v0.36.0: a playlist link says so before it downloads

Pasting a song from a YouTube Mix (watch?v=…&list=RD…) imported song
after song: yt-dlp takes the whole list by default, and a Mix runs to
thousands of rows and loops back on itself, so the linked song came in
again and again with nothing on screen saying why.

Now anything but a plain song link is listed first (--flat-playlist,
streamed into the dialog). One song goes straight through. Several become
a checklist: a song-in-a-list link ticks only its song and offers Just
This Song without waiting, and a playlist link ticks everything. Rows are
de-duplicated by id. The chosen songs download by their own pages, never
the list link, and more than one gets a per-song progress window (Hide
keeps downloading; the status-bar line brings it back).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_round49.py

@@ -50,7 +50,7 @@ if mode == "fail":
 src = os.environ.get("FAKE_YTDLP_AUDIO")
 titles = ["First Song", "Second Song"]
 for i, title in enumerate(titles, 1):
-    print(f"LTSTART {i}\\t{len(titles)}\\t{title}", flush=True)
+    print(f"LTSTART {i}\\t{len(titles)}\\tid{i}\\t{title}", flush=True)
     print("[download] some noise yt-dlp prints", flush=True)
     print("LTPROG  50.0%", flush=True)
     path = os.path.join(dest, f"{title} [id{i}].mp3")
@@ -127,9 +127,10 @@ class TestCommand:
         assert "-o" not in cmd and "--output" not in cmd
 
     @pytest.mark.parametrize("line, expected", [
-        ("LTSTART 2\t5\tSome Song\n", ("start", 2, 5, "Some Song")),
-        ("LTSTART NA\tNA\tSolo\n", ("start", 1, 1, "Solo")),
-        ("LTSTART 1\t1\tTab\tin title\n", ("start", 1, 1, "Tab\tin title")),
+        ("LTSTART 2\t5\tab1\tSome Song\n", ("start", 2, 5, "ab1", "Some Song")),
+        ("LTSTART NA\tNA\tx\tSolo\n", ("start", 1, 1, "x", "Solo")),
+        ("LTSTART 1\t1\tx\tTab\tin title\n",
+         ("start", 1, 1, "x", "Tab\tin title")),
         ("LTFILE /tmp/x/Song [abc].mp3\n", ("file", "/tmp/x/Song [abc].mp3")),
         ("LTPROG  45.3%\n", ("progress", 45)),
         ("LTPROG 100.0%\r\n", ("progress", 100)),
@@ -210,7 +211,8 @@ def _run_worker(url, dest, cancel_on_first=False):
     worker = UrlImportWorker(url)
     worker.temp_dir = dest
     events = []
-    worker.item_started.connect(lambda i, n, t: events.append(("start", i, n, t)))
+    worker.item_started.connect(
+        lambda i, n, vid, t: events.append(("start", i, n, t)))
     worker.progress.connect(lambda p: events.append(("progress", p)))
 
     def on_file(path):
@@ -330,8 +332,13 @@ class TestWindow:
         monkeypatch.setenv("FAKE_YTDLP_AUDIO", str(mp3_file))
 
         class _Dialog:
-            def __init__(self, description, parent=None):
+            cookies_used = None
+            def __init__(self, description, parent=None, **_kw):
                 assert "T2" in description
+            def chosen_entries(self):
+                return []
+            def download_urls(self):
+                return [self.url()]
             def exec(self):
                 return True
             def url(self):