Keep extension chains alive and save each finished segment.

The overall bar made a long queue look stuck at ~9% during the first clip, and nothing was written until the last step. Save checkpoints, use per-step progress, and stop treating a short Comfy history lag as a dropped job.

pages/index.vue

@@ -320,6 +320,7 @@
             </div>
             <p v-if="chainTotal > 1" class="mb-2 text-xs text-amber-200/80">
               Step {{ chainStep }}/{{ chainTotal }}{{ chainLabel ? `: ${chainLabel}` : '' }}
+              <template v-if="overallProgress"> · {{ overallProgress }}% overall</template>
             </p>
             <div class="h-2 overflow-hidden rounded-full bg-zinc-800">
               <div class="h-full rounded-full bg-amber-400 progress-glow transition-all duration-300" :style="{ width: progress + '%' }" />
@@ -696,6 +697,7 @@ const maxStep = ref(8)
 const chainStep = ref(1)
 const chainTotal = ref(1)
 const chainLabel = ref('')
+const overallProgress = ref(0)
 const elapsedMs = ref(0)
 const videoUrl = ref('')
 const jobId = ref('')
@@ -1297,6 +1299,7 @@ async function generateExtension() {
   chainStep.value = 1
   chainTotal.value = 1
   chainLabel.value = ''
+  overallProgress.value = 0
   statusMessage.value = 'Extracting last frame & stitching extension...'
   startTimer()
   try {
@@ -1473,6 +1476,7 @@ async function generate() {
   chainStep.value = 1
   chainTotal.value = 1 + extensionQueue.value.length
   chainLabel.value = extensionQueue.value.length ? 'Initial' : ''
+  overallProgress.value = 0
   startTimer()
   try {
     const body = new FormData()
@@ -1545,12 +1549,24 @@ function applyJobEvent(payload: Record<string, any>, hidden: boolean, folderLock
   if (typeof payload.chainStep === 'number') chainStep.value = payload.chainStep
   if (typeof payload.chainTotal === 'number') chainTotal.value = payload.chainTotal
   if (payload.chainLabel) chainLabel.value = String(payload.chainLabel)
+  if (typeof payload.overallProgress === 'number') overallProgress.value = payload.overallProgress
 
   const failed = payload.type === 'error' || payload.status === 'error' || payload.status === 'cancelled'
   const complete = payload.type === 'complete' || payload.status === 'complete'
   const deferred = payload.type === 'deferred' || payload.status === 'deferred'
   if (settledUi) return
 
+  if (payload.type === 'checkpoint' && payload.clipId) {
+    loadLibrary().catch(() => null)
+    const locked = folderLocked || payload.folderLocked === true
+    if (!watchingLibrary.value && !locked) {
+      currentClipId.value = payload.clipId
+      videoUrl.value = clipVideoUrl(payload.clipId)
+      concealOutput.value = hidden || payload.hideThumbnail === true
+    }
+    return
+  }
+
   if (deferred) {
     settledUi = true
     busy.value = false