feat: add a submarine cable tool

Add find_submarine_cables over the bundled TeleGeography data: cables
passing through or landing in an area, or matching a name, with landing
points and the dataset's attribution. The local MCP server's fetch reads
the bundled data files a browser would load by URL, and nothing outside
that directory.

src/tools/queries/cables.js

@@ -0,0 +1,86 @@
+/** Submarine cables and their landing points. */
+
+import { defineTool, ToolError } from '../catalog.js';
+import { AREA_SCHEMA, areaContains, resolveArea } from '../area.js';
+import { LIMIT_SCHEMA, capRows, countNoun } from '../results.js';
+
+const ATTRIBUTION = '© TeleGeography — submarinecablemap.com (CC BY-NC-SA 3.0)';
+
+function cableLines(feature) {
+  const geometry = feature?.geometry;
+  if (geometry?.type === 'LineString') return [geometry.coordinates];
+  if (geometry?.type === 'MultiLineString') return geometry.coordinates;
+  return [];
+}
+
+export const findSubmarineCables = defineTool({
+  name: 'find_submarine_cables',
+  title: 'Submarine cables',
+  description:
+    'Undersea telecommunication cables and landing points from the ' +
+    'TeleGeography map: those passing through or landing in an area, ' +
+    'and/or those whose name matches.',
+  inputSchema: {
+    type: 'object',
+    properties: {
+      area: AREA_SCHEMA,
+      name: { type: 'string', minLength: 2, maxLength: 80 },
+      limit: LIMIT_SCHEMA,
+    },
+    additionalProperties: false,
+  },
+  requires: ['cables'],
+  async run(args, { services, signal }) {
+    if (!args.area && !args.name)
+      throw new ToolError('invalid_arguments', 'Give an area, a name or both');
+    const area = args.area
+      ? await resolveArea(args.area, { services, signal })
+      : null;
+    const wanted = args.name?.toLowerCase();
+    const { cables, landingPoints } = await services.cables.fetch(signal);
+    const landingRows = (landingPoints?.features || [])
+      .map((feature) => ({
+        id: feature.properties?.id ?? null,
+        name: feature.properties?.name ?? null,
+        lon: feature.geometry?.coordinates?.[0],
+        lat: feature.geometry?.coordinates?.[1],
+      }))
+      .filter(
+        (point) =>
+          point.name &&
+          Number.isFinite(point.lat) &&
+          (!area || areaContains(area, point)),
+      );
+    const rows = (cables?.features || [])
+      .filter((feature) => {
+        const name = String(feature.properties?.name || '');
+        if (!name || (wanted && !name.toLowerCase().includes(wanted)))
+          return false;
+        return (
+          !area ||
+          cableLines(feature).some((line) =>
+            line.some(([lon, lat]) => areaContains(area, { lat, lon })),
+          )
+        );
+      })
+      .map((feature) => ({
+        id: feature.properties.id ?? null,
+        name: feature.properties.name,
+      }))
+      .sort((a, b) => a.name.localeCompare(b.name));
+    const where = area ? ` in ${area.label}` : '';
+    const what = wanted ? ` matching "${args.name}"` : '';
+    return {
+      summary:
+        `${countNoun(rows.length, 'submarine cable')}${what}${where}` +
+        (area
+          ? `, with ${countNoun(landingRows.length, 'landing point')}.`
+          : '.'),
+      data: {
+        ...capRows(rows, args.limit),
+        landing_points: area ? capRows(landingRows, args.limit) : null,
+        attribution: ATTRIBUTION,
+      },
+    };
+  },
+});