Do not create new chat session when an old chat session is deleted (#669)

### Issue
Previously deleting a chat session from the side panel on desktop, web app would sometimes result in also creating a new chat session

### Fix
  `get_conversation_by_user' shouldn't return new conversation if
  conversation with requested id not found.

  It should only return new conversation if no specific conversation
  is requested and no conversations found for user at all

### Miscellaneous Improvements
  - Chat history load should be logged as call to that chat_history api,
    not the "chat" api
  - Show status updates of clearing conversation history in chat input
  - Simplify web, desktop client code by removing unnecessary new variables

### Repro
  - Delete a new chat, this calls loadChat via window.onload which
    calls server /chat/history API endpoint with conversationId set to
    that of just deleted conversation sporadically

    The call to GET chat/history API with conversationId set occurs
    when window.onload triggers before the conversationId is deleted
    by the delete button after the DELETE /chat/history API call (via race)

  - In such a scenario, get_conversation_by_user called by
    chat/history API with conversationId of deleted conversation
    returns a new conversation

src/interface/desktop/chat.html

@@ -626,10 +626,9 @@
 
             let chatBody = document.getElementById("chat-body");
             chatBody.innerHTML = "";
-            let conversationId = chatBody.dataset.conversationId;
             let chatHistoryUrl = `/api/chat/history?client=desktop`;
-            if (conversationId) {
-                chatHistoryUrl += `&conversation_id=${conversationId}`;
+            if (chatBody.dataset.conversationId) {
+                chatHistoryUrl += `&conversation_id=${chatBody.dataset.conversationId}`;
             }
 
             fetch(`${hostURL}${chatHistoryUrl}`, { headers })
@@ -650,6 +649,8 @@
                         // Disable chat input field and update placeholder text
                         document.getElementById("chat-input").setAttribute("disabled", "disabled");
                         document.getElementById("chat-input").setAttribute("placeholder", "Configure Khoj to enable chat");
+                    } else if (data.status != "ok") {
+                        throw new Error(data.message);
                     } else {
                         // Set welcome message on load
                         renderMessage("Hey 👋🏾, what's up?", "khoj");
@@ -657,12 +658,9 @@
                     return data.response;
                 })
                 .then(response => {
-                    conversationId = response.conversation_id;
-                    const conversationTitle = response.slug || `New conversation 🌱`;
-
                     let chatBody = document.getElementById("chat-body");
-                    chatBody.dataset.conversationId = conversationId;
-                    chatBody.dataset.conversationTitle = conversationTitle;
+                    chatBody.dataset.conversationId = response.conversation_id;
+                    chatBody.dataset.conversationTitle = response.slug || `New conversation 🌱`;
 
                     const fullChatLog = response.chat || [];
 
@@ -791,7 +789,7 @@
                     chatBody.dataset.conversationId = "";
                     chatBody.dataset.conversationTitle = "";
                     loadChat();
-                    flashStatusInChatInput("🗑 Cleared conversation history");
+                    flashStatusInChatInput("🗑 Cleared previous conversation history");
                 })
                 .catch(err => {
                     flashStatusInChatInput("⛔️ Failed to clear conversation history");

src/khoj/database/adapters/__init__.py

@@ -405,9 +405,9 @@ class ConversationAdapters:
         else:
             conversation = (
                 Conversation.objects.filter(user=user, client=client_application).order_by("-updated_at").first()
-            )
+            ) or Conversation.objects.create(user=user, client=client_application)
 
-        return conversation or Conversation.objects.create(user=user, client=client_application)
+        return conversation
 
     @staticmethod
     def get_conversation_sessions(user: KhojUser, client_application: ClientApplication = None):

src/khoj/interface/web/chat.html

@@ -786,10 +786,9 @@ To get started, just start typing below. You can also type / to see a list of co
             let chatBody = document.getElementById("chat-body");
             chatBody.innerHTML = "";
             chatBody.classList.add("relative-position");
-            let conversationId = chatBody.dataset.conversationId;
             let chatHistoryUrl = `/api/chat/history?client=web`;
-            if (conversationId) {
-                chatHistoryUrl += `&conversation_id=${conversationId}`;
+            if (chatBody.dataset.conversationId) {
+                chatHistoryUrl += `&conversation_id=${chatBody.dataset.conversationId}`;
             }
 
             if (window.screen.width < 700) {
@@ -814,6 +813,8 @@ To get started, just start typing below. You can also type / to see a list of co
                         // Disable chat input field and update placeholder text
                         document.getElementById("chat-input").setAttribute("disabled", "disabled");
                         document.getElementById("chat-input").setAttribute("placeholder", "Configure Khoj to enable chat");
+                    } else if (data.status != "ok") {
+                        throw new Error(data.message);
                     } else {
                         // Set welcome message on load
                         renderMessage(welcome_message, "khoj");
@@ -822,12 +823,9 @@ To get started, just start typing below. You can also type / to see a list of co
                 })
                 .then(response => {
                     // Render conversation history, if any
-                    conversationId = response.conversation_id;
-                    const conversationTitle = response.slug || `New conversation 🌱`;
-
                     let chatBody = document.getElementById("chat-body");
-                    chatBody.dataset.conversationId = conversationId;
-                    chatBody.dataset.conversationTitle = conversationTitle;
+                    chatBody.dataset.conversationId = response.conversation_id;
+                    chatBody.dataset.conversationTitle = response.slug || `New conversation 🌱`;
 
                     let chatBodyWrapper = document.getElementById("chat-body-wrapper");
                     const fullChatLog = response.chat || [];
@@ -1050,9 +1048,10 @@ To get started, just start typing below. You can also type / to see a list of co
                                             chatBody.dataset.conversationId = "";
                                             chatBody.dataset.conversationTitle = "";
                                             loadChat();
+                                            flashStatusInChatInput("🗑 Cleared previous conversation history");
                                         })
                                         .catch(err => {
-                                            return;
+                                            flashStatusInChatInput("⛔️ Failed to clear conversation history");
                                         });
                                 });
                                 conversationMenu.appendChild(deleteButton);

src/khoj/routers/api_chat.py

@@ -75,8 +75,13 @@ def chat_history(
         user=user, client_application=request.user.client_app, conversation_id=conversation_id
     )
 
-    meta_log = conversation.conversation_log
+    if conversation is None:
+        return Response(
+            content=json.dumps({"status": "error", "message": f"Conversation: {conversation_id} not found"}),
+            status_code=404,
+        )
 
+    meta_log = conversation.conversation_log
     meta_log.update(
         {"conversation_id": conversation.id, "slug": conversation.title if conversation.title else conversation.slug}
     )
@@ -84,7 +89,7 @@ def chat_history(
     update_telemetry_state(
         request=request,
         telemetry_type="api",
-        api="chat",
+        api="chat_history",
         **common.__dict__,
     )