The page stops recursing when a tap ends long after its answer (#378)

endTap reported the tap before clearing it; report's traceparent starts a
new trace when the last is over a minute old, and newTrace ends the open tap
again, so hiding the page (switching apps on the phone) a minute after using
it recursed until the stack ran out. Timings are never throttled, so nothing
broke the loop. Introduced in #376.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/page-unit.js

@@ -242,3 +242,10 @@ test('a tap is its trace\'s root span, reported with its ids once it has an answ
   assert.equal(run(`sent.at(-1)[0]`), '/api/client');
   assert.deepEqual([body.ev, body.ms, body.msg, body.span.length, body.trace.length], ['tap', 250, 'keydown', 16, 32]);
 });
+
+test('a tap ended over a minute after its last request reports once, without recursing (#378)', () => {
+  run(`globalThis.sent = []; fetch = (url, o) => { sent.push([url, o]); return Promise.resolve({ ok: true, status: 204 }); }`);
+  run(`newTrace('pointerdown'); answeredAt = rootAt + 100; traceAt = Date.now() - 120_000`);
+  run('endTap()');
+  assert.equal(run(`sent.filter(([u, o]) => JSON.parse(o.body).ev === 'tap').length`), 1);
+});