A weather source can name its provider for each product

The Rain radar, Lightning density and Satellite clouds rows named NOAA
nowCOAST until a manifest named its own source, whatever the source read.
A weather source may now supply sourceName(kind), kind being radar,
lightning or satellite; the row shows that name until a manifest names one.
The name is read once when the layer is built and held to the same rule as
a manifest's display.source. A source without names, or one whose name is
refused or fails, still shows NOAA nowCOAST.

src/layers/weather/display.js

@@ -39,6 +39,15 @@ function text(value, max) {
     : undefined;
 }
 
+/**
+ * A source name a weather feed supplies itself (`sourceName` on the feed),
+ * held to the same rule as a manifest's `display.source`; undefined when it
+ * is not a fit name.
+ */
+export function weatherSourceName(value) {
+  return text(value, TEXT_LIMITS.source);
+}
+
 /**
  * Whether a label the legend formats as a number reads back exactly as given:
  * within the safe integer range and with no digits lost to rounding, so

src/layers/weather/index.js

@@ -2,7 +2,7 @@ import * as Cesium from 'cesium';
 import { createWeatherRendering } from './rendering.js';
 import { weatherFrameSource } from './source.js';
 import { imageryHostStatus } from './imageryHost.js';
-import { weatherDisplay, insideExtent } from './display.js';
+import { weatherDisplay, weatherSourceName, insideExtent } from './display.js';
 import {
   RADAR_MAX_GAP_MS,
   REGIONAL_INFRARED_MAX_GAP_MS,
@@ -55,7 +55,9 @@ const utc = (value) =>
 
 /** A per-application observation layer, using the existing layer lifecycle and
  * row controls. Its time is the world clock's, so a link made away from live
- * opens its imagery at that time; one made live opens the latest. */
+ * opens its imagery at that time; one made live opens the latest. The feed
+ * may also name its source with `sourceName(kind)`, `kind` being 'radar',
+ * 'lightning' or 'satellite'; NOAA nowCOAST is named otherwise. */
 export function createWeatherLayer({
   feed,
   clock,
@@ -72,6 +74,20 @@ export function createWeatherLayer({
   const radar = id === 'weather-radar';
   const lightning = id === 'weather-lightning';
   const satellite = !radar && !lightning;
+  // A feed may name the source behind each product ('radar', 'lightning' or
+  // 'satellite'); its row then says so before a manifest names it. A name
+  // that fails, like a manifest's, leaves the built-in one.
+  let sourceName = null;
+  try {
+    sourceName =
+      weatherSourceName(
+        feed.sourceName?.(
+          radar ? 'radar' : lightning ? 'lightning' : 'satellite',
+        ),
+      ) ?? null;
+  } catch (cause) {
+    console.warn('[weather] source name unavailable:', cause);
+  }
   let product = radar ? 'radar' : lightning ? 'lightning' : 'clouds-regional';
   let opacity = 'strong';
   let infrared = 100;
@@ -301,7 +317,7 @@ export function createWeatherLayer({
         ? 'Lightning density'
         : 'Satellite clouds',
     icon: radar ? '◉' : lightning ? 'ϟ' : '☁',
-    source: 'NOAA nowCOAST · OBSERVED',
+    source: sourceName ?? 'NOAA nowCOAST · OBSERVED',
     updateInterval: lightning ? 600_000 : 120_000,
     init(nextViewer) {
       viewer = nextViewer;
@@ -870,10 +886,10 @@ export function createWeatherLayer({
         loading,
         error: error || rendering?.getDiagnostics().error || null,
         stale: Boolean(manifest?.stale || observationDelayed()),
-        ...(source === undefined
+        ...(source === undefined && sourceName === null
           ? { source: 'NOAA nowCOAST' }
           : // Source text is data: the panel shows it untranslated.
-            { source, sourceVerbatim: true }),
+            { source: source ?? sourceName, sourceVerbatim: true }),
         observedAt: shownTime(),
       };
     },

src/layers/weather/weather.test.mjs

@@ -2694,3 +2694,40 @@ test('the layer hands rendering a frame source only when its feed is one', () =>
   assert.equal(typeof seen[1].getTile, 'function');
   assert.equal(seen[1].getImage, undefined);
 });
+
+test('a feed names the source behind each product, before any manifest does', (t) => {
+  t.mock.method(console, 'warn', () => {});
+  const quiet = {
+    documentRef: target({ hidden: false }),
+    eventTarget: target(),
+    matchMedia: () => target({ matches: false }),
+  };
+  const asked = [];
+  const feed = {
+    getSnapshot: async () => snapshot,
+    sourceName(kind) {
+      asked.push(kind);
+      if (kind === 'satellite') throw new Error('no name');
+      return kind === 'radar' ? ' NOAA MRMS ' : 'NOAA\u200b GLM';
+    },
+  };
+  const radar = createWeatherLayer({ ...quiet, feed, id: 'weather-radar' });
+  assert.equal(radar.source, 'NOAA MRMS');
+  const stats = radar.getStats();
+  assert.equal(stats.source, 'NOAA MRMS');
+  assert.equal(stats.sourceVerbatim, true);
+  // A name a manifest could not carry, or a failing call, leaves nowCOAST, as
+  // does a feed with no names.
+  for (const id of ['weather-lightning', 'weather-satellite']) {
+    const layer = createWeatherLayer({ ...quiet, feed, id });
+    assert.equal(layer.source, 'NOAA nowCOAST · OBSERVED', id);
+    assert.equal(layer.getStats().source, 'NOAA nowCOAST', id);
+    assert.equal(layer.getStats().sourceVerbatim, undefined, id);
+  }
+  assert.deepEqual(asked, ['radar', 'lightning', 'satellite']);
+  const unnamed = createWeatherLayer({
+    ...quiet,
+    feed: { getSnapshot: async () => snapshot },
+  });
+  assert.equal(unnamed.source, 'NOAA nowCOAST · OBSERVED');
+});