feat: add drag-and-drop image upload and improve image previews

- Add FileDropZone component with overlay for web drag-and-drop
- Add useFileDropZone hook using native addEventListener for web
- Wire up drag-drop to agent screen to add images to input
- Improve image preview styling with visible border
- Show X button on hover with dark overlay for removal

🤖 Generated with [Claude Code](https://claude.com/claude-code)

packages/app/src/app/agent/[serverId]/[agentId].tsx

@@ -41,6 +41,8 @@ import { AgentStreamView } from "@/components/agent-stream-view";
 import { AgentInputArea } from "@/components/agent-input-area";
 import { ImportAgentModal } from "@/components/create-agent-modal";
 import { ExplorerSidebar } from "@/components/explorer-sidebar";
+import { FileDropZone } from "@/components/file-drop-zone";
+import type { ImageAttachment } from "@/components/message-input";
 import {
   ExplorerSidebarAnimationProvider,
   useExplorerSidebarAnimation,
@@ -183,6 +185,15 @@ function AgentScreenContent({
   const [menuContentHeight, setMenuContentHeight] = useState(0);
   const menuButtonRef = useRef<View>(null);
   const [showImportAgentModal, setShowImportAgentModal] = useState(false);
+  const addImagesRef = useRef<((images: ImageAttachment[]) => void) | null>(null);
+
+  const handleFilesDropped = useCallback((files: ImageAttachment[]) => {
+    addImagesRef.current?.(files);
+  }, []);
+
+  const handleAddImagesCallback = useCallback((addImages: (images: ImageAttachment[]) => void) => {
+    addImagesRef.current = addImages;
+  }, []);
 
   const { isOpen: isExplorerOpen, toggle: toggleExplorer, open: openExplorer, close: closeExplorer } = useExplorerSidebarStore();
   const {
@@ -672,6 +683,7 @@ function AgentScreenContent({
 
   const mainContent = (
     <View style={styles.outerContainer}>
+      <FileDropZone onFilesDropped={handleFilesDropped} disabled={isInitializing}>
       <View style={styles.container}>
         {/* Header */}
         <MenuHeader
@@ -735,7 +747,7 @@ function AgentScreenContent({
 
           {/* Agent Input Area */}
           {!isInitializing && agent && resolvedAgentId && (
-            <AgentInputArea agentId={resolvedAgentId} serverId={serverId} autoFocus />
+            <AgentInputArea agentId={resolvedAgentId} serverId={serverId} autoFocus onAddImages={handleAddImagesCallback} />
           )}
 
         {/* Dropdown Menu */}
@@ -899,6 +911,7 @@ function AgentScreenContent({
           </View>
         </Modal>
         </View>
+      </FileDropZone>
 
         {/* Explorer Sidebar - Desktop: inline, Mobile: overlay */}
         {!isMobile && isExplorerOpen && resolvedAgentId && (

packages/app/src/components/agent-input-area.tsx

@@ -46,6 +46,8 @@ interface AgentInputAreaProps {
   onChangeText?: (text: string) => void;
   /** When true, auto-focuses the text input on web. */
   autoFocus?: boolean;
+  /** Callback to expose the addImages function to parent components */
+  onAddImages?: (addImages: (images: ImageAttachment[]) => void) => void;
 }
 
 const EMPTY_ARRAY: readonly QueuedMessage[] = [];
@@ -68,6 +70,7 @@ export function AgentInputArea({
   value,
   onChangeText,
   autoFocus = false,
+  onAddImages,
 }: AgentInputAreaProps) {
   const { theme } = useUnistyles();
   const insets = useSafeAreaInsets();
@@ -130,6 +133,15 @@ export function AgentInputArea({
   const sendAgentMessageRef = useRef(sendAgentMessage);
   const onSubmitMessageRef = useRef(onSubmitMessage);
 
+  // Expose addImages function to parent for drag-and-drop support
+  const addImages = useCallback((images: ImageAttachment[]) => {
+    setSelectedImages((prev) => [...prev, ...images]);
+  }, []);
+
+  useEffect(() => {
+    onAddImages?.(addImages);
+  }, [addImages, onAddImages]);
+
   const submitMessage = useCallback(
     async (text: string, images?: ImageAttachment[]) => {
       if (onSubmitMessageRef.current) {

packages/app/src/components/file-drop-zone.tsx

@@ -0,0 +1,95 @@
+import { View, Text, Platform } from "react-native";
+import { StyleSheet, useUnistyles } from "react-native-unistyles";
+import Animated, {
+  useAnimatedStyle,
+  withTiming,
+  useSharedValue,
+} from "react-native-reanimated";
+import { useEffect } from "react";
+import { Upload } from "lucide-react-native";
+import { useFileDropZone } from "@/hooks/use-file-drop-zone";
+import type { ImageAttachment } from "./message-input";
+
+interface FileDropZoneProps {
+  children: React.ReactNode;
+  onFilesDropped: (files: ImageAttachment[]) => void;
+  disabled?: boolean;
+}
+
+const IS_WEB = Platform.OS === "web";
+
+export function FileDropZone({
+  children,
+  onFilesDropped,
+  disabled = false,
+}: FileDropZoneProps) {
+  const { theme } = useUnistyles();
+  const { isDragging, containerRef } = useFileDropZone({
+    onFilesDropped,
+    disabled,
+  });
+
+  const overlayOpacity = useSharedValue(0);
+
+  useEffect(() => {
+    overlayOpacity.value = withTiming(isDragging ? 1 : 0, { duration: 150 });
+  }, [isDragging, overlayOpacity]);
+
+  const overlayAnimatedStyle = useAnimatedStyle(() => ({
+    opacity: overlayOpacity.value,
+    pointerEvents: overlayOpacity.value > 0 ? "auto" : "none",
+  }));
+
+  // On non-web platforms, just render children
+  if (!IS_WEB) {
+    return <>{children}</>;
+  }
+
+  return (
+    <View
+      // Cast ref for web - View renders as div on web
+      ref={containerRef as unknown as React.RefObject<View>}
+      style={styles.container}
+    >
+      {children}
+
+      {/* Drop overlay */}
+      <Animated.View style={[styles.overlay, overlayAnimatedStyle]}>
+        {/* Backdrop */}
+        <View style={styles.backdrop} />
+        {/* Content */}
+        <View style={styles.overlayContent}>
+          <Upload size={32} color={theme.colors.primary} />
+          <Text style={styles.overlayText}>Drop images here</Text>
+        </View>
+      </Animated.View>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create((theme) => ({
+  container: {
+    flex: 1,
+    position: "relative",
+  },
+  overlay: {
+    ...StyleSheet.absoluteFillObject,
+    alignItems: "center",
+    justifyContent: "center",
+    zIndex: 1000,
+  },
+  backdrop: {
+    ...StyleSheet.absoluteFillObject,
+    backgroundColor: theme.colors.background,
+    opacity: 0.7,
+  },
+  overlayContent: {
+    alignItems: "center",
+    gap: theme.spacing[2],
+  },
+  overlayText: {
+    fontSize: theme.fontSize.base,
+    fontWeight: theme.fontWeight.medium,
+    color: theme.colors.foreground,
+  },
+}));

packages/app/src/components/message-input.tsx

@@ -426,20 +426,30 @@ export function MessageInput({
         {hasImages && (
           <View style={styles.imagePreviewContainer}>
             {images.map((image, index) => (
-              <View key={`${image.uri}-${index}`} style={styles.imagePill}>
-                <Image
-                  source={{ uri: image.uri }}
-                  style={styles.imageThumbnail}
-                />
-                {onRemoveImage && (
-                  <Pressable
-                    onPress={() => onRemoveImage(index)}
-                    style={styles.removeImageButton}
-                  >
-                    <X size={16} color={theme.colors.foreground} />
-                  </Pressable>
+              <Pressable
+                key={`${image.uri}-${index}`}
+                style={styles.imagePill}
+                onPress={onRemoveImage ? () => onRemoveImage(index) : undefined}
+              >
+                {({ hovered }) => (
+                  <>
+                    <Image
+                      source={{ uri: image.uri }}
+                      style={styles.imageThumbnail}
+                    />
+                    {onRemoveImage && (
+                      <View
+                        style={[
+                          styles.removeImageButton,
+                          (hovered || !IS_WEB) && styles.removeImageButtonVisible,
+                        ]}
+                      >
+                        <X size={16} color="white" />
+                      </View>
+                    )}
+                  </>
                 )}
-              </View>
+              </Pressable>
             ))}
           </View>
         )}
@@ -591,23 +601,40 @@ const styles = StyleSheet.create(((theme: any) => ({
     flexWrap: "wrap",
   },
   imagePill: {
-    flexDirection: "row",
-    alignItems: "center",
-    backgroundColor: theme.colors.muted,
-    borderRadius: theme.borderRadius.lg,
-    padding: theme.spacing[1],
-    gap: theme.spacing[2],
+    position: "relative",
+    borderRadius: theme.borderRadius.md,
+    borderWidth: 1,
+    borderColor: theme.colors.accentBorder,
+    overflow: "hidden",
+    ...(IS_WEB
+      ? {
+          cursor: "pointer",
+        }
+      : {}),
   },
   imageThumbnail: {
-    width: 40,
-    height: 40,
-    borderRadius: theme.borderRadius.md,
+    width: 48,
+    height: 48,
   },
   removeImageButton: {
-    width: 24,
-    height: 24,
+    position: "absolute",
+    top: 0,
+    left: 0,
+    right: 0,
+    bottom: 0,
     alignItems: "center",
     justifyContent: "center",
+    backgroundColor: "rgba(0, 0, 0, 0.5)",
+    opacity: 0,
+    ...(IS_WEB
+      ? {
+          transitionProperty: "opacity",
+          transitionDuration: "150ms",
+        }
+      : {}),
+  },
+  removeImageButtonVisible: {
+    opacity: 1,
   },
   textInput: {
     width: "100%",

packages/app/src/hooks/use-file-drop-zone.ts

@@ -0,0 +1,144 @@
+import { useState, useCallback, useRef, useEffect } from "react";
+import { Platform } from "react-native";
+import type { ImageAttachment } from "@/components/message-input";
+
+interface UseFileDropZoneOptions {
+  onFilesDropped: (files: ImageAttachment[]) => void;
+  disabled?: boolean;
+}
+
+interface UseFileDropZoneReturn {
+  isDragging: boolean;
+  containerRef: React.RefObject<HTMLElement | null>;
+}
+
+const IS_WEB = Platform.OS === "web";
+
+function isImageFile(file: File): boolean {
+  return file.type.startsWith("image/");
+}
+
+async function fileToImageAttachment(file: File): Promise<ImageAttachment> {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+    reader.onload = () => {
+      if (typeof reader.result === "string") {
+        resolve({
+          uri: reader.result,
+          mimeType: file.type || "image/jpeg",
+        });
+      } else {
+        reject(new Error("Failed to read file as data URL"));
+      }
+    };
+    reader.onerror = () => reject(reader.error);
+    reader.readAsDataURL(file);
+  });
+}
+
+export function useFileDropZone({
+  onFilesDropped,
+  disabled = false,
+}: UseFileDropZoneOptions): UseFileDropZoneReturn {
+  const [isDragging, setIsDragging] = useState(false);
+  const containerRef = useRef<HTMLElement | null>(null);
+  const dragCounterRef = useRef(0);
+  const onFilesDroppedRef = useRef(onFilesDropped);
+
+  // Keep callback ref up to date
+  useEffect(() => {
+    onFilesDroppedRef.current = onFilesDropped;
+  }, [onFilesDropped]);
+
+  // Reset drag state when disabled changes
+  useEffect(() => {
+    if (disabled) {
+      setIsDragging(false);
+      dragCounterRef.current = 0;
+    }
+  }, [disabled]);
+
+  // Set up event listeners on web
+  useEffect(() => {
+    if (!IS_WEB) return;
+
+    const element = containerRef.current;
+    if (!element) return;
+
+    function handleDragEnter(e: DragEvent) {
+      e.preventDefault();
+      e.stopPropagation();
+
+      if (disabled) return;
+
+      dragCounterRef.current++;
+      if (e.dataTransfer?.types.includes("Files")) {
+        setIsDragging(true);
+      }
+    }
+
+    function handleDragOver(e: DragEvent) {
+      e.preventDefault();
+      e.stopPropagation();
+
+      if (disabled) return;
+
+      if (e.dataTransfer) {
+        e.dataTransfer.dropEffect = "copy";
+      }
+    }
+
+    function handleDragLeave(e: DragEvent) {
+      e.preventDefault();
+      e.stopPropagation();
+
+      if (disabled) return;
+
+      dragCounterRef.current--;
+      if (dragCounterRef.current === 0) {
+        setIsDragging(false);
+      }
+    }
+
+    async function handleDrop(e: DragEvent) {
+      e.preventDefault();
+      e.stopPropagation();
+
+      setIsDragging(false);
+      dragCounterRef.current = 0;
+
+      if (disabled) return;
+
+      const files = Array.from(e.dataTransfer?.files ?? []);
+      const imageFiles = files.filter(isImageFile);
+
+      if (imageFiles.length === 0) return;
+
+      try {
+        const attachments = await Promise.all(
+          imageFiles.map(fileToImageAttachment)
+        );
+        onFilesDroppedRef.current(attachments);
+      } catch (error) {
+        console.error("[useFileDropZone] Failed to process dropped files:", error);
+      }
+    }
+
+    element.addEventListener("dragenter", handleDragEnter);
+    element.addEventListener("dragover", handleDragOver);
+    element.addEventListener("dragleave", handleDragLeave);
+    element.addEventListener("drop", handleDrop);
+
+    return () => {
+      element.removeEventListener("dragenter", handleDragEnter);
+      element.removeEventListener("dragover", handleDragOver);
+      element.removeEventListener("dragleave", handleDragLeave);
+      element.removeEventListener("drop", handleDrop);
+    };
+  }, [disabled]);
+
+  return {
+    isDragging,
+    containerRef,
+  };
+}