tools/functions are currently provided by default
   * helps ai to process stuff that it needs, without having to worry about any previous chat history
     etal messing with the current data's processing.
   * helps ai to process stuff with targeted system prompts of its choosing, for the job at hand.
+  * tool calling is disabled wrt the external_ai's independent session, for now.
+    * it was noticed that else even the external_ai may call into more external_ai calls trying to
+      find answer to the same question. maybe one can enable tool calling, while explicitly disabling
+      external_ai tool call from within external_ai tool call or so ...
   * Could be used by ai for example to
     * summarise a large text content, where it could use the context of the text to generate a
       suitable system prompt for summarising things suitably
@@ -854,6 +858,11 @@ Cleanup in general
 * Use popover ui to allow user to view larger versions of loaded images as well as remove before submitting
   to ai, if and when needed.
 * add external_ai toolcall
+* maintain chat session specific DivStream elements, so that in future, if the logic is updated to allow
+  switching in the middle of a pending tool call or pending ai server response, things dont mess up wrt
+  ui, as they will be updating their respective DivStream and switching sessions will also take care of
+  making the right DivStream the currently active one, so that end user can see the streamed response
+  as it is occuring.
 
 
 #### ToDo

tools/server/public_simplechat/simplechat.js

@@ -919,7 +919,7 @@ class SimpleChat {
                 }
             }
         } finally {
-            elP.remove()
+            elP.replaceChildren()
         }
         console.debug("DBUG:SC:PART:Full:", this.latestResponse.content_equiv());
         return ChatMessageEx.newFrom(this.latestResponse);
@@ -1509,13 +1509,10 @@ class MultiChatUI {
                 this.show_message(this.elDivChat, msg, (i-1), nextMsg)
             }
         }
-        try {
+        if (!this.elDivChat.contains(this.elDivStreams[chatId])) {
-            this.elDivChat.removeChild(this.elDivStreams[chatId])
+            console.log(`DBUG:SimpleChat:MCUI:UiRefresh:${chatId}: DivStream ${this.elDivStreams[chatId].id} missing...`)
-        } catch {
-            console.log(`DBUG:SimpleChat:MCUI:UiRefresh:Removing ${chatId} DivStream ${this.elDivStreams[chatId].id} failed...`)
-        } finally {
-            this.elDivChat.appendChild(this.elDivStreams[chatId])
         }
+        this.elDivChat.appendChild(this.elDivStreams[chatId])
         if (this.elLastChatMessage != null) {
             this.scroll_el_into_view(this.elLastChatMessage)
         }