From 93e6b1b3715cda767c5da758db440d7650e4d254 Mon Sep 17 00:00:00 2001
From: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>
Date: Mon, 30 Dec 2024 13:11:17 +0200
Subject: [PATCH 1/2] Warm up system playlists if they report themselves
 unavailable on the first request

Related to #854
---
 .../Playlists/PlaylistController.cs           | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/YoutubeExplode/Playlists/PlaylistController.cs b/YoutubeExplode/Playlists/PlaylistController.cs
index 9d43bf98..117d4053 100644
--- a/YoutubeExplode/Playlists/PlaylistController.cs
+++ b/YoutubeExplode/Playlists/PlaylistController.cs
@@ -99,10 +99,27 @@ await response.Content.ReadAsStringAsync(cancellationToken)
             if (!playlistResponse.IsAvailable)
             {
                 // Retry if this is not the first request, meaning that the previous requests were successful,
-                // and that the playlist is probably not actually unavailable.
+                // indicating that it's most likely a transient error.
                 if (index > 0 && !string.IsNullOrWhiteSpace(visitorData) && retriesRemaining > 0)
                     continue;
 
+                // Some system playlists are unavailable through this endpoint until their page is opened by
+                // at least one user. Retry if this is the first request and we haven't retried yet.
+                if (index <= 0 && string.IsNullOrWhiteSpace(visitorData) && retriesRemaining >= 5)
+                {
+                    using (
+                        await http.GetAsync(
+                            $"https://youtube.com/playlist?list={playlistId}",
+                            cancellationToken
+                        )
+                    )
+                    {
+                        // We don't actually care about the outcome of this request
+                    }
+
+                    continue;
+                }
+
                 throw new PlaylistUnavailableException(
                     $"Playlist '{playlistId}' is not available."
                 );

From a069f6aab5c0edb60d6b78e9be670a395b3a29df Mon Sep 17 00:00:00 2001
From: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>
Date: Mon, 30 Dec 2024 13:15:17 +0200
Subject: [PATCH 2/2] Review comments

---
 YoutubeExplode/Playlists/PlaylistController.cs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/YoutubeExplode/Playlists/PlaylistController.cs b/YoutubeExplode/Playlists/PlaylistController.cs
index 117d4053..f94adbdb 100644
--- a/YoutubeExplode/Playlists/PlaylistController.cs
+++ b/YoutubeExplode/Playlists/PlaylistController.cs
@@ -61,7 +61,8 @@ public async ValueTask<PlaylistNextResponse> GetPlaylistNextResponseAsync(
         CancellationToken cancellationToken = default
     )
     {
-        for (var retriesRemaining = 5; ; retriesRemaining--)
+        const int retriesCount = 5;
+        for (var retriesRemaining = retriesCount; ; retriesRemaining--)
         {
             using var request = new HttpRequestMessage(
                 HttpMethod.Post,
@@ -104,8 +105,9 @@ await response.Content.ReadAsStringAsync(cancellationToken)
                     continue;
 
                 // Some system playlists are unavailable through this endpoint until their page is opened by
-                // at least one user. Retry if this is the first request and we haven't retried yet.
-                if (index <= 0 && string.IsNullOrWhiteSpace(visitorData) && retriesRemaining >= 5)
+                // at least one user. If this is the first request, and we haven't retried yet, attempt to
+                // warm up the playlist by opening its page, and then retry.
+                if (index <= 0 && string.IsNullOrWhiteSpace(visitorData) && retriesRemaining >= retriesCount)
                 {
                     using (
                         await http.GetAsync(