fix: require valid project directory for session creation

- Backend: POST /api/chat/sessions now validates working_directory
  exists (400 MISSING_DIRECTORY / INVALID_DIRECTORY)
- db.ts: remove process.cwd() fallback in createSession
- ChatListPanel: validate last-working-directory before use,
  open FolderPicker when invalid; add SSR guard for localStorage
- NewChatPage: block sending without a project directory selected

Bump version to 0.10.5.

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

Author: 7418

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "codepilot",
-  "version": "0.10.4",
+  "version": "0.10.5",
   "private": true,
   "author": {
     "name": "op7418",

package.json

@@ -1,4 +1,5 @@
 import { NextRequest } from 'next/server';
+import fs from 'fs/promises';
 import { getAllSessions, createSession } from '@/lib/db';
 import type { CreateSessionRequest, SessionsResponse, SessionResponse } from '@/types';
 
@@ -17,6 +18,25 @@ export async function GET() {
 export async function POST(request: NextRequest) {
   try {
     const body: CreateSessionRequest = await request.json();
+
+    // Validate working_directory is provided
+    if (!body.working_directory) {
+      return Response.json(
+        { error: 'Working directory is required', code: 'MISSING_DIRECTORY' },
+        { status: 400 },
+      );
+    }
+
+    // Validate directory actually exists on disk
+    try {
+      await fs.access(body.working_directory);
+    } catch {
+      return Response.json(
+        { error: 'Directory does not exist', code: 'INVALID_DIRECTORY' },
+        { status: 400 },
+      );
+    }
+
     const session = createSession(
       body.title,
       body.model,

src/app/api/chat/sessions/route.ts

@@ -78,6 +78,20 @@ export default function NewChatPage() {
     async (content: string) => {
       if (isStreaming) return;
 
+      // Require a project directory before sending
+      if (!workingDir.trim()) {
+        const hint: Message = {
+          id: 'hint-' + Date.now(),
+          session_id: '',
+          role: 'assistant',
+          content: '**Please select a project directory first.** Use the folder picker in the toolbar below to choose a working directory before sending a message.',
+          created_at: new Date().toISOString(),
+          token_usage: null,
+        };
+        setMessages((prev) => [...prev, hint]);
+        return;
+      }
+
       setIsStreaming(true);
       setStreamingContent('');
       setToolUses([]);
@@ -90,14 +104,12 @@ export default function NewChatPage() {
       let sessionId = '';
 
       try {
-        // Create a new session with optional working directory
+        // Create a new session with working directory
         const createBody: Record<string, string> = {
           title: content.slice(0, 50),
           mode,
+          working_directory: workingDir.trim(),
         };
-        if (workingDir.trim()) {
-          createBody.working_directory = workingDir.trim();
-        }
 
         const createRes = await fetch('/api/chat/sessions', {
           method: 'POST',

src/app/chat/page.tsx

@@ -53,6 +53,7 @@ function formatRelativeTime(dateStr: string): string {
 const COLLAPSED_PROJECTS_KEY = "codepilot:collapsed-projects";
 
 function loadCollapsedProjects(): Set<string> {
+  if (typeof window === 'undefined') return new Set();
   try {
     const raw = localStorage.getItem(COLLAPSED_PROJECTS_KEY);
     if (raw) return new Set(JSON.parse(raw));
@@ -129,27 +130,45 @@ export function ChatListPanel({ open, width }: ChatListPanelProps) {
   const [creatingChat, setCreatingChat] = useState(false);
 
   const handleNewChat = useCallback(async () => {
-    const lastDir = localStorage.getItem("codepilot:last-working-directory");
+    const lastDir = typeof window !== 'undefined'
+      ? localStorage.getItem("codepilot:last-working-directory")
+      : null;
+
     if (!lastDir) {
-      router.push("/chat");
+      // No saved directory — let user pick one
+      setFolderPickerOpen(true);
       return;
     }
+
+    // Validate the saved directory still exists
     setCreatingChat(true);
     try {
+      const checkRes = await fetch(
+        `/api/files/browse?dir=${encodeURIComponent(lastDir)}`
+      );
+      if (!checkRes.ok) {
+        // Directory is gone — clear stale value and prompt user
+        localStorage.removeItem("codepilot:last-working-directory");
+        setFolderPickerOpen(true);
+        return;
+      }
+
       const res = await fetch("/api/chat/sessions", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify({ working_directory: lastDir }),
       });
       if (!res.ok) {
-        router.push("/chat");
+        // Backend rejected it (e.g. INVALID_DIRECTORY) — prompt user
+        localStorage.removeItem("codepilot:last-working-directory");
+        setFolderPickerOpen(true);
         return;
       }
       const data = await res.json();
       router.push(`/chat/${data.session.id}`);
       window.dispatchEvent(new CustomEvent("session-created"));
     } catch {
-      router.push("/chat");
+      setFolderPickerOpen(true);
     } finally {
       setCreatingChat(false);
     }

src/components/layout/ChatListPanel.tsx

@@ -229,7 +229,7 @@ export function createSession(
   const db = getDb();
   const id = crypto.randomBytes(16).toString('hex');
   const now = new Date().toISOString().replace('T', ' ').split('.')[0];
-  const wd = workingDirectory || process.cwd();
+  const wd = workingDirectory || '';
   const projectName = path.basename(wd);
 
   db.prepare(