add ECB Data Portal source; group-aware stale thresholds

ECB Statistical Data Warehouse joins as a 5th data source — open API,
no key, daily euro-area yield curve data. Symbol format
'ECB:dataset/series_key', e.g. 'ECB:YC/B.U2.EUR.4F.G_N_A.SV_C_YM.SR_10Y'
for daily 10y AAA spot rate.

Bonds tab adds ECB EZ 10y AAA + 2y AAA so there's at least some
currently-fresh European sovereign data alongside the US Treasuries.
Country-specific yields (Bund/OAT/BTP/Gilt/JGB) remain on Eurostat/FRED
monthly mirrors — no free daily source exists for those.

Stale threshold is now per-group instead of a flat 90 days. Daily-tape
groups (bonds, rates, equity, etc.) flag stale after a week or three;
monthly groups (economy, macro, valuation) stay at 60-90 days. The
bonds tab will now correctly show 30-60 day-old country yields as
stale next to the daily US/ECB ones.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/services/market.py

@@ -18,6 +18,7 @@ YAHOO_CHART = "https://query1.finance.yahoo.com/v8/finance/chart/{symbol}"
 FRED_API = "https://api.stlouisfed.org/fred/series/observations"
 EUROSTAT_API = "https://ec.europa.eu/eurostat/api/dissemination/statistics/1.0/data/{dataset}"
 ONS_API = "https://www.ons.gov.uk/{topic}/timeseries/{cdid}/{dataset}/data"
+ECB_API = "https://data-api.ecb.europa.eu/service/data/{dataset}/{series_key}"
 UA = {"User-Agent": "Mozilla/5.0 (cassandra) Python/httpx"}
 
 
@@ -424,6 +425,93 @@ async def fetch_ons(
         return Quote(symbol, "ons", label, note, None, None, None, error=str(e))
 
 
+# --- ECB Data Portal (no API key, daily euro-area data) ---------------------
+
+
+async def fetch_ecb(
+    client: httpx.AsyncClient,
+    symbol: str,
+    label: str,
+    note: str,
+    anchor: str | None = None,
+) -> Quote:
+    """Fetch an ECB Statistical Data Warehouse series. `symbol` format:
+        <dataset>/<series_key>
+    e.g. 'YC/B.U2.EUR.4F.G_N_A.SV_C_YM.SR_10Y' for 10y EZ AAA yield (daily).
+    ECB returns SDMX-JSON; we extract the single observation series."""
+    try:
+        if "/" not in symbol:
+            raise ValueError("ECB symbol must be dataset/series_key")
+        dataset, series_key = symbol.split("/", 1)
+        r = await client.get(
+            ECB_API.format(dataset=dataset, series_key=series_key),
+            params={"format": "jsondata"},
+            headers={**UA, "Accept": "application/json"},
+            timeout=20,
+        )
+        r.raise_for_status()
+        data = r.json()
+
+        # SDMX-JSON: dataSets[0].series[key].observations is { "<idx>": [value, ...] }
+        # where <idx> indexes into structure.dimensions.observation[0].values for time.
+        ds = (data.get("dataSets") or [{}])[0]
+        series_map = ds.get("series") or {}
+        if not series_map:
+            raise ValueError("no series in response")
+        ser = next(iter(series_map.values()))
+        obs = ser.get("observations") or {}
+        times = [
+            v["id"]
+            for v in data["structure"]["dimensions"]["observation"][0]["values"]
+        ]
+
+        rows: list[tuple[str, float]] = []
+        for idx_str in sorted(obs, key=int):
+            v = obs[idx_str][0]
+            if v is None:
+                continue
+            t = times[int(idx_str)]
+            iso = _eurostat_time_to_iso(t)  # reuse: ECB time codes match Eurostat
+            try:
+                rows.append((iso, float(v)))
+            except (TypeError, ValueError):
+                continue
+
+        if not rows:
+            raise ValueError("no observations")
+        last_date, last_val = rows[-1]
+
+        def _find_back(min_days: int) -> float | None:
+            ref = datetime.strptime(last_date, "%Y-%m-%d").date()
+            for d, v in reversed(rows[:-1]):
+                if (ref - datetime.strptime(d, "%Y-%m-%d").date()).days >= min_days:
+                    return v
+            return None
+
+        prev_val = rows[-2][1] if len(rows) >= 2 else None
+        changes = {
+            "1d": _pct(prev_val, last_val),
+            "1m": _pct(_find_back(28), last_val),
+            "1y": _pct(_find_back(360), last_val),
+        }
+        anchor_used: str | None = None
+        if anchor:
+            anchor_d = _parse_date(anchor).date()
+            for d, v in reversed(rows):
+                if datetime.strptime(d, "%Y-%m-%d").date() <= anchor_d:
+                    changes["anchor"] = _pct(v, last_val)
+                    anchor_used = d
+                    break
+
+        return Quote(
+            symbol=symbol, source="ecb", label=label, note=note,
+            price=last_val, currency=None, as_of=last_date,
+            changes=changes, anchor_date=anchor_used,
+        )
+    except Exception as e:
+        return Quote(symbol, "ecb", label, note, None, None, None, error=str(e))
+
+
 # --- Source registry ----------------------------------------------------------
 
 FetcherFn = Callable[..., "Quote"]
@@ -432,6 +520,7 @@ SOURCES: dict[str, FetcherFn] = {
     "FRED":     fetch_fred,
     "EUROSTAT": fetch_eurostat,
     "ONS":      fetch_ons,
+    "ECB":      fetch_ecb,
 }