fix: default to user home dir when no workDir selected on new session

Previously, creating a new session without selecting a project directory
defaulted to process.cwd(), which in the desktop app resolves to the app
installation path. Now it defaults to os.homedir().

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

desktop/src/api/sessions.ts

@@ -30,8 +30,8 @@ export const sessionsApi = {
     return api.get<MessagesResponse>(`/api/sessions/${sessionId}/messages`)
   },
 
-  create(workDir: string) {
-    return api.post<CreateSessionResponse>('/api/sessions', { workDir })
+  create(workDir?: string) {
+    return api.post<CreateSessionResponse>('/api/sessions', workDir ? { workDir } : {})
   },
 
   delete(sessionId: string) {

desktop/src/stores/sessionStore.ts

@@ -48,7 +48,7 @@ export const useSessionStore = create<SessionStore>((set, get) => ({
   },
 
   createSession: async (workDir?: string) => {
-    const { sessionId: id } = await sessionsApi.create(workDir ?? '.')
+    const { sessionId: id } = await sessionsApi.create(workDir || undefined)
     // Refresh session list
     await get().fetchSessions()
     set({ activeSessionId: id })

src/server/api/sessions.ts

@@ -154,8 +154,8 @@ async function createSession(req: Request): Promise<Response> {
     throw ApiError.badRequest('Invalid JSON body')
   }
 
-  if (!body.workDir || typeof body.workDir !== 'string') {
-    throw ApiError.badRequest('workDir (string) is required in request body')
+  if (body.workDir && typeof body.workDir !== 'string') {
+    throw ApiError.badRequest('workDir must be a string')
   }
 
   const result = await sessionService.createSession(body.workDir)

src/server/services/sessionService.ts

@@ -470,13 +470,12 @@ export class SessionService {
   /**
    * Create a new session file for the given working directory.
    */
-  async createSession(workDir: string): Promise<{ sessionId: string }> {
-    if (!workDir) {
-      throw ApiError.badRequest('workDir is required')
-    }
+  async createSession(workDir?: string): Promise<{ sessionId: string }> {
+    // Default to user home directory when no workDir specified
+    const resolvedWorkDir = workDir || os.homedir()
 
     // Resolve to absolute path
-    const absWorkDir = path.resolve(workDir)
+    const absWorkDir = path.resolve(resolvedWorkDir)
     let stat
     try {
       stat = await fs.stat(absWorkDir)

src/server/ws/handler.ts

@@ -8,6 +8,7 @@
 
 import type { ServerWebSocket } from 'bun'
 import type { ClientMessage, ServerMessage } from './events.js'
+import * as os from 'node:os'
 import {
   ConversationStartupError,
   conversationService,
@@ -152,7 +153,7 @@ async function handleUserMessage(
   message: Extract<ClientMessage, { type: 'user_message' }>
 ) {
   const { sessionId } = ws.data
-  let workDir = process.cwd()
+  let workDir = os.homedir()
 
   // Send thinking status
   sendMessage(ws, { type: 'status', state: 'thinking', verb: 'Thinking' })