diff --git a/android/app/build.gradle b/android/app/build.gradle
index fb9483bb..8c7984c5 100644
--- a/android/app/build.gradle
+++ b/android/app/build.gradle
@@ -7,8 +7,8 @@ android {
         applicationId "app.aiaw.glass"
         minSdkVersion rootProject.ext.minSdkVersion
         targetSdkVersion rootProject.ext.targetSdkVersion
-        versionCode 20018
-        versionName "2.0.8.9"
+        versionCode 20019
+        versionName "2.0.8.12"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         aaptOptions {
              // Files and dirs to omit from the packaged assets dir, modified to accommodate modern web apps.
diff --git a/android/app/capacitor.build.gradle b/android/app/capacitor.build.gradle
index beb983bf..a99cac76 100644
--- a/android/app/capacitor.build.gradle
+++ b/android/app/capacitor.build.gradle
@@ -2,8 +2,8 @@
 
 android {
   compileOptions {
-      sourceCompatibility JavaVersion.VERSION_17
-      targetCompatibility JavaVersion.VERSION_17
+      sourceCompatibility JavaVersion.VERSION_21
+      targetCompatibility JavaVersion.VERSION_21
   }
 }
 
diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
index 4af8cc12..2764c064 100644
--- a/android/app/src/main/AndroidManifest.xml
+++ b/android/app/src/main/AndroidManifest.xml
@@ -28,6 +28,7 @@
             android:name=".MainActivity"
             android:label="@string/title_activity_main"
             android:theme="@style/AppTheme.NoActionBarLaunch"
+            android:windowSoftInputMode="adjustResize"
             android:launchMode="singleTask"
             android:exported="true">
             <intent-filter>
diff --git a/android/app/src/main/java/app/aiaw/MainActivity.java b/android/app/src/main/java/app/aiaw/MainActivity.java
index 40efd56e..f96478ec 100644
--- a/android/app/src/main/java/app/aiaw/MainActivity.java
+++ b/android/app/src/main/java/app/aiaw/MainActivity.java
@@ -1,6 +1,7 @@
 package app.aiaw;
 
 import android.os.Bundle;
+import android.view.WindowManager;
 
 import com.getcapacitor.BridgeActivity;
 
@@ -8,6 +9,9 @@ public class MainActivity extends BridgeActivity {
     @Override
     public void onCreate(Bundle savedInstanceState) {
         registerPlugin(LocalFsPlugin.class);
+        // Set this before Capacitor creates the WebView; its edge-to-edge
+        // initialization otherwise overwrites the manifest/runtime mode.
+        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
         super.onCreate(savedInstanceState);
     }
 }
diff --git a/package.json b/package.json
index 905c4504..0cbd65a5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "aiaw",
-  "version": "2.0.8.9",
+  "version": "2.0.8.12",
   "description": "精心设计的 AI (LLM) 客户端。全功能，轻量级；支持多工作区、插件系统、跨平台、本地优先+实时云同步",
   "productName": "AI as Workspace",
   "author": "NitroRCr <i@krytro.com>",
diff --git a/src/App.vue b/src/App.vue
index c4588f36..4594b71d 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -103,6 +103,7 @@ onMounted(() => {
 
 async function migrateBuiltinPluginsAtStartup() {
   try {
+    if (!db.isOpen()) await db.open()
     const assistants = await db.assistants.toArray()
     for (const assistant of assistants) {
       const beforeKeys = Object.keys(assistant.plugins || {})
diff --git a/src/components/MessageInfoDialog.vue b/src/components/MessageInfoDialog.vue
index 1cf47961..c39256f9 100644
--- a/src/components/MessageInfoDialog.vue
+++ b/src/components/MessageInfoDialog.vue
@@ -75,8 +75,8 @@ const props = defineProps<{
   message: Message
 }>()
 
-const length = computed(() => props.message.contents.filter(
-  c => c.type === 'assistant-message' || c.type === 'user-message'
+const length = computed(() => (props.message.contents || []).filter(
+  c => (c.type === 'assistant-message' || c.type === 'user-message') && typeof c.text === 'string'
 ).reduce((prev, cur) => prev + cur.text.length, 0))
 const createdAt = computed(() => idDateString(props.message.id))
 
diff --git a/src/components/MessageItem.vue b/src/components/MessageItem.vue
index c7b803b7..87882532 100644
--- a/src/components/MessageItem.vue
+++ b/src/components/MessageItem.vue
@@ -391,6 +391,7 @@ const props = defineProps<{
   message: Message,
   childNum: number,
   scrollContainer: HTMLElement,
+  lazyPlainText?: boolean,
   branchControl?: {
     current: number,
     max: number,
@@ -416,7 +417,7 @@ function moreInfo() {
 }
 const sourceCodeMode = ref(false)
 
-const contents = computed(() => props.message.contents.map(x => {
+const contents = computed(() => (props.message.contents || []).map(x => {
   if (x.type === 'assistant-message' || x.type === 'user-message') {
     return {
       ...x,
@@ -445,7 +446,7 @@ watchEffect(async () => {
       generatingSession: null,
       status: 'failed',
       error: 'aborted',
-      contents: props.message.contents.map(content => {
+      contents: (props.message.contents || []).map(content => {
         if (content.type === 'assistant-tool' && content.status === 'calling') {
           return {
             ...content,
@@ -459,8 +460,11 @@ watchEffect(async () => {
   }
 })
 
-const textIndex = computed(() => props.message.contents.findIndex(c => ['user-message', 'assistant-message'].includes(c.type)))
-const textContent = computed(() => (props.message.contents[textIndex.value] as UserMessageContent | AssistantMessageContent))
+const textIndex = computed(() => (props.message.contents || []).findIndex(c => ['user-message', 'assistant-message'].includes(c.type)))
+const textContent = computed(() => {
+  const content = (props.message.contents || [])[textIndex.value]
+  return (content || { type: 'assistant-message', text: '' }) as UserMessageContent | AssistantMessageContent
+})
 
 const { perfs } = useUserPerfsStore()
 const assistantsStore = useAssistantsStore()
@@ -517,6 +521,10 @@ function isStreamingAssistantText(content: MessageContent) {
 
 function getStreamingRenderState(content: MessageContent) {
   if (isStreamingAssistantText(content)) return streamingRenderState.value
+  // Off-screen messages: skip expensive KaTeX/markdown rendering
+  if (props.lazyPlainText && (content.type === 'assistant-message' || content.type === 'user-message')) {
+    return { mode: 'plain-text' as const, text: content.text }
+  }
   if (content.type === 'assistant-message' || content.type === 'user-message') {
     return { mode: 'final' as const, text: content.text }
   }
@@ -602,7 +610,9 @@ function onSelect(mode: 'mouse' | 'touch') {
   }
   const range = selection.getRangeAt(0)
   const targetRects = range.getBoundingClientRect()
-  const baseRects = textDiv.value[0].getBoundingClientRect()
+  const textElement = textDiv.value?.[0] as HTMLElement | undefined
+  if (!textElement) return
+  const baseRects = textElement.getBoundingClientRect()
   floatBtnStyle.top = targetRects.top < 48 || mode === 'touch'
     ? targetRects.bottom - baseRects.top + 12 + 'px'
     : targetRects.top - baseRects.top - 48 + 'px'
@@ -776,7 +786,7 @@ function shouldPromoteInlineMath(inlineMath: HTMLElement) {
 }
 
 function injectDisplayMathScroll() {
-  const el: HTMLElement = textDiv.value[0]
+  const el = textDiv.value?.[0] as HTMLElement | undefined
   if (!el) return
 
   clearDisplayMathScroll(el)
@@ -802,25 +812,30 @@ function injectDisplayMathScroll() {
 }
 function injectConvertArtifact() {
   if (!isPlatformEnabled(perfs.artifactsEnabled)) return
-  const el: HTMLElement = textDiv.value[0]
+  const el = textDiv.value?.[0] as HTMLElement | undefined
+  if (!el) return
   el.querySelectorAll('.md-editor-code').forEach(code => {
     if (code.querySelector('.md-editor-convert-artifact')) return
     const anchor = code.querySelector('.md-editor-collapse-tips')
+    const action = code.querySelector('.md-editor-code-action')
+    const source = code.querySelector('pre code')
+    if (!anchor || !action || !source) return
     const btn = document.createElement('span')
     btn.innerHTML = 'convert_to_text'
     btn.classList.add('md-editor-convert-artifact')
     btn.addEventListener('click', (ev) => {
       ev.preventDefault()
       ev.stopPropagation()
-      const text = code.querySelector('pre code').textContent
-      const lang = code.querySelector('pre code').getAttribute('language')
+      const text = source.textContent || ''
+      const lang = source.getAttribute('language') || ''
       const pattern = new RegExp(`\`{3,}.*\\n${escapeRegex(text)}\\s*\`{3,}`, 'g')
       convertArtifact(text, pattern, lang)
     })
     btn.title = t('messageItem.convertToArtifactBtn')
-    code.querySelector('.md-editor-code-action').insertBefore(btn, anchor)
-    code.querySelector<HTMLElement>('.md-editor-copy-button').title = t('messageItem.copyCode')
-    code.querySelector<HTMLElement>('.md-editor-collapse-tips').title = t('messageItem.fold')
+    action.insertBefore(btn, anchor)
+    const copyButton = code.querySelector<HTMLElement>('.md-editor-copy-button')
+    if (copyButton) copyButton.title = t('messageItem.copyCode')
+    anchor.title = t('messageItem.fold')
   })
 }
 const mdPreviewProps = useMdPreviewProps()
diff --git a/src/components/ModelItem.vue b/src/components/ModelItem.vue
index 8d1a19c3..e440eaa2 100644
--- a/src/components/ModelItem.vue
+++ b/src/components/ModelItem.vue
@@ -46,6 +46,6 @@ const avatar = computed<Avatar>(() => {
   if (m.startsWith('grok') || m.startsWith('xai')) return { type: 'svg', name: 'grok' }
   if (m.startsWith('kimi') || m.startsWith('moonshot')) return { type: 'svg', name: 'kimi-c' }
   if (m.startsWith('doubao')) return { type: 'svg', name: 'doubao-c' }
-  return defaultAvatar(m[0].toUpperCase())
+  return defaultAvatar(m?.[0]?.toUpperCase() || '?')
 })
 </script>
diff --git a/src/components/ParseFilesDialog.vue b/src/components/ParseFilesDialog.vue
index 2cc68516..217698cb 100644
--- a/src/components/ParseFilesDialog.vue
+++ b/src/components/ParseFilesDialog.vue
@@ -164,6 +164,7 @@ async function parse() {
     if (!value) return []
     const file = props.files[index]
     const fp = fileparsers.value.find(fp => fp.id === value)
+    if (!fp || !file) return []
     try {
       const result = await fp.execute({ file, range: ranges[index] }, fp.settings)
       return result.map(r => ({ ...r, name: file.name }))
@@ -178,7 +179,7 @@ async function parse() {
 }
 
 const ranges = reactive(props.files.map(() => null))
-const selected = reactive(props.files.map((val, index) => allOptions.value[index][0]))
+const selected = reactive(props.files.map((val, index) => allOptions.value[index]?.[0]).filter(Boolean))
 
 const { dialogRef, onDialogHide, onDialogOK, onDialogCancel } = useDialogPluginComponent()
 </script>
diff --git a/src/components/SearchDialog.vue b/src/components/SearchDialog.vue
index 2a714313..3ab5be6f 100644
--- a/src/components/SearchDialog.vue
+++ b/src/components/SearchDialog.vue
@@ -102,28 +102,6 @@ interface Doc {
   content: string
 }
 
-const global = ref(false)
-const dialogs = ref<Dialog[]>(null)
-const docs = ref<Doc[]>(null)
-watchEffect(async () => {
-  dialogs.value = global.value
-    ? await db.dialogs.toArray()
-    : await db.dialogs.where('workspaceId').equals(props.workspaceId).toArray()
-  const messages = global.value
-    ? await db.messages.toArray()
-    : await db.messages.where('dialogId').anyOf(dialogs.value.map(d => d.id)).toArray()
-  docs.value = messages.map(m => ({
-    id: m.id,
-    dialogId: m.dialogId,
-    content: m.contents
-      .filter(c => c.type === 'assistant-message' || c.type === 'user-message')
-      .map(c => c.text)
-      .join('\n')
-  }))
-  search()
-})
-
-const q = ref('')
 interface Result {
   workspaceId: string
   dialogId: string
@@ -131,11 +109,48 @@ interface Result {
   route: number[]
   preview?: string
 }
-const results = ref<Result[]>(null)
+
+const global = ref(false)
+const dialogs = ref<Dialog[]>([])
+const docs = ref<Doc[]>([])
+const results = ref<Result[]>([])
+watchEffect(async () => {
+  try {
+    dialogs.value = global.value
+      ? await db.dialogs.toArray()
+      : await db.dialogs.where('workspaceId').equals(props.workspaceId).toArray()
+    const messages = global.value
+      ? await db.messages.toArray()
+      : dialogs.value.length
+        ? await db.messages.where('dialogId').anyOf(dialogs.value.map(d => d.id)).toArray()
+        : []
+    docs.value = (messages || []).map(m => ({
+      id: m.id,
+      dialogId: m.dialogId,
+      content: (Array.isArray(m.contents) ? m.contents : [])
+        .filter(c => c && (c.type === 'assistant-message' || c.type === 'user-message'))
+        .map(c => typeof c.text === 'string' ? c.text : '')
+        .join('\n')
+    }))
+    search()
+  } catch (error) {
+    // Search is a sidebar utility and must never take down the whole SPA when
+    // an older/malformed IndexedDB message is encountered.
+    console.error('[SearchDialog] failed to load dialogs', error)
+    dialogs.value = []
+    docs.value = []
+    results.value = []
+  }
+})
+
+const q = ref('')
 const listRef = ref<QList>()
 function search() {
-  if (!q.value) return
-  const hits = docs.value.filter(d => caselessIncludes(d.content, q.value)).slice(0, 100)
+  if (!q.value || !docs.value || !dialogs.value) {
+    results.value = []
+    return
+  }
+  const hits = docs.value.filter(d => d && caselessIncludes(d.content || '', q.value)).slice(0, 100)
   unmark()
   results.value = [
     ...hits.map(h => {
@@ -143,15 +158,15 @@ function search() {
       return dialog && {
         workspaceId: dialog.workspaceId,
         dialogId: dialog.id,
-        title: dialog.name,
-        preview: h.content.match(new RegExp(`^.*${escapeRegex(q.value)}.*$`, 'im'))[0],
-        route: getRoute(dialog.msgTree, h.id)
+        title: dialog.name || '',
+        preview: h.content.match(new RegExp(`^.*${escapeRegex(q.value)}.*$`, 'im'))?.[0] || h.content.slice(0, 240),
+        route: getRoute(dialog.msgTree, h.id) || []
       }
     }).filter(Boolean),
-    ...dialogs.value.filter(d => caselessIncludes(d.name, q.value)).map(d => ({
+    ...dialogs.value.filter(d => caselessIncludes(d.name || '', q.value)).map(d => ({
       workspaceId: d.workspaceId,
       dialogId: d.id,
-      title: d.name,
+      title: d.name || '',
       route: []
     }))
   ].reverse()
@@ -179,10 +194,13 @@ watch(open, val => {
   })
 })
 
-function getRoute(tree: Record<string, string[]>, target: string, curr = '$root') {
-  for (const [i, v] of tree[curr].entries()) {
+function getRoute(tree: Record<string, string[]> | undefined, target: string, curr = '$root', seen = new Set<string>()): number[] | undefined {
+  if (!tree || seen.has(curr)) return
+  seen.add(curr)
+  const children = Array.isArray(tree[curr]) ? tree[curr] : []
+  for (const [i, v] of children.entries()) {
     if (v === target) return [i]
-    const route = getRoute(tree, target, v)
+    const route = getRoute(tree, target, v, seen)
     if (route) return [i, ...route]
   }
 }
diff --git a/src/components/ViewImageDialog.vue b/src/components/ViewImageDialog.vue
index 79b0dba2..97413554 100644
--- a/src/components/ViewImageDialog.vue
+++ b/src/components/ViewImageDialog.vue
@@ -132,6 +132,7 @@ const imageStyle = computed(() => ({
 }))
 
 function onTouchStart(e: TouchEvent) {
+  if (e.touches.length === 0) return
   if (e.touches.length === 2) {
     wasMultiTouch = true
     const cx = (e.touches[0].clientX + e.touches[1].clientX) / 2
@@ -154,6 +155,7 @@ function onTouchStart(e: TouchEvent) {
 }
 
 function onTouchMove(e: TouchEvent) {
+  if (e.touches.length === 0) return
   if (e.touches.length === 2) {
     const dist = Math.hypot(
       e.touches[0].clientX - e.touches[1].clientX,
diff --git a/src/composables/set-theme.ts b/src/composables/set-theme.ts
index 9b784a44..d085dd96 100644
--- a/src/composables/set-theme.ts
+++ b/src/composables/set-theme.ts
@@ -14,6 +14,7 @@ import { EdgeToEdge } from '@capawesome/capacitor-android-edge-to-edge-support'
 let cachedSafeAreaTop = 0
 let cachedSafeAreaBottom = 0
 
+
 export function getSafeAreaTop(): number { return cachedSafeAreaTop }
 export function getSafeAreaBottom(): number { return cachedSafeAreaBottom }
 
@@ -127,8 +128,11 @@ export function useSetTheme() {
         cachedSafeAreaTop = 24
         writeInsets()
       })
-      Keyboard.addListener('keyboardWillShow', (info) => {
-        cachedSafeAreaBottom = info.keyboardHeight
+      Keyboard.addListener('keyboardDidShow', (info) => {
+        // In the current Android edge-to-edge window the WebView is not
+        // resized, so bottom: 0 is physically underneath the IME. The
+        // Capacitor Android value is native pixels; convert it to CSS px.
+        cachedSafeAreaBottom = info.keyboardHeight / Math.max(window.devicePixelRatio || 1, 1)
         writeInsets()
       })
       Keyboard.addListener('keyboardWillHide', () => {
diff --git a/src/composables/use-dialog-artifact.ts b/src/composables/use-dialog-artifact.ts
index d8f6434c..180b9b77 100644
--- a/src/composables/use-dialog-artifact.ts
+++ b/src/composables/use-dialog-artifact.ts
@@ -44,8 +44,10 @@ export function useDialogArtifact(
     })
     if (options.reserveOriginal) return
     const to = `> ${t('dialogView.convertedToArtifact')}: <router-link to="?openArtifact=${id}">${name}</router-link>\n`
-    const index = message.contents.findIndex(c => ['assistant-message', 'user-message'].includes(c.type))
-    const content = message.contents[index] as UserMessageContent | AssistantMessageContent
+    const contents = message.contents || []
+    const index = contents.findIndex(c => ['assistant-message', 'user-message'].includes(c.type))
+    const content = contents[index] as UserMessageContent | AssistantMessageContent | undefined
+    if (!content) return
     await db.messages.update(message.id, {
       [`contents.${index}.text`]: content.text.replace(pattern, to) as any
     })
@@ -62,7 +64,9 @@ export function useDialogArtifact(
     const object: ExtractArtifactResult = JSON.parse(text)
     if (!object.found) return
     const reg = new RegExp(`(\`{3,}.*\\n)?(${object.regex})(\\s*\`{3,})?`)
-    const content = message.contents.find(c => c.type === 'assistant-message')
+    if (!message || !Array.isArray(message.contents)) return
+    const content = (message.contents || []).find(c => c.type === 'assistant-message') as AssistantMessageContent | undefined
+    if (!content || typeof content.text !== 'string') return
     const match = content.text.match(reg)
     if (!match) return
     await extractArtifact(message, match[2], reg, {
diff --git a/src/composables/use-dialog-branch.ts b/src/composables/use-dialog-branch.ts
index d541eb17..597f98b3 100644
--- a/src/composables/use-dialog-branch.ts
+++ b/src/composables/use-dialog-branch.ts
@@ -11,7 +11,7 @@ export function useDialogBranch(
 
     const parentId = chain.value[index - 1]
     const messageId = chain.value[index]
-    const branches = dialog.value.msgTree[parentId]
+    const branches = dialog.value.msgTree[parentId] || []
     if (!Array.isArray(branches) || branches.length <= 1) return null
 
     const message = messageMap.value[messageId]
diff --git a/src/composables/use-dialog-chain.ts b/src/composables/use-dialog-chain.ts
index c272db07..86b2947b 100644
--- a/src/composables/use-dialog-chain.ts
+++ b/src/composables/use-dialog-chain.ts
@@ -13,14 +13,14 @@ export function useDialogChain(
   itemMap: Ref<Record<string, StoredItem>>,
 ) {
   const editingDraftState = ref<{ parentId: string, draftId: string } | null>(null)
-  const chain = computed<string[]>(() => liveDialog.value ? getChain('$root', liveDialog.value.msgRoute)[0] : [])
-  const normalizedRoute = computed<number[]>(() => liveDialog.value ? getChain('$root', liveDialog.value.msgRoute)[1] : [])
+  const chain = computed<string[]>(() => liveDialog.value ? getChain('$root', Array.isArray(liveDialog.value.msgRoute) ? liveDialog.value.msgRoute : [])[0] : [])
+  const normalizedRoute = computed<number[]>(() => liveDialog.value ? getChain('$root', Array.isArray(liveDialog.value.msgRoute) ? liveDialog.value.msgRoute : [])[1] : [])
   const historyChain = ref<string[]>([])
 
   function getChain(node, route: number[]) {
     const tree = liveDialog.value?.msgTree || {}
     const children = tree[node]
-    const r = route.at(0) || 0
+    const r = Number.isInteger(route?.[0]) ? route[0] : 0
     if (!Array.isArray(children) || children.length === 0) {
       return [[node], [r]]
     }
@@ -64,7 +64,8 @@ export function useDialogChain(
   })
 
   function expandMessageTree(root): string[] {
-    return [root, ...liveDialog.value.msgTree[root].flatMap(id => expandMessageTree(id))]
+    const children = liveDialog.value?.msgTree?.[root] || []
+    return [root, ...children.flatMap(id => expandMessageTree(id))]
   }
 
   async function deleteMessageBranch(parent: string, anchor: string) {
@@ -78,7 +79,7 @@ export function useDialogChain(
         references === 0 ? db.items.delete(id) : db.items.update(id, { references })
       })
       const msgTree = { ...toRaw(liveDialog.value.msgTree) }
-      msgTree[parent] = msgTree[parent].filter(id => id !== anchor)
+      msgTree[parent] = (msgTree[parent] || []).filter(id => id !== anchor)
       ids.forEach(id => {
         delete msgTree[id]
       })
@@ -89,8 +90,9 @@ export function useDialogChain(
   async function deleteBranch(index) {
     const parent = chain.value[index - 1]
     const anchor = chain.value[index]
-    const branch = liveDialog.value.msgRoute[index - 1]
-    branch === liveDialog.value.msgTree[parent].length - 1 && switchChain(index - 1, branch - 1)
+    const branch = liveDialog.value?.msgRoute?.[index - 1]
+    const siblingCount = liveDialog.value?.msgTree?.[parent]?.length ?? 0
+    if (Number.isInteger(branch) && branch === siblingCount - 1 && branch > 0) switchChain(index - 1, branch - 1)
     await deleteMessageBranch(parent, anchor)
   }
 
@@ -104,7 +106,8 @@ export function useDialogChain(
         ...info
       } as Message)
       const d = await db.dialogs.get(propsId.value)
-      const children = d.msgTree[target]
+      if (!d) return
+      const children = d.msgTree?.[target] || []
       const changes = insert ? {
         [target]: [id],
         [id]: children
@@ -113,7 +116,7 @@ export function useDialogChain(
         [id]: []
       }
       await db.dialogs.update(propsId.value, {
-        msgTree: { ...d.msgTree, ...changes }
+        msgTree: { ...(d.msgTree || { $root: [] }), ...changes }
       })
     })
     return id
diff --git a/src/composables/use-dialog-input.ts b/src/composables/use-dialog-input.ts
index 6fa68891..5b68e9dc 100644
--- a/src/composables/use-dialog-input.ts
+++ b/src/composables/use-dialog-input.ts
@@ -38,7 +38,7 @@ export function useDialogInput(
       editingDraftState.value = null
       return false
     }
-    const content = draft.contents[0] as UserMessageContent
+    const content = draft.contents?.[0] as UserMessageContent | undefined
     if (content?.text || content?.items?.length) return false
     await deleteMessageBranch(state.parentId, state.draftId)
     editingDraftState.value = null
@@ -55,7 +55,7 @@ export function useDialogInput(
       inputText.value = ''
       return
     }
-    const content = draft.contents[0] as UserMessageContent
+    const content = draft.contents?.[0] as UserMessageContent | undefined
     if (content?.text || content?.items?.length) {
       await deleteMessageBranch(state.parentId, state.draftId)
     }
@@ -191,11 +191,11 @@ export function useDialogInput(
   onUnmounted(() => removeEventListener('paste', onPaste))
 
   async function removeItem({ id, references }: StoredItem) {
-    const items = [...inputMessageContent.value.items]
+    const items = [...(inputMessageContent.value?.items || [])]
     items.splice(items.indexOf(id), 1)
     await db.transaction('rw', db.messages, db.items, () => {
       db.messages.update(activeInputMessageId.value, {
-        contents: [{ ...inputMessageContent.value, items }]
+        contents: [{ ...(inputMessageContent.value || { type: 'user-message', text: '' }), items }]
       })
       references--
       references === 0 ? db.items.delete(id) : db.items.update(id, { references })
@@ -233,7 +233,7 @@ export function useDialogInput(
     if (displayLength(item.contentText) > 200) {
       addInputItems([item])
     } else {
-      const { text } = inputMessageContent.value
+      const text = inputMessageContent.value?.text || ''
       const content = wrapQuote(item.contentText) + '\n\n'
       updateInputText(text ? text + '\n' + content : content)
     }
@@ -244,7 +244,7 @@ export function useDialogInput(
     const ids = storedItems.map(i => i.id)
     await db.transaction('rw', db.messages, db.items, () => {
       db.messages.update(activeInputMessageId.value, {
-        contents: [{ ...inputMessageContent.value, items: [...inputMessageContent.value.items, ...ids] }]
+        contents: [{ ...(inputMessageContent.value || { type: 'user-message', text: '' }), items: [...(inputMessageContent.value?.items || []), ...ids] }]
       })
       saveItemsLocal(storedItems)
     })
diff --git a/src/composables/use-dialog-scroll.ts b/src/composables/use-dialog-scroll.ts
index 45e094f3..05ded3f1 100644
--- a/src/composables/use-dialog-scroll.ts
+++ b/src/composables/use-dialog-scroll.ts
@@ -254,7 +254,8 @@ export function useDialogScroll(
     const id = chain.value[index]
     let to
     const curr = dialog.value.msgRoute[index]
-    const num = dialog.value.msgTree[id].length
+    const num = dialog.value.msgTree[id]?.length ?? 0
+    if (num <= 0) return
     if (target === 'first') to = 0
     else if (target === 'last') to = num - 1
     else if (target === 'prev') to = curr - 1
diff --git a/src/composables/use-message-window.ts b/src/composables/use-message-window.ts
new file mode 100644
index 00000000..439cdd90
--- /dev/null
+++ b/src/composables/use-message-window.ts
@@ -0,0 +1,131 @@
+import { computed, nextTick, onBeforeUnmount, ref, watch, type Ref } from 'vue'
+
+/**
+ * Renders only a sliding window of the message chain to prevent
+ * DOM bloat in long conversations. Older messages are loaded on
+ * scroll-up via IntersectionObserver sentinel placed at the top.
+ *
+ * Architecture:
+ *   - Initial render: last INITIAL_LIMIT messages
+ *   - Scroll to top → sentinel enters viewport → loadMore (LOAD_MORE_SIZE)
+ *   - Scroll position is preserved by compensating scrollHeight delta
+ *   - Observer is gated with cooldown to prevent rapid-fire loads
+ */
+export function useMessageWindow(
+  chain: Ref<string[]>,
+  scrollContainer: Ref<HTMLElement | undefined>,
+) {
+  const INITIAL_LIMIT = 100
+  const LOAD_MORE_SIZE = 50
+  const MAX_RENDER_CAP = 200  // hard limit: never render more than this
+  const SETTLE_DELAY_MS = 500
+  const OBSERVER_COOLDOWN_MS = 600
+
+  const renderStart = ref(Math.max(0, chain.value.length - INITIAL_LIMIT))
+  const renderEnd = ref(chain.value.length)
+  const isLoadingMore = ref(false)
+
+  const reset = () => {
+    renderEnd.value = chain.value.length
+    renderStart.value = Math.max(0, renderEnd.value - INITIAL_LIMIT)
+    isLoadingMore.value = false
+  }
+
+  // Stable-keyed visible slice — keys are message IDs so Vue won't remount
+  const visibleItems = computed(() =>
+    chain.value
+      .slice(renderStart.value, renderEnd.value)
+      .map((id, i) => ({
+        id,
+        originalIndex: renderStart.value + i,
+      })),
+  )
+
+  const hasMore = computed(() => renderStart.value > 0)
+
+  function loadMore() {
+    if (isLoadingMore.value || !hasMore.value) return
+
+    const container = scrollContainer.value
+    // Guard against false triggers: keyboard appearance shrinks viewport,
+    // which can make the sentinel appear "visible" even when user hasn't scrolled.
+    // Require scrollTop near 0 (user actually scrolled to top).
+    if (container && container.scrollTop > 60) return
+
+    isLoadingMore.value = true
+
+    const prevScrollHeight = container?.scrollHeight ?? 0
+    const prevScrollTop = container?.scrollTop ?? 0
+
+    renderStart.value = Math.max(0, renderStart.value - LOAD_MORE_SIZE)
+    // Enforce max cap: if window exceeds limit, drop oldest messages
+    if (renderEnd.value - renderStart.value > MAX_RENDER_CAP) {
+      renderEnd.value = renderStart.value + MAX_RENDER_CAP
+    }
+
+    // Restore scroll position after Vue re-renders expanded content
+    nextTick(() => {
+      if (container) {
+        const newScrollHeight = container.scrollHeight
+        container.scrollTop = prevScrollTop + (newScrollHeight - prevScrollHeight)
+      }
+      // Cooldown: don't let the observer fire again immediately
+      setTimeout(() => {
+        isLoadingMore.value = false
+      }, OBSERVER_COOLDOWN_MS)
+    })
+  }
+
+  // ── IntersectionObserver sentinel ──
+  const sentinelRef = ref<HTMLElement>()
+  let sentinelObserver: IntersectionObserver | null = null
+  let settleTimer: ReturnType<typeof setTimeout> | null = null
+
+  function setupSentinel(el: HTMLElement) {
+    sentinelObserver?.disconnect()
+    sentinelObserver = new IntersectionObserver(
+      (entries) => {
+        if (entries[0]?.isIntersecting) {
+          loadMore()
+        }
+      },
+      { root: scrollContainer.value ?? null, threshold: 0 },
+    )
+    sentinelObserver.observe(el)
+  }
+
+  function teardownSentinel() {
+    sentinelObserver?.disconnect()
+    sentinelObserver = null
+    if (settleTimer) {
+      clearTimeout(settleTimer)
+      settleTimer = null
+    }
+  }
+
+  // Watch the sentinel DOM element: set up observer with delay so
+  // initial scroll restoration has time to settle before detection.
+  watch(sentinelRef, (el) => {
+    teardownSentinel()
+    if (!el) return
+    settleTimer = setTimeout(() => {
+      setupSentinel(el)
+      settleTimer = null
+    }, SETTLE_DELAY_MS)
+  })
+
+  onBeforeUnmount(() => {
+    teardownSentinel()
+  })
+
+  return {
+    visibleItems,
+    renderStart,
+    renderEnd,
+    hasMore,
+    isLoadingMore,
+    loadMore,
+    reset,
+    sentinelRef,
+  }
+}
diff --git a/src/css/app.scss b/src/css/app.scss
index 6df57ca4..6cfcad1a 100644
--- a/src/css/app.scss
+++ b/src/css/app.scss
@@ -144,14 +144,11 @@ body.body--light {
 }
 
 .dialog-composer-area {
-  position: absolute;
+  position: fixed !important;
   left: 0;
   right: 0;
-  bottom: 0;
-  // Bug #8: prefer --sab (set by set-theme.ts from Keyboard plugin) so the
-  // composer sits above the soft keyboard when it's open. env(safe-area-inset-bottom)
-  // covers iOS notch home indicator and Android nav bar when no keyboard is open.
-  padding: 0 12px calc(14px + max(var(--sab, 0px), env(safe-area-inset-bottom, 0px)));
+  bottom: var(--sab, 0px);
+  padding: 0 12px 14px;
   pointer-events: none;
   background: transparent !important;
   box-shadow: none !important;
diff --git a/src/utils/db.ts b/src/utils/db.ts
index 8a5f5d66..c83c1ea7 100644
--- a/src/utils/db.ts
+++ b/src/utils/db.ts
@@ -37,7 +37,7 @@ db.on('blocked', () => {
 // Dexie 4 把 schema version 乘 10 写入 IDB version（schema v7 = IDB v70），
 // 所以"IDB v70"是正常状态，**不要**迁移或删除。
 // 保留这段仅作未来扩展用：只有当 IDB version > 70*10=700（schema v70+）才视为污染。
-const __migratePromise = (async () => {
+void (async () => {
   if (DexieDBURL || typeof indexedDB === 'undefined') return
   try {
     const dbs = await indexedDB.databases?.()
@@ -165,11 +165,13 @@ db.on.populate.subscribe(() => {
 
 // Migration
 db.assistants.hook('reading', assistant => {
+  if (!assistant || typeof assistant !== 'object') return assistant
+  assistant.modelSettings ||= {}
   assistant.promptRole ??= 'system'
   assistant.stream ??= true
   // Migration to v1.8
   const { modelSettings } = assistant
-  if ('maxTokens' in modelSettings) {
+  if (modelSettings && 'maxTokens' in modelSettings) {
     modelSettings.maxOutputTokens = modelSettings.maxTokens as number
     delete modelSettings.maxTokens
   }
@@ -187,7 +189,24 @@ db.workspaces.hook('reading', workspace => {
   return workspace
 })
 
+db.dialogs.hook('reading', dialog => {
+  if (!dialog || typeof dialog !== 'object') return dialog
+  if (!dialog.msgTree || typeof dialog.msgTree !== 'object' || Array.isArray(dialog.msgTree)) {
+    dialog.msgTree = { $root: [] }
+  } else {
+    for (const key of Object.keys(dialog.msgTree)) {
+      if (!Array.isArray(dialog.msgTree[key])) dialog.msgTree[key] = []
+    }
+    dialog.msgTree.$root ??= []
+  }
+  if (!Array.isArray(dialog.msgRoute)) dialog.msgRoute = []
+  return dialog
+})
+
 db.messages.hook('reading', message => {
+  if (!message || typeof message !== 'object') return message
+  if (!Array.isArray(message.contents)) message.contents = []
+  else message.contents = message.contents.filter(content => content && typeof content === 'object')
   const usage = message.usage as any
   if (usage && 'promptTokens' in usage) {
     message.usage = {
@@ -199,5 +218,40 @@ db.messages.hook('reading', message => {
   return message
 })
 
+// Persist normalization for records written by older builds.
+let repairStarted = false
+db.on('ready', () => {
+  if (repairStarted) return
+  repairStarted = true
+  void db.transaction('rw', db.dialogs, db.messages, async () => {
+    const dialogs = await db.dialogs.toArray()
+    for (const dialog of dialogs) {
+      const tree = dialog.msgTree && typeof dialog.msgTree === 'object' && !Array.isArray(dialog.msgTree)
+        ? dialog.msgTree
+        : { $root: [] }
+      let changed = !dialog.msgTree || Array.isArray(dialog.msgTree)
+      for (const key of Object.keys(tree)) {
+        if (!Array.isArray(tree[key])) {
+          tree[key] = []
+          changed = true
+        }
+      }
+      if (!Array.isArray(tree.$root)) {
+        tree.$root = []
+        changed = true
+      }
+      if (!Array.isArray(dialog.msgRoute)) {
+        dialog.msgRoute = []
+        changed = true
+      }
+      if (changed) await db.dialogs.put({ ...dialog, msgTree: tree })
+    }
+    const messages = await db.messages.toArray()
+    for (const message of messages) {
+      if (!Array.isArray(message.contents)) await db.messages.update(message.id, { contents: [] })
+    }
+  }).catch(error => console.error('[db] legacy record repair failed', error))
+})
+
 export { schema, db, defaultModelSettings }
 export type { Db }
diff --git a/src/utils/doc-parse-plugin.ts b/src/utils/doc-parse-plugin.ts
index c7542f8b..2ad6c56b 100644
--- a/src/utils/doc-parse-plugin.ts
+++ b/src/utils/doc-parse-plugin.ts
@@ -106,7 +106,7 @@ async function parseDocx(file: Blob): Promise<ApiResultItem[]> {
 }
 
 function rowsToMarkdown(rows) {
-  if (!rows.length) return ''
+  if (!Array.isArray(rows) || !rows.length || !Array.isArray(rows[0])) return ''
   const head = rows[0].map(c => c == null ? '' : String(c))
   const body = rows.slice(1).map(r =>
     r.map(c => c == null ? '' : String(c))
@@ -136,7 +136,11 @@ async function parsePptx(file: Blob, { targetPages }): Promise<ApiResultItem[]>
 
   const slideFileNames = Object.keys(files).filter(name =>
     /^ppt\/slides\/slide\d+\.xml$/.test(name)
-  ).sort((a, b) => parseInt(a.match(/\d+/)[0]) - parseInt(b.match(/\d+/)[0]))
+  ).sort((a, b) => {
+    const aNum = a.match(/\d+/)?.[0]
+    const bNum = b.match(/\d+/)?.[0]
+    return Number(aNum || 0) - Number(bNum || 0)
+  })
 
   const texts = slideFileNames.map(name => {
     const xmlStr = strFromU8(files[name])
diff --git a/src/utils/plugins.ts b/src/utils/plugins.ts
index 75135bf5..0a39f595 100644
--- a/src/utils/plugins.ts
+++ b/src/utils/plugins.ts
@@ -437,7 +437,9 @@ function buildMcpPlugin(dump: McpPluginDump, available: boolean): Plugin {
           return resourceToResultItem(i.resource)
         } else {
           const resource = await client.readResource({ uri: i.uri }, requestOptions(settings))
-          return resourceToResultItem(resource.contents[0])
+          const resourceContent = resource?.contents?.[0]
+          if (!resourceContent) return { type: 'text' as const, contentText: '' }
+          return resourceToResultItem(resourceContent)
         }
       }))
     }
@@ -453,7 +455,7 @@ function buildMcpPlugin(dump: McpPluginDump, available: boolean): Plugin {
       async execute(args, settings) {
         const client = await getClient(id, applyDerivedProviderHeaders(settings, { type: transport.type, ...settings }))
         const res: ReadResourceResult = await client.readResource({ uri }, requestOptions(settings))
-        return res.contents.map(c => resourceToResultItem(c, name))
+        return res.contents?.map(c => resourceToResultItem(c, name)) || []
       }
     }
   })
@@ -492,7 +494,9 @@ function buildMcpPlugin(dump: McpPluginDump, available: boolean): Plugin {
             return resourceToResultItem(content.resource, content.resource.uri)
           } else {
             const resource = await client.readResource({ uri: content.uri }, requestOptions(settings))
-            return resourceToResultItem(resource.contents[0])
+            const resourceContent = resource?.contents?.[0]
+            if (!resourceContent) return { type: 'text', name, contentText: '' }
+            return resourceToResultItem(resourceContent, content.resource?.uri)
           }
         }))
       }
@@ -721,7 +725,9 @@ const videoTranscriptPlugin: Plugin = {
       if (!AudioEncoderSupported) throw new Error(t('plugins.videoTranscript.audioEncoderError'))
       const rg = range ? range.split('-').map(parseSeconds) : undefined
       const audioBlob = await extractAudioBlob(file, rg as [number, number])
-      return await whisperPlugin.fileparsers[0].execute({ file: audioBlob }, settings)
+      const parser = whisperPlugin.fileparsers?.[0]
+      if (!parser) return [{ type: 'text', contentText: '' }]
+      return await parser.execute({ file: audioBlob }, settings)
     },
     rangeInput: {
       label: t('plugins.videoTranscript.rangeInput.label'),
diff --git a/src/views/DialogView.vue b/src/views/DialogView.vue
index f019a396..4df46368 100644
--- a/src/views/DialogView.vue
+++ b/src/views/DialogView.vue
@@ -157,27 +157,42 @@
           :class="['dialog-scroll-container', { 'rd-r-lg': rightDrawerAbove }]"
           @scroll="onScroll"
         >
+          <div
+            v-if="hasMore"
+            ref="scrollSentinel"
+            class="dialog-scroll-sentinel"
+            :style="{ height: isLoadingMore ? '40px' : '4px' }"
+            aria-hidden="true"
+          >
+            <q-spinner
+              v-if="isLoadingMore"
+              size="24px"
+              color="primary"
+              class="dialog-scroll-sentinel__spinner"
+            />
+          </div>
           <template
-            v-for="(i, index) in chain"
-            :key="i"
+            v-for="item in visibleItems"
+            :key="item.id"
           >
             <message-item
               class="message-item"
-              v-if="messageMap[i] && i !== '$root'"
-              :data-message-id="i"
-              :data-render-index="index - 1"
-              :model-value="dialog.msgRoute[index - 1] + 1"
-              :message="messageMap[i]"
-              :child-num="dialog.msgTree[chain[index - 1]].length"
-              :branch-control="getMessageBranchControl(index)"
+              v-if="messageMap[item.id] && item.id !== '$root' && item.originalIndex > 0 && chain[item.originalIndex - 1] && dialog.msgRoute[item.originalIndex - 1] != null"
+              :data-message-id="item.id"
+              :data-render-index="item.originalIndex - 1"
+              :model-value="dialog.msgRoute[item.originalIndex - 1] + 1"
+              :message="messageMap[item.id]"
+              :lazy-plain-text="item.originalIndex < lazyCutoff"
+              :child-num="dialog.msgTree[chain[item.originalIndex - 1]]?.length ?? 0"
+              :branch-control="getMessageBranchControl(item.originalIndex)"
               :scroll-container
-              @update:model-value="switchChain(index - 1, $event - 1)"
-              @edit="edit(index)"
-              @regenerate="regenerate(index)"
-              @delete="deleteBranch(index)"
+              @update:model-value="switchChain(item.originalIndex - 1, $event - 1)"
+              @edit="edit(item.originalIndex)"
+              @regenerate="regenerate(item.originalIndex)"
+              @delete="deleteBranch(item.originalIndex)"
               @quote="quote"
-              @extract-artifact="extractArtifact(messageMap[i], ...$event)"
-              @rendered="onMessageRendered(messageMap[i])"
+              @extract-artifact="extractArtifact(messageMap[item.id], ...$event)"
+              @rendered="onMessageRendered(messageMap[item.id])"
               pt-2
               pb-4
             />
@@ -547,6 +562,7 @@ import { useDialogChain } from 'src/composables/use-dialog-chain'
 import { useDialogScroll } from 'src/composables/use-dialog-scroll'
 import { useDialogInput } from 'src/composables/use-dialog-input'
 import { collectChainMessageContents, collectConversationMessageContents, collectDialogContents, collectExistingItems, collectReferencedItemIds, getMessageRecord } from 'src/utils/dialog-message-map'
+import { useMessageWindow } from 'src/composables/use-message-window'
 
 const { t, locale } = useI18n()
 
@@ -1011,8 +1027,9 @@ async function cleanupEmptyDialog(dialogId: string) {
     if (msgs.length !== 1) return
     const only = msgs[0]
     if (only.status !== 'inputing') return
-    if (only.contents?.length !== 1) return
-    const c = only.contents[0]
+    if (!Array.isArray(only.contents) || only.contents.length !== 1) return
+    const c = only.contents?.[0]
+    if (!c || typeof c !== 'object') return
     if (c.type !== 'user-message') return
     if ((c.text ?? '').trim() !== '') return
     if ((c.items ?? []).length !== 0) return
@@ -1365,6 +1382,29 @@ const {
   rightDrawerAbove, assistant, activePlugins, perfs, $q,
 )
 
+const {
+  visibleItems, hasMore, isLoadingMore, renderEnd,
+  loadMore, reset: resetMessageWindow,
+  sentinelRef: scrollSentinel,
+} = useMessageWindow(chain, scrollContainer)
+
+// Messages beyond this offset render as plain text to skip KaTeX overhead
+const lazyCutoff = computed(() => renderEnd.value - 30)
+
+// Reset render window when dialog changes
+watch(() => liveDialog.value?.id, () => {
+  resetMessageWindow()
+})
+
+// Recalculate window when chain settles (catches initial data load race)
+watch(() => chain.value.length, (newLen, oldLen) => {
+  // Only fire when chain was at root (dialog not yet loaded) and now has real messages.
+  // Avoids resetting on individual message sends (newLen increases by 1).
+  if (oldLen <= 1 && newLen > oldLen + 5) {
+    resetMessageWindow()
+  }
+})
+
 
 function setModel(name: string) {
   dialog.value.modelOverride = name