fix(lavalink): pin youtube-plugin to the snapshot carrying the TV User-Agent fix

docs/canonical/operations.md

@@ -112,6 +112,34 @@ For a resolution failure, start with a plugin update — cheap and often enough
 
    `docker compose up -d --force-recreate lavalink`
 
+### The plugin is pinned to a snapshot, not a release
+
+`lavalink/application.yml` pins `youtube-plugin` to a `main`-branch commit with `snapshot: true`,
+because a release carrying the fix does not exist yet. Around 2026-08-18 YouTube began rejecting
+Cobalt-family User-Agents on the TVHTML5 player endpoint, answering `UNPLAYABLE` /
+"The page needs to be reloaded." `TV` is the only OAuth-capable client, so that killed
+authenticated playback outright even with a valid refresh token — bot joins, announces, silence.
+Upstream [issue #226](https://github.com/lavalink-devs/youtube-source/issues/226), fixed by
+[#233](https://github.com/lavalink-devs/youtube-source/pull/233) (PlayStation 4 User-Agent),
+merged 2026-08-19; 1.18.2 predates it.
+
+Move back to a released version once one ships the fix (>= 1.18.3), so the deployment is not
+tracking an unreleased build indefinitely. Snapshot versions are commit SHAs, listed at
+<https://maven.lavalink.dev/snapshots/dev/lavalink/youtube/youtube-plugin/maven-metadata.xml>.
+
+Only Lavalink needs recreating after a plugin change — the file is volume-mounted:
+
+`docker compose up -d --force-recreate lavalink`
+
+**Changes to the bot's own code need an image rebuild.** `--force-recreate lavalink` restarts
+Lavalink alone, and `docker compose up -d bot` reuses the existing image, so a `git pull` that
+touched `src/` is not live until:
+
+`docker compose up -d --build bot`
+
+Check `docker compose ps` — the `CREATED` column shows the image age. A bot container created
+long before the last deploy is running old code.
+
 ### Completing the YouTube OAuth login
 
 `plugins.youtube.oauth` is enabled in `lavalink/application.yml`, but it does nothing until an

lavalink/application.yml

@@ -4,8 +4,17 @@ server:
 
 lavalink:
   plugins:
-    - dependency: "dev.lavalink.youtube:youtube-plugin:1.18.2"
-      snapshot: false
+    # Pinned to a main-branch snapshot rather than a release, on purpose. Around 2026-08-18
+    # YouTube started rejecting Cobalt-family User-Agents on the TVHTML5 player endpoint,
+    # answering UNPLAYABLE / "The page needs to be reloaded." Because TV is the only
+    # OAuth-capable client, that takes out authenticated playback entirely - the exact symptom
+    # is every /play joining the channel and staying silent. Upstream issue #226; fixed by #233
+    # (PlayStation 4 User-Agent), merged 2026-08-19. No release carries it yet: 1.18.2 is from
+    # 2026-07-27. This commit also carries #235 (recover total length when contentLength is
+    # omitted). Go back to a released version as soon as one ships the fix (>= 1.18.3):
+    # https://github.com/lavalink-devs/youtube-source/issues/226
+    - dependency: "dev.lavalink.youtube:youtube-plugin:f45bbb7aebfcbc1c553769e04af6cd43afa8b7c3"
+      snapshot: true
     - dependency: "com.github.topi314.lavasrc:lavasrc-plugin:4.8.3"
       repository: "https://maven.lavalink.dev/releases"
       snapshot: false