fix: 岗位会商 handoff 将上游产物镜像到当前席位沙箱

席位线程隔离导致下游 read_file 找不到上游路径；镜像到 workspace/upstream 并改写 handoff 引用，附带安全路径校验与 SQL 回退测试。

Co-authored-by: Cursor <cursoragent@cursor.com>

offline-backend-20260512/backend/CLAUDE.md

@@ -528,8 +528,19 @@ node state stay consistent. A rejected/stale node returns to `done` only after
 a fresh Markdown delivery is recorded.
 For direct-agent handoff, the router resolves artifact paths only inside the
 completed upstream node's own thread, then includes bounded UTF-8 excerpts for
-text outputs; binary artifacts stay as metadata-only references.
-`POST /sessions/{id}/archive` turns a session into a read-only historical
+text outputs; binary artifacts stay as metadata-only references. Because each
+seat runs on an isolated LangGraph thread, a downstream `read_file` on the
+upstream artifact path would fail with "File not found"; the handoff therefore
+also **mirrors** every upstream `outputs/` deliverable into the current seat's
+own `workspace/upstream/` directory (`_mirror_upstream_artifacts`, bytes from
+the upstream sandbox file with the SQL recovery copy as fallback, idempotent
+per turn via size comparison, capped at 8 files / 2 MB each / 8 MB total) and
+rewrites each handoff artifact ref's `path` to the mirror (`upstream_path`
+keeps the original; `mirrored_to_sandbox: true`), with a matching note in the
+hidden instructions telling the agent it may `read_file` the full text. The
+mirror deliberately stays outside `outputs/` so it never appears in the seat's
+own delivery manifest.
+`POST /sessions/{id}/archive` turns the session into a read-only historical
 record: task/intent updates, node binding, hidden-context construction, and
 turn completion are rejected, while read endpoints remain available.
 Built-in summary and action-plan completion also preserves a visible report

offline-backend-20260512/backend/app/gateway/routers/position_roundtable.py

@@ -46,6 +46,17 @@ NODE_STATUSES = {"locked", "ready", "running", "done", "stale", "rejected", "err
 _HANDOFF_TEXT_BUDGET = 12_000
 _MAX_INLINE_ARTIFACTS_PER_NODE = 4
 _MAX_INLINE_ARTIFACT_CHARS = 1_800
+# Upstream deliverables are additionally mirrored into the current seat's own
+# workspace (outputs/<rel> → workspace/upstream/<rel>) before each turn. Every
+# seat runs on an isolated LangGraph thread, so without this copy a downstream
+# ``read_file`` on the upstream artifact path fails with "File not found" and
+# the seat is limited to the short excerpt inlined into the handoff prompt.
+# The mirror deliberately stays outside outputs/ so it never appears in this
+# seat's own delivery manifest.
+_UPSTREAM_MIRROR_PREFIX = "mnt/user-data/workspace/upstream"
+_MAX_MIRRORED_ARTIFACTS = 8
+_MAX_MIRRORED_ARTIFACT_BYTES = 2_000_000
+_MIRRORED_TOTAL_BYTES = 8_000_000
 # The handoff prompt remains intentionally small, but the recovery copy stored
 # in SQL must retain a complete normal Markdown/JSON deliverable.  The ceiling
 # protects the database from an accidental multi-gigabyte log while covering
@@ -685,6 +696,11 @@ def _build_node_context_text(
                         continue
                     artifact_name = artifact.get("name") or artifact.get("path") or "未命名产物"
                     lines.append(f"   - {artifact_name}")
+                    if artifact.get("mirrored_to_sandbox") and artifact.get("path"):
+                        lines.append(
+                            f"     完整文件已同步到本席位沙箱 /{artifact['path']}，可直接用 read_file 读取全文"
+                            "（仅供参考；本席位自己的交付物仍必须写入 /mnt/user-data/outputs/）。"
+                        )
                     content = str(artifact.get("content") or "").strip()
                     if content:
                         lines.append(f"     摘要/正文片段：{content}")
@@ -824,6 +840,95 @@ async def _artifact_refs_with_content(
     return refs, consumed
 
 
+def _outputs_relative_path(value: Any) -> str:
+    """Return the ``outputs/``-relative posix path of a manifest artifact.
+
+    Empty string when the path is not a plain file directly under
+    ``mnt/user-data/outputs/`` (wrong prefix, traversal segment, ...).
+    """
+    path = str(value or "").replace("\\", "/").lstrip("/")
+    prefix = "mnt/user-data/outputs/"
+    if not path.startswith(prefix):
+        return ""
+    relative = path[len(prefix) :]
+    if not relative:
+        return ""
+    segments = relative.split("/")
+    if any(segment in ("", ".", "..") for segment in segments):
+        return ""
+    return relative
+
+
+def _mirror_virtual_path(relative: str) -> str:
+    return f"{_UPSTREAM_MIRROR_PREFIX}/{relative}"
+
+
+async def _mirror_upstream_artifacts(
+    current: dict[str, Any],
+    upstream_candidates: list[dict[str, Any]],
+) -> dict[str, str]:
+    """Copy upstream deliverables into the current seat's workspace sandbox.
+
+    Bytes are preferred from the upstream thread's own sandbox file; the SQL
+    recovery copy persisted in the manifest is the fallback when that disk is
+    gone. Only server-recorded upstream threads and manifest paths that pass
+    :func:`_outputs_relative_path` are read, and the target resolves through
+    the same thread virtual-path resolver, so a client-supplied manifest can
+    never point the copy outside a thread's user-data directory. Idempotent
+    per turn: an identically sized mirror is left untouched. Best effort —
+    failures simply keep the excerpt-only handoff behaviour.
+    """
+    target_thread_id = str(current.get("thread_id") or "")
+    if not target_thread_id or not upstream_candidates:
+        return {}
+
+    mirrored: dict[str, str] = {}
+    total_bytes = 0
+    for node in upstream_candidates:
+        source_thread_id = str(node.get("thread_id") or "")
+        for artifact in node.get("artifact_manifest") or []:
+            if len(mirrored) >= _MAX_MIRRORED_ARTIFACTS or total_bytes >= _MIRRORED_TOTAL_BYTES:
+                return mirrored
+            if not isinstance(artifact, dict):
+                continue
+            original = str(artifact.get("path") or "")
+            relative = _outputs_relative_path(original)
+            if not relative:
+                continue
+            try:
+                payload: bytes | None = None
+                if source_thread_id:
+                    source_path = await aresolve_thread_virtual_path(source_thread_id, original)
+                    if await asyncio.to_thread(source_path.is_file):
+                        stat = await asyncio.to_thread(source_path.stat)
+                        if stat.st_size > _MAX_MIRRORED_ARTIFACT_BYTES:
+                            continue
+                        payload = await asyncio.to_thread(source_path.read_bytes)
+                if payload is None:
+                    content = artifact.get("content")
+                    if not isinstance(content, str) or not content:
+                        continue
+                    payload = content.encode("utf-8")
+                    if len(payload) > _MAX_MIRRORED_ARTIFACT_BYTES:
+                        continue
+                mirror_virtual = _mirror_virtual_path(relative)
+                target_path = await aresolve_thread_virtual_path(target_thread_id, mirror_virtual)
+                if not (
+                    await asyncio.to_thread(target_path.is_file)
+                    and (await asyncio.to_thread(target_path.stat)).st_size == len(payload)
+                ):
+                    await asyncio.to_thread(target_path.parent.mkdir, parents=True, exist_ok=True)
+                    await asyncio.to_thread(target_path.write_bytes, payload)
+                mirrored[original] = mirror_virtual
+                total_bytes += len(payload)
+            except (HTTPException, OSError, ValueError):
+                # The upstream file may have been removed, or a provider may be
+                # unavailable. Skip it; the inline excerpt still carries the
+                # essential content into the handoff.
+                continue
+    return mirrored
+
+
 async def _handoff_context(request: Request, session_id: str, node_key: str) -> dict[str, Any]:
     """Construct bounded, deterministic hidden context for one direct-agent turn."""
     store = _get_store(request)
@@ -877,6 +982,20 @@ async def _handoff_context(request: Request, session_id: str, node_key: str) ->
         )
         if remaining <= 0:
             break
+
+    # Point each artifact ref at the workspace mirror when one exists: the
+    # agent then reads a path that is actually resolvable inside its own
+    # thread sandbox instead of the upstream thread's outputs directory.
+    mirrored_paths = await _mirror_upstream_artifacts(current, upstream_candidates)
+    for node in upstream_nodes:
+        for artifact in node.get("artifacts") or []:
+            mirror = mirrored_paths.get(str(artifact.get("path") or ""))
+            if not mirror:
+                continue
+            artifact["upstream_path"] = artifact["path"]
+            artifact["path"] = mirror
+            artifact["mirrored_to_sandbox"] = True
+
     return {
         "kind": "position_roundtable_handoff",
         "instructions": _build_node_context_text(

offline-backend-20260512/backend/tests/test_position_roundtable_sessions.py

@@ -6,6 +6,7 @@ import asyncio
 import importlib.util
 import json
 import zipfile
+from pathlib import Path
 from types import SimpleNamespace
 from typing import Any
 
@@ -1244,8 +1245,11 @@ def test_activation_requires_a_structured_intent_snapshot() -> None:
 
 @pytest.mark.asyncio
 async def test_handoff_context_inlines_only_upstream_thread_text_artifacts(tmp_path, monkeypatch):
-    artifact = tmp_path / "handoff.md"
+    upstream_dir = tmp_path / "up" / "outputs"
+    upstream_dir.mkdir(parents=True)
+    artifact = upstream_dir / "handoff.md"
     artifact.write_text("上游产物正文：可供下一岗位直接参考。", encoding="utf-8")
+    mirror_root = tmp_path / "current" / "workspace" / "upstream"
     calls: list[tuple[str, str]] = []
 
     class StubStore:
@@ -1307,9 +1311,12 @@ async def test_handoff_context_inlines_only_upstream_thread_text_artifacts(tmp_p
 
     async def resolve(thread_id: str, path: str):
         calls.append((thread_id, path))
-        assert thread_id == "upstream-thread"
-        assert path == "mnt/user-data/outputs/handoff.md"
-        return artifact
+        if thread_id == "upstream-thread":
+            assert path == "mnt/user-data/outputs/handoff.md"
+            return artifact
+        assert thread_id == "current-thread"
+        assert path == "mnt/user-data/workspace/upstream/handoff.md"
+        return mirror_root / "handoff.md"
 
     monkeypatch.setattr(position_roundtable_router, "aresolve_thread_virtual_path", resolve)
     request = SimpleNamespace(
@@ -1325,8 +1332,102 @@ async def test_handoff_context_inlines_only_upstream_thread_text_artifacts(tmp_p
     assert len(context["upstream_nodes"]) == 1
     assert upstream["latest_answer"] == "上游问答结果"
     assert upstream["artifacts"][0]["content"] == "上游产物正文：可供下一岗位直接参考。"
+    assert upstream["artifacts"][0]["upstream_path"] == "mnt/user-data/outputs/handoff.md"
+    assert upstream["artifacts"][0]["path"] == "mnt/user-data/workspace/upstream/handoff.md"
+    assert upstream["artifacts"][0]["mirrored_to_sandbox"] is True
     assert "content" not in upstream["artifacts"][1]
-    assert calls == [("upstream-thread", "mnt/user-data/outputs/handoff.md")]
+    assert "mirrored_to_sandbox" not in upstream["artifacts"][1]
+    assert upstream["artifacts"][1]["path"] == "mnt/user-data/uploads/outside.md"
+    assert (mirror_root / "handoff.md").read_text(encoding="utf-8") == "上游产物正文：可供下一岗位直接参考。"
+    assert "/mnt/user-data/workspace/upstream/handoff.md" in context["instructions"]
+    assert set(calls) == {
+        ("upstream-thread", "mnt/user-data/outputs/handoff.md"),
+        ("current-thread", "mnt/user-data/workspace/upstream/handoff.md"),
+    }
+
+
+@pytest.mark.asyncio
+async def test_handoff_mirror_falls_back_to_persisted_content_and_skips_unsafe_paths(
+    tmp_path, monkeypatch
+):
+    mirror_root = tmp_path / "mirror"
+    resolved: list[tuple[str, str]] = []
+
+    class StubStore:
+        async def get_session(self, session_id, user_id):
+            assert (session_id, user_id) == ("session-a", "user-a")
+            return {"task_snapshot": {"title": "测试任务"}, "intent_snapshot": {}}
+
+        async def list_nodes(self, session_id, user_id):
+            return [
+                {
+                    "node_key": "stage-1-seat-1-agent-a",
+                    "stage_index": 0,
+                    "seat_index": 0,
+                    "agent_id": "agent-a",
+                    "position_id": "planning",
+                    "thread_id": "upstream-thread",
+                    "status": "done",
+                    "revision": 1,
+                    "latest_answer": "上游问答结果",
+                    "artifact_manifest": [
+                        {
+                            "name": "gone.md",
+                            "path": "mnt/user-data/outputs/gone.md",
+                            "mime_type": "text/markdown",
+                            "content": "数据库恢复正文",
+                        },
+                        {
+                            "name": "escape.md",
+                            "path": "mnt/user-data/outputs/../escape.md",
+                            "mime_type": "text/markdown",
+                            "content": "不应被镜像",
+                        },
+                    ],
+                },
+                {
+                    "node_key": "stage-2-seat-1-agent-b",
+                    "stage_index": 1,
+                    "seat_index": 0,
+                    "agent_id": "agent-b",
+                    "position_id": "solution",
+                    "thread_id": "current-thread",
+                    "status": "ready",
+                    "revision": 0,
+                    "latest_answer": None,
+                    "artifact_manifest": [],
+                },
+            ]
+
+    missing_source = tmp_path / "missing-source"
+
+    async def resolve(thread_id: str, path: str):
+        resolved.append((thread_id, path))
+        if thread_id == "upstream-thread":
+            return missing_source / "not-materialized.md"
+        assert thread_id == "current-thread"
+        return mirror_root / Path(path).name
+
+    monkeypatch.setattr(position_roundtable_router, "aresolve_thread_virtual_path", resolve)
+    request = SimpleNamespace(
+        app=SimpleNamespace(state=SimpleNamespace(position_roundtable_store=StubStore())),
+        state=SimpleNamespace(user=SimpleNamespace(id="user-a")),
+    )
+
+    context = await position_roundtable_router._handoff_context(
+        request, "session-a", "stage-2-seat-1-agent-b"
+    )
+
+    artifacts = context["upstream_nodes"][0]["artifacts"]
+    assert artifacts[0]["path"] == "mnt/user-data/workspace/upstream/gone.md"
+    assert artifacts[0]["mirrored_to_sandbox"] is True
+    assert (mirror_root / "gone.md").read_text(encoding="utf-8") == "数据库恢复正文"
+    # 持久化正文同时内嵌，沙箱磁盘丢失也不影响下一岗位读到内容。
+    assert artifacts[0]["content"] == "数据库恢复正文"
+    assert artifacts[1]["path"] == "mnt/user-data/outputs/../escape.md"
+    assert "mirrored_to_sandbox" not in artifacts[1]
+    assert not (mirror_root / "escape.md").exists()
+    assert all(".." not in path for _, path in resolved)
 
 
 @pytest.mark.asyncio