feat: return the view that shows each answer

Tool answers with something to show now include data.view: the view with
the matching layers on, the area framed from above or a single aircraft or
satellite followed, and the link that opens it. Area framing moves to
src/tools/views.js so links and answers frame alike.

src/tools/views.test.mjs

@@ -0,0 +1,102 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { composeCatalog, coreTools } from './index.js';
+import { viewFromParams } from '../view/index.js';
+import { cameraForArea, suggestView } from './views.js';
+import { resolveArea } from './area.js';
+
+const app = { baseUrl: 'https://maps.example/' };
+const snapshot = (records, extra = {}) => ({
+  records,
+  complete: true,
+  source: 'Test feed',
+  observedAtMs: Date.UTC(2026, 0, 1),
+  freshness: 'current',
+  ...extra,
+});
+const aircraft = (id, latitude, longitude, extra = {}) => ({
+  id,
+  latitude,
+  longitude,
+  callsign: 'UAL1',
+  baroAltitudeM: 10000,
+  onGround: false,
+  positionTimeMs: Date.UTC(2026, 0, 1),
+  ...extra,
+});
+const feed = (records) => ({ getSnapshot: async () => snapshot(records) });
+
+test('suggested views frame an area or point and link to the app', async () => {
+  const area = await resolveArea({ lat: 30, lon: -97, radius_km: 10 });
+  const view = suggestView({ app }, { area, layers: ['flights'] });
+  assert.deepEqual(view.camera, {
+    ...cameraForArea(area),
+    altitude_m: Math.round(cameraForArea(area).altitude_m),
+    heading_deg: 0,
+    pitch_deg: -90,
+  });
+  assert.deepEqual(view.layers, ['flights']);
+  const params = new URLSearchParams(new URL(view.url).hash.slice(1));
+  const { url, ...rest } = view;
+  assert.deepEqual(viewFromParams(params), rest);
+  assert.equal(suggestView({}, { area, layers: [] }).url, null);
+  assert.equal(
+    suggestView({ app: { baseUrl: 'not a url' } }, { area }).url,
+    null,
+  );
+  const point = suggestView({ app }, { point: { lat: 1, lon: 2 } });
+  assert.equal(point.camera.altitude_m, 50000);
+});
+
+test('answers carry the view that shows them', async () => {
+  const catalog = composeCatalog({
+    tools: coreTools,
+    services: {
+      app,
+      aircraft: feed([aircraft('abc123', 37.62, -122.38)]),
+      military: feed([]),
+    },
+  });
+  const area = await catalog.call('aircraft_in_area', {
+    area: { lat: 37.62, lon: -122.38, radius_km: 20 },
+  });
+  assert.deepEqual(area.data.view.layers, ['flights']);
+  assert.match(area.data.view.url, /^https:\/\/maps\.example\/#v=2&/);
+  const found = await catalog.call('find_aircraft', { callsign: 'UAL1' });
+  assert.deepEqual(found.data.view.follow, { kind: 'aircraft', id: 'abc123' });
+  assert.deepEqual(found.data.view.layers, ['flights']);
+});
+
+test('the flood and the brief frame what they describe', async () => {
+  const { readFile } = await import('node:fs/promises');
+  const bundled = JSON.parse(
+    await readFile(
+      new URL(
+        '../../public/events/bhote-koshi-2026/event.json',
+        import.meta.url,
+      ),
+      'utf8',
+    ),
+  );
+  const flood = await composeCatalog({
+    tools: coreTools,
+    services: { app, events: { getEvent: async () => bundled } },
+  }).call('get_bhote_koshi_flood', {});
+  assert.deepEqual(flood.data.view.layers, ['bhote-koshi-2026']);
+  assert.ok(Math.abs(flood.data.view.camera.lat - 28.13) < 0.2);
+  assert.ok(Math.abs(flood.data.view.camera.lon - 85.32) < 0.2);
+  const brief = await composeCatalog({
+    tools: coreTools,
+    services: {
+      app,
+      weather: {
+        getConditions: async () => ({ status: 'ready', weather: {} }),
+      },
+      aircraft: feed([]),
+      earthquakes: { getSnapshot: async () => [] },
+    },
+  }).call('situation_brief', {
+    area: { lat: 30, lon: -97, radius_km: 50 },
+  });
+  assert.deepEqual(brief.data.view.layers, ['earthquakes', 'flights']);
+});