Accept authoritative empty vessel coverage without an outage

src/layers/vessels/ingestion.js

@@ -109,7 +109,7 @@ export function createIngestion({
     feed.acceptedRowCount = snapshot.acceptedRowCount;
     feed.partial = payload?.complete === false;
 
-    if (snapshot.acceptedRowCount === 0) {
+    if (snapshot.acceptedRowCount === 0 && !snapshot.emptyCoverage) {
       feed.count = readCount();
       feed.stale = feed.count > 0 || Boolean(payload?.refreshing);
       if (isDefinitiveTransportFailure(snapshot.transportStatus)) {

src/layers/vessels/ownership.test.mjs

@@ -361,3 +361,47 @@ test('partial vessel snapshots preserve freshness and recover after a complete u
   layer.destroy();
   assert.equal(layer.getStats().partial, false);
 });
+
+test('authoritative empty coverage clears old contacts without declaring an outage', async () => {
+  let current = snapshot([observation('111')]);
+  const { layer } = setup({
+    async getSnapshot() {
+      return current;
+    },
+  });
+  await layer.update();
+  current = snapshot([], { observedAtMs: null, lastMessageAt: 500 });
+  await layer.update();
+  assert.ok(!layer.hasContact('111'));
+  assert.equal(layer.getStats().count, 0);
+  assert.equal(layer.getStats().error, null);
+  assert.equal(layer.getStats().stale, false);
+  assert.equal(layer.getStats().lastUpdate, null);
+});
+
+test('empty coverage cannot hide stale, incomplete or rejected source data', async () => {
+  for (const patch of [
+    { freshness: 'unknown' },
+    { freshness: 'stale' },
+    { complete: false },
+    { rawRowCount: 1 },
+    { transportStatus: 'stale' },
+    { lastMessageAt: null },
+  ]) {
+    let current = snapshot([observation('111')]);
+    const { layer } = setup({
+      async getSnapshot() {
+        return current;
+      },
+    });
+    await layer.update();
+    current = snapshot([], {
+      observedAtMs: null,
+      lastMessageAt: 500,
+      ...patch,
+    });
+    await layer.update();
+    assert.equal(layer.hasContact('111'), true, JSON.stringify(patch));
+    assert.ok(layer.getStats().error, JSON.stringify(patch));
+  }
+});

src/layers/vessels/queries.js

@@ -119,7 +119,16 @@ export function createQueries({
       typeof payload?.status === 'string' ? payload.status : null;
     const lastMessageAt = payload?.lastMessageAt ?? null;
     const acceptedRowCount = acceptedRows.length;
+    const emptyCoverage =
+      rawRows.length === 0 &&
+      payload?.rawRowCount === 0 &&
+      payload?.complete === true &&
+      payload?.freshness === 'current' &&
+      AIS_HEALTHY_STATUSES.has(transportStatus) &&
+      Number.isFinite(Number(lastMessageAt)) &&
+      Number(lastMessageAt) > 0;
     return {
+      emptyCoverage,
       transportStatus,
       lastMessageAt,
       rawRows,
@@ -130,9 +139,10 @@ export function createQueries({
           ? payload.rawRowCount
           : rawRows.length,
       acceptedRowCount,
-      error:
-        deriveAisFeedError(payload, acceptedRowCount) ||
-        (acceptedRowCount === 0 ? 'awaiting usable AIS positions…' : null),
+      error: emptyCoverage
+        ? null
+        : deriveAisFeedError(payload, acceptedRowCount) ||
+          (acceptedRowCount === 0 ? 'awaiting usable AIS positions…' : null),
     };
   }