feat: add file drag and drop functionality to chat input

frontend/features/chat/components/app-chat-area.tsx

@@ -51,6 +51,14 @@ import { cn } from "@/lib/utils";
 const MODEL_OPTIONS_STORAGE_PREFIX = "deeix-chat:chat-model-options:";
 const EMPTY_CONVERSATION_OPTIONS: ConversationOptions = {};
 
+function dragEventContainsFiles(event: React.DragEvent<HTMLElement>): boolean {
+  return Array.from(event.dataTransfer.types ?? []).includes("Files");
+}
+
+function droppedFiles(event: React.DragEvent<HTMLElement>): File[] {
+  return Array.from(event.dataTransfer.files ?? []).filter((file) => file.name.trim() || file.size > 0);
+}
+
 function modelOptionsStorageKey(platformModelName: string): string {
   return `${MODEL_OPTIONS_STORAGE_PREFIX}${encodeURIComponent(platformModelName)}`;
 }
@@ -215,6 +223,8 @@ export function AppChatArea() {
   const [selectedToolIDs, setSelectedToolIDs] = React.useState<number[]>([]);
   const htmlVisualPrompt = useHTMLVisualPrompt();
   const initializedOptionsModelRef = React.useRef("");
+  const fileDragDepthRef = React.useRef(0);
+  const [fileDragActive, setFileDragActive] = React.useState(false);
 
   React.useEffect(() => {
     setSelectedToolIDs((current) => {
@@ -359,6 +369,7 @@ export function AppChatArea() {
     activeGenerationRunsRef,
   });
   const generating = sending || Boolean(resumingRunID);
+  const uploadDropDisabled = generating || loading || uploading;
   const showLiveAssistant = showPendingAssistant || Boolean(resumingRunID);
   const latestMessageKey = visibleMessages.at(-1)?.key ?? "";
   const onStopActiveMessage = React.useCallback(() => {
@@ -637,6 +648,59 @@ export function AppChatArea() {
   const selectedModelDefaultOptions = modelOptionPolicyDisabled
     ? EMPTY_CONVERSATION_OPTIONS
     : (selectedModel?.defaultOptions ?? EMPTY_CONVERSATION_OPTIONS);
+  const resetFileDragState = React.useCallback(() => {
+    fileDragDepthRef.current = 0;
+    setFileDragActive(false);
+  }, []);
+  const onFileDragEnter = React.useCallback((event: React.DragEvent<HTMLDivElement>) => {
+    if (!dragEventContainsFiles(event)) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    if (uploadDropDisabled) {
+      return;
+    }
+    fileDragDepthRef.current += 1;
+    setFileDragActive(true);
+  }, [uploadDropDisabled]);
+  const onFileDragOver = React.useCallback((event: React.DragEvent<HTMLDivElement>) => {
+    if (!dragEventContainsFiles(event)) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    event.dataTransfer.dropEffect = uploadDropDisabled ? "none" : "copy";
+  }, [uploadDropDisabled]);
+  const onFileDragLeave = React.useCallback((event: React.DragEvent<HTMLDivElement>) => {
+    if (!dragEventContainsFiles(event)) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    fileDragDepthRef.current = Math.max(0, fileDragDepthRef.current - 1);
+    if (fileDragDepthRef.current === 0) {
+      setFileDragActive(false);
+    }
+  }, []);
+  const onFileDrop = React.useCallback((event: React.DragEvent<HTMLDivElement>) => {
+    if (!dragEventContainsFiles(event)) {
+      return;
+    }
+    event.preventDefault();
+    event.stopPropagation();
+    const files = droppedFiles(event);
+    resetFileDragState();
+    if (uploadDropDisabled || files.length === 0) {
+      return;
+    }
+    void onUploadFiles(files);
+  }, [onUploadFiles, resetFileDragState, uploadDropDisabled]);
+  React.useEffect(() => {
+    if (uploadDropDisabled) {
+      resetFileDragState();
+    }
+  }, [resetFileDragState, uploadDropDisabled]);
 
   const chatInputProps = {
     draft,
@@ -661,6 +725,7 @@ export function AppChatArea() {
     defaultOptions: selectedModelDefaultOptions,
     modelOptionPolicy,
     modelLoading: modelsLoading,
+    dropActive: fileDragActive,
     onDraftChange: setDraft,
     onModelChange: setSelectedPlatformModelName,
     onSelectedToolsChange: setSelectedToolIDs,
@@ -679,7 +744,13 @@ export function AppChatArea() {
     !isConversationLoading && !isConversationLoadFailed && !isConversationMode && messagesWithInlineError.length === 0;
 
   return (
-    <div className="flex h-full min-h-0 w-full flex-1 flex-col overflow-hidden md:overflow-visible">
+    <div
+      className="relative flex h-full min-h-0 w-full flex-1 flex-col overflow-hidden md:overflow-visible"
+      onDragEnter={onFileDragEnter}
+      onDragOver={onFileDragOver}
+      onDragLeave={onFileDragLeave}
+      onDrop={onFileDrop}
+    >
       {shouldUseCenteredComposer ? (
         <div className="flex min-h-0 flex-1 flex-col overflow-hidden">
           <ChatEmptyState greetingTitle={greetingTitle}>

frontend/features/chat/components/sections/chat-input.tsx

@@ -76,6 +76,7 @@ type ChatInputProps = {
   modelOptionPolicy: ModelOptionPolicy | null;
   modelLoading: boolean;
   modelDisabled?: boolean;
+  dropActive?: boolean;
   onDraftChange: (value: string) => void;
   onModelChange: (platformModelName: string) => void;
   onSelectedToolsChange: (toolIDs: number[]) => void;
@@ -178,6 +179,7 @@ function ChatInputComponent({
   modelOptionPolicy,
   modelLoading,
   modelDisabled = false,
+  dropActive = false,
   onDraftChange,
   onModelChange,
   onSelectedToolsChange,
@@ -262,6 +264,7 @@ function ChatInputComponent({
       <InputGroup
         className={cn(
           "bg-pure rounded-3xl border-[0.5px] border-border/70 shadow-xs has-[[data-slot=input-group-control]:focus-visible]:ring-0 has-[[data-slot=input-group-control]:focus-visible]:border-border",
+          dropActive && "border-dashed border-foreground/30 bg-muted/20 shadow-none",
         )}
       >
         {attachments.length > 0 || uploadingAttachments.length > 0 ? (
@@ -379,11 +382,11 @@ function ChatInputComponent({
           value={draft}
           disabled={sending || loading || uploading}
           readOnly={speechInput.active}
-          placeholder={speechInput.placeholder}
+          placeholder={dropActive ? tChat("attachments.dropTitle") : speechInput.placeholder}
           rows={1}
           style={{ fontFamily: "var(--font-chat)", fontWeight: "var(--font-chat-weight)" }}
           className={cn(
-            "rounded-3xl min-h-12 overflow-y-auto px-5 pt-4 text-[15px] leading-6 placeholder:text-[15px] placeholder:font-[inherit] placeholder:leading-6",
+            "rounded-3xl min-h-12 overflow-y-auto px-5 pt-4 text-[15px] leading-6 placeholder:text-[inherit] placeholder:font-[inherit] placeholder:leading-[inherit]",
             inputHeightClassName,
             speechInput.active ? "placeholder:font-normal placeholder:text-muted-foreground" : "",
           )}

frontend/i18n/messages/en-US/chat.json

@@ -195,6 +195,7 @@
     "autoTruncatedDescription": "Kept the first {max} attachments and ignored {count} files over the limit.",
     "uploadFailed": "Upload failed",
     "uploadSignInRequired": "Sign in before uploading files.",
+    "dropTitle": "Drop files to attach",
     "duplicateReused": "Duplicate file detected and reused",
     "partialUploadFailed": "Some files failed to upload",
     "retryFailedFiles": "Please retry the failed files.",

frontend/i18n/messages/zh-CN/chat.json

@@ -195,6 +195,7 @@
     "autoTruncatedDescription": "最多保留前 {max} 个附件，已忽略 {count} 个超出上限的文件。",
     "uploadFailed": "上传失败",
     "uploadSignInRequired": "未登录，无法上传文件。",
+    "dropTitle": "松开以添加附件",
     "duplicateReused": "检测到文件重复，已复用",
     "partialUploadFailed": "部分文件上传失败",
     "retryFailedFiles": "请重试失败的文件。",