Merge origin/main into the chat timeline branch

Why: Main moved the backend pin to the B10 assembly after this branch
was opened, so the Dev pin has to follow the merged backend branch.

Evidence: modules/backend is b1fa89b, which contains origin/main and
the timeline changes. No other path conflicted.

Impact: This branch contains current main. The backend gitlink is the
merged feature tip.

Refs: feature/chat-timeline-preview
Co-authored-by: Cursor <cursoragent@cursor.com>

.task/archive/feature-full-agent-b10-r2.md

@@ -0,0 +1,31 @@
+# feature/full-agent-b10-r2 任务卡
+
+任务主记录：PR #123 https://git-home.u1680832.nyat.app:30319/weichen/Agent-System-Dev/pulls/123（merge 8a205db102）；状态：已完成（回填）；owner：weichen
+
+## 基线与授权
+
+- 权威仓：ssh://git@git-ssh.u1680832.nyat.app:31411/weichen/Agent-System-Dev.git；目标分支：main；R0（initial_base_sha）= 47ebd71667859729a6cbe826fcddfe3da4bb5610
+- 工作区：/home/weichen/projects/Agent-System-Dev-wt-feature-full-agent-b10-r2（worktree）；分支：feature/full-agent-b10-r2
+- 授权与交付终点：<本次允许的动作与终点；未授权事项写明>
+
+## 目标与非目标
+
+<预期结果、受影响入口/模块/契约；明确不做什么。>
+
+## 同步记录
+
+| 节点 | sync_base_sha | tested_head_sha | checked_at |
+|---|---|---|---|
+| 启动 | 47ebd71667859729a6cbe826fcddfe3da4bb5610 | 47ebd71667859729a6cbe826fcddfe3da4bb5610 | 2026-10-01T06:15:04Z |
+
+## 结果与验证
+
+- 结果：
+- 验证：
+- 影响与剩余项：
+
+## 闭合记录（card-autoclose 回填）
+
+- 依据：merge 8a205db1025efe92a9e469657646c0d03a228d9f（PR #123）已包含于 origin/main，分支成果已落盘；本段为合入后回填。
+- 合并主题：Merge pull request 'Point backend at the completed B10 assembly (MCP, subagent bridge, roles, skills)' (#123) from feature/full-agent-b10-r2 into main
+- 归档：随闭合移入 .task/archive/；任务执行期的过程证据见原任务记录与 PR。