fix(analytics): align yoy and detail table contracts

tests/test_analysis_period_linkage.py

@@ -14,7 +14,13 @@ from routes.monthly_routes import (
     _resolve_monthly_period,
     get_monthly_summary_data,
 )
-from routes.sales_routes import _filter_growth_payload, _sorted_valid_month_labels
+import routes.sales_routes as sales_routes
+from routes.sales_routes import (
+    _filter_growth_payload,
+    _period_month_keys,
+    _project_yoy_period,
+    _sorted_valid_month_labels,
+)
 from services.analysis_period_service import make_analysis_period, make_month_period
 
 
@@ -284,10 +290,72 @@ def test_monthly_frontend_has_replayable_period_and_no_fixed_years():
 
 def test_sales_frontend_uses_live_period_linked_api_routes():
     script = (ROOT / "web/static/js/page-sales-analysis.js").read_text(encoding="utf-8")
+    template = (ROOT / "templates/sales_analysis.html").read_text(encoding="utf-8")
 
     assert "buildPeriodApiUrl" in script
     assert "new URLSearchParams(window.location.search)" in script
     assert "/api/sales_analysis/yoy_comparison" in script
     assert "/api/sales_analysis/table_data" in script
+    assert "d.growth_rate" in script
+    assert "d.monthly_breakdown" in script
+    assert "columns," in script
+    assert 'data-field="product_id"' in template
+    assert 'data-field="amount"' in template
     assert "fetch(`/api/yoy?" not in script
     assert "'/api/sales_table?'" not in script
+
+
+def test_yoy_period_projects_selected_dates_to_each_comparison_year():
+    start, end = _project_yoy_period(2025, "2026-04-01", "2026-04-30")
+
+    assert start == date(2025, 4, 1)
+    assert end == date(2025, 4, 30)
+    assert _period_month_keys(start, end) == ["2025-04"]
+
+
+def test_yoy_api_uses_only_the_selected_period_for_totals_and_chart(monkeypatch):
+    engine = create_engine("sqlite:///:memory:")
+    with engine.begin() as conn:
+        conn.exec_driver_sql(
+            'CREATE TABLE realtime_sales_monthly ("日期" TEXT, "總業績" REAL, "數量" REAL, "總成本" REAL)'
+        )
+        conn.exec_driver_sql(
+            """
+            INSERT INTO realtime_sales_monthly ("日期", "總業績", "數量", "總成本")
+            VALUES
+                ('2025/04/10', 100, 2, 60),
+                ('2025/05/10', 900, 9, 100),
+                ('2026/04/10', 150, 3, 80),
+                ('2026/05/10', 1200, 12, 200)
+            """
+        )
+
+    class FakeDatabaseManager:
+        def __init__(self):
+            self.engine = engine
+
+    monkeypatch.setattr(sales_routes, "DatabaseManager", FakeDatabaseManager)
+    app = Flask(__name__)
+    with app.test_request_context(
+        "/api/sales_analysis/yoy_comparison"
+        "?year1=2025&year2=2026&metric=revenue"
+        "&start_date=2026-04-01&end_date=2026-04-30"
+    ):
+        response = sales_routes.api_yoy_comparison.__wrapped__()
+
+    payload = response.get_json()
+    assert payload["period"]["linked"] is True
+    assert payload["period"]["year1"] == {
+        "start_date": "2025-04-01",
+        "end_date": "2025-04-30",
+    }
+    assert payload["year1"]["total"] == 100
+    assert payload["year2"]["total"] == 150
+    assert payload["growth_rate"] == 50
+    assert payload["monthly_breakdown"] == [{
+        "month": 4,
+        "month_label": "4月",
+        "year1_value": 100,
+        "year2_value": 150,
+        "growth_rate": 50,
+    }]