release: prepare Desktop 0.15.6

Include the pending sidebar footer style correction and document frosted appearance, chat rendering, image previews, settings layout, and local MCP recovery. Record schema 52 backup guidance and 886 passing focused tests; Agent remains 0.15.1.

Release note: 新增可选磨砂外观，改善聊天输入、图片预览和本地工具连接恢复，并整理设置与笔记布局。

resources/release-notes.json

@@ -1,6 +1,46 @@
 {
   "formatVersion": 1,
   "releases": [
+    {
+      "version": "0.15.6",
+      "releasedAt": "2026-10-01",
+      "notes": {
+        "zh-CN": {
+          "highlights": [],
+          "features": [
+            "**可选的透明磨砂外观**：在外观设置中开启“透明磨砂特效”，聊天内容可滚动经过顶栏背后，执行清单浮层也使用磨砂背景。默认关闭，选择会保存并在重启后恢复；效果只作用于应用内部，不透出操作系统桌面。"
+          ],
+          "fixes": [
+            "**改善本地 OpenCode 工具连接恢复**：明确的暂时性 MCP 传输故障会在清理成功后最多重试一次，超时或取消后结果不确定的连接名称不再复用，避免晚到初始化覆盖新连接。鉴权、协议和未知错误不会自动重试，Prompt 与工具调用不会重放；该修正不代表远程 Agent 新增恢复能力。",
+            "**减少输入和切换会话时的重复处理**：输入时未变化的消息历史及任务条不再反复渲染，切换已缓存会话时复用稳定的消息回调。实时输出、滚动位置、草稿和异步附件归属保持不变，执行统计索引也减少了轮询时对事件记录的扫描。",
+            "**草稿和队列图片可直接放大预览**：点击图片缩略图即可打开共享查看器，无需先执行 OCR。队列附件保持只读，不再展示解析来源和设置入口；草稿仍可显式提取文字。",
+            "**整理设置导航与笔记间距**：设置按分组排列，持久开关统一右对齐，侧栏底部文字布局一并修正。笔记列表、详情和评论方向栏的标题对齐，文字编辑工具栏与输入区域减少多余留白，保留画布间距。",
+            "**补充本地 MCP 故障诊断**：反馈诊断可包含连接阶段、错误类别及关联摘要，帮助定位初始化和清理问题。诊断不记录令牌、服务地址、请求正文或原始错误内容。"
+          ],
+          "notices": [
+            "首次启动升级到 schema 52，为任务事件增加执行统计索引；历史较多时建立索引可能需要更长时间。升级前请关闭应用并备份完整数据库及相邻 `notes/` 目录；旧客户端不能打开升级后的数据库，降级需恢复升级前备份。",
+            "本轮只更新 Desktop，Agent 保持 **0.15.1**，无需更新 Agent 包。仅提供标准六平台产物，不包含新的 LoongArch 预览。"
+          ]
+        },
+        "en-US": {
+          "highlights": [],
+          "features": [
+            "**Optional frosted-glass appearance**: Enable the effect in Appearance to let chat content scroll behind the header and give execution-checklist panels a frosted background. It is off by default and your choice persists across restarts; the effect is internal to the app and does not reveal the operating-system desktop."
+          ],
+          "fixes": [
+            "**Improve local OpenCode tool connection recovery**: Explicit transient MCP transport failures receive at most one retry after successful cleanup, and names with uncertain timeout or cancellation outcomes are retired so late initialization cannot replace a live connection. Authentication, protocol, and unknown errors are not retried, and prompts or tool calls are not replayed; this is not a new remote Agent recovery capability.",
+            "**Reduce repeated work while typing and switching conversations**: Unchanged message history and task strips avoid repeated renders during typing, with stable callbacks reused across cached conversation switches. Streaming, scroll positions, drafts, and asynchronous attachment ownership remain intact, while execution-statistics indexes reduce event scans during polling.",
+            "**Preview draft and queued images directly**: Click an image thumbnail to open the shared viewer without running OCR first. Queued attachments remain read-only and no longer show parsing-source or settings entries; drafts retain explicit text extraction.",
+            "**Organize settings and tighten note spacing**: Settings navigation is grouped, persistent switches align to the right, and sidebar footer text layout is corrected. Note-list, detail, and comment-direction headers align, with excess gaps removed around text editing controls while preserving canvas spacing.",
+            "**Add local MCP failure diagnostics**: Feedback diagnostics can include connection phases, error categories, and correlation digests to help identify initialization and cleanup failures. They do not record tokens, service addresses, request bodies, or raw error content."
+          ],
+          "notices": [
+            "First launch upgrades to schema 52 and adds task-event indexes for execution statistics; building indexes may take longer with large histories. Close the app and back up the complete database and adjacent `notes/` directory first; older clients cannot open the upgraded database, so downgrading requires a pre-upgrade backup.",
+            "This is a Desktop-only update; Agent remains **0.15.1**, with no Agent package update required. Only the six standard targets are released, with no new LoongArch preview."
+          ]
+        }
+      }
+    },
     {
       "version": "0.15.5",
       "releasedAt": "2026-09-30",