error modal + fix dev mode to use embedded Python and data dir

electron/main/index.ts

@@ -48,10 +48,13 @@ app.setName('Modly')
 
 process.on('uncaughtException', (err) => {
   logger.error(`Uncaught exception: ${err.stack ?? err.message}`)
+  mainWindow?.webContents.send('app:error', err.stack ?? err.message)
 })
 
 process.on('unhandledRejection', (reason) => {
-  logger.error(`Unhandled rejection: ${String(reason)}`)
+  const msg = String(reason)
+  logger.error(`Unhandled rejection: ${msg}`)
+  mainWindow?.webContents.send('app:error', msg)
 })
 
 app.whenReady().then(async () => {

electron/main/ipc-handlers.ts

@@ -32,9 +32,8 @@ export function setupIpcHandlers(pythonBridge: PythonBridge, getWindow: WindowGe
 
   // Setup handlers — skipped in dev (uses .venv instead of python-embed)
   ipcMain.handle('setup:check', async () => {
-    const defaultDataDir = join(app.getPath('documents'), 'LocalMeshy')
-    if (!app.isPackaged) return { needed: false, defaultDataDir }
     const userData = app.getPath('userData')
+    const defaultDataDir = join(app.getPath('documents'), 'Modly')
     return { needed: checkSetupNeeded(userData), defaultDataDir }
   })
 

electron/main/python-bridge.ts

@@ -186,19 +186,14 @@ export class PythonBridge {
       : join(app.getAppPath(), 'resources')
     const userData = app.getPath('userData')
 
-    const candidates = app.isPackaged
-      ? [
-          join(resourcesPath, 'python-embed', 'python.exe'),  // Windows embeddable
-          join(userData, 'venv', 'bin', 'python'),             // Linux/macOS venv (packaged)
-          'python3',
-          'python',
-        ]
-      : [
-          join(apiDir, '.venv', 'Scripts', 'python.exe'), // Windows venv (dev)
-          join(apiDir, '.venv', 'bin', 'python'),          // Unix/Mac venv (dev)
-          'python',
-          'python3',
-        ]
+    const candidates = [
+      join(resourcesPath, 'python-embed', 'python.exe'),  // Windows embedded (dev + packaged)
+      join(userData, 'venv', 'bin', 'python'),             // Linux/macOS venv
+      join(apiDir, '.venv', 'Scripts', 'python.exe'),      // legacy dev fallback
+      join(apiDir, '.venv', 'bin', 'python'),              // legacy dev fallback
+      'python3',
+      'python',
+    ]
 
     for (const candidate of candidates) {
       if (existsSync(candidate)) {

electron/preload/index.ts

@@ -79,7 +79,11 @@ contextBridge.exposeInMainWorld('electron', {
   // App metadata
   app: {
     info: (): Promise<{ version: string; userData: string; modelsDir: string; apiUrl: string }> =>
-      ipcRenderer.invoke('app:info')
+      ipcRenderer.invoke('app:info'),
+    onError:  (cb: (message: string) => void) => {
+      ipcRenderer.on('app:error', (_event, message) => cb(message))
+    },
+    offError: () => ipcRenderer.removeAllListeners('app:error'),
   },
 
   // Logging

src/App.tsx

@@ -3,6 +3,7 @@ import { useAppStore } from '@shared/stores/appStore'
 import FirstRunSetup from '@areas/setup/FirstRunSetup'
 import MainLayout from '@shared/components/layout/MainLayout'
 import { UpdateModal } from '@shared/components/ui/UpdateModal'
+import { ErrorModal } from '@shared/components/ui/ErrorModal'
 
 function compareSemver(a: string, b: string): number {
   const pa = a.replace(/^v/, '').split('.').map(Number)
@@ -15,12 +16,15 @@ function compareSemver(a: string, b: string): number {
 }
 
 export default function App(): JSX.Element {
-  const { checkSetup, setupStatus, initApp, backendStatus } = useAppStore()
+  const { checkSetup, setupStatus, initApp, backendStatus, showError } = useAppStore()
   const [updateVersion, setUpdateVersion] = useState<string | null>(null)
   const [currentVersion, setCurrentVersion] = useState<string>('')
 
   useEffect(() => {
     checkSetup()
+    window.electron.app.onError((message) => showError(message))
+
+return () => { window.electron.app.offError() }
   }, [])
 
   useEffect(() => {
@@ -51,7 +55,13 @@ export default function App(): JSX.Element {
           onDismiss={() => setUpdateVersion(null)}
         />
       )}
+      <ErrorModal />
+    </>
+  )
+  return (
+    <>
+      <FirstRunSetup />
+      <ErrorModal />
     </>
   )
-  return <FirstRunSetup />
 }

src/shared/components/ui/ErrorModal.tsx

@@ -0,0 +1,57 @@
+import { useState } from 'react'
+import { useAppStore } from '@shared/stores/appStore'
+
+export function ErrorModal(): JSX.Element | null {
+  const { errorModal, hideError } = useAppStore()
+  const [copied, setCopied] = useState(false)
+
+  if (!errorModal) return null
+
+  const handleCopy = () => {
+    navigator.clipboard.writeText(errorModal).then(() => {
+      setCopied(true)
+      setTimeout(() => setCopied(false), 2000)
+    })
+  }
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm">
+      <div className="w-full max-w-lg mx-4 bg-surface-300 border border-zinc-700/60 rounded-xl shadow-2xl flex flex-col">
+        {/* Header */}
+        <div className="flex items-center gap-3 px-5 py-4 border-b border-zinc-700/50">
+          <div className="w-7 h-7 rounded-full bg-red-500/15 border border-red-500/30 flex items-center justify-center shrink-0">
+            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" className="text-red-400">
+              <circle cx="12" cy="12" r="10" />
+              <line x1="12" y1="8" x2="12" y2="12" />
+              <line x1="12" y1="16" x2="12.01" y2="16" />
+            </svg>
+          </div>
+          <span className="text-sm font-semibold text-zinc-100">An error occurred</span>
+        </div>
+
+        {/* Error message — selectable */}
+        <div className="px-5 py-4">
+          <pre className="text-xs text-red-400 bg-red-950/30 border border-red-900/30 rounded-lg px-4 py-3 max-h-60 overflow-y-auto whitespace-pre-wrap break-words select-text font-mono leading-relaxed">
+            {errorModal}
+          </pre>
+        </div>
+
+        {/* Actions */}
+        <div className="flex items-center justify-end gap-2 px-5 pb-4">
+          <button
+            onClick={handleCopy}
+            className="px-4 py-2 text-xs font-semibold rounded-lg bg-zinc-700/60 hover:bg-zinc-700 text-zinc-200 transition-colors"
+          >
+            {copied ? 'Copied!' : 'Copy'}
+          </button>
+          <button
+            onClick={hideError}
+            className="px-4 py-2 text-xs font-semibold rounded-lg bg-accent hover:bg-accent-dark text-white transition-colors"
+          >
+            Dismiss
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}

src/shared/stores/appStore.ts

@@ -89,6 +89,11 @@ interface AppState {
   runSetup:       () => Promise<void>
   saveDataDir:    (baseDir: string) => Promise<void>
 
+  // Error modal
+  errorModal: string | null
+  showError: (message: string) => void
+  hideError: () => void
+
   // Actions
   initApp: () => Promise<void>
   setCurrentJob: (job: GenerationJob | null) => void
@@ -140,6 +145,10 @@ export const useAppStore = create<AppState>()(
         window.electron.setup.run()
       },
 
+      errorModal: null,
+      showError: (message) => set({ errorModal: message }),
+      hideError: () => set({ errorModal: null }),
+
       currentJob: null,
       selectedImagePath: null,
       setSelectedImagePath: (path) => set({ selectedImagePath: path }),
@@ -157,8 +166,10 @@ export const useAppStore = create<AppState>()(
         set({ backendStatus: 'starting', backendError: null })
 
         window.electron.python.offCrashed()
-        window.electron.python.onCrashed(() => {
-          set({ backendStatus: 'error', apiUrl: '', backendError: 'FastAPI crashed unexpectedly' })
+        window.electron.python.onCrashed(({ code }) => {
+          const msg = `FastAPI process crashed unexpectedly (exit code: ${code ?? 'unknown'})`
+          set({ backendStatus: 'error', apiUrl: '', backendError: msg })
+          get().showError(msg)
         })
 
         try {
@@ -167,10 +178,9 @@ export const useAppStore = create<AppState>()(
           const { apiUrl } = await window.electron.app.info()
           set({ backendStatus: 'ready', apiUrl })
         } catch (err) {
-          set({
-            backendStatus: 'error',
-            backendError: err instanceof Error ? err.message : String(err),
-          })
+          const msg = err instanceof Error ? err.message : String(err)
+          set({ backendStatus: 'error', backendError: msg })
+          get().showError(msg)
         }
       },
 

src/shared/types/electron.d.ts

@@ -52,6 +52,8 @@ declare global {
           modelsDir: string
           apiUrl:    string
         }>
+        onError:  (cb: (message: string) => void) => void
+        offError: () => void
       }
       log: {
         error:   (message: string) => void