download job: use the panel's exact url list (no server re-expansion)

A YouTube Mix/radio playlist (list=RD…) returns a different set of items on every
/api/playlist call (observed 779 / 1485 / 529 for the same URL). The job used to
re-expand the playlist server-side, so it would download a different list than the
count shown on the decision screen.

The panel now passes the already-expanded `urls[]` into the job, and the executor
uses them verbatim (falling back to expanding `url` only when no list is given).
The job downloads exactly what you decided on. Endpoint takes `urls[]` (stored as
inputs.urls) or `url`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/api/tasks/execute-download.ts

@@ -1,10 +1,12 @@
 import { reclipPlaylist, reclipDownloadOne } from '../../reclip-client';
 
-// The download-job executor — pure scripting, no agent. One phase: expand the playlist, then one download
-// request per item in the chosen format (audio/video), skipping anything that fails (private / deleted /
-// download error). No metadata prefetch — ReClip names the file from the video title itself. Emits a
-// compact `download:progress` snapshot (counters, not per-item events — a playlist can be thousands of
-// items). Throws on abort or a fatal error (playlist expansion); per-item errors are counted + skipped.
+// The download-job executor — pure scripting, no agent. One download request per item in the chosen
+// format (audio/video), skipping anything that fails (private / deleted / download error). No metadata
+// prefetch — ReClip names the file from the video title itself. The item list comes from the caller
+// (inputs.urls — the exact list the panel already expanded, so a Mix/radio playlist that returns a
+// different set each call can't drift); it falls back to expanding inputs.url server-side. Emits a compact
+// `download:progress` snapshot (counters, not per-item events — a playlist can be thousands of items).
+// Throws on abort or a fatal error; per-item errors are counted + skipped.
 
 export type DownloadProgress = {
   phase: 'expanding' | 'download' | 'done';
@@ -30,8 +32,8 @@ export type ExecuteDownloadParams = {
 const EMIT_THROTTLE_MS = 750;
 
 export async function executeDownload(params: ExecuteDownloadParams): Promise<void> {
-  const { url, format, absDir } = params.inputs;
-  if (!url || !absDir) throw new Error('download job missing url or target directory');
+  const { url, urls: urlsJson, format, absDir } = params.inputs;
+  if (!absDir) throw new Error('download job missing target directory');
   const audioOnly = format !== 'video'; // default to audio
 
   const progress: DownloadProgress = { phase: 'expanding', done: 0, failed: 0, total: 0 };
@@ -48,12 +50,20 @@ export async function executeDownload(params: ExecuteDownloadParams): Promise<vo
 
   emit(true);
 
-  // ── Expand ──
-  let urls = [url];
-  if (url.includes('list=')) {
-    const pl = await reclipPlaylist(url);
-    if (pl.error) throw new Error(pl.error);
-    if (pl.urls?.length) urls = pl.urls;
+  // ── Resolve the item list: the caller's exact list, else expand the url server-side ──
+  let urls: string[];
+  if (urlsJson) {
+    urls = JSON.parse(urlsJson) as string[];
+  } else if (url) {
+    if (url.includes('list=')) {
+      const pl = await reclipPlaylist(url);
+      if (pl.error) throw new Error(pl.error);
+      urls = pl.urls?.length ? pl.urls : [url];
+    } else {
+      urls = [url];
+    }
+  } else {
+    throw new Error('download job missing url(s)');
   }
 
   // ── Download: one request per item, skip failures ──

src/servers/api/tasks/pipeline-jobs-routes.ts

@@ -72,21 +72,26 @@ pipelineJobsRouter.post('/', async (c) => {
 });
 
 // POST /download — enqueue a video/audio download job (ReClip). Runs in its own lane, needs no capability
-// task. Body: { url (video or playlist), format:'audio'|'video', dir (target folder, home-relative),
-// root?, label? }. The job expands + fetches metadata (phase 1) then downloads survivors (phase 2).
+// task. Body: { urls[] (the exact list to download — preferred), OR url (expanded server-side),
+// format:'audio'|'video', dir (target folder, home-relative), root?, label? }. Passing `urls` locks the
+// job to the list the panel already expanded, so a Mix/radio playlist can't drift between fetch + job.
 pipelineJobsRouter.post('/download', async (c) => {
   const user = c.get('user');
   const body = await c.req.json<{
-    url: string;
+    url?: string;
+    urls?: string[];
     format?: 'audio' | 'video';
     dir?: string;
     root?: string;
     label?: string;
   }>();
-  if (!body.url) throw errors.BAD_REQUEST('url is required');
+  if (!body.url && !body.urls?.length) throw errors.BAD_REQUEST('url or urls is required');
   const rootDir = getRootDir(user, body.root);
   const absDir = resolveUserPath(rootDir, body.dir ?? '/'); // traversal-guarded
   const format = body.format === 'video' ? 'video' : 'audio';
+  const inputs: Record<string, string> = body.urls?.length
+    ? { urls: JSON.stringify(body.urls), format, absDir }
+    : { url: body.url!, format, absDir };
   const { jobId, status } = await jobManager.enqueueJob(
     {
       userId: user.id,
@@ -95,7 +100,7 @@ pipelineJobsRouter.post('/download', async (c) => {
       mode: 'download',
       taskDirName: 'video-download',
       taskName: body.label || (format === 'audio' ? 'Audio download' : 'Video download'),
-      inputs: { url: body.url, format, absDir },
+      inputs,
       cwd: body.dir ?? '/',
       config: {},
     },

src/workspaces/officerdev/src/apps/FileBrowser/VideoDownloadPanel.tsx

@@ -250,7 +250,7 @@ export const VideoDownloadPanel = () => {
   const startJob = async () => {
     try {
       const res = await client.post<{ jobId: string; status: string }>('/jobs/download', {
-        url: url.trim(),
+        urls: expandedUrls, // the exact list we counted — a Mix playlist won't re-expand to a different set
         format: jobFormat,
         dir: targetDir(),
         root,