feat(client): list cast receivers as they answer

The scan still runs six seconds, but the picker polls what it has found
and shows each receiver immediately. A rescan no longer has its timer
cut short by the scan it replaced.

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

1 files changed, 108 insertions, 0 deletions

diff --git a/packages/meshbay-hub/tests/test_cast_discovery.py b/packages/meshbay-hub/tests/test_cast_discovery.py
new file mode 100644
index 0000000..9e9ce85
--- /dev/null
+++ b/packages/meshbay-hub/tests/test_cast_discovery.py
@@ -0,0 +1,108 @@
+"""
+Cast receivers are listed as they answer, not at the end of the scan.
+
+The scan runs its full length because a receiver coming back from a reset can
+take several seconds to answer, but most answer within two; a picker that showed
+nothing until the end was slow every time it was opened. These tests run the real
+`CastChromecast` with mDNS replaced by a stub that answers on cue, and the clock
+shortened, so what they measure is what the page's poll would see.
+"""
+
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+CLIENT = Path(__file__).resolve().parents[2] / "meshbay-client"
+CHROMECAST = CLIENT / "src" / "cast-chromecast.js"
+
+pytestmark = pytest.mark.skipif(
+    shutil.which("node") is None or not CHROMECAST.exists(),
+    reason="node or the desktop client sources are not available")
+
+# Stubs the two dependencies at `require` time, and makes six seconds of scan
+# last sixty milliseconds by scaling every timer the module arms.
+SCRIPT = r"""
+const Module = require('node:module');
+const browsers = [];
+const realLoad = Module._load;
+Module._load = function (request, ...rest) {
+  if (request === 'bonjour-service') {
+    return { Bonjour: class {
+      find(_q, onUp) {
+        const b = { onUp, stopped: false, stop() { this.stopped = true; } };
+        browsers.push(b);
+        return b;
+      }
+    } };
+  }
+  if (request === 'castv2-client') return { Client: class {}, DefaultMediaReceiver: {} };
+  return realLoad.call(this, request, ...rest);
+};
+const realSetTimeout = global.setTimeout;
+global.setTimeout = (fn, ms, ...a) => realSetTimeout(fn, ms / 100, ...a);
+const wait = (ms) => new Promise((r) => realSetTimeout(r, ms));
+
+const CastChromecast = require(process.argv[2]);
+const tv = (id) => ({ name: id, txt: { id, fn: `TV ${id}` },
+                      addresses: ['10.0.0.9'], port: 8009 });
+
+(async () => {
+  const cc = new CastChromecast();
+  const out = {};
+
+  cc.startScan();
+  out.atStart = cc.devices();
+  browsers[0].onUp(tv('a'));
+  out.afterFirstAnswer = cc.devices();
+  await wait(100);
+  out.afterScan = cc.devices();
+  out.firstBrowserStopped = browsers[0].stopped;
+
+  // A second scan started over a first: the first's timer must not end it.
+  cc.startScan();
+  await wait(40);
+  cc.startScan();
+  await wait(40);
+  out.restartedStillScanning = cc.devices().scanning;
+  out.restartClearedOldDevices = cc.devices().devices.length === 0;
+  await wait(60);
+  out.restartedEnds = !cc.devices().scanning;
+  console.log(JSON.stringify(out));
+})();
+"""
+
+
+@pytest.fixture(scope="module")
+def run(tmp_path_factory):
+    script = tmp_path_factory.mktemp("cd") / "discover.cjs"
+    script.write_text(SCRIPT, encoding="utf-8")
+    proc = subprocess.run(
+        ["node", str(script), str(CHROMECAST)],
+        capture_output=True, text=True, encoding="utf-8", timeout=60)
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+def test_a_receiver_is_listed_before_the_scan_ends(run):
+    assert run["atStart"] == {"devices": [], "scanning": True}
+    assert run["afterFirstAnswer"]["scanning"] is True
+    assert [d["name"] for d in run["afterFirstAnswer"]["devices"]] == ["TV a"]
+
+
+def test_the_scan_ends_on_its_own_and_keeps_what_it_found(run):
+    assert run["afterScan"]["scanning"] is False
+    assert [d["id"] for d in run["afterScan"]["devices"]] == ["a"]
+    assert run["firstBrowserStopped"] is True
+
+
+def test_a_new_scan_is_not_cut_short_by_the_one_it_replaced(run):
+    """
+    The old code left the first scan's timer armed, and it stopped whichever
+    browser was current when it fired — the new one, two thirds early.
+    """
+    assert run["restartedStillScanning"] is True
+    assert run["restartClearedOldDevices"] is True
+    assert run["restartedEnds"] is True