数据目录阶段 1B 流式输出：挑表后发 context 操作，说明这一轮参考了哪些表、怎么挑的、挑表用时，挑表失败时带上原因

backend/app/api/copilot.py

@@ -130,7 +130,7 @@ async def _datasource_context(
 ) -> copilot_context.DatasourceContext:
     """这一轮的数据源上下文：读目录、大库按需求挑表、组装（copilot_context）。挑表失败退回只列表名，不抛异常。
 
-    非流式生成、发布前修复、升级都走这里；流式生成把三步拆开，挑表放进流里（期间发心跳）。
+    非流式生成、发布前修复、升级都走这里；流式生成把三步拆开，挑表放进流里（期间发心跳、挑完发 context 操作）。
     graph 是现有工作流：它的 SQL 查过的表一律给全字段。
     """
     plan = await copilot_context.plan_context(sources, graph=graph)
@@ -666,7 +666,7 @@ async def generate(
         model, _ = await get_chat_model(session, await copilot_model_spec(session, payload))
     except ProviderNotConfigured as e:
         raise HTTPException(400, _unconfigured(e)) from e
-    # 和流式生成同一套数据源上下文
+    # 和流式生成同一套数据源上下文，只是不发 context 操作（这条接口一次返回整张图）
     context = await _datasource_context(
         session, sources, payload, need=await _pick_need(session, payload),
         graph=payload.base_graph if (payload.base_graph or {}).get("nodes")
@@ -1704,6 +1704,8 @@ async def generate_stream(payload: GenerateIn, session: AsyncSession = Depends(g
         # 这一份 system 一直用到最后：自查交回修正时沿用同一份上下文，不重新挑表
         system = system_for(context)
         messages = [("system", system), ("human", human)]
+        if (shown := context.op()) is not None:
+            yield _sse(shown)
         try:
             async for op in _with_heartbeat(_iter_ops(model, messages), started=started):
                 kind = op.get("op")

backend/app/api/copilot_context.py

@@ -22,7 +22,7 @@
 **用法。** plan_context 读目录、按大小定每个源怎么给（不调模型，接口函数在开流之前调，因为请求的会话只在
 那时可用）；pick_model 拿挑表用的模型（同一个助手模型，关掉思考、额度取小）；ContextPlan.resolve 挑表并组装
 （流式生成在流里调，期间照常发心跳）；DatasourceContext 给出提示词片段（section）、工具清单里列出的可查对象
-（listed）。
+（listed）和告诉前端这一轮参考了哪些表的 context 操作（op）。
 """
 from __future__ import annotations
 
@@ -376,7 +376,7 @@ class ContextPlan:
         return out
 
     async def resolve(self, model: Any | None, *, need: str, unavailable: str | None = None) -> DatasourceContext:
-        """挑表并组装。不抛异常：挑表的任何失败都退回只列表名（fallback），原因写进日志。
+        """挑表并组装。不抛异常：挑表的任何失败都退回只列表名（fallback），原因写进 context 操作和日志。
 
         model 是 pick_model 拿到的模型；拿不到时为 None，unavailable 是原因。没有要挑表的源时不调模型。
         """
@@ -529,6 +529,28 @@ class DatasourceContext:
         first = [ctx.qualified(t) for t in ctx.tables]
         return first + [n for n in names if n not in first]
 
+    def op(self) -> dict[str, Any] | None:
+        """告诉前端这一轮参考了哪些表：{"op": "context", "sources": [...], "elapsed_ms"?}。没有可查的表时为 None。
+
+        每个源一项：source 源名，tables 给了全字段的表（全名），selected_by，total 这个源一共几张表；挑表失败的
+        带上 reason。只列了名字的表不进 tables：界面上说的「参考了 N 张表」是模型看得到字段的那些。
+        """
+        rows = []
+        for s in self.sources:
+            if not s.total:
+                continue
+            row: dict[str, Any] = {"source": s.source.name, "tables": [s.qualified(t) for t in s.tables],
+                                   "selected_by": s.selected_by, "total": s.total}
+            if s.selected_by == "fallback" and self.reason:
+                row["reason"] = self.reason
+            rows.append(row)
+        if not rows:
+            return None
+        out: dict[str, Any] = {"op": "context", "sources": rows}
+        if self.elapsed_ms is not None:
+            out["elapsed_ms"] = self.elapsed_ms
+        return out
+
     def section(self) -> str:
         """system 提示词里的数据源一节。没有数据源时返回空串，不占提示词。"""
         if not self.sources:

backend/tests/test_copilot_table_pick.py

@@ -8,7 +8,7 @@
 - 挑表、补路径、组装的结果（合成景区库：入园记录和渠道之间要经关联表 channel_visits）
 - 挑表失败（报错、超时、返回不存在的表、返回为空）一律退回只列表名，生成照常进行
 - 小库保持详细模式，额外带上目录
-- 自查修正沿用同一份上下文，不再重新挑表
+- 流式输出里有 context 操作；自查修正沿用同一份上下文，不再重新挑表
 - 非流式生成、发布前修复、升级共用同一套组装
 """
 from __future__ import annotations
@@ -176,6 +176,12 @@ OTHER_COLUMNS = ("store_code", "sku", "on_hand", "refund_amount")
 JOINS = ("channel_visits.visit_id = visits.id", "channel_visits.channel_id = channels.id")
 
 
+def _context_op(events: list[dict]) -> dict:
+    found = [e for e in events if e.get("op") == "context"]
+    assert len(found) == 1, [e.get("op") for e in events]
+    return found[0]
+
+
 # ---------------------------------------------------------------- 组装
 
 
@@ -289,7 +295,9 @@ async def test_several_sources_pick_with_source_names(scenic_db, tmp_path):
         by_name = {s.source.name: s for s in ctx.sources}
         assert by_name[a.name].tables == ["visits"]
         assert by_name[b.name].tables == ["orders", "payments"]
-        assert all(s.selected_by == "model" for s in ctx.sources)
+        op = ctx.op()
+        assert [s["source"] for s in op["sources"]] == [a.name, b.name]
+        assert all(s["selected_by"] == "model" for s in op["sources"])
     finally:
         await _drop_source(a)
         await _drop_source(b)
@@ -313,7 +321,9 @@ async def test_small_source_keeps_detail_and_carries_the_catalog(small_source):
     # 额外带上目录和连接条件
     assert f"中文名：订单{INFERRED_MARK}" in text and "单位：元" in text
     assert f"orders.customer_id = customers.id（多对一）{INFERRED_MARK}" in text
-    assert ctx.sources[0].selected_by == "all" and ctx.sources[0].tables == ["customers", "orders"]
+    op = ctx.op()
+    assert op["sources"] == [{"source": small_source.name, "tables": ["customers", "orders"], "selected_by": "all",
+                              "total": 2}]
 
 
 # ---------------------------------------------------------------- 回退：绝不阻断生成
@@ -335,6 +345,10 @@ async def test_pick_failures_fall_back_to_names_only(client, monkeypatch, scenic
     events = await _stream(client, monkeypatch, model, {
         "instruction": NEED, "intent": "answer", "datasource_ids": [scenic_source.id]})
 
+    op = _context_op(events)
+    assert op["sources"] == [{"source": scenic_source.name, "tables": [], "selected_by": "fallback",
+                              "total": scenic.TABLE_COUNT + len(scenic.VIEWS), "reason": op["sources"][0]["reason"]}]
+    assert op["sources"][0]["reason"]
     system = model.systems[0]
     # 和以前一样只列表名、提醒先查字段
     assert "channel_visits" in system and "attributed_share" not in system
@@ -344,10 +358,10 @@ async def test_pick_failures_fall_back_to_names_only(client, monkeypatch, scenic
 
 
 
-# ---------------------------------------------------------------- 流式：自查沿用同一份上下文
+# ---------------------------------------------------------------- 流式：context 操作、自查沿用同一份上下文
 
 
-async def test_stream_prompt_carries_selected_tables(client, monkeypatch, scenic_source):
+async def test_stream_reports_the_context_and_prompt_carries_selected_tables(client, monkeypatch, scenic_source):
     from app.api import copilot_context
 
     picker = Picker(PICKED)
@@ -356,7 +370,13 @@ async def test_stream_prompt_carries_selected_tables(client, monkeypatch, scenic
     events = await _stream(client, monkeypatch, model, {
         "instruction": NEED, "intent": "answer", "datasource_ids": [scenic_source.id]})
 
-    assert events[-1]["op"] == "final", events[-1]
+    op = _context_op(events)
+    assert op["sources"] == [{"source": scenic_source.name, "tables": ["visits", "channels", "channel_visits"],
+                              "selected_by": "model", "total": scenic.TABLE_COUNT + len(scenic.VIEWS)}]
+    assert isinstance(op["elapsed_ms"], int) and op["elapsed_ms"] >= 0
+    # context 在模型首帧之后、第一条图操作之前
+    kinds = [e["op"] for e in events]
+    assert kinds.index("model") < kinds.index("context") < kinds.index("add_node")
 
     # 挑表用同一个助手模型，关掉思考、额度取小
     (spec,) = specs
@@ -409,7 +429,8 @@ async def test_small_sources_do_not_call_the_picker(client, monkeypatch, small_s
     model = Scripted(_graph_using(f"db_query__{small_source.name}"))
     events = await _stream(client, monkeypatch, model, {
         "instruction": "订单总额", "intent": "answer", "datasource_ids": [small_source.id]})
-    assert events[-1]["op"] == "final", events[-1]
+    op = _context_op(events)
+    assert op["sources"][0]["selected_by"] == "all" and "elapsed_ms" not in op
     assert not picker.calls
     assert "· orders[表]" in model.systems[0]
 
@@ -450,7 +471,7 @@ def _node(nid, ntype, label, **config):
 
 
 async def test_publish_fix_shares_the_context(monkeypatch, scenic_source):
-    """发布前修复：现有图查的表一定带上，需求写的是挡住发布的问题。"""
+    """发布前修复：现有图查的表一定带上，需求写的是挡住发布的问题；不发 context 操作（返回值里没有）。"""
     import app.api.copilot as copilot
 
     picker = Picker({"tables": [{"source": scenic_source.name, "table": "visits"},
@@ -477,6 +498,7 @@ async def test_publish_fix_shares_the_context(monkeypatch, scenic_source):
     assert len(picker.calls) == 1 and "发布前检查" in picker.calls[0]
     system = model.systems[0]
     assert "attributed_share  REAL" in system and "sold_at  TEXT" in system
+    assert "context" not in json.dumps(out, ensure_ascii=False)
 
 
 async def test_upgrade_shares_the_context(monkeypatch, scenic_source):