release(v1.7.15-alpha): bulletproof downloads — resume, retry, real progress

download_update
  Each component download is now resumable via HTTP Range requests
  (Range: bytes=N-) and retried up to 6 times with exponential
  backoff (5/15/30/60/120/180s). On a dropped connection the next
  attempt picks up at the last written byte offset instead of
  restarting at zero. Streams via reqwest::Response::chunk() to the
  staging file so a 160 MB frontend tarball doesn't sit in RAM. SHA
  is verified over the complete file at the end of each component;
  mismatch nukes the staged file and restarts from scratch.

Real download progress counters
  New AtomicU64 globals DOWNLOAD_BYTES/DOWNLOAD_TOTAL are updated
  from the chunk loop. update.status exposes them as
  download_progress.{bytes_downloaded, total_bytes, active}. The
  SystemUpdate.vue progress bar now polls update.status every
  second instead of incrementing a fake random counter — and
  crucially, if the user navigates away and back, the component
  picks up the in-progress download from the backend atomics
  immediately.

Update-check retries
  handle_update_check now retries the manifest fetch up to 3 times
  with a 5s gap if the first try hits a transport error, so a
  momentary gitea hiccup doesn't make a node report "up to date"
  when there actually is a new release. Tight 10s connect timeout
  per attempt keeps the total bounded.

Artefacts:
  archipelago                                      1070c87f…c081c162b  40584792
  archipelago-frontend-1.7.15-alpha.tar.gz         8e630eba…63fd43f   162078068

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

neode-ui/src/views/SystemUpdate.vue

@@ -324,6 +324,29 @@ const statusMessage = ref('')
 const statusIsError = ref(false)
 const downloadPercent = ref(0)
 const downloadPercentFormatted = computed(() => downloadPercent.value.toFixed(2))
+
+// Poll the backend for the real bytes_downloaded / total_bytes so the
+// progress bar tracks actual download state (and survives route
+// changes). Returns true if a download is currently in progress.
+async function pollDownloadProgress(): Promise<boolean> {
+  try {
+    const res = await rpcClient.call<{
+      download_progress?: {
+        bytes_downloaded: number
+        total_bytes: number
+        active: boolean
+      } | null
+    }>({ method: 'update.status' })
+    const p = res.download_progress
+    if (p && p.total_bytes > 0) {
+      downloadPercent.value = Math.min(100, (p.bytes_downloaded / p.total_bytes) * 100)
+      return p.active
+    }
+    return false
+  } catch {
+    return false
+  }
+}
 // Shown next to the progress bar when the fake increment has maxed out
 // at 95% but the real RPC hasn't returned yet — lets the user know the
 // UI hasn't frozen while SHA verification and disk writes finish.
@@ -486,14 +509,12 @@ async function downloadUpdate() {
   downloadPercent.value = 0
   statusMessage.value = ''
 
-  // Simulate incremental progress while waiting for the RPC. Capped at
-  // 95% so the bar never shows >100% before the real completion jumps it
-  // to 100 — previously the random increment could overshoot.
-  const progressInterval = setInterval(() => {
-    if (downloadPercent.value < 95) {
-      downloadPercent.value = Math.min(95, downloadPercent.value + Math.random() * 3)
-    }
-  }, 500)
+  // Poll the backend's real byte counter every second instead of
+  // faking progress. The backend exposes bytes_downloaded/total_bytes
+  // via update.status, updated per chunk. This also means the bar
+  // resumes correctly after navigating away and back — no more
+  // "95% for some time" mystery.
+  const progressInterval = setInterval(() => { void pollDownloadProgress() }, 1000)
 
   try {
     const res = await rpcClient.call<{
@@ -616,8 +637,24 @@ async function setSchedule(value: ScheduleValue) {
   }
 }
 
-onMounted(() => {
-  Promise.all([loadStatus(), loadSchedule(), checkForUpdates()])
+onMounted(async () => {
+  await Promise.all([loadStatus(), loadSchedule(), checkForUpdates()])
+  // If a download was already running when the user navigated here
+  // (or refreshed), pick up the progress bar where it is and keep
+  // polling until the backend reports done. No RPC call to start the
+  // download — the backend's already running it.
+  const active = await pollDownloadProgress()
+  if (active) {
+    downloading.value = true
+    const resumeInterval = setInterval(async () => {
+      const stillActive = await pollDownloadProgress()
+      if (!stillActive) {
+        clearInterval(resumeInterval)
+        downloading.value = false
+        downloaded.value = true
+      }
+    }, 1000)
+  }
 })
 </script>