feat(orchestrator): 续写链前一章无已验收终稿发 warning——静默丢前文引子可观测（CR-L1）

packages/core/tests/test_chain_graph.py

@@ -13,6 +13,7 @@ from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
 from typing import Any
 
+import structlog
 from langchain_core.runnables import RunnableConfig
 from langgraph.checkpoint.memory import MemorySaver
 from langgraph.types import Command
@@ -446,6 +447,57 @@ async def test_write_chapter_continue_volume_injects_prior_accepted_text() -> No
     assert "前文正文" in write_input  # build_continuation_context 的小节标题
 
 
+async def test_continue_volume_warns_when_prior_chapter_unaccepted() -> None:
+    """continue_volume 写第 2 章但第 1 章无已验收终稿 → 静默丢前文引子须发 warning（CR-L1）。"""
+    h = _make_harness(conflicts=[])
+    # accepted_store 故意留空：第 1 章尚无已验收正文 → 续写丢失前文引子（静默降级）。
+    state = initial_chain_state(
+        project_id=PROJECT,
+        user_id=USER,
+        start_chapter_no=2,
+        count=1,
+        chain_key="continue_volume",
+    )
+
+    with structlog.testing.capture_logs() as logs:
+        await write_chapter(
+            state,
+            gateway_builder=h["gateway_builder"],
+            session_factory=h["session_factory"],
+            memory_repos_factory=h["memory_repos_factory"],
+            chapter_repo_factory=h["chapter_repo_factory"],
+            assemble=h["assemble"],
+        )
+
+    warning = next(e for e in logs if e["event"] == "chain_prior_accepted_missing")
+    assert warning["log_level"] == "warning"
+    assert warning["chapter_no"] == 2
+
+
+async def test_continue_volume_first_chapter_does_not_warn() -> None:
+    """第 1 章前一章号 < 1，无前文属预期（非降级）→ 不应发缺前文 warning。"""
+    h = _make_harness(conflicts=[])
+    state = initial_chain_state(
+        project_id=PROJECT,
+        user_id=USER,
+        start_chapter_no=1,
+        count=1,
+        chain_key="continue_volume",
+    )
+
+    with structlog.testing.capture_logs() as logs:
+        await write_chapter(
+            state,
+            gateway_builder=h["gateway_builder"],
+            session_factory=h["session_factory"],
+            memory_repos_factory=h["memory_repos_factory"],
+            chapter_repo_factory=h["chapter_repo_factory"],
+            assemble=h["assemble"],
+        )
+
+    assert not [e for e in logs if e["event"] == "chain_prior_accepted_missing"]
+
+
 async def test_continue_volume_chain_second_chapter_sees_first_chapter_text() -> None:
     """全图 E2E：continue_volume 两章——第 2 章请求上下文含第 1 章正文（不变量 #1/#5）。"""
     h = _make_harness(conflicts=[])

packages/core/ww_core/orchestrator/chain/nodes.py

@@ -325,7 +325,17 @@ async def _read_prior_accepted(
     if chapter_no <= 1:
         return ""
     view = await chapter_repo.latest_accepted(project_id, chapter_no - 1)
-    return view.content if view is not None else ""
+    if view is None:
+        # 静默降级须可观测（CR-L1）：续写式链本章续接的前一章尚无已验收终稿——续写会丢失
+        # 前文引子（降级为 build_continuation_context 的占位）。发 warning 便于查错，勿静默吞。
+        log.warning(
+            "chain_prior_accepted_missing",
+            project_id=str(project_id),
+            chapter_no=chapter_no,
+            prior_chapter_no=chapter_no - 1,
+        )
+        return ""
+    return view.content
 
 
 async def _commit(session: CommitSession) -> None: