feat: add update_meta to SongRepositoryPort and PATCH /songs/{id}

crates/api/src/routes/songs.rs

@@ -48,12 +48,36 @@ pub async fn list_songs(
         .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, Json(ErrorResponse { error: e.to_string() })))
 }
 
+#[derive(serde::Deserialize)]
+pub struct UpdateSongRequest {
+    pub title: Option<String>,
+    pub artist: Option<String>,
+    pub original_key: Option<String>,
+}
+
 pub async fn update_song(
-    State(_state): State<Arc<AppState>>,
-    Path(_id): Path<String>,
-    Json(_body): Json<serde_json::Value>,
-) -> StatusCode {
-    StatusCode::NOT_IMPLEMENTED
+    State(state): State<Arc<AppState>>,
+    Path(id): Path<String>,
+    Json(body): Json<UpdateSongRequest>,
+) -> Result<Json<domain::SongSummary>, (StatusCode, Json<ErrorResponse>)> {
+    let uuid = Uuid::parse_str(&id).map_err(|_| {
+        (StatusCode::BAD_REQUEST, Json(ErrorResponse { error: "Invalid ID".into() }))
+    })?;
+
+    state.songs
+        .update_meta(
+            uuid,
+            body.title.as_deref(),
+            body.artist.as_deref(),
+            body.original_key.as_deref(),
+        )
+        .await
+        .map(Json)
+        .map_err(|e| match e {
+            domain::RepositoryError::NotFound =>
+                (StatusCode::NOT_FOUND, Json(ErrorResponse { error: "Not found".into() })),
+            e => (StatusCode::INTERNAL_SERVER_ERROR, Json(ErrorResponse { error: e.to_string() })),
+        })
 }
 
 pub async fn get_song(

crates/common/src/lib.rs

@@ -25,6 +25,16 @@ impl SongService {
     pub async fn delete(&self, id: Uuid) -> Result<(), RepositoryError> {
         self.repo.delete(id).await
     }
+
+    pub async fn update_meta(
+        &self,
+        id: Uuid,
+        title: Option<&str>,
+        artist: Option<&str>,
+        original_key: Option<&str>,
+    ) -> Result<domain::SongSummary, domain::RepositoryError> {
+        self.repo.update_meta(id, title, artist, original_key).await
+    }
 }
 
 pub struct SongSearchService {

crates/domain/src/ports.rs

@@ -53,6 +53,13 @@ pub trait SongRepositoryPort: Send + Sync {
     async fn list(&self) -> Result<Vec<SongSummary>, RepositoryError>;
     async fn get(&self, id: Uuid) -> Result<Option<Song>, RepositoryError>;
     async fn delete(&self, id: Uuid) -> Result<(), RepositoryError>;
+    async fn update_meta(
+        &self,
+        id: Uuid,
+        title: Option<&str>,
+        artist: Option<&str>,
+        original_key: Option<&str>,
+    ) -> Result<SongSummary, RepositoryError>;
 }
 
 #[async_trait]

crates/infrastructure/persistence/src/lib.rs

@@ -102,6 +102,58 @@ impl SongRepositoryPort for SqliteSongRepository {
             Ok(())
         }
     }
+
+    async fn update_meta(
+        &self,
+        id: Uuid,
+        title: Option<&str>,
+        artist: Option<&str>,
+        original_key: Option<&str>,
+    ) -> Result<SongSummary, RepositoryError> {
+        let id_str = id.to_string();
+
+        let row = sqlx::query_as::<_, SongRow>(
+            "SELECT id, title, artist, original_key, preview_chords, body FROM songs WHERE id = ?"
+        )
+        .bind(&id_str)
+        .fetch_optional(&self.pool)
+        .await
+        .map_err(|e| RepositoryError::Internal(e.to_string()))?
+        .ok_or(RepositoryError::NotFound)?;
+
+        let mut song: Song = serde_json::from_str(&row.body)
+            .map_err(|e| RepositoryError::Internal(e.to_string()))?;
+        if let Some(t) = title { song.meta.title = t.to_string(); }
+        if let Some(a) = artist { song.meta.artist = a.to_string(); }
+        if let Some(k) = original_key { song.meta.original_key = Some(k.to_string()); }
+        let new_body = serde_json::to_string(&song)
+            .map_err(|e| RepositoryError::Internal(e.to_string()))?;
+
+        let new_title = title.unwrap_or(&row.title);
+        let new_artist = artist.unwrap_or(&row.artist);
+        let new_key: Option<&str> = original_key.or(row.original_key.as_deref());
+
+        sqlx::query(
+            "UPDATE songs SET title = ?, artist = ?, original_key = ?, body = ? WHERE id = ?"
+        )
+        .bind(new_title)
+        .bind(new_artist)
+        .bind(new_key)
+        .bind(&new_body)
+        .bind(&id_str)
+        .execute(&self.pool)
+        .await
+        .map_err(|e| RepositoryError::Internal(e.to_string()))?;
+
+        let preview_chords: Vec<String> = serde_json::from_str(&row.preview_chords)
+            .map_err(|e| RepositoryError::Internal(e.to_string()))?;
+
+        Ok(SongSummary {
+            id,
+            meta: song.meta,
+            preview_chords,
+        })
+    }
 }
 
 #[async_trait]