fix: validation OHLCV fallback prefers fresher live data over stale SQL cache

Root cause: fetch_ohlcv()'s freshness gate rejected a source's data purely for
not being as fresh as 'today', even when the caller (validation's backdated
window fetch) only needed historical bars covering a past target date. This
threw away good data (e.g. jugaad lagging 'today' by a day) and fell back to
a multi-days-older SQL cache, so the window never covered the target date and
validation stayed stuck at 0 with an ever-growing overdue backlog.

Fix: track the most-recent non-fresh live result during the source loop and
prefer it over the SQL cache in the final fallback step when it's newer.
No signature change.

data_sources.py

@@ -723,6 +723,12 @@ def fetch_ohlcv(ticker_ns: str, period: str = "1y"):
         ]
 
         # ── 2b. Try each source ────────────────────────────────────────────────
+        # A source can return correct data that just isn't "fresh" (doesn't reach
+        # yesterday's bar yet, e.g. jugaad often lags a day) — that's still far
+        # better than a multi-day-old SQL cache for callers validating a backdated
+        # window. Remember the most-recent non-fresh result seen so 2d can prefer
+        # it over stale_cached instead of raising / serving even-older data.
+        best_live, best_live_last_date = None, None
         for fn in sources:
             try:
                 result = fn(ticker_ns, period)
@@ -730,10 +736,14 @@ def fetch_ohlcv(ticker_ns: str, period: str = "1y"):
                     sc, sh, sl, sv = result
                     if ticker_ns in sc.columns and not sc[ticker_ns].dropna().empty:
                         if not _is_data_fresh(sc, ticker_ns):
+                            last_date = str(sc.index[-1])[:10]
                             logging.warning(
                                 "OHLCV source %s returned stale data for %s (last: %s), trying next",
-                                fn.__name__, ticker_ns, str(sc.index[-1])[:10],
+                                fn.__name__, ticker_ns, last_date,
                             )
+                            if best_live_last_date is None or last_date > best_live_last_date:
+                                best_live_last_date = last_date
+                                best_live = (sc.ffill(), sh.ffill(), sl.ffill(), sv.ffill())
                             continue
                         sc, sh, sl, sv = sc.ffill(), sh.ffill(), sl.ffill(), sv.ffill()
                         _save_sql_cache(ticker_ns, period, sc, sh, sl, sv)
@@ -769,6 +779,19 @@ def fetch_ohlcv(ticker_ns: str, period: str = "1y"):
         # threads (1D, 3D, 5D all queued behind 5D that just exhausted all sources)
         # skip the full 73s chain and reach stale-cache / error in <1s.
         _ohlcv_mark_failed(ticker_ns, period)
+
+        # Prefer a live source's non-fresh-but-recent data over the SQL cache if it's
+        # newer (fixes backdated validation returning nothing when e.g. jugaad has the
+        # target date but lags "today" by a day, while the SQL cache predates it further).
+        stale_cache_last_date = str(stale_cached[0].index[-1])[:10] if stale_cached is not None else None
+        if best_live is not None and (stale_cache_last_date is None or best_live_last_date > stale_cache_last_date):
+            _save_sql_cache(ticker_ns, period, *best_live)
+            logging.warning(
+                "Using non-fresh live OHLCV for %s (last: %s) — newer than SQL cache (last: %s)",
+                ticker_ns, best_live_last_date, stale_cache_last_date,
+            )
+            return best_live
+
         if stale_cached is not None:
             logging.warning(
                 "All live sources failed for %s — serving stale cached OHLCV", ticker_ns,