improvement(chat-export): 优化导出取消响应并补充保存进度反馈

- 导出弹层展示实际生成位置、浏览器目录保存进度和取消中状态\n- 导出服务补充取消检查、链路追踪与实时同步暂停恢复\n- 预建媒体索引并减少 emoji 空查找开销，补充相关测试

frontend/components/chat/ChatOverlays.vue

@@ -1440,39 +1440,12 @@
             <div>
               <div class="text-sm font-medium text-gray-800 mb-2">消息类型（导出内容）</div>
               <div class="mt-2 p-3 bg-gray-50 rounded-md border border-gray-200">
-                <div class="flex items-center gap-2 mb-2">
-                  <button
-                    type="button"
-                    class="text-xs px-2 py-1 rounded border border-gray-200 bg-white hover:bg-gray-50"
-                    @click="exportMessageTypes = exportMessageTypeOptions.map((x) => x.value)"
+                <div class="grid grid-cols-2 gap-x-2 gap-y-2 text-[13px] text-gray-700 md:grid-cols-[repeat(13,max-content)] md:justify-between md:gap-x-3 md:gap-y-0">
+                  <label
+                    v-for="opt in exportMessageTypeOptions"
+                    :key="opt.value"
+                    class="flex items-center gap-1.5 whitespace-nowrap md:flex-shrink-0"
                   >
-                    全选
-                  </button>
-                  <button
-                    type="button"
-                    class="text-xs px-2 py-1 rounded border border-gray-200 bg-white hover:bg-gray-50"
-                    @click="exportMessageTypes = ['voice']"
-                  >
-                    只语音
-                  </button>
-                  <button
-                    type="button"
-                    class="text-xs px-2 py-1 rounded border border-gray-200 bg-white hover:bg-gray-50"
-                    @click="exportMessageTypes = ['transfer']"
-                  >
-                    只转账
-                  </button>
-                  <button
-                    type="button"
-                    class="text-xs px-2 py-1 rounded border border-gray-200 bg-white hover:bg-gray-50"
-                    @click="exportMessageTypes = ['redPacket']"
-                  >
-                    只红包
-                  </button>
-                  <div class="ml-auto text-xs text-gray-500">已选 {{ exportMessageTypes.length }} 项</div>
-                </div>
-                <div class="grid grid-cols-3 md:grid-cols-4 gap-2 text-sm text-gray-700">
-                  <label v-for="opt in exportMessageTypeOptions" :key="opt.value" class="flex items-center gap-2">
                     <input type="checkbox" :value="opt.value" v-model="exportMessageTypes" />
                     <span>{{ opt.label }}</span>
                   </label>
@@ -1512,7 +1485,7 @@
                     v-if="exportFolder"
                     type="button"
                     class="text-sm px-3 py-2 rounded-md bg-white border border-gray-200 hover:bg-gray-50"
-                    @click="exportFolder = ''; exportFolderHandle = null; exportSaveMsg = ''"
+                    @click="clearExportFolderSelection"
                   >
                     清空
                   </button>
@@ -1563,34 +1536,32 @@
               <div>消息：{{ exportJob.progress?.messagesExported || 0 }}；媒体：{{ exportJob.progress?.mediaCopied || 0 }}；缺失：{{ exportJob.progress?.mediaMissing || 0 }}</div>
             </div>
 
-            <div class="mt-3 flex items-center gap-2">
-              <button
-                v-if="exportJob.status === 'done' && hasWebExportFolder"
-                class="text-sm px-3 py-2 rounded-md bg-[#03C160] text-white hover:bg-[#02a650] disabled:opacity-60"
-                type="button"
-                :disabled="exportSaveBusy"
-                @click="saveExportToSelectedFolder"
-              >
-                {{ exportSaveBusy ? '保存中...' : '保存到已选目录' }}
-              </button>
+            <div v-if="exportJob.status === 'done'" class="mt-3 rounded-md border border-gray-200 bg-white/80 px-3 py-2 text-xs text-gray-700 space-y-2">
+              <div>
+                <span class="font-medium text-gray-900">实际生成位置：</span>
+                <div class="mt-1 break-all">{{ exportBackendZipPath || '未生成' }}</div>
+              </div>
+              <div v-if="hasWebExportFolder">
+                <span class="font-medium text-gray-900">浏览器目录：</span>
+                <div class="mt-1 break-all">{{ exportFolder || '未选择' }}</div>
+              </div>
+              <div v-if="exportSaveState === 'saving'" class="text-sky-600 whitespace-pre-wrap">{{ exportSaveProgressText }}</div>
+              <div v-else-if="exportSaveMsg" class="text-green-600 whitespace-pre-wrap">{{ exportSaveMsg }}</div>
+              <div v-else-if="exportSaveError" class="text-red-600 whitespace-pre-wrap">{{ exportSaveError }}</div>
+              <div v-if="hasWebExportFolder" class="text-gray-500">
+                浏览器模式通常会在写入完成后才显示文件，且出于安全限制，这里只能显示目录名，不能显示完整磁盘路径。
+              </div>
+            </div>
+
+            <div v-if="exportJob.status === 'done' && !hasWebExportFolder" class="mt-3 flex items-center gap-2">
               <a
-                v-if="exportJob.status === 'done' && !hasWebExportFolder"
                 class="text-sm px-3 py-2 rounded-md bg-[#03C160] text-white hover:bg-[#02a650]"
                 :href="getExportDownloadUrl(exportJob.exportId)"
                 target="_blank"
               >
                 下载 ZIP
               </a>
-              <button
-                v-if="exportJob.status === 'running'"
-                class="text-sm px-3 py-2 rounded-md bg-white border border-gray-200 hover:bg-gray-50"
-                type="button"
-                @click="cancelCurrentExport"
-              >
-                取消任务
-              </button>
             </div>
-            <div v-if="exportSaveMsg" class="mt-2 text-xs text-green-600 whitespace-pre-wrap">{{ exportSaveMsg }}</div>
 
             <div v-if="exportJob.status === 'error'" class="mt-2 text-sm text-red-600 whitespace-pre-wrap">
               {{ exportJob.error || '导出失败' }}
@@ -1603,6 +1574,7 @@
             关闭
           </button>
           <button
+            v-if="!(exportJob && (exportJob.status === 'queued' || exportJob.status === 'running'))"
             class="text-sm px-3 py-2 rounded-md bg-[#03C160] text-white hover:bg-[#02a650] disabled:opacity-60"
             type="button"
             @click="startChatExport"
@@ -1610,6 +1582,15 @@
           >
             {{ isExportCreating ? '创建中...' : '开始导出' }}
           </button>
+          <button
+            v-else
+            class="text-sm px-3 py-2 rounded-md bg-white border border-red-200 text-red-600 hover:bg-red-50 disabled:opacity-60"
+            type="button"
+            @click="cancelCurrentExport"
+            :disabled="exportCancelRequested"
+          >
+            {{ exportCancelRequested ? '取消中...' : '取消任务' }}
+          </button>
         </div>
       </div>
     </div>

frontend/composables/chat/useChatExport.js

@@ -35,7 +35,12 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
   const exportFolderHandle = ref(null)
   const exportSaveBusy = ref(false)
   const exportSaveMsg = ref('')
+  const exportSaveError = ref('')
+  const exportSaveState = ref('idle')
+  const exportSaveBytesWritten = ref(0)
+  const exportSaveBytesTotal = ref(0)
   const exportAutoSavedFor = ref('')
+  const exportCancelRequested = ref(false)
 
   const exportSearchQuery = ref('')
   const exportListTab = ref('all')
@@ -50,6 +55,27 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     const next = Number(value)
     return Number.isFinite(next) ? next : 0
   }
+  const formatBytes = (value) => {
+    const bytes = Number(value)
+    if (!Number.isFinite(bytes) || bytes <= 0) return '0 B'
+    const units = ['B', 'KB', 'MB', 'GB', 'TB']
+    let size = bytes
+    let index = 0
+    while (size >= 1024 && index < units.length - 1) {
+      size /= 1024
+      index += 1
+    }
+    const digits = size >= 100 || index === 0 ? 0 : size >= 10 ? 1 : 2
+    return `${size.toFixed(digits)} ${units[index]}`
+  }
+  const resetExportSaveFeedback = ({ resetAutoSavedFor = false } = {}) => {
+    exportSaveMsg.value = ''
+    exportSaveError.value = ''
+    exportSaveState.value = 'idle'
+    exportSaveBytesWritten.value = 0
+    exportSaveBytesTotal.value = 0
+    if (resetAutoSavedFor) exportAutoSavedFor.value = ''
+  }
 
   const exportOverallPercent = computed(() => {
     const job = exportJob.value
@@ -72,6 +98,17 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     if (total <= 0) return null
     return Math.round(clamp01(done / total) * 100)
   })
+  const exportBackendZipPath = computed(() => {
+    return String(exportJob.value?.zipPath || '').trim()
+  })
+  const exportSaveProgressText = computed(() => {
+    if (exportSaveState.value !== 'saving') return ''
+    const fileName = guessExportZipName(exportJob.value)
+    if (exportSaveBytesTotal.value > 0) {
+      return `正在保存到浏览器目录：${fileName}（${formatBytes(exportSaveBytesWritten.value)} / ${formatBytes(exportSaveBytesTotal.value)}）`
+    }
+    return `正在保存到浏览器目录：${fileName}（${formatBytes(exportSaveBytesWritten.value)}）`
+  })
 
   const normalizeExportSelectedUsernames = (list) => {
     const seen = new Set()
@@ -179,7 +216,7 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
 
   const chooseExportFolder = async () => {
     exportError.value = ''
-    exportSaveMsg.value = ''
+    resetExportSaveFeedback()
     try {
       if (!process.client) {
         exportError.value = '当前环境不支持选择导出目录'
@@ -206,6 +243,10 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
 
       exportError.value = '当前浏览器不支持目录选择，请使用桌面端或 Chromium 新版浏览器'
     } catch (error) {
+      const message = String(error?.message || '').trim()
+      if (error?.name === 'AbortError' || message.includes('The user aborted a request')) {
+        return
+      }
       exportError.value = error?.message || '选择导出目录失败'
     }
   }
@@ -227,7 +268,7 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
   const saveExportToSelectedFolder = async (options = {}) => {
     const autoSave = !!options?.auto
     exportError.value = ''
-    exportSaveMsg.value = ''
+    resetExportSaveFeedback()
     if (!process.client || !isWebDirectoryPickerSupported()) {
       exportError.value = '当前环境不支持保存到浏览器目录'
       return
@@ -245,6 +286,7 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     }
 
     exportSaveBusy.value = true
+    exportSaveState.value = 'saving'
     try {
       const response = await fetch(getExportDownloadUrl(exportId))
       if (!response.ok) {
@@ -256,18 +298,46 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
         })
         throw new Error(`下载导出文件失败（${response.status}）`)
       }
-      const blob = await response.blob()
+      exportSaveBytesTotal.value = asNumber(response.headers.get('Content-Length'))
       const fileName = guessExportZipName(exportJob.value)
       const fileHandle = await handle.getFileHandle(fileName, { create: true })
       const writable = await fileHandle.createWritable()
-      await writable.write(blob)
-      await writable.close()
+      if (response.body && typeof response.body.getReader === 'function') {
+        const reader = response.body.getReader()
+        try {
+          while (true) {
+            const { done, value } = await reader.read()
+            if (done) break
+            if (!value || !value.byteLength) continue
+            await writable.write(value)
+            exportSaveBytesWritten.value += value.byteLength
+          }
+          await writable.close()
+        } catch (error) {
+          try {
+            await reader.cancel()
+          } catch {}
+          try {
+            await writable.abort()
+          } catch {}
+          throw error
+        }
+      } else {
+        const blob = await response.blob()
+        exportSaveBytesWritten.value = asNumber(blob.size)
+        if (exportSaveBytesTotal.value <= 0) exportSaveBytesTotal.value = exportSaveBytesWritten.value
+        await writable.write(blob)
+        await writable.close()
+      }
       exportAutoSavedFor.value = String(exportId)
+      exportSaveState.value = 'success'
+      const folderLabel = String(exportFolder.value || '').trim() || '已选目录'
       exportSaveMsg.value = autoSave
-        ? `已自动保存到已选目录：${fileName}`
-        : `已保存到已选目录：${fileName}`
+        ? `浏览器目录自动保存成功：${fileName}\n位置：${folderLabel}`
+        : `浏览器目录保存成功：${fileName}\n位置：${folderLabel}`
     } catch (error) {
-      exportError.value = error?.message || '保存到浏览器目录失败'
+      exportSaveState.value = 'error'
+      exportSaveError.value = `浏览器目录保存失败：${error?.message || '未知错误'}`
     } finally {
       exportSaveBusy.value = false
     }
@@ -337,7 +407,8 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
   const openExportModal = () => {
     exportModalOpen.value = true
     exportError.value = ''
-    exportSaveMsg.value = ''
+    resetExportSaveFeedback({ resetAutoSavedFor: true })
+    exportCancelRequested.value = false
     exportSearchQuery.value = ''
     exportListTab.value = 'all'
     exportSelectedUsernames.value = []
@@ -356,6 +427,12 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     exportError.value = ''
   }
 
+  const clearExportFolderSelection = () => {
+    exportFolder.value = ''
+    exportFolderHandle.value = null
+    resetExportSaveFeedback({ resetAutoSavedFor: true })
+  }
+
   watch(exportModalOpen, (open) => {
     if (!process.client) return
     if (!open) {
@@ -382,6 +459,9 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
       status: String(exportJob.value?.status || '')
     }),
     async ({ exportId, status }) => {
+      if (status !== 'queued' && status !== 'running') {
+        exportCancelRequested.value = false
+      }
       if (!process.client || status !== 'done' || !exportId) return
       if (!hasWebExportFolder.value) return
       if (exportAutoSavedFor.value === exportId) return
@@ -392,7 +472,8 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
 
   const startChatExport = async () => {
     exportError.value = ''
-    exportSaveMsg.value = ''
+    resetExportSaveFeedback({ resetAutoSavedFor: true })
+    exportCancelRequested.value = false
     if (!selectedAccount.value) {
       exportError.value = '未选择账号'
       return
@@ -490,13 +571,17 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
 
   const cancelCurrentExport = async () => {
     const exportId = exportJob.value?.exportId
-    if (!exportId) return
+    const status = String(exportJob.value?.status || '')
+    if (!exportId || (status !== 'queued' && status !== 'running') || exportCancelRequested.value) return
 
+    exportError.value = ''
+    exportCancelRequested.value = true
     try {
       await api.cancelChatExport(exportId)
       const response = await api.getChatExport(exportId)
       exportJob.value = response?.job || exportJob.value
     } catch (error) {
+      exportCancelRequested.value = false
       exportError.value = error?.message || '取消导出失败'
     }
   }
@@ -518,7 +603,12 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     exportFolderHandle,
     exportSaveBusy,
     exportSaveMsg,
+    exportSaveError,
+    exportSaveState,
+    exportSaveProgressText,
+    exportBackendZipPath,
     exportAutoSavedFor,
+    exportCancelRequested,
     exportSearchQuery,
     exportListTab,
     exportSelectedUsernames,
@@ -532,6 +622,7 @@ export const useChatExport = ({ api, apiBase, contacts, selectedAccount, selecte
     isExportContactSelected,
     hasWebExportFolder,
     chooseExportFolder,
+    clearExportFolderSelection,
     getExportDownloadUrl,
     saveExportToSelectedFolder,
     openExportModal,

tests/test_chat_export_cancel_responsiveness.py

@@ -0,0 +1,163 @@
+import importlib
+import sys
+import threading
+import unittest
+import zipfile
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / "src"))
+
+
+class TestChatExportCancelResponsiveness(unittest.TestCase):
+    def _reload_export_module(self):
+        import wechat_decrypt_tool.chat_export_service as chat_export_service
+
+        importlib.reload(chat_export_service)
+        return chat_export_service
+
+    def test_json_writer_checks_cancel_between_messages(self):
+        svc = self._reload_export_module()
+        job = svc.ExportJob(export_id="exp_cancel", account="wxid_test", status="running")
+        rows = [
+            svc._Row(
+                db_stem="message_0",
+                table_name="msg_demo",
+                local_id=1,
+                server_id=1001,
+                local_type=1,
+                sort_seq=1,
+                create_time=1735689601,
+                raw_text="第一条",
+                sender_username="wxid_friend",
+                is_sent=False,
+            ),
+            svc._Row(
+                db_stem="message_0",
+                table_name="msg_demo",
+                local_id=2,
+                server_id=1002,
+                local_type=1,
+                sort_seq=2,
+                create_time=1735689602,
+                raw_text="第二条",
+                sender_username="wxid_friend",
+                is_sent=False,
+            ),
+        ]
+
+        original_iter = svc._iter_rows_for_conversation
+        original_parse = svc._parse_message_for_export
+        try:
+            def fake_iter_rows_for_conversation(**_kwargs):
+                yield rows[0]
+                job.cancel_requested = True
+                yield rows[1]
+
+            def fake_parse_message_for_export(**kwargs):
+                row = kwargs["row"]
+                return {
+                    "id": f"{row.db_stem}:{row.table_name}:{row.local_id}",
+                    "localId": row.local_id,
+                    "serverId": row.server_id,
+                    "createTime": row.create_time,
+                    "createTimeText": "2025-01-01 08:00:00",
+                    "sortSeq": row.sort_seq,
+                    "type": row.local_type,
+                    "renderType": "text",
+                    "isSent": bool(row.is_sent),
+                    "senderUsername": row.sender_username,
+                    "conversationUsername": kwargs["conv_username"],
+                    "isGroup": False,
+                    "content": row.raw_text,
+                    "title": "",
+                    "url": "",
+                    "from": "",
+                    "fromUsername": "",
+                    "linkType": "",
+                    "linkStyle": "",
+                    "objectId": "",
+                    "objectNonceId": "",
+                    "recordItem": "",
+                    "thumbUrl": "",
+                    "imageMd5": "",
+                    "imageFileId": "",
+                    "imageMd5Candidates": [],
+                    "imageFileIdCandidates": [],
+                    "imageUrl": "",
+                    "emojiMd5": "",
+                    "emojiUrl": "",
+                    "videoMd5": "",
+                    "videoThumbMd5": "",
+                    "videoFileId": "",
+                    "videoThumbFileId": "",
+                    "videoUrl": "",
+                    "videoThumbUrl": "",
+                    "voiceLength": "",
+                    "quoteUsername": "",
+                    "quoteServerId": "",
+                    "quoteType": "",
+                    "quoteThumbUrl": "",
+                    "quoteVoiceLength": "",
+                    "quoteTitle": "",
+                    "quoteContent": "",
+                    "amount": "",
+                    "coverUrl": "",
+                    "fileSize": "",
+                    "fileMd5": "",
+                    "paySubType": "",
+                    "transferStatus": "",
+                    "transferId": "",
+                    "voipType": "",
+                    "locationLat": None,
+                    "locationLng": None,
+                    "locationPoiname": "",
+                    "locationLabel": "",
+                }
+
+            svc._iter_rows_for_conversation = fake_iter_rows_for_conversation
+            svc._parse_message_for_export = fake_parse_message_for_export
+
+            with TemporaryDirectory() as td:
+                zip_path = Path(td) / "out.zip"
+                with zipfile.ZipFile(zip_path, "w", compression=zipfile.ZIP_DEFLATED) as zf:
+                    with self.assertRaises(svc._JobCancelled):
+                        svc._write_conversation_json(
+                            zf=zf,
+                            conv_dir="conversations/demo",
+                            account_dir=Path(td),
+                            conv_username="wxid_friend",
+                            conv_name="测试好友",
+                            conv_avatar_path="",
+                            conv_is_group=False,
+                            start_time=None,
+                            end_time=None,
+                            want_types=None,
+                            local_types=None,
+                            resource_conn=None,
+                            resource_chat_id=None,
+                            head_image_conn=None,
+                            resolve_display_name=lambda username: username,
+                            privacy_mode=False,
+                            include_media=False,
+                            media_kinds=[],
+                            media_written={},
+                            avatar_written={},
+                            report={"errors": [], "missingMedia": []},
+                            allow_process_key_extract=False,
+                            media_db_path=Path(td) / "media_0.db",
+                            media_index=None,
+                            job=job,
+                            lock=threading.Lock(),
+                        )
+            self.assertEqual(job.progress.messages_exported, 1)
+            self.assertTrue(job.cancel_requested)
+        finally:
+            svc._iter_rows_for_conversation = original_iter
+            svc._parse_message_for_export = original_parse
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_chat_export_emoji_fast_miss.py

@@ -0,0 +1,130 @@
+import importlib
+import io
+import unittest
+import zipfile
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+
+class TestChatExportEmojiFastMiss(unittest.TestCase):
+    def _reload_export_module(self):
+        import wechat_decrypt_tool.chat_export_service as chat_export_service
+
+        importlib.reload(chat_export_service)
+        return chat_export_service
+
+    def test_emoji_miss_skips_fallback_scan_and_caches_negative_result(self):
+        svc = self._reload_export_module()
+        md5 = "8f436b616da7832e5c206ba3d781a714"
+        calls: list[dict[str, object]] = []
+
+        original_try_find = svc._try_find_decrypted_resource
+        original_resolve_kind = svc._resolve_media_path_for_kind
+        try:
+            svc._try_find_decrypted_resource = lambda *args, **kwargs: None
+
+            def fake_resolve_kind(account_dir, kind, md5, username, allow_fallback_scan=True):
+                calls.append(
+                    {
+                        "account_dir": account_dir,
+                        "kind": kind,
+                        "md5": md5,
+                        "username": username,
+                        "allow_fallback_scan": allow_fallback_scan,
+                    }
+                )
+                return None
+
+            svc._resolve_media_path_for_kind = fake_resolve_kind
+
+            with TemporaryDirectory() as td:
+                media_written: dict[str, str] = {}
+                with io.BytesIO() as buf, zipfile.ZipFile(buf, "w") as zf:
+                    arc1, is_new1 = svc._materialize_media(
+                        zf=zf,
+                        account_dir=Path(td),
+                        conv_username="room@chatroom",
+                        kind="emoji",
+                        md5=md5,
+                        file_id="",
+                        media_written=media_written,
+                        suggested_name="",
+                        media_index=None,
+                    )
+                    arc2, is_new2 = svc._materialize_media(
+                        zf=zf,
+                        account_dir=Path(td),
+                        conv_username="room@chatroom",
+                        kind="emoji",
+                        md5=md5,
+                        file_id="",
+                        media_written=media_written,
+                        suggested_name="",
+                        media_index=None,
+                    )
+
+            self.assertEqual(arc1, "")
+            self.assertEqual(arc2, "")
+            self.assertFalse(is_new1)
+            self.assertFalse(is_new2)
+            self.assertEqual(len(calls), 1)
+            self.assertEqual(calls[0]["kind"], "emoji")
+            self.assertEqual(calls[0]["md5"], md5)
+            self.assertEqual(calls[0]["username"], "room@chatroom")
+            self.assertFalse(bool(calls[0]["allow_fallback_scan"]))
+            self.assertIn("emoji:" + md5, media_written)
+            self.assertEqual(media_written["emoji:" + md5], "")
+        finally:
+            svc._try_find_decrypted_resource = original_try_find
+            svc._resolve_media_path_for_kind = original_resolve_kind
+
+    def test_image_lookup_keeps_fallback_scan_enabled(self):
+        svc = self._reload_export_module()
+        md5 = "80793a35a19810699a03579c654f4c50"
+        calls: list[dict[str, object]] = []
+
+        original_try_find = svc._try_find_decrypted_resource
+        original_resolve_kind = svc._resolve_media_path_for_kind
+        try:
+            svc._try_find_decrypted_resource = lambda *args, **kwargs: None
+
+            def fake_resolve_kind(account_dir, kind, md5, username, allow_fallback_scan=True):
+                calls.append(
+                    {
+                        "kind": kind,
+                        "md5": md5,
+                        "allow_fallback_scan": allow_fallback_scan,
+                    }
+                )
+                return None
+
+            svc._resolve_media_path_for_kind = fake_resolve_kind
+
+            with TemporaryDirectory() as td:
+                with io.BytesIO() as buf, zipfile.ZipFile(buf, "w") as zf:
+                    arc, is_new = svc._materialize_media(
+                        zf=zf,
+                        account_dir=Path(td),
+                        conv_username="friend",
+                        kind="image",
+                        md5=md5,
+                        file_id="",
+                        media_written={},
+                        suggested_name="",
+                        media_index=None,
+                    )
+
+            self.assertEqual(arc, "")
+            self.assertFalse(is_new)
+            self.assertEqual(len(calls), 2)
+            self.assertEqual(calls[0]["kind"], "image")
+            self.assertFalse(bool(calls[0]["allow_fallback_scan"]))
+            self.assertEqual(calls[1]["kind"], "image")
+            self.assertTrue(bool(calls[1]["allow_fallback_scan"]))
+        finally:
+            svc._try_find_decrypted_resource = original_try_find
+            svc._resolve_media_path_for_kind = original_resolve_kind
+
+
+if __name__ == "__main__":
+    unittest.main()