Let chart views avoid the dashboard utility bulk

The intraday chart data builder lived inside dashboard-utils with observation-source and TAF helpers, so chart consumers had to depend on the large dashboard utility surface. This moves chart data preparation, observation-source helpers, and TAF marker labels into focused modules while keeping dashboard-utils re-export compatibility.

Constraint: Preserve existing chart data shape, observation labels, TAF labels, and legacy dashboard-utils exports.

Rejected: Rewrite chart data generation while moving it | this pass is a boundary move only so visual behavior remains stable.

Confidence: high

Scope-risk: moderate

Reversibility: clean

Tested: TypeScript diagnostics for chart-utils, dashboard-utils, observation-source-utils, and taf-utils

Tested: npm run build

Not-tested: Browser visual regression across every chart city.

frontend/components/dashboard/DetailPanel.tsx

@@ -12,10 +12,10 @@ import { getOfficialSourceLinks } from "@/lib/dashboard-official-sources";
 import { CityDetail } from "@/lib/dashboard-types";
 import { trackAppEvent } from "@/lib/app-analytics";
 import { getTodayPolymarketUrl } from "@/lib/polymarket-market-links";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getCityProfileStats,
   getRiskBadgeLabel,
-  getTemperatureChartData,
 } from "@/lib/dashboard-utils";
 import { normalizeObservationSourceLabel } from "@/lib/source-labels";
 

frontend/components/dashboard/FutureForecastModal.tsx

@@ -23,11 +23,11 @@ import {
   ModelForecast,
   ProbabilityDistribution,
 } from "@/components/dashboard/PanelSections";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getFutureModalView,
   getModelView,
   getProbabilityView,
-  getTemperatureChartData,
   getWeatherSummary,
 } from "@/lib/dashboard-utils";
 import { getTodayPaceView } from "@/lib/pace-utils";

frontend/components/dashboard/PanelSections.tsx

@@ -12,12 +12,12 @@ import {
   MarketTopBucket,
   ProbabilityBucket,
 } from "@/lib/dashboard-types";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getHeroMetaItems,
   getModelView,
   getProbabilityView,
   getRiskBadgeLabel,
-  getTemperatureChartData,
   getWeatherSummary,
 } from "@/lib/dashboard-utils";
 import {

frontend/components/dashboard/scan-terminal/AiCityTemperatureChart.tsx

@@ -4,7 +4,7 @@ import { BarChart3 } from "lucide-react";
 import type { CityDetail } from "@/lib/dashboard-types";
 import { useChart } from "@/hooks/useChart";
 import { useI18n } from "@/hooks/useI18n";
-import { getTemperatureChartData } from "@/lib/dashboard-utils";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 
 type TemperatureChartData = NonNullable<ReturnType<typeof getTemperatureChartData>>;
 

frontend/lib/chart-utils.ts

@@ -0,0 +1,765 @@
+import type { CityDetail } from "@/lib/dashboard-types";
+import type { Locale } from "@/lib/i18n";
+import {
+  getNoaaStationCode,
+  getObservationSourceCode,
+  getObservationSourceTag,
+  getRealtimeObservationTag,
+  isTurkishMgmCity,
+} from "@/lib/observation-source-utils";
+import { normalizeTemperatureSymbol } from "@/lib/temperature-utils";
+import { formatTafMarkerType } from "@/lib/taf-utils";
+import {
+  hmToMinutes,
+  interpolateSeriesAtMinutes,
+  normalizeHm,
+} from "@/lib/time-utils";
+
+function isEnglish(locale: Locale) {
+  return locale === "en-US";
+}
+function findNearestTimeIndex(
+  times: string[],
+  targetTime?: string | null,
+) {
+  const targetMinutes = hmToMinutes(targetTime);
+  if (targetMinutes == null || !times.length) return -1;
+  let nearestIndex = -1;
+  let nearestDelta = Number.POSITIVE_INFINITY;
+  times.forEach((time, index) => {
+    const minute = hmToMinutes(time);
+    if (minute == null) return;
+    const delta = Math.abs(minute - targetMinutes);
+    if (delta < nearestDelta) {
+      nearestDelta = delta;
+      nearestIndex = index;
+    }
+  });
+  return nearestIndex;
+}
+
+function buildTemperatureTickLabels(times: string[]) {
+  const lastIndex = Math.max(0, times.length - 1);
+  return times.map((time, index) => {
+    if (index === 0 || index === lastIndex) return time;
+    const minute = hmToMinutes(time);
+    if (minute == null) return "";
+    const hour = Math.floor(minute / 60);
+    const minutePart = minute % 60;
+    if (minutePart !== 0) return "";
+    return hour % 2 === 0 ? time : "";
+  });
+}
+
+function getNiceTemperatureScale(values: number[], tempSymbol?: string | null) {
+  const numericValues = values.filter((value) => Number.isFinite(Number(value)));
+  if (!numericValues.length) {
+    return { max: 1, min: 0, step: 1 };
+  }
+
+  const rawMin = Math.min(...numericValues);
+  const rawMax = Math.max(...numericValues);
+  const spread = Math.max(0.1, rawMax - rawMin);
+  const isFahrenheit = normalizeTemperatureSymbol(tempSymbol) === "°F";
+  const padding = Math.max(isFahrenheit ? 1.5 : 0.8, spread * 0.12);
+  const paddedMin = rawMin - padding;
+  const paddedMax = rawMax + padding;
+  const paddedSpread = Math.max(0.1, paddedMax - paddedMin);
+  const candidates = isFahrenheit ? [1, 2, 5, 10, 20] : [0.5, 1, 2, 5, 10];
+  let step =
+    candidates.find((candidate) => candidate >= paddedSpread / 4) ||
+    candidates[candidates.length - 1];
+  let min = Math.floor(paddedMin / step) * step;
+  let max = Math.ceil(paddedMax / step) * step;
+
+  if (min < 0 && rawMin >= 0 && rawMin <= step * 1.25) min = 0;
+  if (max <= min) max = min + step * 4;
+
+  while ((max - min) / step + 1 > 6) {
+    const nextStep = candidates.find((candidate) => candidate > step);
+    if (!nextStep) break;
+    step = nextStep;
+    min = Math.floor(paddedMin / step) * step;
+    max = Math.ceil(paddedMax / step) * step;
+    if (min < 0 && rawMin >= 0 && rawMin <= step * 1.25) min = 0;
+  }
+
+  return { max, min, step };
+}
+
+function buildSeriesPoints(
+  times: string[],
+  values: Array<number | null | undefined>,
+) {
+  return times
+    .map((time, index) => {
+      const x = hmToMinutes(time);
+      const y = values[index];
+      return x != null && y != null && Number.isFinite(Number(y))
+        ? { index, labelTime: time, x, y: Number(y) }
+        : null;
+    })
+    .filter(
+      (point): point is { index: number; labelTime: string; x: number; y: number } =>
+        point != null,
+    );
+}
+
+function buildObservationPoints(items: Array<{ time?: string; temp?: number | null }>) {
+  return items
+    .map((item) => {
+      const labelTime = normalizeHm(String(item.time || ""));
+      const x = hmToMinutes(labelTime);
+      const y = item.temp;
+      return x != null && y != null && Number.isFinite(Number(y))
+        ? { labelTime: labelTime || "", x, y: Number(y) }
+        : null;
+    })
+    .filter((point): point is { labelTime: string; x: number; y: number } => point != null);
+}
+
+function sortObservationItemsByTime<T extends { time?: string | null }>(items: T[]) {
+  return [...items].sort((left, right) => {
+    const leftMinutes = hmToMinutes(left.time);
+    const rightMinutes = hmToMinutes(right.time);
+    if (leftMinutes == null && rightMinutes == null) return 0;
+    if (leftMinutes == null) return 1;
+    if (rightMinutes == null) return -1;
+    return leftMinutes - rightMinutes;
+  });
+}
+
+function dedupeObservationItems<T extends { temp?: number | null; time?: string | null }>(
+  items: T[],
+) {
+  const byTime = new Map<string, T>();
+  items.forEach((item) => {
+    const time = normalizeHm(item.time);
+    const value = Number(item.temp);
+    if (!time || !Number.isFinite(value)) return;
+    const existing = byTime.get(time);
+    if (!existing || Number(item.temp) >= Number(existing.temp)) {
+      byTime.set(time, { ...item, time });
+    }
+  });
+  return sortObservationItemsByTime([...byTime.values()]);
+}
+
+function looksLikeForecastMirror(
+  observations: Array<{ temp?: number | null; time?: string | null }>,
+  forecastTimes: string[],
+  forecastValues: Array<number | null | undefined>,
+) {
+  const unique = dedupeObservationItems(observations);
+  if (unique.length < 6 || forecastTimes.length < 6) return false;
+  if (unique.length < Math.max(6, Math.floor(forecastTimes.length * 0.4))) {
+    return false;
+  }
+
+  let compared = 0;
+  let exactMatches = 0;
+  unique.forEach((item) => {
+    const minute = hmToMinutes(item.time);
+    const observed = Number(item.temp);
+    if (minute == null || !Number.isFinite(observed)) return;
+    const expected = interpolateSeriesAtMinutes(
+      forecastTimes,
+      forecastValues,
+      minute,
+    );
+    if (expected == null || !Number.isFinite(expected)) return;
+    compared += 1;
+    if (Math.abs(observed - expected) <= 0.05) {
+      exactMatches += 1;
+    }
+  });
+
+  return compared >= 6 && exactMatches / compared >= 0.65;
+}
+
+function normalizeObservationTimeForChart(
+  value: unknown,
+  detail: CityDetail,
+) {
+  const raw = String(value || "").trim();
+  if (raw && !raw.includes("T")) {
+    return normalizeHm(raw) || raw;
+  }
+  return normalizeHm(detail.local_time) || normalizeHm(raw) || raw;
+}
+
+function buildCurrentObservationFallback(
+  detail: CityDetail,
+): Array<{ time?: string; temp?: number | null; sourceLabel?: string | null }> {
+  const candidates: Array<{
+    sourceLabel?: string | null;
+    temp?: number | null;
+    time?: string | null;
+  }> = [
+    {
+      sourceLabel: detail.current?.settlement_source_label,
+      temp: detail.current?.temp,
+      time: detail.current?.obs_time || detail.current?.report_time,
+    },
+    {
+      sourceLabel: detail.airport_primary?.source_label || "METAR",
+      temp: detail.airport_primary?.temp,
+      time: detail.airport_primary?.obs_time || detail.airport_primary?.report_time,
+    },
+    {
+      sourceLabel: detail.airport_current?.source_label || "METAR",
+      temp: detail.airport_current?.temp,
+      time: detail.airport_current?.obs_time || detail.airport_current?.report_time,
+    },
+  ];
+
+  const first = candidates.find((item) => {
+    const numeric = Number(item.temp);
+    return Number.isFinite(numeric);
+  });
+  if (!first) return [];
+
+  return [
+    {
+      sourceLabel: first.sourceLabel,
+      temp: Number(first.temp),
+      time: normalizeObservationTimeForChart(first.time, detail),
+    },
+  ];
+}
+
+export function getTemperatureChartData(
+  detail: CityDetail,
+  locale: Locale = "zh-CN",
+) {
+  const hourly = detail.hourly || {};
+  const rawTimes = Array.isArray(hourly.times) ? hourly.times : [];
+  const rawTemps = Array.isArray(hourly.temps) ? hourly.temps : [];
+  const times = rawTimes
+    .map((time) => String(time || "").trim())
+    .filter(Boolean);
+  const temps = times.map((_, index) => {
+    const value = Number(rawTemps[index]);
+    return Number.isFinite(value) ? value : null;
+  });
+  const suppressAnkaraMgmObservation = isTurkishMgmCity(detail);
+
+  if (!times.length) return null;
+
+  const currentIndex = findNearestTimeIndex(times, detail.local_time);
+  const omMax = detail.forecast?.today_high;
+  const debMax = detail.deb?.prediction;
+  const offset =
+    debMax != null && omMax != null ? Number(debMax) - Number(omMax) : 0;
+  const debTemps = temps.map((temp) =>
+    temp != null && Number.isFinite(temp)
+      ? Number((temp + offset).toFixed(1))
+      : null,
+  );
+  const debPast = debTemps.map((temp, index) =>
+    currentIndex >= 0 && index <= currentIndex ? temp : null,
+  );
+  const debFuture = debTemps.map((temp, index) =>
+    currentIndex < 0 || index >= currentIndex ? temp : null,
+  );
+
+  const observationTag = getRealtimeObservationTag(detail);
+  const observationCode = getObservationSourceCode(detail);
+  const settlementSource =
+    observationCode === "hko" ||
+    observationCode === "cwa" ||
+    observationCode === "noaa" ||
+    observationCode === "wunderground";
+  const useSettlementObservationSource = settlementSource;
+  const officialObservationSource =
+    useSettlementObservationSource
+      ? detail.settlement_today_obs?.length
+        ? detail.settlement_today_obs
+        : detail.current?.obs_time && detail.current?.temp != null
+          ? [{ time: detail.current.obs_time, temp: detail.current.temp }]
+          : []
+      : [];
+  const currentObservationFallback = buildCurrentObservationFallback(detail);
+  const minPlausibleObservationTemp = (() => {
+    const name = String(detail.name || "").trim().toLowerCase();
+    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
+    if (name === "karachi" || name === "masroor air base" || icao === "OPKC" || icao === "OPMR") {
+      return detail.temp_symbol === "°F" ? 41 : 5;
+    }
+    return null;
+  })();
+  const filterPlausibleObservations = <T extends { temp?: number | null }>(
+    rows?: T[] | null,
+  ) =>
+    (Array.isArray(rows) ? rows : []).filter((row) => {
+      const value = Number(row?.temp);
+      if (!Number.isFinite(value)) return false;
+      return minPlausibleObservationTemp == null || value >= minPlausibleObservationTemp;
+    });
+  const plausibleMetarTodayObs = filterPlausibleObservations(detail.metar_today_obs);
+  const plausibleTrendRecent = filterPlausibleObservations(detail.trend?.recent);
+  const plausibleCurrentFallback = filterPlausibleObservations(currentObservationFallback);
+  const metarObservationSource = plausibleMetarTodayObs.length
+    ? plausibleMetarTodayObs
+    : plausibleTrendRecent.length
+      ? plausibleTrendRecent
+      : plausibleCurrentFallback;
+  const usingCurrentObservationFallback =
+    !plausibleMetarTodayObs.length &&
+    !plausibleTrendRecent.length &&
+    plausibleCurrentFallback.length > 0;
+  const currentFallbackTag =
+    currentObservationFallback[0]?.sourceLabel ||
+    getObservationSourceTag(detail);
+  const allowMetarFallback = settlementSource && observationCode !== "hko";
+  const shouldUseMetarFallback =
+    allowMetarFallback &&
+    officialObservationSource.length > 0 &&
+    officialObservationSource.length < 3 &&
+    metarObservationSource.length >= 3;
+  let usingMetarObservationSource =
+    !useSettlementObservationSource || shouldUseMetarFallback;
+  let observationSource = useSettlementObservationSource
+    ? shouldUseMetarFallback
+      ? metarObservationSource
+      : officialObservationSource
+    : metarObservationSource;
+  let usingMirrorFallback = false;
+  if (looksLikeForecastMirror(observationSource, times, debTemps)) {
+    const fallbackCandidates = [
+      plausibleTrendRecent,
+      plausibleCurrentFallback,
+      metarObservationSource,
+    ];
+    const fallback = fallbackCandidates.find(
+      (candidate) =>
+        candidate.length > 0 &&
+        candidate !== observationSource &&
+        !looksLikeForecastMirror(candidate, times, debTemps),
+    );
+    if (fallback) {
+      observationSource = fallback;
+      usingMetarObservationSource = fallback === metarObservationSource;
+      usingMirrorFallback = true;
+    }
+  }
+  observationSource = dedupeObservationItems(observationSource);
+  const airportMetarSource: Array<{ time?: string; temp?: number | null }> = [];
+  const metarFallbackTag = (() => {
+    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
+    if (!icao) return "METAR";
+    return `${icao} METAR`;
+  })();
+  const observationDisplayTag =
+    usingCurrentObservationFallback
+      ? String(currentFallbackTag).toUpperCase()
+      : observationCode === "wunderground" && usingMetarObservationSource
+      ? metarFallbackTag
+      : observationCode === "wunderground"
+        ? metarFallbackTag
+      : useSettlementObservationSource && shouldUseMetarFallback
+      ? metarFallbackTag
+      : observationCode === "noaa"
+        ? `NOAA ${getNoaaStationCode(detail)}`
+        : observationTag;
+
+  const metarPoints = new Array(times.length).fill(null);
+  observationSource.forEach((item) => {
+    const index = findNearestTimeIndex(times, String(item.time || ""));
+    const temp = Number(item.temp);
+    if (index >= 0 && Number.isFinite(temp)) {
+      const existing = metarPoints[index];
+      // Multiple reports can land in the same hour bucket. Keep the peak
+      // value so an intrahour high is not hidden by a later weaker report.
+      metarPoints[index] =
+        existing == null ? temp : Math.max(Number(existing), temp);
+    }
+  });
+  const airportMetarPoints = new Array(times.length).fill(null);
+  airportMetarSource.forEach((item) => {
+    const index = findNearestTimeIndex(times, String(item.time || ""));
+    const temp = Number(item.temp);
+    if (index >= 0 && Number.isFinite(temp)) {
+      const existing = airportMetarPoints[index];
+      airportMetarPoints[index] =
+        existing == null ? temp : Math.max(Number(existing), temp);
+    }
+  });
+
+  const mgmPoints = new Array(times.length).fill(null);
+  if (
+    !suppressAnkaraMgmObservation &&
+    detail.mgm?.temp != null &&
+    detail.mgm?.time
+  ) {
+    const index = findNearestTimeIndex(times, detail.mgm.time);
+    const temp = Number(detail.mgm.temp);
+    if (index >= 0 && Number.isFinite(temp)) {
+      mgmPoints[index] = temp;
+    }
+  }
+
+  const mgmHourlyPoints = new Array(times.length).fill(null);
+  let hasMgmHourly = false;
+  const mgmHourlyRows = Array.isArray(detail.mgm?.hourly)
+    ? detail.mgm?.hourly || []
+    : [];
+  mgmHourlyRows.forEach((item) => {
+    const index = findNearestTimeIndex(times, String(item.time || ""));
+    const temp = Number(item.temp);
+    if (index >= 0 && Number.isFinite(temp)) {
+      mgmHourlyPoints[index] = temp;
+      hasMgmHourly = true;
+    }
+  });
+
+  const allValues = [
+    ...debTemps.filter((value) => value != null),
+    ...metarPoints.filter((value) => value != null),
+    ...airportMetarPoints.filter((value) => value != null),
+    ...mgmPoints.filter((value) => value != null),
+    ...mgmHourlyPoints.filter((value) => value != null),
+  ] as number[];
+
+  if (!allValues.length) return null;
+
+  const yScale = getNiceTemperatureScale(allValues, detail.temp_symbol);
+  const min = yScale.min;
+  const max = yScale.max;
+  const yTickStep = yScale.step;
+  const tafMarkersRaw = Array.isArray(detail.taf?.signal?.markers)
+    ? detail.taf?.signal?.markers || []
+    : [];
+  const normalizeHm = (value: unknown): string | null => {
+    const match = String(value || "").match(/(\d{1,2}):(\d{2})/);
+    if (!match) return null;
+    const hour = Number.parseInt(match[1], 10);
+    const minute = Number.parseInt(match[2], 10);
+    if (
+      !Number.isFinite(hour) ||
+      !Number.isFinite(minute) ||
+      hour < 0 ||
+      hour > 23 ||
+      minute < 0 ||
+      minute > 59
+    ) {
+      return null;
+    }
+    return `${String(hour).padStart(2, "0")}:${String(minute).padStart(2, "0")}`;
+  };
+  const hmToMinutes = (value: string | null) => {
+    if (!value) return null;
+    const [hourPart, minutePart] = value.split(":");
+    const hour = Number.parseInt(hourPart || "", 10);
+    const minute = Number.parseInt(minutePart || "", 10);
+    if (
+      !Number.isFinite(hour) ||
+      !Number.isFinite(minute) ||
+      hour < 0 ||
+      hour > 23 ||
+      minute < 0 ||
+      minute > 59
+    ) {
+      return null;
+    }
+    return hour * 60 + minute;
+  };
+  const currentMinutes = hmToMinutes(normalizeHm(detail.local_time));
+  const peakFirstHour = Number(detail.peak?.first_h);
+  const peakLastHour = Number(detail.peak?.last_h);
+  const peakWindowStartMinutes =
+    Number.isFinite(peakFirstHour) && peakFirstHour >= 0
+      ? Math.max(0, (peakFirstHour - 2) * 60)
+      : null;
+  const peakWindowEndMinutes =
+    Number.isFinite(peakLastHour) && peakLastHour >= peakFirstHour
+      ? Math.min(23 * 60 + 59, (peakLastHour + 1) * 60)
+      : null;
+  const tafMarkerValue = max - 0.4;
+  const tafMarkerPoints = new Array(times.length).fill(null);
+  const tafCurrentMarkerPoints = new Array(times.length).fill(null);
+  const tafPeakWindowMarkerPoints = new Array(times.length).fill(null);
+  const sameMarker = (
+    left:
+      | { markerType?: string | null; startLocal?: string | null; endLocal?: string | null }
+      | null
+      | undefined,
+    right:
+      | { markerType?: string | null; startLocal?: string | null; endLocal?: string | null }
+      | null
+      | undefined,
+  ) =>
+    !!left &&
+    !!right &&
+    String(left.markerType || "") === String(right.markerType || "") &&
+    String(left.startLocal || "") === String(right.startLocal || "") &&
+    String(left.endLocal || "") === String(right.endLocal || "");
+  const tafMarkers = tafMarkersRaw
+    .map((marker) => {
+      const labelTime = String(marker?.label_time || "").trim();
+      const index = findNearestTimeIndex(times, labelTime);
+      if (index >= 0) {
+        tafMarkerPoints[index] = tafMarkerValue;
+      }
+      return {
+        displayType: formatTafMarkerType(
+          String(marker?.marker_type || "").trim(),
+          locale,
+        ),
+        endLocal: String(marker?.end_local || "").trim(),
+        index,
+        labelTime,
+        markerType: String(marker?.marker_type || "").trim(),
+        startLocal: String(marker?.start_local || "").trim(),
+        summary:
+          isEnglish(locale)
+            ? String(marker?.summary_en || "").trim()
+            : String(marker?.summary_zh || "").trim(),
+        isCurrent: false,
+        isPeakWindow: false,
+        suppressionLevel: String(marker?.suppression_level || "").trim(),
+      };
+    })
+    .filter((marker) => marker.index >= 0);
+  const currentTafMarker =
+    currentMinutes !== null
+      ? tafMarkers.find((marker) => {
+          const start = hmToMinutes(normalizeHm(marker.startLocal));
+          const end = hmToMinutes(normalizeHm(marker.endLocal));
+          return start !== null && end !== null && currentMinutes >= start && currentMinutes <= end;
+        }) || null
+      : null;
+  const nextTafMarker =
+    currentMinutes !== null && !currentTafMarker
+      ? tafMarkers.find((marker) => {
+          const start = hmToMinutes(normalizeHm(marker.startLocal));
+          return start !== null && start > currentMinutes;
+        }) || null
+      : null;
+  const peakWindowTafMarker =
+    peakWindowStartMinutes !== null && peakWindowEndMinutes !== null
+      ? tafMarkers.find((marker) => {
+          const start = hmToMinutes(normalizeHm(marker.startLocal));
+          const end = hmToMinutes(normalizeHm(marker.endLocal));
+          return (
+            start !== null &&
+            end !== null &&
+            start <= peakWindowEndMinutes &&
+            end >= peakWindowStartMinutes
+          );
+        }) || null
+      : null;
+  tafMarkers.forEach((marker) => {
+    const isPrimaryTafMarker =
+      sameMarker(marker, currentTafMarker) || sameMarker(marker, nextTafMarker);
+    const isPeakReferenceMarker = sameMarker(marker, peakWindowTafMarker);
+    if (isPrimaryTafMarker) {
+      marker.isCurrent = true;
+      tafCurrentMarkerPoints[marker.index] = tafMarkerValue;
+    }
+    if (isPeakReferenceMarker) {
+      marker.isPeakWindow = true;
+      if (!isPrimaryTafMarker) {
+        tafPeakWindowMarkerPoints[marker.index] = tafMarkerValue - 0.15;
+      }
+    }
+  });
+  const formatTafLegendMarker = (
+    marker:
+      | { displayType?: string | null; startLocal?: string | null; endLocal?: string | null; summary?: string | null }
+      | null
+      | undefined,
+  ) => {
+    if (!marker) return "";
+    const range = `${marker.startLocal || "--:--"}-${marker.endLocal || "--:--"}`;
+    const status = String(marker.summary || "").trim();
+    return status
+      ? `${marker.displayType || ""} ${range} ${status}`.trim()
+      : `${marker.displayType || ""} ${range}`.trim();
+  };
+
+  const legendParts: string[] = [];
+  if (!suppressAnkaraMgmObservation && detail.mgm?.temp != null) {
+    legendParts.push(`MGM: ${detail.mgm.temp}${detail.temp_symbol}`);
+  }
+  if (!hasMgmHourly && debMax != null && omMax != null && Math.abs(offset) > 0.3) {
+    const sign = offset > 0 ? "+" : "";
+    legendParts.push(
+      isEnglish(locale)
+        ? `DEB offset ${sign}${offset.toFixed(1)}${detail.temp_symbol} vs OM`
+        : `DEB 偏移 ${sign}${offset.toFixed(1)}${detail.temp_symbol} vs OM`,
+    );
+  }
+  if (hasMgmHourly) {
+    legendParts.push(
+      isEnglish(locale)
+        ? "Using MGM hourly forecast to replace DEB curve"
+        : "已使用 MGM 小时预报替代 DEB 曲线",
+    );
+  }
+  if ((detail.trend?.recent?.length || 0) > 0 || observationSource.length > 0) {
+    const recentData = sortObservationItemsByTime(
+      observationSource.length > 0
+        ? [...observationSource]
+        : [...(detail.trend?.recent || [])],
+    );
+    const recentText = recentData
+      .slice(-4)
+      .map((item) => `${item.temp}${detail.temp_symbol}@${item.time}`)
+      .join(" -> ");
+    legendParts.push(`${observationDisplayTag}: ${recentText}`);
+  }
+  if (airportMetarSource.length > 0) {
+    const airportRecentText = sortObservationItemsByTime([...airportMetarSource])
+      .slice(-4)
+      .map((item) => `${item.temp}${detail.temp_symbol}@${item.time}`)
+      .join(" -> ");
+    legendParts.push(
+      isEnglish(locale)
+        ? `${metarFallbackTag}: ${airportRecentText}`
+        : `${metarFallbackTag}: ${airportRecentText}`,
+    );
+  }
+  if (detail.metar_status?.stale_for_today) {
+    const dateText = detail.metar_status.last_observation_local_date || "";
+    const tempText =
+      detail.metar_status.last_temp != null
+        ? `${detail.metar_status.last_temp}${detail.temp_symbol}`
+        : "";
+    legendParts.push(
+      isEnglish(locale)
+        ? `No same-day ${metarFallbackTag} report yet; latest report${dateText ? ` was ${dateText}` : ""}${tempText ? ` at ${tempText}` : ""}.`
+        : `今日暂无同日 ${metarFallbackTag} 报文；最近一报${dateText ? `为 ${dateText}` : ""}${tempText ? `，${tempText}` : ""}。`,
+    );
+  }
+  if (shouldUseMetarFallback) {
+    legendParts.push(
+      isEnglish(locale)
+        ? `Official ${observationTag} feed is sparse today, so the continuous observation line switches to ${metarFallbackTag}.`
+        : `今日官方 ${observationTag} 点位较稀疏，连续实测线改用 ${metarFallbackTag}。`,
+    );
+  }
+  if (usingMirrorFallback) {
+    legendParts.push(
+      isEnglish(locale)
+        ? "Dense observation feed matched the forecast curve exactly, so it was ignored for this chart refresh."
+        : "本次高密度观测源与预测曲线逐点重合，已忽略该异常源。",
+    );
+  } else if (observationCode === "hko") {
+    legendParts.push(
+      isEnglish(locale)
+        ? "This city uses HKO official readings. The chart keeps official HKO points instead of switching to airport METAR."
+        : "该城市按 HKO 官方读数展示；图中保留 HKO 官方点位，不切换到机场 METAR 连续线。",
+    );
+  } else if (observationCode === "noaa") {
+    const noaaCode = getNoaaStationCode(detail);
+    legendParts.push(
+      isEnglish(locale)
+        ? `This city settles on NOAA ${noaaCode} using the finalized highest rounded whole-degree Celsius Temp reading; the plotted line is a settlement reference.`
+        : `该城市按 NOAA ${noaaCode} 最终完成质控后的最高整度摄氏 Temp 读数结算；图中曲线仅作为结算参考线。`,
+    );
+  }
+  if (tafMarkers.length) {
+    const primaryTafMarker = currentTafMarker || nextTafMarker;
+    if (primaryTafMarker) {
+      legendParts.push(
+        isEnglish(locale)
+          ? `Current TAF: ${formatTafLegendMarker(primaryTafMarker)}`
+          : `当前 TAF：${formatTafLegendMarker(primaryTafMarker)}`,
+      );
+    }
+    if (peakWindowTafMarker && !sameMarker(peakWindowTafMarker, primaryTafMarker)) {
+      legendParts.push(
+        isEnglish(locale)
+          ? `Peak-window TAF: ${formatTafLegendMarker(peakWindowTafMarker)}`
+          : `峰值窗口 TAF：${formatTafLegendMarker(peakWindowTafMarker)}`,
+      );
+    }
+    legendParts.push(
+      isEnglish(locale)
+        ? "Use the current TAF segment as primary; peak-window segments are reference only."
+        : "以当前 TAF 时段为准，峰值窗口时段仅作参考。",
+    );
+  }
+
+  const debPastSeries = buildSeriesPoints(times, debPast);
+  const debFutureSeries = buildSeriesPoints(times, debFuture);
+  const tempsSeries = buildSeriesPoints(times, temps);
+  const mgmHourlySeries = buildSeriesPoints(times, mgmHourlyPoints);
+  const metarSeries = buildObservationPoints(observationSource);
+  const airportMetarSeries = buildObservationPoints(airportMetarSource);
+  const mgmSeries =
+    !suppressAnkaraMgmObservation && detail.mgm?.temp != null && detail.mgm?.time
+      ? buildObservationPoints([{ time: detail.mgm.time, temp: detail.mgm.temp }])
+      : [];
+  const tafCurrentMarkerSeries = tafMarkers
+    .filter((marker) => marker.isCurrent)
+    .map((marker) => ({
+      marker,
+      x: hmToMinutes(marker.labelTime) ?? 0,
+      y: tafMarkerValue,
+    }))
+    .filter((point) => point.x > 0);
+  const tafPeakWindowMarkerSeries = tafMarkers
+    .filter((marker) => marker.isPeakWindow && !marker.isCurrent)
+    .map((marker) => ({
+      marker,
+      x: hmToMinutes(marker.labelTime) ?? 0,
+      y: tafMarkerValue - 0.15,
+    }))
+    .filter((point) => point.x > 0);
+  const tafMarkerSeries = tafMarkers
+    .map((marker) => ({
+      marker,
+      x: hmToMinutes(marker.labelTime) ?? 0,
+      y: tafMarkerValue,
+    }))
+    .filter((point) => point.x > 0);
+  const xMin = times.length ? hmToMinutes(times[0]) ?? 0 : 0;
+  const xMax = times.length ? hmToMinutes(times[times.length - 1]) ?? 24 * 60 : 24 * 60;
+
+  return {
+    datasets: {
+      airportMetarPoints,
+      airportMetarSeries,
+      debFuture,
+      debFutureSeries,
+      debPast,
+      debPastSeries,
+      hasMgmHourly,
+      metarPoints,
+      metarSeries,
+      mgmHourlyPoints,
+      mgmHourlySeries,
+      mgmPoints,
+      mgmSeries,
+      offset,
+      tafCurrentMarkerPoints,
+      tafCurrentMarkerSeries,
+      tafMarkerPoints,
+      tafMarkerSeries,
+      tafPeakWindowMarkerPoints,
+      tafPeakWindowMarkerSeries,
+      temps,
+      tempsSeries,
+    },
+    observationLabel:
+    observationCode === "noaa" &&
+    !shouldUseMetarFallback
+        ? isEnglish(locale)
+          ? `${observationDisplayTag} Settlement Reference`
+          : `${observationDisplayTag} 结算参考`
+        : isEnglish(locale)
+          ? `${observationDisplayTag} Observation`
+          : `${observationDisplayTag} 实况`,
+    legendText: legendParts.join(" | "),
+    max,
+    min,
+    tafMarkers,
+    tickLabels: buildTemperatureTickLabels(times),
+    times,
+    xMax,
+    xMin,
+    yTickStep,
+  };
+}

frontend/lib/dashboard-utils.ts

@@ -5,18 +5,23 @@ import {
   HistoryPoint,
   NearbyStation,
 } from "@/lib/dashboard-types";
-import { normalizeObservationSourceLabel } from "@/lib/source-labels";
+import {
+  getNoaaStationCode,
+  getNoaaStationName,
+  getObservationSourceCode,
+  getObservationSourceTag,
+  getRealtimeObservationTag,
+  isTurkishMgmCity,
+} from "@/lib/observation-source-utils";
 import {
   formatTemperatureValue,
   normalizeTemperatureLabel,
   normalizeTemperatureSymbol,
 } from "@/lib/temperature-utils";
-import {
+import { formatTafMarkerType } from "@/lib/taf-utils";
-  hmToMinutes,
+import { normalizeHm } from "@/lib/time-utils";
-  interpolateSeriesAtMinutes,
-  normalizeHm,
-} from "@/lib/time-utils";
 
+export { getTemperatureChartData } from "@/lib/chart-utils";
 export { getTodayPaceView } from "@/lib/pace-utils";
 export {
   formatTemperatureValue,
@@ -88,78 +93,6 @@ function getLocalizedDynamicCommentary(
   };
 }
 
-function isTurkishMgmCity(detail: CityDetail) {
-  const city = String(detail.name || detail.display_name || "")
-    .trim()
-    .toLowerCase();
-  return city === "ankara" || city === "istanbul";
-}
-
-function getObservationSourceCode(detail: CityDetail): string {
-  const source = String(detail.current?.settlement_source || "")
-    .trim()
-    .toLowerCase();
-  if (source) return source;
-
-  const city = String(detail.name || detail.display_name || "")
-    .trim()
-    .toLowerCase();
-  if (
-    city === "hong kong" ||
-    city === "shek kong" ||
-    city === "lau fau shan"
-  ) {
-    return "hko";
-  }
-  if (city === "taipei") return "noaa";
-  return "metar";
-}
-
-function getObservationSourceTag(detail: CityDetail): string {
-  const label = normalizeObservationSourceLabel(
-    detail.current?.settlement_source_label,
-    "",
-  )
-    .trim()
-    .toUpperCase();
-  if (label) return label;
-  const code = getObservationSourceCode(detail);
-  if (code === "hko") return "HKO";
-  if (code === "cwa") return "CWA";
-  if (code === "noaa") return "NOAA";
-  if (code === "wunderground") {
-    const icao = String(detail.risk?.icao || detail.current?.station_code || "")
-      .trim()
-      .toUpperCase();
-    return icao ? `${icao} METAR` : "METAR";
-  }
-  if (code === "mgm") return "MGM";
-  return "METAR";
-}
-
-function getRealtimeObservationTag(detail: CityDetail): string {
-  const code = getObservationSourceCode(detail);
-  if (code === "wunderground") {
-    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
-    return icao ? `${icao} METAR` : "METAR";
-  }
-  return getObservationSourceTag(detail);
-}
-
-function getNoaaStationCode(detail: CityDetail): string {
-  return String(detail.current?.station_code || detail.risk?.icao || "NOAA")
-    .trim()
-    .toUpperCase();
-}
-
-function getNoaaStationName(detail: CityDetail): string {
-  return (
-    String(detail.current?.station_name || "").trim() ||
-    String(detail.risk?.airport || "").trim() ||
-    getNoaaStationCode(detail)
-  );
-}
-
 function normalizeCloudSummary(
   cloudDesc: string | null | undefined,
   locale: Locale,
@@ -246,216 +179,6 @@ export function getWeatherSummary(detail: CityDetail, locale: Locale = "zh-CN")
   return { weatherIcon, weatherText };
 }
 
-function findNearestTimeIndex(
-  times: string[],
-  targetTime?: string | null,
-) {
-  const targetMinutes = hmToMinutes(targetTime);
-  if (targetMinutes == null || !times.length) return -1;
-  let nearestIndex = -1;
-  let nearestDelta = Number.POSITIVE_INFINITY;
-  times.forEach((time, index) => {
-    const minute = hmToMinutes(time);
-    if (minute == null) return;
-    const delta = Math.abs(minute - targetMinutes);
-    if (delta < nearestDelta) {
-      nearestDelta = delta;
-      nearestIndex = index;
-    }
-  });
-  return nearestIndex;
-}
-
-function buildTemperatureTickLabels(times: string[]) {
-  const lastIndex = Math.max(0, times.length - 1);
-  return times.map((time, index) => {
-    if (index === 0 || index === lastIndex) return time;
-    const minute = hmToMinutes(time);
-    if (minute == null) return "";
-    const hour = Math.floor(minute / 60);
-    const minutePart = minute % 60;
-    if (minutePart !== 0) return "";
-    return hour % 2 === 0 ? time : "";
-  });
-}
-
-function getNiceTemperatureScale(values: number[], tempSymbol?: string | null) {
-  const numericValues = values.filter((value) => Number.isFinite(Number(value)));
-  if (!numericValues.length) {
-    return { max: 1, min: 0, step: 1 };
-  }
-
-  const rawMin = Math.min(...numericValues);
-  const rawMax = Math.max(...numericValues);
-  const spread = Math.max(0.1, rawMax - rawMin);
-  const isFahrenheit = normalizeTemperatureSymbol(tempSymbol) === "°F";
-  const padding = Math.max(isFahrenheit ? 1.5 : 0.8, spread * 0.12);
-  const paddedMin = rawMin - padding;
-  const paddedMax = rawMax + padding;
-  const paddedSpread = Math.max(0.1, paddedMax - paddedMin);
-  const candidates = isFahrenheit ? [1, 2, 5, 10, 20] : [0.5, 1, 2, 5, 10];
-  let step =
-    candidates.find((candidate) => candidate >= paddedSpread / 4) ||
-    candidates[candidates.length - 1];
-  let min = Math.floor(paddedMin / step) * step;
-  let max = Math.ceil(paddedMax / step) * step;
-
-  if (min < 0 && rawMin >= 0 && rawMin <= step * 1.25) min = 0;
-  if (max <= min) max = min + step * 4;
-
-  while ((max - min) / step + 1 > 6) {
-    const nextStep = candidates.find((candidate) => candidate > step);
-    if (!nextStep) break;
-    step = nextStep;
-    min = Math.floor(paddedMin / step) * step;
-    max = Math.ceil(paddedMax / step) * step;
-    if (min < 0 && rawMin >= 0 && rawMin <= step * 1.25) min = 0;
-  }
-
-  return { max, min, step };
-}
-
-function buildSeriesPoints(
-  times: string[],
-  values: Array<number | null | undefined>,
-) {
-  return times
-    .map((time, index) => {
-      const x = hmToMinutes(time);
-      const y = values[index];
-      return x != null && y != null && Number.isFinite(Number(y))
-        ? { index, labelTime: time, x, y: Number(y) }
-        : null;
-    })
-    .filter(
-      (point): point is { index: number; labelTime: string; x: number; y: number } =>
-        point != null,
-    );
-}
-
-function buildObservationPoints(items: Array<{ time?: string; temp?: number | null }>) {
-  return items
-    .map((item) => {
-      const labelTime = normalizeHm(String(item.time || ""));
-      const x = hmToMinutes(labelTime);
-      const y = item.temp;
-      return x != null && y != null && Number.isFinite(Number(y))
-        ? { labelTime: labelTime || "", x, y: Number(y) }
-        : null;
-    })
-    .filter((point): point is { labelTime: string; x: number; y: number } => point != null);
-}
-
-function sortObservationItemsByTime<T extends { time?: string | null }>(items: T[]) {
-  return [...items].sort((left, right) => {
-    const leftMinutes = hmToMinutes(left.time);
-    const rightMinutes = hmToMinutes(right.time);
-    if (leftMinutes == null && rightMinutes == null) return 0;
-    if (leftMinutes == null) return 1;
-    if (rightMinutes == null) return -1;
-    return leftMinutes - rightMinutes;
-  });
-}
-
-function dedupeObservationItems<T extends { temp?: number | null; time?: string | null }>(
-  items: T[],
-) {
-  const byTime = new Map<string, T>();
-  items.forEach((item) => {
-    const time = normalizeHm(item.time);
-    const value = Number(item.temp);
-    if (!time || !Number.isFinite(value)) return;
-    const existing = byTime.get(time);
-    if (!existing || Number(item.temp) >= Number(existing.temp)) {
-      byTime.set(time, { ...item, time });
-    }
-  });
-  return sortObservationItemsByTime([...byTime.values()]);
-}
-
-function looksLikeForecastMirror(
-  observations: Array<{ temp?: number | null; time?: string | null }>,
-  forecastTimes: string[],
-  forecastValues: Array<number | null | undefined>,
-) {
-  const unique = dedupeObservationItems(observations);
-  if (unique.length < 6 || forecastTimes.length < 6) return false;
-  if (unique.length < Math.max(6, Math.floor(forecastTimes.length * 0.4))) {
-    return false;
-  }
-
-  let compared = 0;
-  let exactMatches = 0;
-  unique.forEach((item) => {
-    const minute = hmToMinutes(item.time);
-    const observed = Number(item.temp);
-    if (minute == null || !Number.isFinite(observed)) return;
-    const expected = interpolateSeriesAtMinutes(
-      forecastTimes,
-      forecastValues,
-      minute,
-    );
-    if (expected == null || !Number.isFinite(expected)) return;
-    compared += 1;
-    if (Math.abs(observed - expected) <= 0.05) {
-      exactMatches += 1;
-    }
-  });
-
-  return compared >= 6 && exactMatches / compared >= 0.65;
-}
-
-function normalizeObservationTimeForChart(
-  value: unknown,
-  detail: CityDetail,
-) {
-  const raw = String(value || "").trim();
-  if (raw && !raw.includes("T")) {
-    return normalizeHm(raw) || raw;
-  }
-  return normalizeHm(detail.local_time) || normalizeHm(raw) || raw;
-}
-
-function buildCurrentObservationFallback(
-  detail: CityDetail,
-): Array<{ time?: string; temp?: number | null; sourceLabel?: string | null }> {
-  const candidates: Array<{
-    sourceLabel?: string | null;
-    temp?: number | null;
-    time?: string | null;
-  }> = [
-    {
-      sourceLabel: detail.current?.settlement_source_label,
-      temp: detail.current?.temp,
-      time: detail.current?.obs_time || detail.current?.report_time,
-    },
-    {
-      sourceLabel: detail.airport_primary?.source_label || "METAR",
-      temp: detail.airport_primary?.temp,
-      time: detail.airport_primary?.obs_time || detail.airport_primary?.report_time,
-    },
-    {
-      sourceLabel: detail.airport_current?.source_label || "METAR",
-      temp: detail.airport_current?.temp,
-      time: detail.airport_current?.obs_time || detail.airport_current?.report_time,
-    },
-  ];
-
-  const first = candidates.find((item) => {
-    const numeric = Number(item.temp);
-    return Number.isFinite(numeric);
-  });
-  if (!first) return [];
-
-  return [
-    {
-      sourceLabel: first.sourceLabel,
-      temp: Number(first.temp),
-      time: normalizeObservationTimeForChart(first.time, detail),
-    },
-  ];
-}
-
 export function getHeroMetaItems(detail: CityDetail, locale: Locale = "zh-CN") {
   const current = detail.current || {};
   const parts: string[] = [];
@@ -523,542 +246,6 @@ export function getHeroMetaItems(detail: CityDetail, locale: Locale = "zh-CN") {
   return parts;
 }
 
-export function getTemperatureChartData(
-  detail: CityDetail,
-  locale: Locale = "zh-CN",
-) {
-  const hourly = detail.hourly || {};
-  const rawTimes = Array.isArray(hourly.times) ? hourly.times : [];
-  const rawTemps = Array.isArray(hourly.temps) ? hourly.temps : [];
-  const times = rawTimes
-    .map((time) => String(time || "").trim())
-    .filter(Boolean);
-  const temps = times.map((_, index) => {
-    const value = Number(rawTemps[index]);
-    return Number.isFinite(value) ? value : null;
-  });
-  const suppressAnkaraMgmObservation = isTurkishMgmCity(detail);
-
-  if (!times.length) return null;
-
-  const currentIndex = findNearestTimeIndex(times, detail.local_time);
-  const omMax = detail.forecast?.today_high;
-  const debMax = detail.deb?.prediction;
-  const offset =
-    debMax != null && omMax != null ? Number(debMax) - Number(omMax) : 0;
-  const debTemps = temps.map((temp) =>
-    temp != null && Number.isFinite(temp)
-      ? Number((temp + offset).toFixed(1))
-      : null,
-  );
-  const debPast = debTemps.map((temp, index) =>
-    currentIndex >= 0 && index <= currentIndex ? temp : null,
-  );
-  const debFuture = debTemps.map((temp, index) =>
-    currentIndex < 0 || index >= currentIndex ? temp : null,
-  );
-
-  const observationTag = getRealtimeObservationTag(detail);
-  const observationCode = getObservationSourceCode(detail);
-  const settlementSource =
-    observationCode === "hko" ||
-    observationCode === "cwa" ||
-    observationCode === "noaa" ||
-    observationCode === "wunderground";
-  const useSettlementObservationSource = settlementSource;
-  const officialObservationSource =
-    useSettlementObservationSource
-      ? detail.settlement_today_obs?.length
-        ? detail.settlement_today_obs
-        : detail.current?.obs_time && detail.current?.temp != null
-          ? [{ time: detail.current.obs_time, temp: detail.current.temp }]
-          : []
-      : [];
-  const currentObservationFallback = buildCurrentObservationFallback(detail);
-  const minPlausibleObservationTemp = (() => {
-    const name = String(detail.name || "").trim().toLowerCase();
-    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
-    if (name === "karachi" || name === "masroor air base" || icao === "OPKC" || icao === "OPMR") {
-      return detail.temp_symbol === "°F" ? 41 : 5;
-    }
-    return null;
-  })();
-  const filterPlausibleObservations = <T extends { temp?: number | null }>(
-    rows?: T[] | null,
-  ) =>
-    (Array.isArray(rows) ? rows : []).filter((row) => {
-      const value = Number(row?.temp);
-      if (!Number.isFinite(value)) return false;
-      return minPlausibleObservationTemp == null || value >= minPlausibleObservationTemp;
-    });
-  const plausibleMetarTodayObs = filterPlausibleObservations(detail.metar_today_obs);
-  const plausibleTrendRecent = filterPlausibleObservations(detail.trend?.recent);
-  const plausibleCurrentFallback = filterPlausibleObservations(currentObservationFallback);
-  const metarObservationSource = plausibleMetarTodayObs.length
-    ? plausibleMetarTodayObs
-    : plausibleTrendRecent.length
-      ? plausibleTrendRecent
-      : plausibleCurrentFallback;
-  const usingCurrentObservationFallback =
-    !plausibleMetarTodayObs.length &&
-    !plausibleTrendRecent.length &&
-    plausibleCurrentFallback.length > 0;
-  const currentFallbackTag =
-    currentObservationFallback[0]?.sourceLabel ||
-    getObservationSourceTag(detail);
-  const allowMetarFallback = settlementSource && observationCode !== "hko";
-  const shouldUseMetarFallback =
-    allowMetarFallback &&
-    officialObservationSource.length > 0 &&
-    officialObservationSource.length < 3 &&
-    metarObservationSource.length >= 3;
-  let usingMetarObservationSource =
-    !useSettlementObservationSource || shouldUseMetarFallback;
-  let observationSource = useSettlementObservationSource
-    ? shouldUseMetarFallback
-      ? metarObservationSource
-      : officialObservationSource
-    : metarObservationSource;
-  let usingMirrorFallback = false;
-  if (looksLikeForecastMirror(observationSource, times, debTemps)) {
-    const fallbackCandidates = [
-      plausibleTrendRecent,
-      plausibleCurrentFallback,
-      metarObservationSource,
-    ];
-    const fallback = fallbackCandidates.find(
-      (candidate) =>
-        candidate.length > 0 &&
-        candidate !== observationSource &&
-        !looksLikeForecastMirror(candidate, times, debTemps),
-    );
-    if (fallback) {
-      observationSource = fallback;
-      usingMetarObservationSource = fallback === metarObservationSource;
-      usingMirrorFallback = true;
-    }
-  }
-  observationSource = dedupeObservationItems(observationSource);
-  const airportMetarSource: Array<{ time?: string; temp?: number | null }> = [];
-  const metarFallbackTag = (() => {
-    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
-    if (!icao) return "METAR";
-    return `${icao} METAR`;
-  })();
-  const observationDisplayTag =
-    usingCurrentObservationFallback
-      ? String(currentFallbackTag).toUpperCase()
-      : observationCode === "wunderground" && usingMetarObservationSource
-      ? metarFallbackTag
-      : observationCode === "wunderground"
-        ? metarFallbackTag
-      : useSettlementObservationSource && shouldUseMetarFallback
-      ? metarFallbackTag
-      : observationCode === "noaa"
-        ? `NOAA ${getNoaaStationCode(detail)}`
-        : observationTag;
-
-  const metarPoints = new Array(times.length).fill(null);
-  observationSource.forEach((item) => {
-    const index = findNearestTimeIndex(times, String(item.time || ""));
-    const temp = Number(item.temp);
-    if (index >= 0 && Number.isFinite(temp)) {
-      const existing = metarPoints[index];
-      // Multiple reports can land in the same hour bucket. Keep the peak
-      // value so an intrahour high is not hidden by a later weaker report.
-      metarPoints[index] =
-        existing == null ? temp : Math.max(Number(existing), temp);
-    }
-  });
-  const airportMetarPoints = new Array(times.length).fill(null);
-  airportMetarSource.forEach((item) => {
-    const index = findNearestTimeIndex(times, String(item.time || ""));
-    const temp = Number(item.temp);
-    if (index >= 0 && Number.isFinite(temp)) {
-      const existing = airportMetarPoints[index];
-      airportMetarPoints[index] =
-        existing == null ? temp : Math.max(Number(existing), temp);
-    }
-  });
-
-  const mgmPoints = new Array(times.length).fill(null);
-  if (
-    !suppressAnkaraMgmObservation &&
-    detail.mgm?.temp != null &&
-    detail.mgm?.time
-  ) {
-    const index = findNearestTimeIndex(times, detail.mgm.time);
-    const temp = Number(detail.mgm.temp);
-    if (index >= 0 && Number.isFinite(temp)) {
-      mgmPoints[index] = temp;
-    }
-  }
-
-  const mgmHourlyPoints = new Array(times.length).fill(null);
-  let hasMgmHourly = false;
-  const mgmHourlyRows = Array.isArray(detail.mgm?.hourly)
-    ? detail.mgm?.hourly || []
-    : [];
-  mgmHourlyRows.forEach((item) => {
-    const index = findNearestTimeIndex(times, String(item.time || ""));
-    const temp = Number(item.temp);
-    if (index >= 0 && Number.isFinite(temp)) {
-      mgmHourlyPoints[index] = temp;
-      hasMgmHourly = true;
-    }
-  });
-
-  const allValues = [
-    ...debTemps.filter((value) => value != null),
-    ...metarPoints.filter((value) => value != null),
-    ...airportMetarPoints.filter((value) => value != null),
-    ...mgmPoints.filter((value) => value != null),
-    ...mgmHourlyPoints.filter((value) => value != null),
-  ] as number[];
-
-  if (!allValues.length) return null;
-
-  const yScale = getNiceTemperatureScale(allValues, detail.temp_symbol);
-  const min = yScale.min;
-  const max = yScale.max;
-  const yTickStep = yScale.step;
-  const tafMarkersRaw = Array.isArray(detail.taf?.signal?.markers)
-    ? detail.taf?.signal?.markers || []
-    : [];
-  const normalizeHm = (value: unknown): string | null => {
-    const match = String(value || "").match(/(\d{1,2}):(\d{2})/);
-    if (!match) return null;
-    const hour = Number.parseInt(match[1], 10);
-    const minute = Number.parseInt(match[2], 10);
-    if (
-      !Number.isFinite(hour) ||
-      !Number.isFinite(minute) ||
-      hour < 0 ||
-      hour > 23 ||
-      minute < 0 ||
-      minute > 59
-    ) {
-      return null;
-    }
-    return `${String(hour).padStart(2, "0")}:${String(minute).padStart(2, "0")}`;
-  };
-  const hmToMinutes = (value: string | null) => {
-    if (!value) return null;
-    const [hourPart, minutePart] = value.split(":");
-    const hour = Number.parseInt(hourPart || "", 10);
-    const minute = Number.parseInt(minutePart || "", 10);
-    if (
-      !Number.isFinite(hour) ||
-      !Number.isFinite(minute) ||
-      hour < 0 ||
-      hour > 23 ||
-      minute < 0 ||
-      minute > 59
-    ) {
-      return null;
-    }
-    return hour * 60 + minute;
-  };
-  const currentMinutes = hmToMinutes(normalizeHm(detail.local_time));
-  const peakFirstHour = Number(detail.peak?.first_h);
-  const peakLastHour = Number(detail.peak?.last_h);
-  const peakWindowStartMinutes =
-    Number.isFinite(peakFirstHour) && peakFirstHour >= 0
-      ? Math.max(0, (peakFirstHour - 2) * 60)
-      : null;
-  const peakWindowEndMinutes =
-    Number.isFinite(peakLastHour) && peakLastHour >= peakFirstHour
-      ? Math.min(23 * 60 + 59, (peakLastHour + 1) * 60)
-      : null;
-  const tafMarkerValue = max - 0.4;
-  const tafMarkerPoints = new Array(times.length).fill(null);
-  const tafCurrentMarkerPoints = new Array(times.length).fill(null);
-  const tafPeakWindowMarkerPoints = new Array(times.length).fill(null);
-  const sameMarker = (
-    left:
-      | { markerType?: string | null; startLocal?: string | null; endLocal?: string | null }
-      | null
-      | undefined,
-    right:
-      | { markerType?: string | null; startLocal?: string | null; endLocal?: string | null }
-      | null
-      | undefined,
-  ) =>
-    !!left &&
-    !!right &&
-    String(left.markerType || "") === String(right.markerType || "") &&
-    String(left.startLocal || "") === String(right.startLocal || "") &&
-    String(left.endLocal || "") === String(right.endLocal || "");
-  const tafMarkers = tafMarkersRaw
-    .map((marker) => {
-      const labelTime = String(marker?.label_time || "").trim();
-      const index = findNearestTimeIndex(times, labelTime);
-      if (index >= 0) {
-        tafMarkerPoints[index] = tafMarkerValue;
-      }
-      return {
-        displayType: formatTafMarkerType(
-          String(marker?.marker_type || "").trim(),
-          locale,
-        ),
-        endLocal: String(marker?.end_local || "").trim(),
-        index,
-        labelTime,
-        markerType: String(marker?.marker_type || "").trim(),
-        startLocal: String(marker?.start_local || "").trim(),
-        summary:
-          isEnglish(locale)
-            ? String(marker?.summary_en || "").trim()
-            : String(marker?.summary_zh || "").trim(),
-        isCurrent: false,
-        isPeakWindow: false,
-        suppressionLevel: String(marker?.suppression_level || "").trim(),
-      };
-    })
-    .filter((marker) => marker.index >= 0);
-  const currentTafMarker =
-    currentMinutes !== null
-      ? tafMarkers.find((marker) => {
-          const start = hmToMinutes(normalizeHm(marker.startLocal));
-          const end = hmToMinutes(normalizeHm(marker.endLocal));
-          return start !== null && end !== null && currentMinutes >= start && currentMinutes <= end;
-        }) || null
-      : null;
-  const nextTafMarker =
-    currentMinutes !== null && !currentTafMarker
-      ? tafMarkers.find((marker) => {
-          const start = hmToMinutes(normalizeHm(marker.startLocal));
-          return start !== null && start > currentMinutes;
-        }) || null
-      : null;
-  const peakWindowTafMarker =
-    peakWindowStartMinutes !== null && peakWindowEndMinutes !== null
-      ? tafMarkers.find((marker) => {
-          const start = hmToMinutes(normalizeHm(marker.startLocal));
-          const end = hmToMinutes(normalizeHm(marker.endLocal));
-          return (
-            start !== null &&
-            end !== null &&
-            start <= peakWindowEndMinutes &&
-            end >= peakWindowStartMinutes
-          );
-        }) || null
-      : null;
-  tafMarkers.forEach((marker) => {
-    const isPrimaryTafMarker =
-      sameMarker(marker, currentTafMarker) || sameMarker(marker, nextTafMarker);
-    const isPeakReferenceMarker = sameMarker(marker, peakWindowTafMarker);
-    if (isPrimaryTafMarker) {
-      marker.isCurrent = true;
-      tafCurrentMarkerPoints[marker.index] = tafMarkerValue;
-    }
-    if (isPeakReferenceMarker) {
-      marker.isPeakWindow = true;
-      if (!isPrimaryTafMarker) {
-        tafPeakWindowMarkerPoints[marker.index] = tafMarkerValue - 0.15;
-      }
-    }
-  });
-  const formatTafLegendMarker = (
-    marker:
-      | { displayType?: string | null; startLocal?: string | null; endLocal?: string | null; summary?: string | null }
-      | null
-      | undefined,
-  ) => {
-    if (!marker) return "";
-    const range = `${marker.startLocal || "--:--"}-${marker.endLocal || "--:--"}`;
-    const status = String(marker.summary || "").trim();
-    return status
-      ? `${marker.displayType || ""} ${range} ${status}`.trim()
-      : `${marker.displayType || ""} ${range}`.trim();
-  };
-
-  const legendParts: string[] = [];
-  if (!suppressAnkaraMgmObservation && detail.mgm?.temp != null) {
-    legendParts.push(`MGM: ${detail.mgm.temp}${detail.temp_symbol}`);
-  }
-  if (!hasMgmHourly && debMax != null && omMax != null && Math.abs(offset) > 0.3) {
-    const sign = offset > 0 ? "+" : "";
-    legendParts.push(
-      isEnglish(locale)
-        ? `DEB offset ${sign}${offset.toFixed(1)}${detail.temp_symbol} vs OM`
-        : `DEB 偏移 ${sign}${offset.toFixed(1)}${detail.temp_symbol} vs OM`,
-    );
-  }
-  if (hasMgmHourly) {
-    legendParts.push(
-      isEnglish(locale)
-        ? "Using MGM hourly forecast to replace DEB curve"
-        : "已使用 MGM 小时预报替代 DEB 曲线",
-    );
-  }
-  if ((detail.trend?.recent?.length || 0) > 0 || observationSource.length > 0) {
-    const recentData = sortObservationItemsByTime(
-      observationSource.length > 0
-        ? [...observationSource]
-        : [...(detail.trend?.recent || [])],
-    );
-    const recentText = recentData
-      .slice(-4)
-      .map((item) => `${item.temp}${detail.temp_symbol}@${item.time}`)
-      .join(" -> ");
-    legendParts.push(`${observationDisplayTag}: ${recentText}`);
-  }
-  if (airportMetarSource.length > 0) {
-    const airportRecentText = sortObservationItemsByTime([...airportMetarSource])
-      .slice(-4)
-      .map((item) => `${item.temp}${detail.temp_symbol}@${item.time}`)
-      .join(" -> ");
-    legendParts.push(
-      isEnglish(locale)
-        ? `${metarFallbackTag}: ${airportRecentText}`
-        : `${metarFallbackTag}: ${airportRecentText}`,
-    );
-  }
-  if (detail.metar_status?.stale_for_today) {
-    const dateText = detail.metar_status.last_observation_local_date || "";
-    const tempText =
-      detail.metar_status.last_temp != null
-        ? `${detail.metar_status.last_temp}${detail.temp_symbol}`
-        : "";
-    legendParts.push(
-      isEnglish(locale)
-        ? `No same-day ${metarFallbackTag} report yet; latest report${dateText ? ` was ${dateText}` : ""}${tempText ? ` at ${tempText}` : ""}.`
-        : `今日暂无同日 ${metarFallbackTag} 报文；最近一报${dateText ? `为 ${dateText}` : ""}${tempText ? `，${tempText}` : ""}。`,
-    );
-  }
-  if (shouldUseMetarFallback) {
-    legendParts.push(
-      isEnglish(locale)
-        ? `Official ${observationTag} feed is sparse today, so the continuous observation line switches to ${metarFallbackTag}.`
-        : `今日官方 ${observationTag} 点位较稀疏，连续实测线改用 ${metarFallbackTag}。`,
-    );
-  }
-  if (usingMirrorFallback) {
-    legendParts.push(
-      isEnglish(locale)
-        ? "Dense observation feed matched the forecast curve exactly, so it was ignored for this chart refresh."
-        : "本次高密度观测源与预测曲线逐点重合，已忽略该异常源。",
-    );
-  } else if (observationCode === "hko") {
-    legendParts.push(
-      isEnglish(locale)
-        ? "This city uses HKO official readings. The chart keeps official HKO points instead of switching to airport METAR."
-        : "该城市按 HKO 官方读数展示；图中保留 HKO 官方点位，不切换到机场 METAR 连续线。",
-    );
-  } else if (observationCode === "noaa") {
-    const noaaCode = getNoaaStationCode(detail);
-    legendParts.push(
-      isEnglish(locale)
-        ? `This city settles on NOAA ${noaaCode} using the finalized highest rounded whole-degree Celsius Temp reading; the plotted line is a settlement reference.`
-        : `该城市按 NOAA ${noaaCode} 最终完成质控后的最高整度摄氏 Temp 读数结算；图中曲线仅作为结算参考线。`,
-    );
-  }
-  if (tafMarkers.length) {
-    const primaryTafMarker = currentTafMarker || nextTafMarker;
-    if (primaryTafMarker) {
-      legendParts.push(
-        isEnglish(locale)
-          ? `Current TAF: ${formatTafLegendMarker(primaryTafMarker)}`
-          : `当前 TAF：${formatTafLegendMarker(primaryTafMarker)}`,
-      );
-    }
-    if (peakWindowTafMarker && !sameMarker(peakWindowTafMarker, primaryTafMarker)) {
-      legendParts.push(
-        isEnglish(locale)
-          ? `Peak-window TAF: ${formatTafLegendMarker(peakWindowTafMarker)}`
-          : `峰值窗口 TAF：${formatTafLegendMarker(peakWindowTafMarker)}`,
-      );
-    }
-    legendParts.push(
-      isEnglish(locale)
-        ? "Use the current TAF segment as primary; peak-window segments are reference only."
-        : "以当前 TAF 时段为准，峰值窗口时段仅作参考。",
-    );
-  }
-
-  const debPastSeries = buildSeriesPoints(times, debPast);
-  const debFutureSeries = buildSeriesPoints(times, debFuture);
-  const tempsSeries = buildSeriesPoints(times, temps);
-  const mgmHourlySeries = buildSeriesPoints(times, mgmHourlyPoints);
-  const metarSeries = buildObservationPoints(observationSource);
-  const airportMetarSeries = buildObservationPoints(airportMetarSource);
-  const mgmSeries =
-    !suppressAnkaraMgmObservation && detail.mgm?.temp != null && detail.mgm?.time
-      ? buildObservationPoints([{ time: detail.mgm.time, temp: detail.mgm.temp }])
-      : [];
-  const tafCurrentMarkerSeries = tafMarkers
-    .filter((marker) => marker.isCurrent)
-    .map((marker) => ({
-      marker,
-      x: hmToMinutes(marker.labelTime) ?? 0,
-      y: tafMarkerValue,
-    }))
-    .filter((point) => point.x > 0);
-  const tafPeakWindowMarkerSeries = tafMarkers
-    .filter((marker) => marker.isPeakWindow && !marker.isCurrent)
-    .map((marker) => ({
-      marker,
-      x: hmToMinutes(marker.labelTime) ?? 0,
-      y: tafMarkerValue - 0.15,
-    }))
-    .filter((point) => point.x > 0);
-  const tafMarkerSeries = tafMarkers
-    .map((marker) => ({
-      marker,
-      x: hmToMinutes(marker.labelTime) ?? 0,
-      y: tafMarkerValue,
-    }))
-    .filter((point) => point.x > 0);
-  const xMin = times.length ? hmToMinutes(times[0]) ?? 0 : 0;
-  const xMax = times.length ? hmToMinutes(times[times.length - 1]) ?? 24 * 60 : 24 * 60;
-
-  return {
-    datasets: {
-      airportMetarPoints,
-      airportMetarSeries,
-      debFuture,
-      debFutureSeries,
-      debPast,
-      debPastSeries,
-      hasMgmHourly,
-      metarPoints,
-      metarSeries,
-      mgmHourlyPoints,
-      mgmHourlySeries,
-      mgmPoints,
-      mgmSeries,
-      offset,
-      tafCurrentMarkerPoints,
-      tafCurrentMarkerSeries,
-      tafMarkerPoints,
-      tafMarkerSeries,
-      tafPeakWindowMarkerPoints,
-      tafPeakWindowMarkerSeries,
-      temps,
-      tempsSeries,
-    },
-    observationLabel:
-    observationCode === "noaa" &&
-    !shouldUseMetarFallback
-        ? isEnglish(locale)
-          ? `${observationDisplayTag} Settlement Reference`
-          : `${observationDisplayTag} 结算参考`
-        : isEnglish(locale)
-          ? `${observationDisplayTag} Observation`
-          : `${observationDisplayTag} 实况`,
-    legendText: legendParts.join(" | "),
-    max,
-    min,
-    tafMarkers,
-    tickLabels: buildTemperatureTickLabels(times),
-    times,
-    xMax,
-    xMin,
-    yTickStep,
-  };
-}
-
 export function getProbabilityView(detail: CityDetail, targetDate?: string | null) {
   const date = targetDate || detail.local_date;
   if (date === detail.local_date) {
@@ -1373,36 +560,6 @@ function bucketLabel(bucket: string | null, locale: Locale = "zh-CN") {
   );
 }
 
-function formatTafMarkerType(type: string, locale: Locale = "zh-CN") {
-  const normalized = String(type || "").trim().toUpperCase();
-  if (isEnglish(locale)) {
-    return (
-      {
-        BASE: "Base regime",
-        FM: "Hard shift",
-        TEMPO: "Temporary swing",
-        BECMG: "Gradual shift",
-        PROB30: "30% risk window",
-        PROB40: "40% risk window",
-        "PROB30 TEMPO": "30% temporary swing",
-        "PROB40 TEMPO": "40% temporary swing",
-      }[normalized] || normalized
-    );
-  }
-  return (
-    {
-      BASE: "基础时段",
-      FM: "明确切换",
-      TEMPO: "临时波动",
-      BECMG: "逐步转变",
-      PROB30: "30% 风险窗",
-      PROB40: "40% 风险窗",
-      "PROB30 TEMPO": "30% 临时波动",
-      "PROB40 TEMPO": "40% 临时波动",
-    }[normalized] || normalized
-  );
-}
-
 export function wuRound(value: number | null | undefined) {
   const numeric = Number(value);
   if (!Number.isFinite(numeric)) return null;

frontend/lib/observation-source-utils.ts

@@ -0,0 +1,74 @@
+import type { CityDetail } from "@/lib/dashboard-types";
+import { normalizeObservationSourceLabel } from "@/lib/source-labels";
+
+export function isTurkishMgmCity(detail: CityDetail) {
+  const city = String(detail.name || detail.display_name || "")
+    .trim()
+    .toLowerCase();
+  return city === "ankara" || city === "istanbul";
+}
+
+export function getObservationSourceCode(detail: CityDetail): string {
+  const source = String(detail.current?.settlement_source || "")
+    .trim()
+    .toLowerCase();
+  if (source) return source;
+
+  const city = String(detail.name || detail.display_name || "")
+    .trim()
+    .toLowerCase();
+  if (
+    city === "hong kong" ||
+    city === "shek kong" ||
+    city === "lau fau shan"
+  ) {
+    return "hko";
+  }
+  if (city === "taipei") return "noaa";
+  return "metar";
+}
+
+export function getObservationSourceTag(detail: CityDetail): string {
+  const label = normalizeObservationSourceLabel(
+    detail.current?.settlement_source_label,
+    "",
+  )
+    .trim()
+    .toUpperCase();
+  if (label) return label;
+  const code = getObservationSourceCode(detail);
+  if (code === "hko") return "HKO";
+  if (code === "cwa") return "CWA";
+  if (code === "noaa") return "NOAA";
+  if (code === "wunderground") {
+    const icao = String(detail.risk?.icao || detail.current?.station_code || "")
+      .trim()
+      .toUpperCase();
+    return icao ? `${icao} METAR` : "METAR";
+  }
+  if (code === "mgm") return "MGM";
+  return "METAR";
+}
+
+export function getRealtimeObservationTag(detail: CityDetail): string {
+  const code = getObservationSourceCode(detail);
+  if (code === "wunderground") {
+    const icao = String(detail.risk?.icao || "").trim().toUpperCase();
+    return icao ? `${icao} METAR` : "METAR";
+  }
+  return getObservationSourceTag(detail);
+}
+
+export function getNoaaStationCode(detail: CityDetail): string {
+  return String(detail.current?.station_code || detail.risk?.icao || "NOAA")
+    .trim()
+    .toUpperCase();
+}
+
+export function getNoaaStationName(detail: CityDetail): string {
+  return (
+    String(detail.current?.station_name || "").trim() ||
+    String(detail.risk?.airport || "").trim() ||
+    getNoaaStationCode(detail)
+  );
+}

frontend/lib/taf-utils.ts

@@ -0,0 +1,35 @@
+import type { Locale } from "@/lib/i18n";
+
+function isEnglish(locale: Locale) {
+  return locale === "en-US";
+}
+
+export function formatTafMarkerType(type: string, locale: Locale = "zh-CN") {
+  const normalized = String(type || "").trim().toUpperCase();
+  if (isEnglish(locale)) {
+    return (
+      {
+        BASE: "Base regime",
+        FM: "Hard shift",
+        TEMPO: "Temporary swing",
+        BECMG: "Gradual shift",
+        PROB30: "30% risk window",
+        PROB40: "40% risk window",
+        "PROB30 TEMPO": "30% temporary swing",
+        "PROB40 TEMPO": "40% temporary swing",
+      }[normalized] || normalized
+    );
+  }
+  return (
+    {
+      BASE: "基础时段",
+      FM: "明确切换",
+      TEMPO: "临时波动",
+      BECMG: "逐步转变",
+      PROB30: "30% 风险窗",
+      PROB40: "40% 风险窗",
+      "PROB30 TEMPO": "30% 临时波动",
+      "PROB40 TEMPO": "40% 临时波动",
+    }[normalized] || normalized
+  );
+}