fix(downloads): support offline fallback drafts

- launch Firefox handoffs through authenticated reconnect
- preserve usable drafts when metadata lookup fails
- reject stale metadata results and retry failed rows only

src/utils/addDownloadMetadata.ts

@@ -0,0 +1,159 @@
+import {
+  canonicalizeDownloadFileName,
+  fileNameFromUrl,
+  isMediaUrl
+} from './downloads';
+
+export type MetadataStatus = 'loading' | 'ready' | 'metadata-error' | 'invalid';
+
+export interface AddMediaFormat {
+  name: string;
+  selector: string;
+  ext: string;
+  formatLabel: string;
+  detail: string;
+  type: string;
+  bytes: number;
+  isApproximate?: boolean;
+}
+
+export interface AddDownloadDraftRow {
+  id: string;
+  sourceUrl: string;
+  downloadUrl: string;
+  file: string;
+  size?: string;
+  sizeBytes?: number;
+  status: MetadataStatus;
+  generation: number;
+  isMedia: boolean;
+  formats?: AddMediaFormat[];
+  selectedFormat?: number;
+}
+
+const ALLOWED_SCHEMES = new Set(['http:', 'https:', 'ftp:', 'sftp:']);
+
+type ParsedInput = {
+  identity: string;
+  sourceUrl: string;
+  valid: boolean;
+};
+
+const parseInputLines = (rawText: string): ParsedInput[] => {
+  const seen = new Set<string>();
+  const parsed: ParsedInput[] = [];
+
+  for (const rawLine of rawText.split('\n')) {
+    const line = rawLine.trim();
+    if (!line) continue;
+
+    let sourceUrl = line;
+    let valid = false;
+    try {
+      const url = new URL(line);
+      valid = ALLOWED_SCHEMES.has(url.protocol);
+      if (valid) sourceUrl = url.href;
+    } catch {
+      valid = false;
+    }
+
+    const identity = valid ? sourceUrl : `invalid:${line}`;
+    if (seen.has(identity)) continue;
+    seen.add(identity);
+    parsed.push({ identity, sourceUrl, valid });
+  }
+
+  return parsed;
+};
+
+export const reconcileDownloadRows = (
+  rawText: string,
+  currentRows: AddDownloadDraftRow[],
+  pendingFilename?: string,
+  createId: () => string = () => crypto.randomUUID()
+): AddDownloadDraftRow[] => {
+  const inputs = parseInputLines(rawText);
+  const existing = new Map(currentRows.map(row => [row.sourceUrl, row]));
+
+  return inputs.map(input => {
+    const preserved = existing.get(input.sourceUrl);
+    if (preserved) return preserved;
+
+    const fallback = canonicalizeDownloadFileName(
+      inputs.length === 1 && pendingFilename
+        ? pendingFilename
+        : fileNameFromUrl(input.sourceUrl)
+    );
+
+    return {
+      id: createId(),
+      sourceUrl: input.sourceUrl,
+      downloadUrl: input.sourceUrl,
+      file: fallback,
+      status: input.valid ? 'loading' : 'invalid',
+      generation: input.valid ? 1 : 0,
+      isMedia: input.valid && isMediaUrl(input.sourceUrl)
+    };
+  });
+};
+
+export const updateRowIfCurrent = (
+  rows: AddDownloadDraftRow[],
+  id: string,
+  sourceUrl: string,
+  generation: number,
+  update: (row: AddDownloadDraftRow) => AddDownloadDraftRow
+): AddDownloadDraftRow[] => rows.map(row =>
+  row.id === id && row.sourceUrl === sourceUrl && row.generation === generation
+    ? update(row)
+    : row
+);
+
+export const refreshFailedMetadataRows = (
+  rows: AddDownloadDraftRow[]
+): AddDownloadDraftRow[] => rows.map(row =>
+  row.status === 'metadata-error'
+    ? {
+        ...row,
+        status: 'loading',
+        generation: row.generation + 1
+      }
+    : row
+);
+
+export const canSubmitMetadataRows = (rows: AddDownloadDraftRow[]): boolean =>
+  rows.length > 0
+  && rows.every(row => row.status === 'ready' || row.status === 'metadata-error');
+
+export const mediaFormatSelectorForRow = (
+  row: AddDownloadDraftRow
+): string | undefined => {
+  if (!row.isMedia || row.status !== 'ready' || row.selectedFormat === undefined) {
+    return undefined;
+  }
+  return row.formats?.[row.selectedFormat]?.selector;
+};
+
+export const metadataSummaryMessage = (rows: AddDownloadDraftRow[]): string => {
+  if (rows.length === 0) return 'Paste one or more links.';
+
+  const invalid = rows.filter(row => row.status === 'invalid').length;
+  if (invalid > 0) {
+    return `Correct or remove ${invalid} invalid URL${invalid === 1 ? '' : 's'} before continuing.`;
+  }
+
+  const loading = rows.filter(row => row.status === 'loading').length;
+  if (loading > 0) {
+    return `Waiting for metadata for ${loading} download${loading === 1 ? '' : 's'}.`;
+  }
+
+  const failed = rows.filter(row => row.status === 'metadata-error').length;
+  const ready = rows.filter(row => row.status === 'ready').length;
+  if (failed === rows.length) {
+    return 'Metadata is unavailable. Downloads can still be added using fallback details.';
+  }
+  if (failed > 0) {
+    return `${ready} download${ready === 1 ? '' : 's'} ready; ${failed} will use fallback filename and unknown size.`;
+  }
+  return `Ready to add ${ready} download${ready === 1 ? '' : 's'}.`;
+};