feat(serverRotation): latency-aware server selection with 404-safe rotation by Copilot · Pull Request #52 · Moonrend/Classworks

Copilot · 2026-04-17T13:53:08Z

Server rotation blindly retried all errors (including 404) across every server, always started from the same fixed server, and re-probed on every request with no caching.

Changes

404 ≠ rotation trigger — shouldRotateOnError() now only rotates on network errors or HTTP 5xx. A 4xx response means the server is healthy; propagate immediately instead of wasting a round-trip on the backup.
Latency-based preference — probeServer() / updateServerPreference() concurrently HEAD-probes all cloud servers and caches the fastest reachable one. getOrderedCloudServers() puts the preferred server first without blocking the caller.
5-minute TTL cache, no polling — Preference is stored in a module-level serverPreference object. Stale cache triggers a fire-and-forget background re-probe; callers are never blocked. Real-traffic successes in tryWithRotation also update the cache via setCachedPreference().
getEffectiveServerUrl now returns the cached preferred server instead of always hardcoding CLASSWORKS_CLOUD_SERVERS[0].

// Before: any error (including 404) caused rotation + always started from server[0]
// After: 404 from server A propagates immediately; background probe keeps fastest server first

function shouldRotateOnError(error) {
  if (!error.response) return true;      // network / timeout → rotate
  return error.response.status >= 500;   // 5xx → rotate; 4xx → throw immediately
}

…ing, and 404-aware rotation Agent-Logs-Url: https://github.com/Moonrend/Classworks/sessions/d254def7-bda7-413a-83b1-c553c1571523 Co-authored-by: Sunwuyuan <88357633+Sunwuyuan@users.noreply.github.com>

… serverRotation Agent-Logs-Url: https://github.com/Moonrend/Classworks/sessions/d254def7-bda7-413a-83b1-c553c1571523 Co-authored-by: Sunwuyuan <88357633+Sunwuyuan@users.noreply.github.com>

vercel · 2026-04-17T13:53:14Z

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Project	Deployment	Actions	Updated (UTC)
classworks	Ready	Preview, Comment	Apr 17, 2026 1:53pm

Copilot

Pull request overview

This PR enhances Classworks Cloud server selection by making rotation error-aware (avoid rotating on 4xx), adding latency-based preferred server caching with background probing, and updating the effective server URL to use the cached preference. It also includes widespread Vue template formatting/slot syntax cleanup and a small ESLint globals update to support the new probing implementation.

Changes:

Update serverRotation to rotate only on network/5xx errors, and to prefer/cached the fastest reachable server via background probes.
Replace hardcoded Classworks Cloud base server selection with cached preference in getEffectiveServerUrl.
Apply broad Vue template formatting normalization and add AbortController to ESLint globals.

Reviewed changes

Copilot reviewed 64 out of 71 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/utils/serverRotation.js	Latency-aware preferred server caching, 4xx-safe rotation logic, background probing/TTL behavior
src/pages/socket-debugger.vue	Template formatting normalization
src/pages/settings.vue	Template formatting normalization
src/pages/list/index.vue	Template formatting normalization
src/pages/list/[id].vue	Template formatting normalization
src/pages/index.vue	Template formatting normalization
src/pages/examschedule.vue	Template formatting normalization (incl. placeholder escaping)
src/pages/exam-editor/[id].vue	Template formatting normalization
src/pages/debug.vue	Template formatting normalization
src/pages/debug-socket.vue	Template formatting normalization
src/pages/debug-init.vue	Template formatting normalization
src/pages/cses2wakeup.vue	Template formatting normalization
src/pages/authorize.vue	Template formatting normalization
src/pages/CacheManagement.vue	Template formatting normalization
src/pages/404.vue	Template formatting normalization
src/components/settings/cards/ThemeSettingsCard.vue	Minor option API reordering + template formatting
src/components/settings/cards/SubjectManagementCard.vue	Slot syntax normalization + template formatting
src/components/settings/cards/RefreshSettingsCard.vue	Template formatting normalization
src/components/settings/cards/RandomPickerCard.vue	Template formatting normalization
src/components/settings/cards/KvDatabaseCard.vue	Template formatting normalization
src/components/settings/cards/HomeworkTemplateCard.vue	Slot syntax normalization + template formatting
src/components/settings/cards/EditSettingsCard.vue	Template formatting normalization
src/components/settings/cards/EchoChamberCard.vue	Lifecycle hook ordering + template formatting
src/components/settings/cards/DisplaySettingsCard.vue	Template formatting normalization
src/components/settings/cards/DataProviderSettingsCard.vue	Template formatting normalization (rotation integration context)
src/components/settings/cards/CloudNamespaceInfoCard.vue	Template formatting normalization
src/components/settings/cards/BackgroundSettingsCard.vue	Template formatting normalization
src/components/settings/TeacherListCard.vue	Template formatting normalization (incl. placeholder escaping)
src/components/settings/StudentListCard.vue	Template formatting normalization
src/components/settings/SettingsExplorer.vue	Template formatting normalization
src/components/settings/SettingItem.vue	Slot syntax normalization + template formatting
src/components/settings/SettingGroup.vue	Template formatting normalization
src/components/settings/NotificationSoundSettings.vue	Template formatting normalization
src/components/settings/CloudMigrationDialog.vue	Slot syntax normalization + template formatting
src/components/settings/AboutCard.vue	Template formatting normalization
src/components/home/HomeworkGrid.vue	Minor option API reordering + template formatting
src/components/home/HomeActions.vue	Template formatting normalization
src/components/home/ExamScheduleCard.vue	Template formatting normalization
src/components/home/ConciseExamCard.vue	Template formatting normalization
src/components/error/404.vue	Template formatting + minor router call simplification
src/components/common/HomeSkeleton.vue	Template formatting normalization
src/components/common/AsyncLoadingPlaceholder.vue	Template formatting normalization
src/components/auth/TokenInputDialog.vue	Template formatting normalization
src/components/auth/ProgressiveRegisterPage.vue	Template formatting normalization
src/components/auth/FirstTimeGuide.vue	Template formatting normalization
src/components/auth/DeviceAuthDialog.vue	Template formatting normalization
src/components/auth/AlternativeCodeDialog.vue	Template formatting normalization
src/components/attendance/AttendanceSidebar.vue	Template formatting normalization
src/components/attendance/AttendanceManagementDialog.vue	Template formatting normalization
src/components/UrgentTestDialog.vue	Template formatting normalization
src/components/UrgentNotification.vue	Template formatting normalization
src/components/TimeCard.vue	Template formatting normalization
src/components/StudentNameManager.vue	Template formatting normalization
src/components/SettingsLinkGenerator.vue	Watcher reordering + template formatting normalization
src/components/SettingsCard.vue	Template formatting normalization
src/components/ReadOnlyTokenWarning.vue	Template formatting normalization
src/components/RateLimitModal.vue	Template formatting (introduces a rendering bug with divider scope)
src/components/RandomPicker.vue	Template formatting normalization
src/components/PwaInstallCard.vue	Template formatting normalization
src/components/NoiseMonitorCard.vue	Template formatting normalization
src/components/MessageLog.vue	Template formatting normalization
src/components/HomeworkEditDialog.vue	Template formatting normalization
src/components/HitokotoSettings.vue	Template formatting normalization
src/components/HelloWorld.vue	Template formatting normalization
src/components/GlobalMessage.vue	Template formatting normalization
src/components/FloatingToolbar.vue	Template formatting normalization
src/components/CacheManager.vue	Template formatting normalization
src/components/AppHeader.vue	Slot syntax normalization + template formatting
src/App.vue	Template formatting normalization
eslint.config.js	Add `AbortController` to globals for new probing code

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Copilot · 2026-04-17T13:58:53Z

+async function updateServerPreference() {
+  if (serverPreference.probing) return;
+  serverPreference.probing = true;
+  try {
+    const results = await Promise.all(
+      CLASSWORKS_CLOUD_SERVERS.map(async (url) => ({
+        url,
+        latency: await probeServer(url),
+      }))
+    );
+    const reachable = results
+      .filter((r) => r.latency < Infinity)
+      .sort((a, b) => a.latency - b.latency);
+    if (reachable.length > 0) {
+      setCachedPreference(reachable[0].url);
+    }
+  } catch {
+    // Probe failure is non-fatal; keep existing preference
+  } finally {
+    serverPreference.probing = false;
+  }


updateServerPreference() only updates cachedAt when at least one server is reachable. If all probes fail (e.g. outage/CORS), cachedAt stays 0 so getOrderedCloudServers() will trigger a new background probe on every call, causing repeated HEAD requests and undermining the intended 5‑minute TTL. Consider recording a lastProbedAt/updating cachedAt even on failure (or adding backoff) to avoid continuous probing during outages.

Copilot · 2026-04-17T13:58:54Z

+      // For HTTP 4xx errors the server is alive — propagate immediately without rotation
+      if (!shouldRotateOnError(error)) {
+        triedServers[triedServers.length - 1].status = "client-error";
+        if (hasCallback) {
+          onServerTried({ url: serverUrl, status: "client-error", error, tried: [...triedServers] });
+        }
+        throw error;


In the non-rotating (4xx) path, the last triedServers entry is marked as client-error but its .error field is never populated. Callers that display per-server failure details (e.g. mapping s.error) will lose the status/message for the final attempt. Consider storing a normalized error string on that entry as well (similar to the failed path).

Copilot · 2026-04-17T13:58:54Z

@@ -27,12 +44,11 @@
                  {{ request.method }} {{ request.path }}
                </v-list-item-subtitle>
              </v-list-item>
-            </v-list
-            >
+            </v-list>
            <v-divider
              v-if="index < activeRequests.length - 1"
              class="my-3"
-            ></v-divider>
+            />


<v-divider v-if="index < activeRequests.length - 1" ... /> is outside the v-for that defines index, so index is undefined here and this will either fail template compilation or behave incorrectly. Move the divider inside the loop (or wrap the item+divider in a <template v-for> block) so index is in scope.

Copilot AI and others added 2 commits April 17, 2026 13:49

feat: optimize server selection with latency caching, background prob…

ef1ff77

…ing, and 404-aware rotation Agent-Logs-Url: https://github.com/Moonrend/Classworks/sessions/d254def7-bda7-413a-83b1-c553c1571523 Co-authored-by: Sunwuyuan <88357633+Sunwuyuan@users.noreply.github.com>

refactor: extract setCachedPreference helper to remove duplication in…

e6c5855

… serverRotation Agent-Logs-Url: https://github.com/Moonrend/Classworks/sessions/d254def7-bda7-413a-83b1-c553c1571523 Co-authored-by: Sunwuyuan <88357633+Sunwuyuan@users.noreply.github.com>

Copilot AI self-assigned this Apr 17, 2026

Sunwuyuan merged commit e9a7b66 into main Apr 17, 2026
8 of 10 checks passed

Copilot AI reviewed Apr 17, 2026

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feat(serverRotation): latency-aware server selection with 404-safe rotation#52

feat(serverRotation): latency-aware server selection with 404-safe rotation#52
Sunwuyuan merged 2 commits into
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