fix(sports): share the ESPN rejected-range memo with the background service

BackgroundDataService always sent a season range first and, on a 400,
fell back to chunks without recording the rejection, so every background
season fetch spent a doomed request and live scoreboards learned nothing
from it (or it from them). The worker now consults and sets the same
6-hour memo fetch_espn_scoreboard() uses: a known rejection goes straight
to month/day chunks, and if every chunk fails the range is asked once for
a real error without re-spending the chunks.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/background_data_service.py

@@ -25,7 +25,14 @@ from enum import Enum
 import queue
 from concurrent.futures import ThreadPoolExecutor
 from src.cache_manager import CacheManager
-from src.common.espn_dates import clamp_espn_limit, fetch_espn_date_chunks
+from src.common.espn_dates import (
+    RANGE_RETRY_SECONDS,
+    _note_range_rejected,
+    _ranges_known_rejected,
+    clamp_espn_limit,
+    fetch_espn_date_chunks,
+    parse_espn_date_range,
+)
 # Configure logging
 logger = logging.getLogger(__name__)
 
@@ -350,13 +357,32 @@ class BackgroundDataService:
             
             logger.info(f"Starting background fetch for {request.sport} {request.year}")
             
-            # Perform HTTP request with retry logic
-            response = self._make_request_with_retry(request)
-
             # ESPN stopped accepting dates=YYYYMMDD-YYYYMMDD on 2026-09-15 and
             # answers 400 for every sport. Re-ask in months and days rather
             # than let a whole season fail. See src/common/espn_dates.py.
-            if response.status_code == 400:
+            # The "ranges are rejected" memo is shared with
+            # fetch_espn_scoreboard(): once either path has seen a range
+            # rejected, the other skips the doomed range request too.
+            is_range = parse_espn_date_range(request.params.get("dates")) is not None
+            data = None
+            chunks_tried = False
+            if is_range and _ranges_known_rejected():
+                data = self._fetch_in_date_chunks(request)
+                # Every chunk failed: ask for the range itself below so the
+                # failure carries a real HTTP error, without re-spending chunks.
+                chunks_tried = data is None
+
+            if data is None:
+                # Perform HTTP request with retry logic
+                response = self._make_request_with_retry(request)
+                if is_range and response.status_code == 400 and not chunks_tried:
+                    _note_range_rejected()
+                    logger.warning(
+                        "ESPN rejected the date range %s (400); fetching it as "
+                        "month/day chunks, and fetching ranges that way for the "
+                        "next %d hours",
+                        request.params.get("dates"), RANGE_RETRY_SECONDS // 3600,
+                    )
                     data = self._fetch_in_date_chunks(request)
                     if data is None:
                         response.raise_for_status()

test/test_background_data_service_espn_ranges.py

@@ -13,7 +13,12 @@ from unittest.mock import MagicMock, patch
 import pytest
 
 from src.background_data_service import BackgroundDataService
-from src.common.espn_dates import ESPN_MAX_LIMIT, parse_espn_date_range
+from src.common import espn_dates
+from src.common.espn_dates import (
+    ESPN_MAX_LIMIT,
+    fetch_espn_scoreboard,
+    parse_espn_date_range,
+)
 
 URL = "https://site.api.espn.com/apis/site/v2/sports/football/nfl/scoreboard"
 
@@ -50,6 +55,12 @@ class RangeRejectingSession:
         return FakeResponse(200, {"events": self.events_by_chunk.get(dates, [])})
 
 
+@pytest.fixture(autouse=True)
+def ranges_not_yet_rejected(monkeypatch):
+    # The "ranges are rejected" memo is process-wide; every test starts clean.
+    monkeypatch.setattr(espn_dates, "_ranges_rejected_until", 0.0)
+
+
 @pytest.fixture
 def cache():
     manager = MagicMock()
@@ -161,3 +172,42 @@ def test_a_400_on_a_single_day_is_still_a_failure(service, cache):
     assert not result.success
     assert len(session.calls) == 1
     cache.set.assert_not_called()
+
+
+def test_a_rejection_seen_by_the_service_is_remembered_for_scoreboards(service):
+    submit_and_wait(service, RangeRejectingSession({"202609": [{"id": "a"}]}),
+                    "20260901-20260930")
+
+    # A live scoreboard asking for a range next must not spend a doomed 400.
+    session = RangeRejectingSession({"202609": [{"id": "a"}]})
+    data = fetch_espn_scoreboard(session, URL, params={"dates": "20260901-20260930"})
+    assert [call["dates"] for call in session.calls] == ["202609"]
+    assert [event["id"] for event in data["events"]] == ["a"]
+
+
+def test_a_rejection_seen_by_a_scoreboard_skips_the_range_in_the_service(service, cache):
+    fetch_espn_scoreboard(RangeRejectingSession(), URL,
+                          params={"dates": "20260901-20260930"})
+
+    session = RangeRejectingSession({"202609": [{"id": "a"}]})
+    result = submit_and_wait(service, session, "20260901-20261001")
+    assert result.success, result.error
+    assert [call["dates"] for call in session.calls] == ["202609", "20261001"]
+
+
+def test_known_rejection_with_every_chunk_failing_asks_the_range_once(service, cache):
+    espn_dates._note_range_rejected()
+    session = RangeRejectingSession(fail_chunks={"202609"})
+    result = submit_and_wait(service, session, "20260901-20260930")
+
+    assert not result.success
+    # Chunks once, then the range for a real error -- not the chunks again.
+    assert [call["dates"] for call in session.calls] == ["202609", "20260901-20260930"]
+    cache.set.assert_not_called()
+
+
+def test_ranges_are_tried_again_once_the_memo_expires(service, monkeypatch):
+    monkeypatch.setattr(espn_dates, "_ranges_rejected_until", time.monotonic() - 1)
+    session = RangeRejectingSession({"202609": [{"id": "a"}]})
+    submit_and_wait(service, session, "20260901-20260930")
+    assert [call["dates"] for call in session.calls] == ["20260901-20260930", "202609"]