feat(cbr): USD и CNY тянутся всегда, новая валюта — с начала леджера

Валюта, впервые появившаяся в ZenMoney между двумя запусками, раньше показывала «нет курса» до следующего синка. Для валюты без сохранённых курсов история берётся с начала леджера, а не от общего курсора.

backend/tests/sources/test_cbr.py

@@ -19,6 +19,7 @@ from fintracker.sources.cbr.sync import CbrSource
 
 USD_ID = "R01235"
 JPY_ID = "R01820"
+CNY_ID = "R01375"
 
 
 def settings() -> Settings:
@@ -39,7 +40,11 @@ def mock_cbr(mock_http, fixture_bytes, *, dynamic: dict[str, str] | None = None)
     daily = mock_http.get(DAILY_URL).mock(
         return_value=httpx.Response(200, content=fixture_bytes("cbr", "daily.xml"))
     )
-    files = dynamic or {USD_ID: "dynamic_usd.xml", JPY_ID: "dynamic_jpy.xml"}
+    files = dynamic or {
+        USD_ID: "dynamic_usd.xml",
+        JPY_ID: "dynamic_jpy.xml",
+        CNY_ID: "dynamic_cny.xml",
+    }
 
     def _dynamic(request: httpx.Request) -> httpx.Response:
         cbr_id = request.url.params.get("VAL_NM_RQ", "")
@@ -51,17 +56,19 @@ def mock_cbr(mock_http, fixture_bytes, *, dynamic: dict[str, str] | None = None)
     return daily, mock_http.get(DYNAMIC_URL).mock(side_effect=_dynamic)
 
 
-async def test_only_currencies_in_use_are_requested(app, mock_http, fixture_bytes, run_sync):
+async def test_currencies_in_use_are_requested_besides_the_always_quoted_pair(
+    app, mock_http, fixture_bytes, run_sync
+):
     await make_account(currency="RUB")
-    await make_account(currency="USD", source_id="usd-cash")
-    await make_txn(date(2026, 9, 1), outcome="100", outcome_currency="USD")
+    await make_account(currency="JPY", source_id="jpy-cash")
+    await make_txn(date(2026, 9, 1), outcome="100", outcome_currency="JPY")
 
     _, dynamic = mock_cbr(mock_http, fixture_bytes)
     result = await run_sync(CbrSource(), settings=settings())
 
     requested = {params["VAL_NM_RQ"] for params in route_params(dynamic)}
-    assert requested == {USD_ID}  # EUR and JPY are quoted by CBR but unused here
-    assert result.counts == {"currencies": 1, "rates": 3}
+    assert requested == {USD_ID, CNY_ID, JPY_ID}  # EUR is quoted by CBR, but nobody uses it
+    assert result.counts["currencies"] == 3
     assert result.warnings == []
     assert result.changed is True
     assert result.cursor_after is not None
@@ -88,13 +95,13 @@ async def test_currency_cbr_does_not_quote_is_a_warning(app, mock_http, fixture_
     _, dynamic = mock_cbr(mock_http, fixture_bytes)
     result = await run_sync(CbrSource(), settings=settings())
 
-    assert {params["VAL_NM_RQ"] for params in route_params(dynamic)} == {USD_ID}
+    assert {params["VAL_NM_RQ"] for params in route_params(dynamic)} == {USD_ID, CNY_ID}
     assert sorted(result.warnings) == [
         "BTC is not quoted by CBR — skipped (crypto or metal?)",
         "XAU is not quoted by CBR — skipped (crypto or metal?)",
     ]
-    assert result.counts["currencies"] == 1
-    assert result.counts["rates"] == 3
+    assert result.counts["currencies"] == 2
+    assert result.counts["rates"] == 6
 
 
 async def test_range_starts_before_the_first_transaction(app, mock_http, fixture_bytes, run_sync):
@@ -129,15 +136,43 @@ async def test_cursor_shortens_the_range_and_reruns_are_idempotent(
     assert params["date_req1"] == expected_start.strftime("%d/%m/%Y")
 
 
-async def test_no_foreign_currency_skips_the_network(app, mock_http, fixture_bytes, run_sync):
+async def test_the_dollar_and_the_yuan_are_fetched_even_with_only_roubles(
+    app, mock_http, fixture_bytes, run_sync
+):
+    """A currency that shows up in ZenMoney between two runs must already have its rate."""
     await make_account(currency="RUB")
     daily, dynamic = mock_cbr(mock_http, fixture_bytes)
 
     result = await run_sync(CbrSource(), settings=settings())
 
-    assert not daily.called and not dynamic.called
-    assert result.changed is False
-    assert result.counts == {"currencies": 0, "rates": 0}
+    assert daily.called
+    assert {params["VAL_NM_RQ"] for params in route_params(dynamic)} == {USD_ID, CNY_ID}
+    assert result.changed is True
+    assert result.counts == {"currencies": 2, "rates": 6}
+    rates = await stored_rates()
+    assert rates[("CNY", "2026-09-03")] == (1, Decimal("12.7654"))
+
+
+async def test_a_currency_new_to_the_table_is_backfilled_from_the_start_of_the_ledger(
+    app, mock_http, fixture_bytes, run_sync
+):
+    """The cursor only knows what the other currencies have; a new one needs its whole past."""
+    first = today_local() - timedelta(days=10)
+    await make_account(currency="USD", source_id="usd")
+    await make_txn(first, outcome="10", outcome_currency="USD")
+    _, dynamic = mock_cbr(mock_http, fixture_bytes)
+    earlier = await run_sync(CbrSource(), settings=settings())
+
+    await make_account(currency="JPY", source_id="jpy")
+    await make_txn(first + timedelta(days=2), outcome="1000", outcome_currency="JPY")
+    seen = len(dynamic.calls)
+    await run_sync(CbrSource(), settings=settings(), cursor=earlier.cursor_after)
+
+    starts = {p["VAL_NM_RQ"]: p["date_req1"] for p in route_params(dynamic)[seen:]}
+    incremental = date.fromisoformat(earlier.cursor_after or "") - timedelta(days=3)
+    assert starts[JPY_ID] == (first - timedelta(days=7)).strftime("%d/%m/%Y")
+    assert starts[USD_ID] == incremental.strftime("%d/%m/%Y")
+    assert starts[CNY_ID] == incremental.strftime("%d/%m/%Y")
 
 
 def test_long_ranges_are_chunked_by_year():