M4：单个工作流接口的 run_count 和列表接口按同一个函数算

验收时 GET /api/workflows/{id} 的 run_count 恒为 0，同一时刻列表接口里同一个工作流是 2 次、4 次：只有列表接口按
Run.workflow_id 计数，详情、保存（PATCH）、恢复旧版、新建、复制直接返回数据库对象，落在 WorkflowOut 的默认值 0 上。
计数抽成 _run_counts，列表和返回单个工作流的接口（_workflow_out）都走它，次数一致；新建、复制出来的工作流照实是 0。

backend/app/api/workflows.py

@@ -65,14 +65,28 @@ class WorkflowOut(BaseModel):
     model_config = {"from_attributes": True}
 
 
+async def _run_counts(session: AsyncSession, ids: list[str] | None = None) -> dict[str, int]:
+    """各工作流的运行次数 {工作流 id: 次数}，ids 为 None 时算全部。列表和单个工作流的接口都按它算：以前只有列表
+    计数，详情、保存、恢复的返回落在 WorkflowOut 的默认值 0 上，同一个工作流两处说的次数不一样。"""
+    stmt = select(Run.workflow_id, func.count(Run.id)).group_by(Run.workflow_id)
+    if ids is not None:
+        stmt = stmt.where(Run.workflow_id.in_(ids))
+    return dict((await session.execute(stmt)).all())
+
+
+async def _workflow_out(session: AsyncSession, workflow: Workflow) -> WorkflowOut:
+    """返回单个工作流的接口都走这里，run_count 和列表一致。"""
+    item = WorkflowOut.model_validate(workflow)
+    item.run_count = (await _run_counts(session, [workflow.id])).get(workflow.id, 0)
+    return item
+
+
 @router.get("", response_model=list[WorkflowOut])
 async def list_workflows(session: AsyncSession = Depends(get_session)) -> list[WorkflowOut]:
     rows = list(
         (await session.execute(select(Workflow).order_by(Workflow.updated_at.desc()))).scalars()
     )
-    counts = dict(
-        (await session.execute(select(Run.workflow_id, func.count(Run.id)).group_by(Run.workflow_id))).all()
-    )
+    counts = await _run_counts(session)
     out: list[WorkflowOut] = []
     for row in rows:
         item = WorkflowOut.model_validate(row)
@@ -84,7 +98,7 @@ async def list_workflows(session: AsyncSession = Depends(get_session)) -> list[W
 @router.post("", response_model=WorkflowOut, status_code=201)
 async def create_workflow(
     payload: WorkflowIn, session: AsyncSession = Depends(get_session)
-) -> Workflow:
+) -> WorkflowOut:
     workflow = Workflow(
         name=payload.name,
         description=payload.description,
@@ -99,23 +113,23 @@ async def create_workflow(
     )
     await session.commit()
     await session.refresh(workflow)
-    return workflow
+    return await _workflow_out(session, workflow)
 
 
 @router.get("/{workflow_id}", response_model=WorkflowOut)
 async def get_workflow(
     workflow_id: str, session: AsyncSession = Depends(get_session)
-) -> Workflow:
+) -> WorkflowOut:
     workflow = await session.get(Workflow, workflow_id)
     if not workflow:
         raise HTTPException(404, _GONE)
-    return workflow
+    return await _workflow_out(session, workflow)
 
 
 @router.patch("/{workflow_id}", response_model=WorkflowOut)
 async def update_workflow(
     workflow_id: str, payload: WorkflowPatch, session: AsyncSession = Depends(get_session)
-) -> Workflow:
+) -> WorkflowOut:
     workflow = await session.get(Workflow, workflow_id)
     if not workflow:
         raise HTTPException(404, _GONE)
@@ -146,7 +160,7 @@ async def update_workflow(
             workflow.status = "draft"
     await session.commit()
     await session.refresh(workflow)
-    return workflow
+    return await _workflow_out(session, workflow)
 
 
 @router.delete("/{workflow_id}", status_code=204)
@@ -172,7 +186,7 @@ async def delete_workflow(
 @router.post("/{workflow_id}/duplicate", response_model=WorkflowOut, status_code=201)
 async def duplicate_workflow(
     workflow_id: str, session: AsyncSession = Depends(get_session)
-) -> Workflow:
+) -> WorkflowOut:
     source = await session.get(Workflow, workflow_id)
     if not source:
         raise HTTPException(404, _GONE)
@@ -185,7 +199,7 @@ async def duplicate_workflow(
     session.add(copy)
     await session.commit()
     await session.refresh(copy)
-    return copy
+    return await _workflow_out(session, copy)
 
 
 class VersionOut(BaseModel):
@@ -267,7 +281,7 @@ async def get_version(
 @router.post("/{workflow_id}/versions/{version}/restore", response_model=WorkflowOut)
 async def restore_version(
     workflow_id: str, version: int, session: AsyncSession = Depends(get_session)
-) -> Workflow:
+) -> WorkflowOut:
     workflow = await session.get(Workflow, workflow_id)
     if not workflow:
         raise HTTPException(404, _GONE)
@@ -298,7 +312,7 @@ async def restore_version(
         workflow.status = "draft"
     await session.commit()
     await session.refresh(workflow)
-    return workflow
+    return await _workflow_out(session, workflow)
 
 
 class PublishIn(BaseModel):

backend/tests/test_workflow_run_count.py

@@ -0,0 +1,84 @@
+"""单个工作流接口的 run_count 和列表接口按同一个函数算。
+
+2026-10 验收：GET /api/workflows/{id} 的 run_count 恒为 0，同一时刻列表接口（GET /api/workflows）里这个工作流是
+2 次、运行列表按 workflow_id 筛出来也是 2 条——只有列表接口按 Run.workflow_id 计数，详情、保存（PATCH）、恢复旧版
+直接返回数据库对象，WorkflowOut.run_count 落在默认值 0 上。现在凡是返回工作流的接口都按同一个函数算，次数和列表一致。
+
+工作流名、图、运行都是虚构的。
+"""
+from __future__ import annotations
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from app.db.base import SessionLocal
+from app.db.models import Run
+from app.main import app
+
+GRAPH = {
+    "nodes": [
+        {"id": "start", "type": "input", "position": {"x": 0, "y": 0},
+         "data": {"label": "输入", "config": {"fields": [{"name": "week"}]}}},
+        {"id": "out", "type": "output", "position": {"x": 300, "y": 0},
+         "data": {"label": "成果", "config": {"fields": [{"name": "r", "value": "{{ input.week }}"}]}}},
+    ],
+    "edges": [{"source": "start", "target": "out"}],
+}
+
+
+@pytest.fixture
+async def client():
+    async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as c:
+        yield c
+
+
+async def _add_runs(workflow_id: str | None, n: int, status: str = "succeeded") -> None:
+    async with SessionLocal() as session:
+        for _ in range(n):
+            session.add(Run(workflow_id=workflow_id, workflow_name="灯塔周报", graph=GRAPH, input={}, status=status))
+        await session.commit()
+
+
+async def _listed(client, workflow_id: str) -> int:
+    [row] = [w for w in (await client.get("/api/workflows")).json() if w["id"] == workflow_id]
+    return row["run_count"]
+
+
+async def test_the_single_workflow_counts_its_runs_like_the_list(client):
+    made = (await client.post("/api/workflows", json={"name": "灯塔周报", "graph": GRAPH})).json()
+    other = (await client.post("/api/workflows", json={"name": "潮汐日报", "graph": GRAPH})).json()
+    await _add_runs(made["id"], 3)
+    await _add_runs(made["id"], 1, status="failed")
+    # 别的工作流、没挂在工作流上的运行不算进来
+    await _add_runs(other["id"], 2)
+    await _add_runs(None, 1)
+
+    assert await _listed(client, made["id"]) == 4
+    got = await client.get(f"/api/workflows/{made['id']}")
+    assert got.status_code == 200 and got.json()["run_count"] == 4
+    assert (await client.get(f"/api/workflows/{other['id']}")).json()["run_count"] == await _listed(client, other["id"]) == 2
+
+
+async def test_save_and_restore_answer_with_the_same_count(client):
+    """保存、恢复旧版的返回也是这个工作流：界面拿它替换手里的那一份，次数不能变回 0。"""
+    made = (await client.post("/api/workflows", json={"name": "灯塔周报", "graph": GRAPH})).json()
+    await _add_runs(made["id"], 2)
+
+    renamed = await client.patch(f"/api/workflows/{made['id']}", json={"name": "灯塔周报（新）"})
+    assert renamed.status_code == 200 and renamed.json()["run_count"] == 2
+    changed = {**GRAPH, "nodes": [*GRAPH["nodes"][:1], {**GRAPH["nodes"][1], "position": {"x": 320, "y": 0}}]}
+    saved = await client.patch(f"/api/workflows/{made['id']}", json={"graph": changed, "note": "挪了一下"})
+    assert saved.status_code == 200 and saved.json()["version"] == 2 and saved.json()["run_count"] == 2
+    restored = await client.post(f"/api/workflows/{made['id']}/versions/1/restore")
+    assert restored.status_code == 200 and restored.json()["run_count"] == 2
+    assert await _listed(client, made["id"]) == 2
+
+
+async def test_new_and_copied_workflows_have_no_runs_yet(client):
+    """新建、复制出来的是新工作流，还没有运行；复制不带上原来那个的次数。"""
+    made = (await client.post("/api/workflows", json={"name": "灯塔周报", "graph": GRAPH})).json()
+    assert made["run_count"] == 0
+    await _add_runs(made["id"], 3)
+    copy = await client.post(f"/api/workflows/{made['id']}/duplicate")
+    assert copy.status_code == 201 and copy.json()["run_count"] == 0
+    assert (await client.get(f"/api/workflows/{made['id']}")).json()["run_count"] == 3