Add drag-and-drop file upload, fix project creation modal and API endpoints

- Add file upload to Overleaf projects via multipart POST with correct
  "name" text field (server reads filename from req.body.name, not from
  Content-Disposition filename)
- Add drag-and-drop support in file tree panel with visual feedback
- Replace window.prompt() with custom modal for new project creation
  (prompt() returns null in Electron)
- Fix API endpoints: /api/project/new → /project/new

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

4 files changed, 99 insertions, 6 deletions

diff --git a/src/renderer/src/App.css b/src/renderer/src/App.css
index 63dc8bf..c6d8126 100644
--- a/src/renderer/src/App.css
+++ b/src/renderer/src/App.css
@@ -303,6 +303,11 @@ html, body, #root {
   background: var(--bg-secondary);
   user-select: none;
 }
+.file-tree-dragover {
+  outline: 2px dashed #4ECDA0;
+  outline-offset: -2px;
+  background: rgba(78, 205, 160, 0.08);
+}
 
 .file-tree-header {
   display: flex;
diff --git a/src/renderer/src/App.tsx b/src/renderer/src/App.tsx
index df9e251..869bdae 100644
--- a/src/renderer/src/App.tsx
+++ b/src/renderer/src/App.tsx
@@ -53,6 +53,17 @@ export default function App() {
 
   const [checkingSession, setCheckingSession] = useState(true)
 
+  // Prevent Electron from navigating to dropped files
+  useEffect(() => {
+    const prevent = (e: DragEvent) => e.preventDefault()
+    document.addEventListener('dragover', prevent)
+    document.addEventListener('drop', prevent)
+    return () => {
+      document.removeEventListener('dragover', prevent)
+      document.removeEventListener('drop', prevent)
+    }
+  }, [])
+
   // Check session on startup
   useEffect(() => {
     window.api.overleafHasWebSession().then(({ loggedIn }) => {
diff --git a/src/renderer/src/components/FileTree.tsx b/src/renderer/src/components/FileTree.tsx
index 0dda560..a95b0c3 100644
--- a/src/renderer/src/components/FileTree.tsx
+++ b/src/renderer/src/components/FileTree.tsx
@@ -263,6 +263,51 @@ export default function FileTree() {
     closeMenu()
   }
 
+  const [dragOver, setDragOver] = useState(false)
+
+  const handleDragOver = useCallback((e: React.DragEvent) => {
+    e.preventDefault()
+    e.stopPropagation()
+    setDragOver(true)
+  }, [])
+
+  const handleDragLeave = useCallback((e: React.DragEvent) => {
+    e.preventDefault()
+    e.stopPropagation()
+    setDragOver(false)
+  }, [])
+
+  const handleDrop = useCallback(async (e: React.DragEvent) => {
+    e.preventDefault()
+    e.stopPropagation()
+    setDragOver(false)
+
+    const projectId = useAppStore.getState().overleafProjectId
+    const folderId = useAppStore.getState().rootFolderId
+    if (!projectId || !folderId) return
+
+    const droppedFiles = e.dataTransfer.files
+    if (droppedFiles.length === 0) return
+
+    for (let i = 0; i < droppedFiles.length; i++) {
+      const file = droppedFiles[i]
+      const filePath = window.api.getPathForFile(file)
+      const fileName = file.name
+
+      useAppStore.getState().setStatusMessage(`Uploading ${fileName}...`)
+      const result = await window.api.uploadFileToProject(projectId, folderId, filePath, fileName)
+      if (result.success) {
+        useAppStore.getState().setStatusMessage(`Uploaded ${fileName}`)
+      } else {
+        useAppStore.getState().setStatusMessage(`Upload failed: ${result.message}`)
+        return
+      }
+    }
+
+    // Refresh file tree
+    await reconnectProject(projectId)
+  }, [])
+
   const handleOpenInOverleaf = () => {
     const projectId = useAppStore.getState().overleafProjectId
     if (projectId) {
@@ -272,7 +317,12 @@ export default function FileTree() {
   }
 
   return (
-    <div className="file-tree">
+    <div
+      className={`file-tree${dragOver ? ' file-tree-dragover' : ''}`}
+      onDragOver={handleDragOver}
+      onDragLeave={handleDragLeave}
+      onDrop={handleDrop}
+    >
       <div className="file-tree-header">
         <span>FILES</span>
       </div>
diff --git a/src/renderer/src/components/ProjectList.tsx b/src/renderer/src/components/ProjectList.tsx
index a3c9c37..58a6bb0 100644
--- a/src/renderer/src/components/ProjectList.tsx
+++ b/src/renderer/src/components/ProjectList.tsx
@@ -30,6 +30,8 @@ export default function ProjectList({ onOpenProject }: Props) {
   const [busyText, setBusyText] = useState('')
   const [sortBy, setSortBy] = useState<SortKey>('lastUpdated')
   const [sortOrder, setSortOrder] = useState<SortOrder>('desc')
+  const [showNewProject, setShowNewProject] = useState(false)
+  const [newProjectName, setNewProjectName] = useState('Untitled Project')
   const { setStatusMessage } = useAppStore()
 
   const loadProjects = useCallback(async () => {
@@ -76,18 +78,20 @@ export default function ProjectList({ onOpenProject }: Props) {
   }
 
   const handleCreateProject = async () => {
-    const name = prompt('Project name:', 'Untitled Project')
-    if (!name?.trim()) return
+    const name = newProjectName.trim()
+    if (!name) return
 
+    setShowNewProject(false)
     setError('')
     setBusy(true)
     setBusyText('Creating project...')
 
-    const result = await window.api.overleafCreateProject(name.trim())
+    const result = await window.api.overleafCreateProject(name)
     setBusy(false)
 
     if (result.success && result.projectId) {
-      setStatusMessage(`Created "${name.trim()}"`)
+      setStatusMessage(`Created "${name}"`)
+      setNewProjectName('Untitled Project')
       loadProjects()
     } else {
       setError(result.message || 'Failed to create project')
@@ -225,7 +229,7 @@ export default function ProjectList({ onOpenProject }: Props) {
                 placeholder="Search projects..."
                 autoFocus
               />
-              <button className="btn btn-primary btn-sm" onClick={handleCreateProject}>
+              <button className="btn btn-primary btn-sm" onClick={() => setShowNewProject(true)}>
                 New Project
               </button>
               <button className="btn btn-secondary btn-sm" onClick={handleUploadProject}>
@@ -284,6 +288,29 @@ export default function ProjectList({ onOpenProject }: Props) {
           </>
         )}
       </div>
+      {showNewProject && (
+        <div className="modal-overlay" onClick={() => setShowNewProject(false)}>
+          <div className="modal-box" onClick={(e) => e.stopPropagation()}>
+            <h3 style={{ margin: '0 0 12px' }}>New Project</h3>
+            <input
+              type="text"
+              className="projects-search"
+              value={newProjectName}
+              onChange={(e) => setNewProjectName(e.target.value)}
+              onKeyDown={(e) => {
+                if (e.key === 'Enter') handleCreateProject()
+                if (e.key === 'Escape') setShowNewProject(false)
+              }}
+              autoFocus
+              style={{ width: '100%', marginBottom: 12 }}
+            />
+            <div style={{ display: 'flex', gap: 8, justifyContent: 'flex-end' }}>
+              <button className="btn btn-secondary btn-sm" onClick={() => setShowNewProject(false)}>Cancel</button>
+              <button className="btn btn-primary btn-sm" onClick={handleCreateProject}>Create</button>
+            </div>
+          </div>
+        </div>
+      )}
     </div>
   )
 }