feat(subscriptions): dry-run backfill preview — B4 preview (plan #708)

Owning the walk lets an operator gauge "is this source worth a backfill?" before arming one. ingest_core.Ingester.preview walks the first few feed pages and counts media NOT already in the seen/dead ledgers, downloading nothing (read-only). download_backends.preview_source resolves the campaign id + runs it (native-only, mirrors verify_source_credential / run_download); POST /api/sources/{id}/preview returns {total_new, posts_scanned, has_more, sample[]} (409 on auth/drift/unresolvable, 400 for gallery-dl platforms). PatreonClient gains post_meta(post) for the sample's title/date. UI: a Patreon-only Preview button (mdi-eye-outline) on SourceRow + SourceCard opens PreviewDialog — self-fetches with loading / error / empty / result states and a "Start backfill" shortcut. Store action previewSource. Tests: preview counts new media without downloading + samples only posts with new items; page_limit caps the walk + flags has_more. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-06 12:18:08 -04:00
parent cd43439401
commit e82c2ee57b
10 changed files with 368 additions and 2 deletions
@@ -0,0 +1,113 @@
+<template>
+  <!-- Plan #708 B4: dry-run preview — what a backfill WOULD download, without
+       downloading. Self-fetches on open; loading / error / empty / result. -->
+  <v-dialog
+    :model-value="modelValue" max-width="520"
+    @update:model-value="$emit('update:modelValue', $event)"
+  >
+    <v-card v-if="source">
+      <v-card-title class="d-flex align-center">
+        <v-icon class="mr-2">mdi-eye-outline</v-icon>
+        Preview · {{ source.artist_name }}
+      </v-card-title>
+      <v-card-subtitle class="fc-preview__url">{{ source.url }}</v-card-subtitle>
+
+      <v-card-text>
+        <div v-if="loading" class="text-center py-8">
+          <v-progress-circular indeterminate color="accent" />
+          <div class="text-caption mt-3 text-medium-emphasis">Walking the feed…</div>
+        </div>
+
+        <v-alert
+          v-else-if="error" type="error" variant="tonal" density="comfortable"
+        >{{ error }}</v-alert>
+
+        <div v-else-if="result">
+          <div class="text-h5">
+            {{ result.total_new }} new item{{ result.total_new === 1 ? '' : 's' }}
+          </div>
+          <div class="text-body-2 text-medium-emphasis mb-3">
+            in the {{ result.posts_scanned }} most recent
+            post{{ result.posts_scanned === 1 ? '' : 's' }}<span
+              v-if="result.has_more"> · more pages not scanned</span>
+          </div>
+
+          <div
+            v-if="result.total_new === 0"
+            class="text-body-2 text-medium-emphasis"
+          >You’re caught up — nothing new to download.</div>
+
+          <v-list v-else density="compact" class="fc-preview__list" bg-color="transparent">
+            <v-list-item v-for="(row, i) in result.sample" :key="i" class="px-0">
+              <template #prepend>
+                <v-chip
+                  size="x-small" color="info" variant="tonal" label class="mr-3"
+                >+{{ row.new }}</v-chip>
+              </template>
+              <v-list-item-title class="text-body-2">{{ row.title }}</v-list-item-title>
+              <v-list-item-subtitle v-if="row.date" class="text-caption">
+                {{ formatRelative(row.date) }}
+              </v-list-item-subtitle>
+            </v-list-item>
+          </v-list>
+        </div>
+      </v-card-text>
+
+      <v-card-actions>
+        <v-spacer />
+        <v-btn variant="text" @click="$emit('update:modelValue', false)">Close</v-btn>
+        <v-btn
+          v-if="result && result.total_new > 0"
+          color="accent" variant="flat"
+          @click="$emit('backfill', source)"
+        >Start backfill</v-btn>
+      </v-card-actions>
+    </v-card>
+  </v-dialog>
+</template>
+
+<script setup>
+import { ref, watch } from 'vue'
+import { useSourcesStore } from '../../stores/sources.js'
+import { formatRelative } from '../../utils/date.js'
+
+const props = defineProps({
+  modelValue: { type: Boolean, default: false },
+  source: { type: Object, default: null },
+})
+defineEmits(['update:modelValue', 'backfill'])
+
+const store = useSourcesStore()
+const loading = ref(false)
+const error = ref('')
+const result = ref(null)
+
+watch(
+  () => props.modelValue,
+  async (open) => {
+    if (!open || !props.source) return
+    loading.value = true
+    error.value = ''
+    result.value = null
+    try {
+      result.value = await store.previewSource(props.source.id)
+    } catch (e) {
+      error.value = e?.body?.detail || e?.message || 'Preview failed'
+    } finally {
+      loading.value = false
+    }
+  },
+)
+</script>
+
+<style scoped>
+.fc-preview__url {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.fc-preview__list {
+  max-height: 320px;
+  overflow-y: auto;
+}
+</style>