diff --git a/backend/app/api/action_plans.py b/backend/app/api/action_plans.py
index 43237e36..46393f2b 100644
--- a/backend/app/api/action_plans.py
+++ b/backend/app/api/action_plans.py
@@ -62,6 +62,32 @@ def _validate_due_date_against_quarter(due_date: datetime, quarter: str):
             f"KR截止日期({due.date()})超出本季度范围({q_end.date()})，最大截止为{q_end.date()}")
 
 
+# ──────────────────────────────────────────────
+# 「已逾期」派生口径（单一来源，2026-09-21 project-20260921-actionplan-overdue-filter）
+# ──────────────────────────────────────────────
+# 口径：overdue = status in (pending, in_progress) AND due_date < now
+#
+# 为什么要有这个函数（缺陷根因）：status 的取值域只有
+#   pending / in_progress / completed / cancelled —— **没有** overdue 这个值。
+#   前端把统计卡片的 key（'overdue'）直接当 status 传给列表端点
+#   （frontend/src/views/ActionPlanLibrary.vue:414 卡片 key、:26 filterStatus、:422 params.status），
+#   而 list_plans 原实现按 `ActionPlan.status == 'overdue'` 直查 → 恒 0 条，
+#   于是出现「卡片 7 条 ≠ 列表 0 条」。
+#   统计端点 plan_stats 早就用的是派生口径 —— 两处口径分家正是本次不一致的来源。
+#   故把派生口径抽成本函数，plan_stats 与 list_plans **共用同一实现**（同源），
+#   今后口径只此一处，不再出现「卡片 ≠ 列表」。
+OVERDUE_KEY = "overdue"
+OVERDUE_STATUSES = ("pending", "in_progress")
+
+
+def _apply_overdue(query):
+    """把「已逾期」派生口径施加到 ActionPlan 查询上（stats / list 共用）。"""
+    return query.filter(
+        ActionPlan.status.in_(list(OVERDUE_STATUSES)),
+        ActionPlan.due_date < datetime.now(),
+    )
+
+
 def plan_to_dict(p: ActionPlan) -> dict:
     return {
         "id": p.id,
@@ -100,7 +126,12 @@ def list_plans(
     """获取行动计划列表（账套隔离: join KPI按企业过滤, 2026-08-23 P1b）"""
     query = db.query(ActionPlan).join(KPIDefinition, KPIDefinition.id == ActionPlan.kpi_id).filter(KPIDefinition.entity_id == entity_id).order_by(ActionPlan.created_at.desc())
 
-    if status:
+    if status == OVERDUE_KEY:
+        # 「已逾期」是**派生条件**而非 status 值（口径与 /stats 同源，2026-09-21）
+        # 前端统计卡片直接把 key='overdue' 当 status 传来，故此处按派生口径过滤，
+        # 与 plan_stats 共用 _apply_overdue，保证「卡片条数 = 列表条数」。
+        query = _apply_overdue(query)
+    elif status:
         query = query.filter(ActionPlan.status == status)
     if kpi_id:
         query = query.filter(ActionPlan.kpi_id == kpi_id)
@@ -352,8 +383,7 @@ def plan_stats(db: Session = Depends(get_db), current_user: User = Depends(requi
     pending = query.filter(ActionPlan.status == "pending").count()
     in_progress = query.filter(ActionPlan.status == "in_progress").count()
     completed = query.filter(ActionPlan.status == "completed").count()
-    from datetime import datetime
-    overdue = query.filter(ActionPlan.status.in_(["pending", "in_progress"]), ActionPlan.due_date < datetime.now()).count()
+    overdue = _apply_overdue(query).count()
     return {
         "total": total,
         "pending": pending,
diff --git a/backend/tests/test_actionplan_overdue_filter_20260921.py b/backend/tests/test_actionplan_overdue_filter_20260921.py
new file mode 100644
index 00000000..10c28493
--- /dev/null
+++ b/backend/tests/test_actionplan_overdue_filter_20260921.py
@@ -0,0 +1,297 @@
+"""行动方案库「已逾期」口径一致性测试
+
+任务：project-20260921-actionplan-overdue-filter
+（卡片 7 条 → 列表 0 条）
+
+缺陷
+    前端统计卡片把 key='overdue' 直接当 status 传给
+    GET /api/cma/action-plans（ActionPlanLibrary.vue:414 卡片 key / :26 filterStatus / :422 params.status），
+    而 list_plans 原实现按 `ActionPlan.status == 'overdue'` 直查 —— status 取值域只有
+    pending / in_progress / completed / cancelled，**没有 overdue** → 恒 0 条。
+    /stats 的 overdue 是派生口径：status in (pending, in_progress) AND due_date < now。
+    两处口径分家 ⇒ 同一张卡片「数 7 条 / 列表 0 条」。
+
+修复
+    list_plans 在 status == 'overdue' 时走 _apply_overdue()，与 plan_stats **共用同一实现**。
+
+本文件覆盖
+    ① 已逾期列表条数 == stats.overdue（HTTP 全链路：鉴权 + 账套 + 查询参数）
+    ② 其余卡片（total/pending/in_progress/completed）列表条数与 stats 逐项相符
+    ③ 口径同源：派生集合 ⊆ {pending,in_progress} 且 due_date < now；status=completed/cancelled
+       即使已过期也不计入
+    ④ 边界：刚过期（-60s）计入 / 未到期（+60s）不计入 / due_date 为空不计入
+    ⑤ 账套隔离：e1 会话只看 e1 KPI 下的计划，e2 逾期计划不出现在 e1 的逾期列表
+    ⑥ business 角色过滤：只统计/返回自己的计划（列表与统计同时收窄）
+    ⑦ 负对照：同一批夹具下「旧口径」status=='overdue' 确为 0 条（证明夹具真能复现缺陷）
+"""
+import inspect
+from datetime import datetime, timedelta
+
+from fastapi.testclient import TestClient
+from sqlalchemy.orm import Session
+
+from app.api import action_plans as ap
+from app.models import ActionPlan, Entity, KPIDefinition
+from tests.conftest import TEST_USER_PASSWORD, auth_header, create_test_user, create_test_kpi
+
+E1_KPI_CODE = "ZZ_APOVD_E1_KPI_001"
+E2_KPI_CODE = "ZZ_APOVD_E2_KPI_001"
+
+T_OVERDUE_PENDING = "逾期待处理"
+T_OVERDUE_INPROG = "逾期进行中"
+T_FUTURE_PENDING = "未到期待处理"
+T_OVERDUE_COMPLETED = "已完成且已过期"
+T_OVERDUE_CANCELLED = "已取消且已过期"
+T_NO_DUE_PENDING = "无截止日待处理"
+
+
+# ──────────────────────────────────────────────
+# 夹具
+# ──────────────────────────────────────────────
+
+def _ensure_entity(db: Session, eid: int, name: str) -> Entity:
+    ent = db.query(Entity).filter(Entity.id == eid).first()
+    if not ent:
+        ent = Entity(id=eid, name=name, short_name=name, status="active")
+        db.add(ent)
+        db.commit()
+        db.refresh(ent)
+    return ent
+
+
+def _mk_kpi(db: Session, code: str, eid: int) -> KPIDefinition:
+    return create_test_kpi(db, kpi_code=code, kpi_name=f"{code}-名称", entity_id=eid)
+
+
+def _mk_plan(db: Session, kpi_id: int, title: str, status: str, due_delta_sec,
+             assignee: str = "张三") -> ActionPlan:
+    due = None if due_delta_sec is None else datetime.now() + timedelta(seconds=due_delta_sec)
+    plan = ActionPlan(
+        entity_id=1,
+        kpi_id=kpi_id,
+        title=title,
+        status=status,
+        due_date=due,
+        assignee=assignee,
+        priority="medium",
+        progress=0,
+        created_by="testadmin",
+    )
+    db.add(plan)
+    db.commit()
+    db.refresh(plan)
+    return plan
+
+
+def _login(client: TestClient, entity_id: int, username: str = "testadmin") -> str:
+    resp = client.post("/api/cma/auth/login", json={
+        "username": username,
+        "password": TEST_USER_PASSWORD,
+        "entity_id": entity_id,
+    })
+    assert resp.status_code == 200, f"登录 entity{entity_id} 失败: {resp.text[:300]}"
+    return resp.json()["token"]
+
+
+def _seed_e1(db: Session):
+    """e1 夹具：2 条逾期 + 4 条不计入（未到期 / 已完成 / 已取消 / 无截止日）"""
+    _ensure_entity(db, 1, "酣客")
+    create_test_user(db)
+    kpi = _mk_kpi(db, E1_KPI_CODE, 1)
+    _mk_plan(db, kpi.id, T_OVERDUE_PENDING, "pending", -86400)          # 逾期
+    _mk_plan(db, kpi.id, T_OVERDUE_INPROG, "in_progress", -3600)        # 逾期
+    _mk_plan(db, kpi.id, T_FUTURE_PENDING, "pending", +86400)           # 未到期
+    _mk_plan(db, kpi.id, T_OVERDUE_COMPLETED, "completed", -86400)      # 已完成→不算逾期
+    _mk_plan(db, kpi.id, T_OVERDUE_CANCELLED, "cancelled", -86400)      # 已取消→不算逾期
+    _mk_plan(db, kpi.id, T_NO_DUE_PENDING, "pending", None)             # 无截止日
+    return kpi
+
+
+def _titles(resp_json) -> set:
+    return {row["title"] for row in resp_json["data"]}
+
+
+# ──────────────────────────────────────────────
+# ① 已逾期列表条数 == stats.overdue（HTTP 全链路）
+# ──────────────────────────────────────────────
+
+def test_overdue_list_count_equals_stats(client: TestClient, db: Session):
+    """核心验收：?status=overdue 的条数 == /stats 的 overdue，且只含派生口径内的行"""
+    _seed_e1(db)
+    token = _login(client, 1)
+    h = auth_header(token)
+
+    stats = client.get("/api/cma/action-plans/stats", headers=h).json()
+    listed = client.get("/api/cma/action-plans?status=overdue", headers=h).json()
+
+    assert stats["overdue"] == 2, f"夹具期望 overdue=2，实际 {stats['overdue']}"
+    assert len(listed["data"]) == stats["overdue"], (
+        f"卡片 overdue={stats['overdue']} 与列表 {len(listed['data'])} 条不一致"
+        "（缺陷复现：卡片数≠列表数）"
+    )
+    assert _titles(listed) == {T_OVERDUE_PENDING, T_OVERDUE_INPROG}, (
+        f"逾期列表内容应为 2 条逾期待办，实际 {sorted(_titles(listed))}"
+    )
+    # 口径内容断言：全部落在 status ∈ {pending, in_progress} 且 due_date < now
+    for row in listed["data"]:
+        assert row["status"] in ("pending", "in_progress"), row
+        assert row["due_date"] and datetime.fromisoformat(row["due_date"]) < datetime.now(), row
+
+
+# ──────────────────────────────────────────────
+# ② 其余卡片逐项相符
+# ──────────────────────────────────────────────
+
+def test_other_cards_match_stats(client: TestClient, db: Session):
+    """回归：total/pending/in_progress/completed 列表条数与 stats 逐项相符"""
+    _seed_e1(db)
+    token = _login(client, 1)
+    h = auth_header(token)
+
+    stats = client.get("/api/cma/action-plans/stats", headers=h).json()
+    assert stats == {"total": 6, "pending": 3, "in_progress": 1,
+                     "completed": 1, "overdue": 2}, stats
+
+    cards = {"total": "", "pending": "pending", "in_progress": "in_progress",
+             "completed": "completed", "overdue": "overdue"}
+    for key, param in cards.items():
+        url = "/api/cma/action-plans" + (f"?status={param}" if param else "")
+        rows = client.get(url, headers=h).json()["data"]
+        assert len(rows) == stats[key], f"卡片 {key}: stats={stats[key]} 列表={len(rows)}"
+
+
+# ──────────────────────────────────────────────
+# ③ 口径同源（派生集合 + 源码单一来源）
+# ──────────────────────────────────────────────
+
+def test_overdue_excludes_completed_and_cancelled(client: TestClient, db: Session):
+    """已完成/已取消即使早已过期也不计入逾期（口径 = status ∈ {pending,in_progress}）"""
+    _seed_e1(db)
+    token = _login(client, 1)
+    h = auth_header(token)
+
+    titles = _titles(client.get("/api/cma/action-plans?status=overdue", headers=h).json())
+    assert T_OVERDUE_COMPLETED not in titles
+    assert T_OVERDUE_CANCELLED not in titles
+    assert T_NO_DUE_PENDING not in titles
+
+    # 字面 status 过滤未被改动（仍按 status 直查）
+    assert _titles(client.get("/api/cma/action-plans?status=cancelled", headers=h).json()) == {
+        T_OVERDUE_CANCELLED}
+    assert len(client.get("/api/cma/action-plans?status=pending", headers=h).json()["data"]) == 3
+
+
+def test_overdue_caliber_is_single_source():
+    """统计与列表共用同一实现：plan_stats 与 list_plans 都调用 _apply_overdue"""
+    stats_src = inspect.getsource(ap.plan_stats)
+    list_src = inspect.getsource(ap.list_plans)
+    assert "_apply_overdue(query)" in stats_src, "plan_stats 未走 _apply_overdue（口径分家）"
+    assert "_apply_overdue(query)" in list_src, "list_plans 未走 _apply_overdue（口径分家）"
+    assert ap.OVERDUE_STATUSES == ("pending", "in_progress")
+    assert ap.OVERDUE_KEY == "overdue"
+
+
+# ──────────────────────────────────────────────
+# ④ 边界
+# ──────────────────────────────────────────────
+
+def test_overdue_boundary_and_null_due_date(client: TestClient, db: Session):
+    """边界：-60s 计入、+60s 不计入、due_date 为空不计入"""
+    _ensure_entity(db, 1, "酣客")
+    create_test_user(db)
+    kpi = _mk_kpi(db, E1_KPI_CODE, 1)
+    _mk_plan(db, kpi.id, "刚过期60秒", "pending", -60)
+    _mk_plan(db, kpi.id, "还有60秒到期", "pending", +60)
+    _mk_plan(db, kpi.id, "无截止日", "pending", None)
+
+    token = _login(client, 1)
+    h = auth_header(token)
+    titles = _titles(client.get("/api/cma/action-plans?status=overdue", headers=h).json())
+    assert titles == {"刚过期60秒"}, titles
+    stats = client.get("/api/cma/action-plans/stats", headers=h).json()
+    assert stats["overdue"] == 1 and stats["pending"] == 3 and stats["total"] == 3, stats
+
+
+# ──────────────────────────────────────────────
+# ⑤ 账套隔离
+# ──────────────────────────────────────────────
+
+def test_overdue_entity_isolation(client: TestClient, db: Session):
+    """e1/e2 各自只看到本账套 KPI 下的计划；逾期口径同样按账套收窄"""
+    _ensure_entity(db, 1, "酣客")
+    _ensure_entity(db, 2, "博海")
+    create_test_user(db)
+    k1 = _mk_kpi(db, E1_KPI_CODE, 1)
+    k2 = _mk_kpi(db, E2_KPI_CODE, 2)
+    _mk_plan(db, k1.id, "e1逾期", "pending", -3600)
+    p2 = _mk_plan(db, k2.id, "e2逾期", "pending", -3600)
+    p2.entity_id = 2
+    db.commit()
+
+    h1 = auth_header(_login(client, 1))
+    h2 = auth_header(_login(client, 2))
+
+    s1 = client.get("/api/cma/action-plans/stats", headers=h1).json()
+    s2 = client.get("/api/cma/action-plans/stats", headers=h2).json()
+    l1 = _titles(client.get("/api/cma/action-plans?status=overdue", headers=h1).json())
+    l2 = _titles(client.get("/api/cma/action-plans?status=overdue", headers=h2).json())
+
+    assert s1["overdue"] == 1 and s2["overdue"] == 1, (s1, s2)
+    assert l1 == {"e1逾期"}, l1
+    assert l2 == {"e2逾期"}, l2
+    assert len(client.get("/api/cma/action-plans", headers=h1).json()["data"]) == s1["total"] == 1
+    assert len(client.get("/api/cma/action-plans", headers=h2).json()["data"]) == s2["total"] == 1
+
+
+# ──────────────────────────────────────────────
+# ⑥ business 角色过滤
+# ──────────────────────────────────────────────
+
+def test_overdue_business_role_filter(client: TestClient, db: Session):
+    """business 角色：列表与统计同时只收窄到自己名下（逾期口径也随之下沉）"""
+    _ensure_entity(db, 1, "酣客")
+    create_test_user(db)
+    create_test_user(db, username="业务小王", name="业务小王", role="business")
+    kpi = _mk_kpi(db, E1_KPI_CODE, 1)
+    _mk_plan(db, kpi.id, "小王的逾期", "pending", -3600, assignee="业务小王")
+    _mk_plan(db, kpi.id, "张三的逾期", "pending", -3600, assignee="张三")
+    _mk_plan(db, kpi.id, "小王的未到期", "pending", +3600, assignee="业务小王")
+
+    h = auth_header(_login(client, 1, username="业务小王"))
+    stats = client.get("/api/cma/action-plans/stats", headers=h).json()
+    assert stats == {"total": 2, "pending": 2, "in_progress": 0,
+                     "completed": 0, "overdue": 1}, stats
+    listed = client.get("/api/cma/action-plans?status=overdue", headers=h).json()["data"]
+    assert len(listed) == stats["overdue"] == 1
+    assert listed[0]["title"] == "小王的逾期"
+    assert len(client.get("/api/cma/action-plans", headers=h).json()["data"]) == stats["total"]
+
+
+def test_overdue_with_other_filters_compose(client: TestClient, db: Session):
+    """派生口径与 kpi_id / keyword 组合时仍成立（不覆盖既有筛选）"""
+    kpi = _seed_e1(db)
+    token = _login(client, 1)
+    h = auth_header(token)
+
+    hit = client.get(f"/api/cma/action-plans?status=overdue&kpi_id={kpi.id}", headers=h).json()
+    assert len(hit["data"]) == 2
+    miss = client.get(f"/api/cma/action-plans?status=overdue&kpi_id={kpi.id + 999}", headers=h).json()
+    assert miss["data"] == []
+    kw = client.get("/api/cma/action-plans?status=overdue&keyword=逾期", headers=h).json()
+    assert _titles(kw) == {T_OVERDUE_PENDING, T_OVERDUE_INPROG}
+
+
+# ──────────────────────────────────────────────
+# ⑦ 负对照：旧口径在同一夹具上确为 0
+# ──────────────────────────────────────────────
+
+def test_negative_control_legacy_caliber_returns_zero(db: Session):
+    """负对照：同一批夹具下 `status=='overdue'` 的行数 = 0、派生口径 = 2
+
+    证明夹具真的能复现该缺陷（若这里两边相等，用例就没有鉴别力）。
+    """
+    _seed_e1(db)
+    literal = db.query(ActionPlan).filter(ActionPlan.status == "overdue").count()
+    derived = ap._apply_overdue(db.query(ActionPlan)).count()
+    assert literal == 0, "status 域不应存在 'overdue' 值"
+    assert derived == 2, derived