feat(artists): show provider-neutral upcoming concerts

rust_backend/crates/extensions/src/backend/provider_metadata.rs

@@ -88,6 +88,7 @@ impl Backend {
                 "listeners".into(),
                 json!(value["listeners"].as_i64().unwrap_or_default()),
             );
+            info.insert("concerts".into(), array(value, "concerts").into());
             for key in ["albums", "releases"] {
                 let values = array(value, key);
                 if !values.is_empty() {
@@ -450,6 +451,7 @@ fn response(kind: &str, value: &Value, check: &Check<'_>) -> Result<Value, Resol
             );
             info.insert("images".into(), json!(image));
             info.insert("cover_url".into(), json!(cover));
+            info.insert("concerts".into(), array(value, "concerts").into());
             if value["listeners"].as_i64().unwrap_or_default() > 0 {
                 info.insert("listeners".into(), value["listeners"].clone());
             }

rust_backend/crates/extensions/src/backend/provider_metadata/value_tests.rs

@@ -19,9 +19,13 @@ function collection(id) {
 }
 function getArtist(id) {
     return {id, name: "Example Artist", image_url: "https://example.invalid/portrait.jpg",
+        concerts: id === "bad-concerts" ? {} : [{id: "event-1", location: "Example City",
+            venue: "Example Hall", startAt: "2026-10-07T01:00:00Z", timeZone: "America/New_York",
+            url: "https://example.invalid/events/1"}],
         headerLogo: "https://example.invalid/logo.png", albumsNext: "artist-page-2", albums: []};
 }
-registerExtension({getAlbum: collection, getPlaylist: collection, getArtist});
+function handleUrl() { return {type: "artist", artist: getArtist("artist-1")}; }
+registerExtension({getAlbum: collection, getPlaylist: collection, getArtist, handleUrl});
 "#;
 
 fn fixture() -> (tempfile::TempDir, Backend) {
@@ -31,7 +35,8 @@ fn fixture() -> (tempfile::TempDir, Backend) {
     std::fs::write(
         source.join("manifest.json"),
         json!({"name":ID,"displayName":"Example Metadata","version":"1",
-            "description":"Generic metadata fixture","type":["metadata_provider"]})
+            "description":"Generic metadata fixture","type":["metadata_provider"],
+            "urlHandler":{"enabled":true,"patterns":["example.invalid"]}})
         .to_string(),
     )
     .unwrap();
@@ -104,6 +109,37 @@ fn artist_metadata_preserves_logo_separately_from_portrait() {
     backend.shutdown();
 }
 
+#[test]
+fn artist_concerts_survive_metadata_and_url_routes_without_provider_special_cases() {
+    let (_root, backend) = fixture();
+    let metadata: Value = serde_json::from_str(
+        &backend
+            .get_provider_metadata_json(ID, "artist", "artist-1", &|| Ok(()))
+            .unwrap(),
+    )
+    .unwrap();
+    let concerts = &metadata["artist_info"]["concerts"];
+    assert_eq!(concerts[0]["start_at"], "2026-10-07T01:00:00Z");
+    assert_eq!(concerts[0]["time_zone"], "America/New_York");
+    assert_eq!(concerts[0]["venue"], "Example Hall");
+    let handled: Value = serde_json::from_str(
+        &backend
+            .handle_url_json("https://example.invalid/artist/1")
+            .unwrap(),
+    )
+    .unwrap();
+    assert_eq!(&handled["artist"]["concerts"], concerts);
+    let malformed: Value = serde_json::from_str(
+        &backend
+            .get_provider_metadata_json(ID, "artist", "bad-concerts", &|| Ok(()))
+            .unwrap(),
+    )
+    .unwrap();
+    assert_eq!(malformed["artist_info"]["concerts"], json!([]));
+    assert_eq!(malformed["artist_info"]["name"], "Example Artist");
+    backend.shutdown();
+}
+
 #[test]
 fn metadata_value_bridge_preserves_album_playlist_and_public_json() {
     let (_root, backend) = fixture();

rust_backend/crates/extensions/src/provider.js

@@ -200,8 +200,16 @@
         if (albums.length) result.albums = albums;
         if (releases.length) result.releases = releases;
         if (tracks.length) result.top_tracks = tracks;
+        const concertItems = first(object(value), ["concerts"]);
+        const concerts = isArray(concertItems) ? array(concertItems.slice(0, 500), concert) : [];
+        if (concerts.length) result.concerts = concerts;
         return result;
     }
+    function concert(value) {
+        return fields(value, [["id","s"],["location","s"],["venue","s"],
+            ["start_at","s","startAt"],["time_zone","s","timeZone"],
+            ["url","s"]], ["id","location","start_at"]);
+    }
     function decryption(value) {
         if (empty(value)) return null;
         const result = fields(value, [["strategy","s"],["key","s"],["iv","s"],