fix(status): preserve cached aircraft age and independent refresh errors

src/tooling/liveProviders.test.mjs

@@ -258,10 +258,12 @@ test('military aircraft route serves stale cache on an upstream 429 and cools do
   assert.equal(limited.body, first.body);
   assert.equal(limited.headers['x-ads-b-cache'], 'STALE');
   assert.equal(limited.headers['x-ads-b-upstream-status'], '429');
+  assert.equal(limited.headers['x-ads-b-cache-age-ms'], '13000');
   now += 5_000;
   const cooling = await request('/api/adsblol/mil');
   assert.equal(calls, 2, 'no upstream call inside the Retry-After window');
   assert.equal(cooling.headers['x-ads-b-cache'], 'STALE');
+  assert.equal(cooling.headers['x-ads-b-cache-age-ms'], '18000');
   now += 16_000;
   await request('/api/adsblol/mil');
   assert.equal(calls, 3, 'upstream is retried once Retry-After elapses');
@@ -277,6 +279,7 @@ test('military aircraft route relays an upstream 429 when nothing is cached', as
   const request = install(providers.adsbLolProxy());
   const limited = await request('/api/adsblol/mil');
   assert.equal(limited.statusCode, 429);
+  assert.ok(limited.headers['retry-after']);
   const again = await request('/api/adsblol/mil');
   assert.equal(again.statusCode, 429);
   assert.equal(
@@ -289,3 +292,64 @@ test('military aircraft route relays an upstream 429 when nothing is cached', as
     'a cooling-down miss carries Retry-After',
   );
 });
+
+test('military fallback cancels a stalled 5xx body and starts cooldown at receipt', async (t) => {
+  let now = 1_800_000_000_000;
+  let calls = 0;
+  let cancelled = false;
+  t.mock.method(Date, 'now', () => now);
+  t.mock.method(console, 'warn', () => {});
+  t.mock.method(globalThis, 'fetch', async () => {
+    if (++calls === 1) return Response.json({ ac: [] });
+    now += 10000;
+    return new Response(
+      new ReadableStream({
+        cancel() {
+          cancelled = true;
+        },
+      }),
+      {
+        status: 503,
+        headers: { 'Retry-After': new Date(now + 20000).toUTCString() },
+      },
+    );
+  });
+  const request = install(providers.adsbLolProxy());
+  await request('/api/adsblol/mil');
+  now += 1000;
+  const hit = await request('/api/adsblol/mil');
+  assert.equal(hit.headers['x-ads-b-cache-age-ms'], '1000');
+  now += 12000;
+  const fallback = await request('/api/adsblol/mil');
+  assert.equal(fallback.statusCode, 200);
+  assert.equal(cancelled, true);
+  assert.equal(fallback.headers['x-ads-b-cache-age-ms'], '23000');
+  assert.equal(fallback.headers['x-ads-b-retry-after-seconds'], '20');
+  now += 19000;
+  await request('/api/adsblol/mil');
+  assert.equal(calls, 2);
+  now += 2000;
+  await request('/api/adsblol/mil');
+  assert.equal(calls, 3);
+});
+
+test('military cooldown bounds untrusted Retry-After and defaults server errors', async (t) => {
+  t.mock.method(console, 'warn', () => {});
+  for (const [status, raw, seconds] of [
+    [429, '1', 5],
+    [429, '99999', 120],
+    [503, 'invalid', 15],
+  ]) {
+    t.mock.method(
+      globalThis,
+      'fetch',
+      async () =>
+        new Response('{}', {
+          status,
+          headers: { 'Retry-After': raw },
+        }),
+    );
+    const result = await install(providers.adsbLolProxy())('/api/adsblol/mil');
+    assert.equal(Number(result.headers['retry-after']), seconds);
+  }
+});