feat(v2): T-M2 采纳 pi branch-summarization——折叠摘要携带文件清单 + rollup 行带产物锚点

- AgentService._history_from_session：从全部轮次的 write_file/edit_file
  工具调用提取已读写文件清单（去重/单路径裁 120 字符/封顶 20 个），以摘要轮
  注入对话上下文——轮次滑出窗口后事实清单仍在（丢上下文不丢事实）
- Workspace.rollup：done 折叠行追加（产出: <artifact 锚点>），上下文折叠后
  产物事实在 a:// 锚点体系内仍可寻址；既有子串断言全部兼容
- 新增 tests/test_branch_manifest.py 4 项

tests/test_branch_manifest.py

@@ -0,0 +1,73 @@
+"""折叠摘要携带文件清单（T-M2，采纳 pi branch-summarization 设计）。"""
+import gateway.agent as ag
+from gateway.agent import AgentSession, AgentService
+from router_system.workspace import Workspace
+
+
+def _mk_turn(rid, task, tool_calls=None, state="done", response="好"):
+    return {"request_id": rid, "task": task, "response": response,
+            "state": state, "tool_calls": tool_calls or [], "tokens": 10,
+            "error": None, "ts": 0.0}
+
+
+def _sess(turns):
+    return AgentSession({"id": "as-x", "title": "s", "turns": turns})
+
+
+def test_history_carries_file_manifest_from_out_of_window_turns():
+    """文件清单来自全部轮次：写文件轮滑出窗口后清单仍在摘要里。"""
+    turns = [
+        _mk_turn("t1", "建笔记", tool_calls=[
+            {"id": "c1", "name": "write_file", "arguments": {"path": "notes.md"}},
+        ]),
+        _mk_turn("t2", "改笔记", tool_calls=[
+            {"id": "c2", "name": "edit_file", "arguments": {"path": "notes.md"}},
+        ]),
+        _mk_turn("t3", "闲聊"),
+    ]
+    hist = AgentService._history_from_session(_sess(turns), max_turns=1)
+    flat = "".join(str(m.get("content")) for m in hist)
+    # 窗口只剩 t3，但文件清单（t1/t2 产生）随摘要进入上下文
+    assert "notes.md" in flat
+    assert "上下文摘要" in flat
+    # 重复路径去重
+    assert flat.count("notes.md") >= 1
+
+
+def test_history_without_file_tools_has_no_manifest():
+    """无写文件工具调用 -> 不注入摘要轮（零噪音）。"""
+    turns = [_mk_turn("t1", "问个问题", tool_calls=[
+        {"id": "c1", "name": "web_fetch", "arguments": {"url": "https://x"}},
+    ])]
+    hist = AgentService._history_from_session(_sess(turns), max_turns=6)
+    assert all("上下文摘要" not in str(m.get("content")) for m in hist)
+
+
+def test_manifest_caps_path_length_and_count():
+    """路径裁剪 120 字符、清单封顶 20 个，防摘要膨胀。"""
+    turns = [_mk_turn(f"t{i}", "写", tool_calls=[
+        {"id": f"c{i}", "name": "write_file", "arguments": {"path": f"很长的路径{i}" * 30}},
+    ]) for i in range(25)]
+    hist = AgentService._history_from_session(_sess(turns), max_turns=0)
+    manifest = next(m for m in hist if "上下文摘要" in str(m.get("content")))
+    content = str(manifest["content"])
+    assert "等共 25 个" in content
+    body = content.split("：", 1)[1]  # 剥掉固定前缀后逐段校验单路径裁剪
+    for seg in body.split("（等共")[0].split("、"):
+        assert len(seg) <= 120
+
+
+def test_rollup_line_carries_artifact_anchor():
+    """workspace rollup 折叠行携带产物锚点（a:// 体系内可寻址）。"""
+    ws = Workspace.new(request_id="abc123def456", query="写个快排",
+                       api_token_cap=8000, rounds_cap=6)
+    ws.apply_brief({
+        "goal": "快排", "constraints": [], "tags": ["code"],
+        "acceptance": [{"id": "a1", "check": "可运行", "machine_checkable": True}],
+        "plan": [{"id": "s1", "task": "实现", "deps": [], "done_criteria": "过"}],
+    })
+    ws.add_progress("s1", "done", "完成", "a://s1_main.py")
+    ws.rollup()
+    archive = "".join(ws["archive"])
+    assert "s1" in archive
+    assert "（产出: a://s1_main.py）" in archive