From 182e6ceddd8a9731770cc0cbe9376ea2d671b8c5 Mon Sep 17 00:00:00 2001
From: Aditya <205600203+Rohilalala@users.noreply.github.com>
Date: Wed, 28 Oct 2026 15:13:15 +0530
Subject: [PATCH] fix(tools): list a split submarine cable once in
 find_submarine_cables

TeleGeography stores 17 cables (2Africa, Echo, Hawaiki...) as several
features under one id, and the tool made a row per feature, so "Echo"
read "3 submarine cables" and area counts ran high. Rows are now unique
by cable id, and a cable still matches when any of its parts does.
---
 docs/CURRENT-STATE.md             |  3 ++
 src/tools/queries/cables.js       |  6 ++++
 src/tools/queries/cables.test.mjs | 53 +++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index c55031a6a..34a8ee692 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -179,6 +179,9 @@ catalog, loaded on first use. See [tools and the MCP server](TOOLS.md).
 Aircraft altitude-band queries require a reported barometric or geometric altitude
 for each match, so a grounded contact that reports none is left out of a band too.
 Queries without an altitude band retain unknown-altitude contacts.
+`find_submarine_cables` lists and counts each cable once: TeleGeography splits
+a few cables (2Africa, Echo) into several features under one id, and such a
+cable matches when any of its parts crosses the area.
 
 Catalog calls check their cancellation signal immediately before executing a
 tool. Already-cancelled queries do not start; cancellation after execution starts
diff --git a/src/tools/queries/cables.js b/src/tools/queries/cables.js
index 8d8c0cecf..a4f020150 100644
--- a/src/tools/queries/cables.js
+++ b/src/tools/queries/cables.js
@@ -57,6 +57,7 @@ export const findSubmarineCables = defineTool({
           Number.isFinite(point.lat) &&
           (!area || areaContains(area, point)),
       );
+    const seen = new Set();
     const rows = (cables?.features || [])
       .filter((feature) => {
         const name = String(feature.properties?.name || '');
@@ -71,6 +72,11 @@ export const findSubmarineCables = defineTool({
         id: feature.properties.id ?? null,
         name: feature.properties.name,
       }))
+      // TeleGeography splits some cables into several features under one id.
+      .filter((row) => {
+        const key = row.id ?? row.name;
+        return !seen.has(key) && seen.add(key);
+      })
       .sort((a, b) => a.name.localeCompare(b.name));
     const where = area ? ` in ${area.label}` : '';
     const what = wanted ? ` matching "${args.name}"` : '';
diff --git a/src/tools/queries/cables.test.mjs b/src/tools/queries/cables.test.mjs
index f74457087..37c18fa61 100644
--- a/src/tools/queries/cables.test.mjs
+++ b/src/tools/queries/cables.test.mjs
@@ -89,6 +89,59 @@ test('cables are found by area and name, with landing points and attribution', a
   );
 });
 
+test('a cable split into several features is listed once', async () => {
+  // TeleGeography splits a few cables (2Africa, Echo, Hawaiki) into several
+  // features under one id.
+  const cable = (id, name, coordinates) => ({
+    properties: { id, name },
+    geometry: { type: 'MultiLineString', coordinates: [coordinates] },
+  });
+  const split = {
+    async fetch() {
+      return {
+        cables: {
+          features: [
+            cable('2africa', '2Africa', [
+              [60, 18],
+              [57, 22],
+            ]),
+            cable('equiano', 'Equiano', [
+              [-10, 5],
+              [3, 6],
+            ]),
+            cable('2africa', '2Africa', [
+              [-21, 16],
+              [-17, 14],
+            ]),
+          ],
+        },
+        landingPoints: { features: [] },
+      };
+    },
+  };
+  const catalog = composeCatalog({
+    tools: coreTools,
+    services: { cables: split },
+  });
+  const named = await catalog.call('find_submarine_cables', {
+    name: '2africa',
+  });
+  assert.equal(named.summary, '1 submarine cable matching "2africa".');
+  assert.deepEqual(named.data.rows, [{ id: '2africa', name: '2Africa' }]);
+  const both = await catalog.call('find_submarine_cables', {
+    area: { bbox: [-30, 0, 70, 30] },
+  });
+  assert.deepEqual(
+    both.data.rows.map((row) => row.id),
+    ['2africa', 'equiano'],
+  );
+  // Only the second part crosses this box; the cable is still found.
+  const west = await catalog.call('find_submarine_cables', {
+    area: { bbox: [-25, 10, -10, 20] },
+  });
+  assert.deepEqual(west.data.rows, [{ id: '2africa', name: '2Africa' }]);
+});
+
 test('the local fetch serves bundled data files and nothing outside them', async () => {
   const fetchImpl = createApiFetch({
     apiBase: 'http://127.0.0.1:1',