fix(frontend): persist upload requirement to sessionStorage; friendly error when files lost on refresh

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

frontend/src/store/pendingUpload.js

@@ -1,15 +1,16 @@
 /**
- * 临时存储待上传的文件和需求
- * 用于首页点击启动引擎后立即跳转，在Process页面再进行API调用
+ * Temporary storage for files and simulation requirement.
+ * - simulationRequirement: persisted to sessionStorage (survives refresh within the tab)
+ * - files: in-memory only (File objects are not JSON-serializable)
  */
 import { reactive } from 'vue'
 
 const state = reactive({
   files: [],
-  simulationRequirement: '',
-  isPending: false,
+  simulationRequirement: sessionStorage.getItem('pendingRequirement') || '',
+  isPending: sessionStorage.getItem('pendingIsPending') === 'true',
   importOntologyMode: false,
-  ontologyFile: null
+  ontologyFile: null,
 })
 
 export function setPendingUpload(files, requirement, importOntologyMode = false, ontologyFile = null) {
@@ -18,6 +19,8 @@ export function setPendingUpload(files, requirement, importOntologyMode = false,
   state.isPending = true
   state.importOntologyMode = importOntologyMode
   state.ontologyFile = ontologyFile
+  sessionStorage.setItem('pendingRequirement', requirement)
+  sessionStorage.setItem('pendingIsPending', 'true')
 }
 
 export function getPendingUpload() {
@@ -26,7 +29,7 @@ export function getPendingUpload() {
     simulationRequirement: state.simulationRequirement,
     isPending: state.isPending,
     importOntologyMode: state.importOntologyMode,
-    ontologyFile: state.ontologyFile
+    ontologyFile: state.ontologyFile,
   }
 }
 
@@ -36,6 +39,8 @@ export function clearPendingUpload() {
   state.isPending = false
   state.importOntologyMode = false
   state.ontologyFile = null
+  sessionStorage.removeItem('pendingRequirement')
+  sessionStorage.removeItem('pendingIsPending')
 }
 
 export default state

frontend/src/views/MainView.vue

@@ -197,9 +197,16 @@ const initProject = async () => {
 
 const handleNewProject = async () => {
   const pending = getPendingUpload()
-  if (!pending.isPending || pending.files.length === 0) {
-    error.value = 'No pending files found.'
-    addLog('Error: No pending files found for new project.')
+
+  if (!pending.isPending) {
+    return  // not a new-project session
+  }
+
+  if (pending.files.length === 0) {
+    error.value = t('error.filesLostAfterRefresh')
+    addLog(t('error.filesLostAfterRefresh'))
+    clearPendingUpload()
+    setTimeout(() => router.push('/'), 3000)
     return
   }
 

locales/ca.json

@@ -706,5 +706,8 @@
     "submit": "Entrar",
     "loading": "Autenticant...",
     "invalidCredentials": "Usuari o contrasenya incorrectes"
+  },
+  "error": {
+    "filesLostAfterRefresh": "Els fitxers s'han perdut en refrescar la pàgina. Redirigint a l'inici per tornar a seleccionar-los…"
   }
 }

locales/en.json

@@ -707,5 +707,8 @@
     "submit": "Enter",
     "loading": "Authenticating...",
     "invalidCredentials": "Invalid username or password"
+  },
+  "error": {
+    "filesLostAfterRefresh": "Files were lost after page refresh. Redirecting to home to re-select files…"
   }
 }

locales/es.json

@@ -706,5 +706,8 @@
     "submit": "Entrar",
     "loading": "Autenticando...",
     "invalidCredentials": "Usuario o contraseña incorrectos"
+  },
+  "error": {
+    "filesLostAfterRefresh": "Los archivos se perdieron al refrescar la página. Redirigiendo al inicio para volver a seleccionarlos…"
   }
 }

locales/zh.json

@@ -707,5 +707,8 @@
     "submit": "登录",
     "loading": "验证中...",
     "invalidCredentials": "用户名或密码错误"
+  },
+  "error": {
+    "filesLostAfterRefresh": "刷新页面后文件丢失，正在跳转到首页重新选择文件…"
   }
 }