fix(orchestrator): a view transition skipped by the next switch stays quiet

apply() starts a view transition on every hash change; a quick second switch skips the running one, whose ready promise then rejected with an unhandled AbortError, which the presence e2e counted as a page error in Chromium and Firefox. The skip is expected, so its AbortError is caught; every other ready failure is rethrown and still surfaces.

🎯 Fix: 92 %
💥 Break: 2 %
💸 Cost: 100 %
⏱️ Time: 100 %
🛡️ Security: 100 %
🏆 Score: 90
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

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

orchestrator/templates/page-screens.js

@@ -37,7 +37,11 @@
       ui.views[route.screen] = route.view;
     }
     if (document.startViewTransition && drawn.screen && !calm.matches) {
-      document.startViewTransition(() => render(true));
+      document.startViewTransition(() => render(true)).ready.catch((error) => {
+        if (error.name !== "AbortError") {
+          throw error;
+        }
+      });
     } else {
       render(true);
     }

tests/test_hub_nav.py

@@ -4,7 +4,38 @@ import json
 import subprocess
 import unittest
 
-from hub_support import NAV
+from hub_support import HUB, NAV
+
+SCREENS = HUB / "templates" / "page-screens.js"
+TRANSITION_PROBE = """
+const fs = require("fs");
+const vm = require("vm");
+const code = fs.readFileSync(process.argv[1], "utf8");
+const unhandled = [];
+process.on("unhandledRejection", (error) => unhandled.push(error.name));
+const settle = () => new Promise((resolve) => setImmediate(resolve));
+function switched(name) {
+  const error = new Error(`transition ${name}`);
+  error.name = name;
+  const started = [];
+  vm.runInNewContext(`${code}\\napply();`, {
+    Nav: {TABS: [], route: () => ({screen: "agents", view: "chord"})}, ui: {views: {}}, drawn: {screen: true}, calm: {matches: false}, h: () => null,
+    window: {location: {hash: "#agents/chord"}, history: {replaceState: () => null}},
+    document: {getElementById: () => ({append: () => null}), startViewTransition: (update) => {
+      started.push(typeof update);
+      return {ready: Promise.reject(error), finished: Promise.resolve(), updateCallbackDone: Promise.resolve()};
+    }},
+  });
+  return started;
+}
+(async () => {
+  const started = [...switched("AbortError"), ...switched("InvalidStateError")];
+  for (let round = 0; round < 5; round += 1) {
+    await settle();
+  }
+  console.log(JSON.stringify({started, unhandled}));
+})().catch((error) => console.log(JSON.stringify({crash: String(error)})));
+"""
 
 NAV_PROBE = """
 const N = require(process.argv[1]);
@@ -90,5 +121,11 @@ class TestNavModule(unittest.TestCase):
         self.assertEqual(self.data["tabOf"], ["stream", "stream", "stream", "agents", "artifacts", "tasks"])
 
 
+class TestScreenTransition(unittest.TestCase):
+    def test_a_view_transition_skipped_by_the_next_switch_stays_quiet_and_other_failures_still_surface(self):
+        done = subprocess.run(["node", "-e", TRANSITION_PROBE, str(SCREENS)], capture_output=True, text=True, timeout=60, check=True)
+        self.assertEqual(json.loads(done.stdout), {"started": ["function", "function"], "unhandled": ["InvalidStateError"]})
+
+
 if __name__ == "__main__":
     unittest.main()