diff --git a/src/renderer/src/commands/CommandsPanel.tsx b/src/renderer/src/commands/CommandsPanel.tsx
index f61c292..a73bdbf 100644
--- a/src/renderer/src/commands/CommandsPanel.tsx
+++ b/src/renderer/src/commands/CommandsPanel.tsx
@@ -1,5 +1,5 @@
 import { useCallback, useEffect, useState } from 'react'
-import { Button, Modal, Popconfirm, Tabs } from 'antd'
+import { App, Button, Modal, Popconfirm, Tabs } from 'antd'
 import { DeleteOutlined, PlusOutlined } from '@ant-design/icons'
 import type { CommandItem } from '@shared/commands'
 import { t } from '@shared/i18n'
@@ -24,6 +24,7 @@ export function formatClock(ts: number): string {
  * runs the command via the parent workspace's `onRun`.
  */
 export function CommandsPanel({ onRun }: CommandsPanelProps): React.JSX.Element {
+  const { message } = App.useApp()
   const [history, setHistory] = useState<CommandItem[]>([])
   const [library, setLibrary] = useState<CommandItem[]>([])
   const [loaded, setLoaded] = useState(false)
@@ -54,16 +55,27 @@ export function CommandsPanel({ onRun }: CommandsPanelProps): React.JSX.Element
   }, [refresh])
 
   const handleClearHistory = useCallback(async (): Promise<void> => {
-    await window.api.clearHistory()
+    try {
+      await window.api.clearHistory()
+    } catch (err) {
+      // Nothing was removed, so a refresh would repaint the same rows.
+      message.error((err as Error)?.message || t('common.saveFailed'))
+      return
+    }
     refresh()
-  }, [refresh])
+  }, [refresh, message])
 
   const handleDeleteLibrary = useCallback(
     async (id: string): Promise<void> => {
-      await window.api.deleteLibraryItem(id)
+      try {
+        await window.api.deleteLibraryItem(id)
+      } catch (err) {
+        message.error((err as Error)?.message || t('common.saveFailed'))
+        return
+      }
       refresh()
     },
-    [refresh]
+    [refresh, message]
   )
 
   const handleAdd = useCallback((): void => {
diff --git a/src/renderer/src/connections/ConnectionSidebar.tsx b/src/renderer/src/connections/ConnectionSidebar.tsx
index a213f18..8048641 100644
--- a/src/renderer/src/connections/ConnectionSidebar.tsx
+++ b/src/renderer/src/connections/ConnectionSidebar.tsx
@@ -1,5 +1,5 @@
 import { forwardRef, useEffect, useImperativeHandle, useMemo, useState } from 'react'
-import { Button, Collapse, Popconfirm, Tooltip } from 'antd'
+import { App, Button, Collapse, Popconfirm, Tooltip } from 'antd'
 import { DeleteOutlined, EditOutlined, PlusOutlined } from '@ant-design/icons'
 import type { SshConnection } from '@shared/connections'
 import { t } from '@shared/i18n'
@@ -61,6 +61,7 @@ export const ConnectionSidebar = forwardRef<ConnectionSidebarHandle, ConnectionS
     }: ConnectionSidebarProps,
     ref
   ): React.JSX.Element {
+    const { message } = App.useApp()
     const mode = useWorkspaceModeStore((s) => s.mode)
     const isTerminal = mode === 'terminal'
     const [connections, setConnections] = useState<SshConnection[]>([])
@@ -117,7 +118,14 @@ export const ConnectionSidebar = forwardRef<ConnectionSidebarHandle, ConnectionS
     }
 
     const handleDelete = async (id: string): Promise<void> => {
-      await window.api.deleteConnection(id)
+      try {
+        await window.api.deleteConnection(id)
+      } catch (err) {
+        // The row is still there, so a refresh would just re-render the same
+        // list — report the failure and leave it alone.
+        message.error((err as Error)?.message || t('common.saveFailed'))
+        return
+      }
       await refresh()
     }
 
diff --git a/src/renderer/src/monitor/MonitorPanel.tsx b/src/renderer/src/monitor/MonitorPanel.tsx
index fbd544d..8cc93da 100644
--- a/src/renderer/src/monitor/MonitorPanel.tsx
+++ b/src/renderer/src/monitor/MonitorPanel.tsx
@@ -182,6 +182,16 @@ export function MonitorPanel({ sessionId }: MonitorPanelProps): React.JSX.Elemen
   }, [sessionId, workspaceMode])
 
   if (!meta || !sample) {
+    // `meta` is only broadcast after a first sample succeeds, so a session that
+    // fails from the start would otherwise spin here forever with its error
+    // sample hidden behind the meta gate.
+    if (sample?.error) {
+      return (
+        <div className="mm-root mm-empty mm-failed">
+          <div className="mm-error">{t('ssh.monitor.interrupted', { error: sample.error })}</div>
+        </div>
+      )
+    }
     return (
       <div className="mm-root mm-empty">
         <span className="mm-dots"><span /> <span /> <span /></span>
diff --git a/src/renderer/src/settings/HighlightImportExport.tsx b/src/renderer/src/settings/HighlightImportExport.tsx
index 0a0cb63..4df048f 100644
--- a/src/renderer/src/settings/HighlightImportExport.tsx
+++ b/src/renderer/src/settings/HighlightImportExport.tsx
@@ -1,5 +1,5 @@
 import { useEffect, useMemo, useState } from 'react'
-import { Alert, Button, Input, Modal, Popconfirm, Radio, Space } from 'antd'
+import { Alert, App, Button, Input, Modal, Popconfirm, Radio, Space } from 'antd'
 import { t } from '@shared/i18n'
 import { exportHighlightRules, mergeRules, parseHighlightRules } from '@shared/highlightIO'
 import type { ImportError } from '@shared/highlightIO'
@@ -24,6 +24,7 @@ export function HighlightImportExport({
   open: boolean
   onClose: () => void
 }): React.JSX.Element {
+  const { message } = App.useApp()
   const highlightRules = useSettingsStore((s) => s.settings.highlightRules)
   const setHighlightRules = useSettingsStore((s) => s.setHighlightRules)
 
@@ -59,18 +60,22 @@ export function HighlightImportExport({
     link.href = url
     link.download = 'openterminal-highlight-rules.json'
     link.click()
-    URL.revokeObjectURL(url)
+    // Chromium reads the blob asynchronously after the click, so revoking the
+    // URL synchronously aborts the download before it can start.
+    window.setTimeout(() => URL.revokeObjectURL(url), 0)
   }
 
   const handleFile = (file: File): void => {
     const reader = new FileReader()
     reader.onload = () => setDraft(typeof reader.result === 'string' ? reader.result : '')
+    reader.onerror = () => message.error(t('settings.highlight.importReadFailed'))
     reader.readAsText(file)
   }
 
   const errorText = (error: ImportError): string => {
     if (error === 'not-json') return t('settings.highlight.importBadJson')
     if (error === 'wrong-kind') return t('settings.highlight.importWrongKind')
+    if (error === 'wrong-version') return t('settings.highlight.importWrongVersion')
     return t('settings.highlight.importEmpty')
   }
 
diff --git a/src/renderer/src/settings/HighlightTab.tsx b/src/renderer/src/settings/HighlightTab.tsx
index dd769d4..3b37506 100644
--- a/src/renderer/src/settings/HighlightTab.tsx
+++ b/src/renderer/src/settings/HighlightTab.tsx
@@ -549,7 +549,10 @@ function HighlightEditor({
           ...(draft.basic ? { basic: true as const } : {}),
           note: draft.note?.trim() ? draft.note.trim() : undefined
         }
-        await setHighlightRules([...highlightRules, rule])
+        // read at call time: the render-scoped array goes stale inside a React
+        // batch, and another write in the same batch would silently drop the first
+        const current = useSettingsStore.getState().settings.highlightRules
+        await setHighlightRules([...current, rule])
       } else if (editing !== undefined) {
         const rule: HighlightRule = {
           ...editing,
diff --git a/src/renderer/src/sftp/FilePanel.tsx b/src/renderer/src/sftp/FilePanel.tsx
index 87376a8..1c00057 100644
--- a/src/renderer/src/sftp/FilePanel.tsx
+++ b/src/renderer/src/sftp/FilePanel.tsx
@@ -536,6 +536,17 @@ export const FilePanel = memo(function FilePanel({ sessionId }: FilePanelProps):
   const refreshSeqRef = useRef(0)
   /** Mirrors `dir` for callbacks created before a navigation (upload finish). */
   const dirRef = useRef(dir)
+  /** Unsubscribe for the transfer listener the in-flight upload registered. */
+  const uploadOffRef = useRef<(() => void) | null>(null)
+
+  useEffect(() => {
+    return () => {
+      // An upload can still be running — or never deliver a terminal event —
+      // when the panel unmounts; without this its IPC listener outlives it.
+      uploadOffRef.current?.()
+      uploadOffRef.current = null
+    }
+  }, [])
 
   const refresh = useCallback(
     async (target: string): Promise<void> => {
@@ -602,6 +613,7 @@ export const FilePanel = memo(function FilePanel({ sessionId }: FilePanelProps):
       }
       if (e.transferId === targetId) finish()
     })
+    uploadOffRef.current = off
     window.api.uploadRemote(sessionId, files, dir).then(
       (id: string) => {
         targetId = id
diff --git a/src/shared/highlightIO.ts b/src/shared/highlightIO.ts
index e39a095..7f9c5e5 100644
--- a/src/shared/highlightIO.ts
+++ b/src/shared/highlightIO.ts
@@ -5,10 +5,11 @@ import { isHighlightCategory, type HighlightRule } from './settings'
  * a copy before experimenting.
  *
  * The envelope carries a kind + version so pasting the wrong JSON (a layout, a
- * connection list) fails loudly instead of importing nonsense. Validation here
- * stays deliberately light: it only rejects what cannot be a rule at all
- * (unparseable JSON, no `rules` array, an unusable regex). Everything else is
- * repaired by the settings store on save, which already owns that job.
+ * connection list, a file from a future format) fails loudly instead of
+ * importing nonsense. Validation here stays deliberately light: past that
+ * envelope it only rejects what cannot be a rule at all (no `rules` array, an
+ * unusable regex). Everything else is repaired by the settings store on save,
+ * which already owns that job.
  */
 
 export const HIGHLIGHT_FILE_KIND = 'openterminal.highlight-rules'
@@ -27,7 +28,7 @@ export interface HighlightFile {
 }
 
 /** Reasons a paste can be refused, as codes the UI turns into a message. */
-export type ImportError = 'not-json' | 'no-rules' | 'wrong-kind'
+export type ImportError = 'not-json' | 'no-rules' | 'wrong-kind' | 'wrong-version'
 
 export interface ParsedHighlightFile {
   rules: HighlightRule[]
@@ -68,10 +69,16 @@ export function parseHighlightRules(text: string): ParsedHighlightFile {
   if (Array.isArray(raw)) {
     list = raw
   } else if (raw !== null && typeof raw === 'object' && Array.isArray((raw as { rules?: unknown }).rules)) {
-    const kind = (raw as { kind?: unknown }).kind
-    if (typeof kind === 'string' && kind !== HIGHLIGHT_FILE_KIND) {
+    // An envelope is only trusted when both stamps match: a missing `kind`
+    // means the JSON is not ours, and a foreign `version` means it was written
+    // by a format this build does not know how to read.
+    const { kind, version } = raw as { kind?: unknown; version?: unknown }
+    if (kind !== HIGHLIGHT_FILE_KIND) {
       return { rules: [], warnings: [], error: 'wrong-kind' }
     }
+    if (version !== HIGHLIGHT_FILE_VERSION) {
+      return { rules: [], warnings: [], error: 'wrong-version' }
+    }
     list = (raw as { rules: unknown[] }).rules
   } else {
     return { rules: [], warnings: [], error: 'no-rules' }
diff --git a/src/shared/i18n/dicts/en/settings.ts b/src/shared/i18n/dicts/en/settings.ts
index 234bacf..c2839de 100644
--- a/src/shared/i18n/dicts/en/settings.ts
+++ b/src/shared/i18n/dicts/en/settings.ts
@@ -205,6 +205,8 @@ const settings: Record<string, string> = {
   'settings.highlight.importEmpty': 'No usable rules found',
   'settings.highlight.importBadJson': 'Not valid JSON',
   'settings.highlight.importWrongKind': 'This JSON is not a highlight-rule file',
+  'settings.highlight.importWrongVersion': 'This JSON has an unsupported version',
+  'settings.highlight.importReadFailed': 'Could not read the file',
   'settings.highlight.importSkipped': 'Skipped {n}: {list}',
   'settings.highlight.imported': 'Imported {n} rule(s)',
   'settings.highlight.testText': 'Test text',
@@ -268,6 +270,7 @@ const settings: Record<string, string> = {
   'settings.highlight.builtin.loglevel': 'Log levels',
   'settings.highlight.builtin.rootat': 'Root prompt (root@)',
   'settings.highlight.builtin.exitcode': 'Exit codes',
+  'settings.highlight.builtin.percent': 'Percentages & progress',
   'settings.highlight.builtin.http': 'HTTP status codes',
   'settings.highlight.builtin.latency': 'Durations (milliseconds)',
   'settings.highlight.builtin.delop': 'Delete / move / overwrite operations',
diff --git a/src/shared/i18n/dicts/ja/settings.ts b/src/shared/i18n/dicts/ja/settings.ts
index fc1af46..42c656d 100644
--- a/src/shared/i18n/dicts/ja/settings.ts
+++ b/src/shared/i18n/dicts/ja/settings.ts
@@ -201,6 +201,8 @@ const settings: Record<string, string> = {
   'settings.highlight.importEmpty': '有効なルールが見つかりません',
   'settings.highlight.importBadJson': '有効な JSON ではありません',
   'settings.highlight.importWrongKind': 'この JSON はハイライトルールのファイルではありません',
+  'settings.highlight.importWrongVersion': 'この JSON のバージョンは対応していません',
+  'settings.highlight.importReadFailed': 'ファイルを読み込めませんでした',
   'settings.highlight.importSkipped': '{n} 件をスキップ：{list}',
   'settings.highlight.imported': '{n} 件のルールを取り込みました',
   'settings.highlight.testText': 'テスト文字列',
@@ -263,6 +265,7 @@ const settings: Record<string, string> = {
   'settings.highlight.builtin.loglevel': 'ログレベル',
   'settings.highlight.builtin.rootat': 'root プロンプト（root@）',
   'settings.highlight.builtin.exitcode': '終了コード',
+  'settings.highlight.builtin.percent': 'パーセントと進捗',
   'settings.highlight.builtin.http': 'HTTP ステータスコード',
   'settings.highlight.builtin.latency': '所要時間（ミリ秒）',
   'settings.highlight.builtin.delop': '削除・移動・上書きの操作',
diff --git a/src/shared/i18n/dicts/zh-CN/settings.ts b/src/shared/i18n/dicts/zh-CN/settings.ts
index 83d26be..9cfdd42 100644
--- a/src/shared/i18n/dicts/zh-CN/settings.ts
+++ b/src/shared/i18n/dicts/zh-CN/settings.ts
@@ -194,6 +194,8 @@ const settings: Record<string, string> = {
   'settings.highlight.importEmpty': '没有解析到可用规则',
   'settings.highlight.importBadJson': '不是有效的 JSON',
   'settings.highlight.importWrongKind': '这份 JSON 不是高亮规则文件',
+  'settings.highlight.importWrongVersion': '这份 JSON 的版本不受支持',
+  'settings.highlight.importReadFailed': '读取文件失败',
   'settings.highlight.importSkipped': '已跳过 {n} 条：{list}',
   'settings.highlight.imported': '已导入 {n} 条规则',
   'settings.highlight.testText': '测试文本',
@@ -252,6 +254,7 @@ const settings: Record<string, string> = {
   'settings.highlight.builtin.loglevel': '日志级别',
   'settings.highlight.builtin.rootat': '管理员提示符 root@',
   'settings.highlight.builtin.exitcode': '退出码',
+  'settings.highlight.builtin.percent': '百分比与进度',
   'settings.highlight.builtin.http': 'HTTP 状态码',
   'settings.highlight.builtin.latency': '耗时（毫秒）',
   'settings.highlight.builtin.delop': '删除/移动/覆盖操作',
diff --git a/src/shared/i18n/dicts/zh-TW/settings.ts b/src/shared/i18n/dicts/zh-TW/settings.ts
index 8b66505..6e46bd4 100644
--- a/src/shared/i18n/dicts/zh-TW/settings.ts
+++ b/src/shared/i18n/dicts/zh-TW/settings.ts
@@ -194,6 +194,8 @@ const settings: Record<string, string> = {
   'settings.highlight.importEmpty': '沒有解析到可用規則',
   'settings.highlight.importBadJson': '不是有效的 JSON',
   'settings.highlight.importWrongKind': '這份 JSON 不是高亮規則檔案',
+  'settings.highlight.importWrongVersion': '這份 JSON 的版本不受支援',
+  'settings.highlight.importReadFailed': '讀取檔案失敗',
   'settings.highlight.importSkipped': '已略過 {n} 條：{list}',
   'settings.highlight.imported': '已匯入 {n} 條規則',
   'settings.highlight.testText': '測試文字',
@@ -252,6 +254,7 @@ const settings: Record<string, string> = {
   'settings.highlight.builtin.loglevel': '日誌等級',
   'settings.highlight.builtin.rootat': '管理員提示字元 root@',
   'settings.highlight.builtin.exitcode': '結束碼',
+  'settings.highlight.builtin.percent': '百分比與進度',
   'settings.highlight.builtin.http': 'HTTP 狀態碼',
   'settings.highlight.builtin.latency': '耗時（毫秒）',
   'settings.highlight.builtin.delop': '刪除／移動／覆蓋操作',
diff --git a/tests/hl-rules.mjs b/tests/hl-rules.mjs
index 2747c2a..0bc98f5 100644
--- a/tests/hl-rules.mjs
+++ b/tests/hl-rules.mjs
@@ -15,7 +15,13 @@
 import { compileRules, applyHighlights, __testHooks as hooks } from '../src/renderer/src/terminal/highlightEngine.ts'
 import { previewSpans } from '../src/renderer/src/terminal/highlightEngine.ts'
 import { DEFAULT_HIGHLIGHT_RULES } from '../src/shared/settings.ts'
-import { exportHighlightRules, mergeRules, parseHighlightRules } from '../src/shared/highlightIO.ts'
+import {
+  exportHighlightRules,
+  HIGHLIGHT_FILE_KIND,
+  HIGHLIGHT_FILE_VERSION,
+  mergeRules,
+  parseHighlightRules
+} from '../src/shared/highlightIO.ts'
 import {
   excludedByProfile,
   rulesForProfile,
@@ -549,11 +555,26 @@ console.log('[import / export]')
     parseHighlightRules('{"kind":"openterminal.layout","rules":[]}').error === 'wrong-kind',
     'a foreign envelope is refused'
   )
+  ok(
+    parseHighlightRules('{"rules":[]}').error === 'wrong-kind',
+    'an envelope with no kind at all is refused'
+  )
+  ok(
+    parseHighlightRules(JSON.stringify({ kind: HIGHLIGHT_FILE_KIND, version: HIGHLIGHT_FILE_VERSION + 1, rules: [] }))
+      .error === 'wrong-version',
+    'an envelope from another version is refused'
+  )
+  ok(
+    parseHighlightRules(JSON.stringify({ kind: HIGHLIGHT_FILE_KIND, rules: [] })).error === 'wrong-version',
+    'an envelope with no version at all is refused'
+  )
   ok(parseHighlightRules('{"nope":1}').error === 'no-rules', 'JSON without a rules array is refused')
   ok(parseHighlightRules('[]').error === undefined, 'a bare empty array is accepted')
 
   const partial = parseHighlightRules(
     JSON.stringify({
+      kind: HIGHLIGHT_FILE_KIND,
+      version: HIGHLIGHT_FILE_VERSION,
       rules: [
         { pattern: '\\bOK\\b', priority: 500, color: { fg: 'red' } },
         { pattern: '[' },