fix: refresh latest regime trading session

.env.example

@@ -28,7 +28,7 @@ FINNHUB_API_KEY=
 ALPHA_VANTAGE_API_KEY=
 
 # Regime Monitor — FRED (VIX + HY credit spreads). Free key: https://fred.stlouisfed.org/docs/api/api_key.html
-# Optional: without it the VIX (P5) and credit-spread (F2) signals show as n/a.
+# Optional: without it the volatility (V1) and credit (C1) pillars show as n/a.
 FRED_API_KEY=
 
 # Scheduled Jobs

app/services/regime_monitor_service.py

@@ -772,7 +772,7 @@ async def update_regime_monitor(db: AsyncSession, rebuild_sessions: int = REBUIL
         written, latest_result = await _upsert_snapshot(
             db,
             computed,
-            rewrite_existing_v2=rebuilding or snapshot_date == date.today(),
+            rewrite_existing_v2=rebuilding or snapshot_date == latest_date,
         )
         snapshots_written += int(written)
     await db.commit()

docs/research/regime-monitor-v2.md

@@ -48,6 +48,11 @@ Each snapshot stores the fixed basket symbols, hash, and freeze date. Reconstruc
 history before that freeze date is retrospective/exploratory; readings after it
 form the forward record.
 
+The automatic 400-session rebuild is intentionally one-shot: it runs only when
+no v2 snapshot exists. If an initial seed used partial data or the wrong basket,
+the operational reseed procedure is to remove the v2 snapshot rows and run the
+Regime Monitor job again. There is no routine force-rebuild flag.
+
 ## Warning study
 
 The study calls the outcome a **10% correction**, not a regime break. The first

frontend/src/pages/RegimePage.tsx

@@ -328,6 +328,12 @@ export default function RegimePage() {
               footnote={<>Breadth divergence, SMH/SPY rollover, and point-in-time fundamental observations. Unknown or stale fundamentals reduce coverage; they never default to 50.</>}
             />
           </div>
+          <p className="text-xs text-gray-600">
+            Data quality · oldest market input:{' '}
+            {data.data_quality?.oldest_market_input_age_days == null
+              ? 'unavailable'
+              : `${data.data_quality.oldest_market_input_age_days}d`}
+          </p>
 
           <Suspense fallback={<SkeletonCard className="h-80" />}><RegimeQuadrant /></Suspense>
           <Suspense fallback={<SkeletonCard className="h-72" />}><ScoreHistoryChart /></Suspense>

tests/unit/test_regime_monitor.py

@@ -169,6 +169,59 @@ async def test_prior_v2_snapshot_is_immutable_without_explicit_rebuild(db_sessio
     assert row.total_score == 10.0
 
 
+@pytest.mark.asyncio
+async def test_routine_can_refresh_latest_trading_session_after_civil_day_rolls(
+    monkeypatch,
+):
+    latest_date = date(2020, 1, 3)
+    config = copy.deepcopy(DEFAULT_CONFIG)
+    prices = {
+        "SMH": [(latest_date, 100.0)],
+        "QQQ": [(latest_date, 100.0)],
+        "SPY": [(latest_date, 100.0)],
+    }
+    rewrites: list[bool] = []
+
+    async def fake_config(_db):
+        return config
+
+    async def fake_overrides(_db):
+        return {"locked": True, "fetched_at": None, "effective_date": None}
+
+    async def fake_prices(_config, _start, _end):
+        return prices
+
+    async def fake_fred(_series_id, _start, _end):
+        return None
+
+    async def fake_breadth(_db, _symbols, window, min_tickers):
+        return {}, {}
+
+    async def fake_latest(_db):
+        return object(), {"methodology": "v2"}
+
+    async def fake_upsert(_db, result, *, rewrite_existing_v2):
+        rewrites.append(rewrite_existing_v2)
+        return True, result
+
+    class FakeDB:
+        async def commit(self):
+            return None
+
+    monkeypatch.setattr(rms, "get_regime_config", fake_config)
+    monkeypatch.setattr(rms, "get_fundamental_overrides", fake_overrides)
+    monkeypatch.setattr(rms, "_fetch_prices", fake_prices)
+    monkeypatch.setattr(rms, "_fetch_fred_series", fake_fred)
+    monkeypatch.setattr(rms.breadth_service, "compute_breadth_details", fake_breadth)
+    monkeypatch.setattr(rms, "_latest_v2_row", fake_latest)
+    monkeypatch.setattr(rms, "_upsert_snapshot", fake_upsert)
+
+    result = await rms.update_regime_monitor(FakeDB())
+
+    assert result["date"] == latest_date.isoformat()
+    assert rewrites == [True]
+
+
 def test_compute_index_uses_one_max_price_vote_and_has_no_combined_score():
     end = date(2026, 6, 26)
     rising = [100.0 + index * 0.2 for index in range(700)]