Fix mobile performance degradation during typing and after image upload

Memoize blob URL creation to prevent leak on every keystroke, wrap
MessageInput in React.memo with stable useCallback props, remove
expensive backdrop-blur-sm from chat footer, and use instant scroll
during streaming to avoid queuing smooth scroll animations.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

blueprints/conversation/__init__.py

@@ -3,7 +3,7 @@ import json
 import logging
 import uuid
 
-from quart import Blueprint, Response, jsonify, make_response, request
+from quart import Blueprint, jsonify, make_response, request
 from quart_jwt_extended import (
     get_jwt_identity,
     jwt_refresh_token_required,
@@ -12,6 +12,7 @@ from quart_jwt_extended import (
 import blueprints.users.models
 from utils.image_process import analyze_user_image
 from utils.image_upload import ImageValidationError, process_image
+from utils.s3_client import generate_presigned_url as s3_presigned_url
 from utils.s3_client import get_image as s3_get_image
 from utils.s3_client import upload_image as s3_upload_image
 
@@ -122,27 +123,14 @@ async def upload_image():
 
     await s3_upload_image(processed_bytes, key, output_content_type)
 
-    return jsonify(
-        {
-            "image_key": key,
-            "image_url": f"/api/conversation/image/{key}",
-        }
-    )
+    return jsonify({"image_key": key})
 
 
 @conversation_blueprint.get("/image/<path:image_key>")
 @jwt_refresh_token_required
 async def serve_image(image_key: str):
-    try:
-        image_bytes, content_type = await s3_get_image(image_key)
-    except Exception:
-        return jsonify({"error": "Image not found"}), 404
-
-    return Response(
-        image_bytes,
-        content_type=content_type,
-        headers={"Cache-Control": "private, max-age=3600"},
-    )
+    url = await s3_presigned_url(image_key)
+    return jsonify({"url": url})
 
 
 @conversation_blueprint.post("/stream-query")

raggr-frontend/src/api/conversationService.ts

@@ -125,7 +125,7 @@ class ConversationService {
   async uploadImage(
     file: File,
     conversationId: string,
-  ): Promise<{ image_key: string; image_url: string }> {
+  ): Promise<{ image_key: string }> {
     const formData = new FormData();
     formData.append("file", file);
     formData.append("conversation_id", conversationId);
@@ -147,8 +147,15 @@ class ConversationService {
     return await response.json();
   }
 
-  getImageUrl(imageKey: string): string {
-    return `/api/conversation/image/${imageKey}`;
+  async getPresignedImageUrl(imageKey: string): Promise<string> {
+    const response = await userService.fetchWithRefreshToken(
+      `${this.conversationBaseUrl}/image/${imageKey}`,
+    );
+    if (!response.ok) {
+      throw new Error("Failed to get image URL");
+    }
+    const data = await response.json();
+    return data.url;
   }
 
   async streamQuery(

raggr-frontend/src/components/ChatScreen.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState, useRef } from "react";
+import { useCallback, useEffect, useState, useRef } from "react";
 import { LogOut, Shield, PanelLeftClose, PanelLeftOpen, Menu, X } from "lucide-react";
 import { conversationService } from "../api/conversationService";
 import { userService } from "../api/userService";
@@ -63,9 +63,13 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
   const abortControllerRef = useRef<AbortController | null>(null);
   const simbaAnswers = ["meow.", "hiss...", "purrrrrr", "yowOWROWWowowr"];
 
-  const scrollToBottom = () => {
-    messagesEndRef.current?.scrollIntoView({ behavior: "smooth" });
-  };
+  const scrollToBottom = useCallback(() => {
+    requestAnimationFrame(() => {
+      messagesEndRef.current?.scrollIntoView({
+        behavior: isLoading ? "instant" : "smooth",
+      });
+    });
+  }, [isLoading]);
 
   useEffect(() => {
     isMountedRef.current = true;
@@ -130,7 +134,7 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
     load();
   }, [selectedConversation?.id]);
 
-  const handleQuestionSubmit = async () => {
+  const handleQuestionSubmit = useCallback(async () => {
     if ((!query.trim() && !pendingImage) || isLoading) return;
 
     let activeConversation = selectedConversation;
@@ -214,19 +218,22 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
       if (isMountedRef.current) setIsLoading(false);
       abortControllerRef.current = null;
     }
-  };
+  }, [query, pendingImage, isLoading, selectedConversation, simbaMode, messages, setAuthenticated]);
 
-  const handleQueryChange = (event: React.ChangeEvent<HTMLTextAreaElement>) => {
+  const handleQueryChange = useCallback((event: React.ChangeEvent<HTMLTextAreaElement>) => {
     setQuery(event.target.value);
-  };
+  }, []);
 
-  const handleKeyDown = (event: React.ChangeEvent<HTMLTextAreaElement>) => {
+  const handleKeyDown = useCallback((event: React.ChangeEvent<HTMLTextAreaElement>) => {
     const kev = event as unknown as React.KeyboardEvent<HTMLTextAreaElement>;
     if (kev.key === "Enter" && !kev.shiftKey) {
       kev.preventDefault();
       handleQuestionSubmit();
     }
-  };
+  }, [handleQuestionSubmit]);
+
+  const handleImageSelect = useCallback((file: File) => setPendingImage(file), []);
+  const handleClearImage = useCallback(() => setPendingImage(null), []);
 
   const handleLogout = () => {
     localStorage.removeItem("access_token");
@@ -380,8 +387,8 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
                 setSimbaMode={setSimbaMode}
                 isLoading={isLoading}
                 pendingImage={pendingImage}
-                onImageSelect={(file) => setPendingImage(file)}
-                onClearImage={() => setPendingImage(null)}
+                onImageSelect={handleImageSelect}
+                onClearImage={handleClearImage}
               />
             </div>
           </div>
@@ -416,7 +423,7 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
               </div>
             </div>
 
-            <footer className="border-t border-sand-light/40 bg-cream/80 backdrop-blur-sm">
+            <footer className="border-t border-sand-light/40 bg-cream">
               <div className="max-w-2xl mx-auto px-4 py-3">
                 <MessageInput
                   query={query}
@@ -425,6 +432,9 @@ export const ChatScreen = ({ setAuthenticated }: ChatScreenProps) => {
                   handleQuestionSubmit={handleQuestionSubmit}
                   setSimbaMode={setSimbaMode}
                   isLoading={isLoading}
+                  pendingImage={pendingImage}
+                  onImageSelect={(file) => setPendingImage(file)}
+                  onClearImage={() => setPendingImage(null)}
                 />
               </div>
             </footer>

raggr-frontend/src/components/MessageInput.tsx

@@ -1,4 +1,4 @@
-import { useRef, useState } from "react";
+import React, { useEffect, useMemo, useRef, useState } from "react";
 import { ArrowUp, ImagePlus, X } from "lucide-react";
 import { cn } from "../lib/utils";
 import { Textarea } from "./ui/textarea";
@@ -15,7 +15,7 @@ type MessageInputProps = {
   onClearImage: () => void;
 };
 
-export const MessageInput = ({
+export const MessageInput = React.memo(({
   query,
   handleKeyDown,
   handleQueryChange,
@@ -29,6 +29,18 @@ export const MessageInput = ({
   const [simbaMode, setLocalSimbaMode] = useState(false);
   const fileInputRef = useRef<HTMLInputElement>(null);
 
+  // Create blob URL once per file, revoke on cleanup
+  const previewUrl = useMemo(
+    () => (pendingImage ? URL.createObjectURL(pendingImage) : null),
+    [pendingImage],
+  );
+
+  useEffect(() => {
+    return () => {
+      if (previewUrl) URL.revokeObjectURL(previewUrl);
+    };
+  }, [previewUrl]);
+
   const toggleSimbaMode = () => {
     const next = !simbaMode;
     setLocalSimbaMode(next);
@@ -59,7 +71,7 @@ export const MessageInput = ({
         <div className="px-3 pt-3">
           <div className="relative inline-block">
             <img
-              src={URL.createObjectURL(pendingImage)}
+              src={previewUrl!}
               alt="Pending upload"
               className="h-20 rounded-lg object-cover border border-sand"
             />
@@ -145,4 +157,4 @@ export const MessageInput = ({
       </div>
     </div>
   );
-};
+});

raggr-frontend/src/components/QuestionBubble.tsx

@@ -1,3 +1,4 @@
+import { useEffect, useState } from "react";
 import { cn } from "../lib/utils";
 import { conversationService } from "../api/conversationService";
 
@@ -7,6 +8,20 @@ type QuestionBubbleProps = {
 };
 
 export const QuestionBubble = ({ text, image_key }: QuestionBubbleProps) => {
+  const [imageUrl, setImageUrl] = useState<string | null>(null);
+  const [imageError, setImageError] = useState(false);
+
+  useEffect(() => {
+    if (!image_key) return;
+    conversationService
+      .getPresignedImageUrl(image_key)
+      .then(setImageUrl)
+      .catch((err) => {
+        console.error("Failed to load image:", err);
+        setImageError(true);
+      });
+  }, [image_key]);
+
   return (
     <div className="flex justify-end message-enter">
       <div
@@ -17,9 +32,15 @@ export const QuestionBubble = ({ text, image_key }: QuestionBubbleProps) => {
           "shadow-sm shadow-leaf/10",
         )}
       >
-        {image_key && (
+        {imageError && (
+          <div className="flex items-center gap-2 text-xs text-charcoal/50 bg-charcoal/5 rounded-xl px-3 py-2 mb-2">
+            <span>🖼️</span>
+            <span>Image failed to load</span>
+          </div>
+        )}
+        {imageUrl && (
           <img
-            src={conversationService.getImageUrl(image_key)}
+            src={imageUrl}
             alt="Uploaded image"
             className="max-w-full rounded-xl mb-2"
           />

utils/s3_client.py

@@ -47,6 +47,16 @@ async def get_image(key: str) -> tuple[bytes, str]:
     return body, content_type
 
 
+async def generate_presigned_url(key: str, expires_in: int = 3600) -> str:
+    async with _get_client() as client:
+        url = await client.generate_presigned_url(
+            "get_object",
+            Params={"Bucket": S3_BUCKET_NAME, "Key": key},
+            ExpiresIn=expires_in,
+        )
+    return url
+
+
 async def delete_image(key: str) -> None:
     async with _get_client() as client:
         await client.delete_object(Bucket=S3_BUCKET_NAME, Key=key)