diff --git a/Cargo.lock b/Cargo.lock
index 973ab80..1c4b3dd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -616,6 +616,27 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "csv"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52cd9d68cf7efc6ddfaaee42e7288d3a99d613d4b50f76ce9827ae0c6e14f938"
+dependencies = [
+ "csv-core",
+ "itoa",
+ "ryu",
+ "serde_core",
+]
+
+[[package]]
+name = "csv-core"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "704a3c26996a80471189265814dbc2c257598b96b8a7feae2d31ace646bb9782"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "dashmap"
 version = "5.5.3"
@@ -2020,8 +2041,10 @@ name = "musicfs-grpc"
 version = "0.1.0"
 dependencies = [
  "chrono",
+ "csv",
  "hex",
  "hmac",
+ "musicfs-cache",
  "musicfs-core",
  "musicfs-search",
  "prost",
diff --git a/crates/musicfs-grpc/Cargo.toml b/crates/musicfs-grpc/Cargo.toml
index 76d3670..f9742bb 100644
--- a/crates/musicfs-grpc/Cargo.toml
+++ b/crates/musicfs-grpc/Cargo.toml
@@ -4,6 +4,7 @@ version.workspace = true
 edition.workspace = true
 
 [dependencies]
+musicfs-cache = { path = "../musicfs-cache" }
 musicfs-search = { path = "../musicfs-search" }
 musicfs-core = { path = "../musicfs-core" }
 tonic.workspace = true
@@ -15,6 +16,7 @@ thiserror.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 chrono.workspace = true
+csv = "1.3"
 reqwest = { version = "0.11", features = ["json"] }
 hmac = "0.12"
 sha2 = "0.10"
diff --git a/crates/musicfs-grpc/src/lib.rs b/crates/musicfs-grpc/src/lib.rs
index 37424a5..b480215 100644
--- a/crates/musicfs-grpc/src/lib.rs
+++ b/crates/musicfs-grpc/src/lib.rs
@@ -6,10 +6,13 @@ pub mod proto {
     }
 }
 
+mod metadata;
 mod search_service;
 mod server;
 mod webhook;
 
+pub use metadata::MetadataServiceImpl;
+pub use proto::musicfs::v1::metadata_service_server::MetadataServiceServer;
 pub use proto::musicfs::v1::music_fs_server::{MusicFs, MusicFsServer as MusicFsGrpcServer};
 pub use proto::musicfs::v1::*;
 pub use search_service::SearchService;
diff --git a/crates/musicfs-grpc/src/metadata.rs b/crates/musicfs-grpc/src/metadata.rs
new file mode 100644
index 0000000..a679a40
--- /dev/null
+++ b/crates/musicfs-grpc/src/metadata.rs
@@ -0,0 +1,754 @@
+//! MetadataService gRPC handlers for metadata overlay operations.
+
+use crate::proto::musicfs::v1::{
+    metadata_service_server::MetadataService, BatchUpdateProgress, BatchUpdateRequest,
+    ClearOverlayRequest, ClearOverlayResponse, GetMetadataRequest, ImportMetadataRequest,
+    ImportProgress, MetadataResponse, UpdateMetadataRequest, UpdateMetadataResponse,
+};
+use musicfs_cache::Database;
+use musicfs_core::{AudioMeta, FileId, VirtualPath};
+use std::sync::Arc;
+use tokio::sync::mpsc;
+use tokio_stream::wrappers::ReceiverStream;
+use tonic::{Request, Response, Status};
+use tracing::{debug, info, instrument, warn};
+
+/// gRPC service implementation for metadata operations.
+pub struct MetadataServiceImpl {
+    db: Arc<Database>,
+}
+
+impl MetadataServiceImpl {
+    /// Create a new MetadataServiceImpl with the given database.
+    pub fn new(db: Arc<Database>) -> Self {
+        Self { db }
+    }
+
+    /// Convert AudioMeta to MetadataResponse proto message.
+    fn audio_meta_to_response(file_id: FileId, meta: &AudioMeta) -> MetadataResponse {
+        MetadataResponse {
+            file_id: file_id.0,
+            title: meta.title.clone(),
+            artist: meta.artist.clone(),
+            album: meta.album.clone(),
+            album_artist: meta.album_artist.clone(),
+            year: meta.year,
+            track: meta.track,
+            disc: meta.disc,
+            genre: meta.genre.clone(),
+            format: Some(format!("{:?}", meta.format)),
+            duration_ms: meta.duration_ms,
+            bitrate: meta.bitrate.map(|b| b as u64),
+            track_total: meta.track_total,
+            disc_total: meta.disc_total,
+            date: meta.date.clone(),
+            composer: meta.composer.clone(),
+            comment: meta.comment.clone(),
+            lyrics: meta.lyrics.clone(),
+            copyright: meta.copyright.clone(),
+            compilation: meta.compilation,
+            artist_sort: meta.artist_sort.clone(),
+            album_artist_sort: meta.album_artist_sort.clone(),
+            album_sort: meta.album_sort.clone(),
+            title_sort: meta.title_sort.clone(),
+            mb_recording_id: meta.mb_recording_id.clone(),
+            mb_album_id: meta.mb_album_id.clone(),
+            mb_artist_id: meta.mb_artist_id.clone(),
+            mb_album_artist_id: meta.mb_album_artist_id.clone(),
+            mb_release_group_id: meta.mb_release_group_id.clone(),
+            replaygain_track_gain: meta.replaygain_track_gain,
+            replaygain_track_peak: meta.replaygain_track_peak,
+            replaygain_album_gain: meta.replaygain_album_gain,
+            replaygain_album_peak: meta.replaygain_album_peak,
+            channels: meta.channels,
+            bits_per_sample: meta.bits_per_sample,
+            encoder: meta.encoder.clone(),
+            custom_tags: Default::default(),
+        }
+    }
+
+    /// Convert UpdateMetadataRequest to AudioMeta for database update.
+    fn request_to_audio_meta(req: &UpdateMetadataRequest) -> AudioMeta {
+        AudioMeta {
+            title: req.title.clone(),
+            artist: req.artist.clone(),
+            album: req.album.clone(),
+            album_artist: req.album_artist.clone(),
+            genre: req.genre.clone(),
+            year: None,
+            track: req.track_number,
+            disc: req.disc_number,
+            duration_ms: None,
+            bitrate: None,
+            sample_rate: None,
+            format: musicfs_core::AudioFormat::Unknown,
+            track_total: None,
+            disc_total: None,
+            date: req.date.clone(),
+            composer: req.composer.clone(),
+            comment: req.comment.clone(),
+            lyrics: req.lyrics.clone(),
+            copyright: req.copyright.clone(),
+            compilation: req.compilation,
+            artist_sort: req.artist_sort.clone(),
+            album_artist_sort: req.album_artist_sort.clone(),
+            album_sort: req.album_sort.clone(),
+            title_sort: req.title_sort.clone(),
+            mb_recording_id: req.mb_recording_id.clone(),
+            mb_album_id: req.mb_album_id.clone(),
+            mb_artist_id: req.mb_artist_id.clone(),
+            mb_album_artist_id: None,
+            mb_release_group_id: None,
+            replaygain_track_gain: req.replaygain_track_gain,
+            replaygain_track_peak: req.replaygain_track_peak,
+            replaygain_album_gain: req.replaygain_album_gain,
+            replaygain_album_peak: req.replaygain_album_peak,
+            channels: None,
+            bits_per_sample: None,
+            encoder: None,
+        }
+    }
+}
+
+#[tonic::async_trait]
+impl MetadataService for MetadataServiceImpl {
+    #[instrument(level = "debug", skip(self, request), fields(method = "get_metadata"))]
+    async fn get_metadata(
+        &self,
+        request: Request<GetMetadataRequest>,
+    ) -> Result<Response<MetadataResponse>, Status> {
+        let req = request.into_inner();
+        debug!(virtual_path = %req.virtual_path, "GetMetadata request");
+
+        if req.virtual_path.is_empty() {
+            return Err(Status::invalid_argument("virtual_path cannot be empty"));
+        }
+
+        let vpath = VirtualPath::new(&req.virtual_path);
+
+        let file_meta = self
+            .db
+            .get_file_by_virtual_path(&vpath)
+            .map_err(|e| Status::internal(format!("Database error: {}", e)))?
+            .ok_or_else(|| Status::not_found(format!("File not found: {}", req.virtual_path)))?;
+
+        let audio_meta = self
+            .db
+            .get_file_metadata_row(file_meta.id)
+            .map_err(|e| Status::internal(format!("Failed to get metadata: {}", e)))?;
+
+        let response = Self::audio_meta_to_response(file_meta.id, &audio_meta);
+        Ok(Response::new(response))
+    }
+
+    #[instrument(
+        level = "info",
+        skip(self, request),
+        fields(method = "update_metadata")
+    )]
+    async fn update_metadata(
+        &self,
+        request: Request<UpdateMetadataRequest>,
+    ) -> Result<Response<UpdateMetadataResponse>, Status> {
+        let req = request.into_inner();
+        let file_id = FileId(req.file_id);
+        info!(file_id = req.file_id, "UpdateMetadata request");
+
+        if req.file_id <= 0 {
+            return Err(Status::invalid_argument("file_id must be positive"));
+        }
+
+        let audio_meta = Self::request_to_audio_meta(&req);
+
+        match self.db.update_metadata(file_id, &audio_meta) {
+            Ok(()) => {
+                debug!(file_id = req.file_id, "Metadata updated successfully");
+                Ok(Response::new(UpdateMetadataResponse {
+                    file_id: req.file_id,
+                    success: true,
+                    error_message: None,
+                }))
+            }
+            Err(e) => {
+                warn!(file_id = req.file_id, error = %e, "Failed to update metadata");
+                Ok(Response::new(UpdateMetadataResponse {
+                    file_id: req.file_id,
+                    success: false,
+                    error_message: Some(e.to_string()),
+                }))
+            }
+        }
+    }
+
+    #[instrument(level = "info", skip(self, request), fields(method = "clear_overlay"))]
+    async fn clear_overlay(
+        &self,
+        request: Request<ClearOverlayRequest>,
+    ) -> Result<Response<ClearOverlayResponse>, Status> {
+        let req = request.into_inner();
+        let file_id = FileId(req.file_id);
+        info!(file_id = req.file_id, "ClearOverlay request");
+
+        if req.file_id <= 0 {
+            return Err(Status::invalid_argument("file_id must be positive"));
+        }
+
+        match self.db.clear_overlay(file_id) {
+            Ok(()) => {
+                debug!(file_id = req.file_id, "Overlay cleared successfully");
+                Ok(Response::new(ClearOverlayResponse {
+                    file_id: req.file_id,
+                    success: true,
+                    error_message: None,
+                }))
+            }
+            Err(e) => {
+                warn!(file_id = req.file_id, error = %e, "Failed to clear overlay");
+                Ok(Response::new(ClearOverlayResponse {
+                    file_id: req.file_id,
+                    success: false,
+                    error_message: Some(e.to_string()),
+                }))
+            }
+        }
+    }
+
+    type BatchUpdateMetadataStream = ReceiverStream<Result<BatchUpdateProgress, Status>>;
+
+    #[instrument(
+        level = "info",
+        skip(self, request),
+        fields(method = "batch_update_metadata")
+    )]
+    async fn batch_update_metadata(
+        &self,
+        request: Request<BatchUpdateRequest>,
+    ) -> Result<Response<Self::BatchUpdateMetadataStream>, Status> {
+        let req = request.into_inner();
+        let total = req.items.len() as u32;
+        info!(item_count = total, "BatchUpdateMetadata request");
+
+        let (tx, rx) = mpsc::channel(32);
+        let db = Arc::clone(&self.db);
+
+        tokio::spawn(async move {
+            for (i, item) in req.items.into_iter().enumerate() {
+                let file_id = FileId(item.file_id);
+                let completed = (i + 1) as u32;
+
+                let error_message = if let Some(ref metadata_req) = item.metadata {
+                    let audio_meta = MetadataServiceImpl::request_to_audio_meta(metadata_req);
+                    match db.update_metadata(file_id, &audio_meta) {
+                        Ok(()) => None,
+                        Err(e) => Some(e.to_string()),
+                    }
+                } else {
+                    Some("Missing metadata in batch item".to_string())
+                };
+
+                let progress = BatchUpdateProgress {
+                    completed,
+                    total,
+                    current_file_id: Some(item.file_id),
+                    error_message,
+                };
+
+                if tx.send(Ok(progress)).await.is_err() {
+                    break;
+                }
+            }
+        });
+
+        Ok(Response::new(ReceiverStream::new(rx)))
+    }
+
+    type ImportMetadataStream = ReceiverStream<Result<ImportProgress, Status>>;
+
+    #[instrument(
+        level = "info",
+        skip(self, request),
+        fields(method = "import_metadata")
+    )]
+    async fn import_metadata(
+        &self,
+        request: Request<ImportMetadataRequest>,
+    ) -> Result<Response<Self::ImportMetadataStream>, Status> {
+        let req = request.into_inner();
+        info!(source_path = %req.source_path, format = ?req.format, "ImportMetadata request");
+
+        if req.source_path.is_empty() {
+            return Err(Status::invalid_argument("source_path cannot be empty"));
+        }
+
+        let (tx, rx) = mpsc::channel(32);
+        let db = Arc::clone(&self.db);
+        let source_path = req.source_path.clone();
+        let format = req.format.clone();
+
+        tokio::spawn(async move {
+            let file_format = format.as_deref().unwrap_or_else(|| {
+                if source_path.ends_with(".csv") {
+                    "csv"
+                } else if source_path.ends_with(".json") {
+                    "json"
+                } else {
+                    "unknown"
+                }
+            });
+
+            let content = match tokio::fs::read_to_string(&source_path).await {
+                Ok(c) => c,
+                Err(e) => {
+                    let _ = tx
+                        .send(Ok(ImportProgress {
+                            imported: 0,
+                            total: 0,
+                            current_file: None,
+                            error_message: Some(format!("Failed to read file: {}", e)),
+                        }))
+                        .await;
+                    return;
+                }
+            };
+
+            let entries: Vec<ImportEntry> = match file_format {
+                "json" => match serde_json::from_str::<Vec<ImportEntry>>(&content) {
+                    Ok(e) => e,
+                    Err(e) => {
+                        let _ = tx
+                            .send(Ok(ImportProgress {
+                                imported: 0,
+                                total: 0,
+                                current_file: None,
+                                error_message: Some(format!("Failed to parse JSON: {}", e)),
+                            }))
+                            .await;
+                        return;
+                    }
+                },
+                "csv" => match parse_csv_entries(&content) {
+                    Ok(e) => e,
+                    Err(e) => {
+                        let _ = tx
+                            .send(Ok(ImportProgress {
+                                imported: 0,
+                                total: 0,
+                                current_file: None,
+                                error_message: Some(format!("Failed to parse CSV: {}", e)),
+                            }))
+                            .await;
+                        return;
+                    }
+                },
+                _ => {
+                    let _ = tx
+                        .send(Ok(ImportProgress {
+                            imported: 0,
+                            total: 0,
+                            current_file: None,
+                            error_message: Some(format!("Unsupported format: {}", file_format)),
+                        }))
+                        .await;
+                    return;
+                }
+            };
+
+            let total = entries.len() as u32;
+            let mut imported = 0u32;
+
+            for entry in entries {
+                let vpath = VirtualPath::new(&entry.virtual_path);
+
+                let file_meta = match db.get_file_by_virtual_path(&vpath) {
+                    Ok(Some(f)) => f,
+                    Ok(None) => {
+                        let progress = ImportProgress {
+                            imported,
+                            total,
+                            current_file: Some(entry.virtual_path.clone()),
+                            error_message: Some(format!("File not found: {}", entry.virtual_path)),
+                        };
+                        if tx.send(Ok(progress)).await.is_err() {
+                            break;
+                        }
+                        continue;
+                    }
+                    Err(e) => {
+                        let progress = ImportProgress {
+                            imported,
+                            total,
+                            current_file: Some(entry.virtual_path.clone()),
+                            error_message: Some(format!("Database error: {}", e)),
+                        };
+                        if tx.send(Ok(progress)).await.is_err() {
+                            break;
+                        }
+                        continue;
+                    }
+                };
+
+                let audio_meta = entry.to_audio_meta();
+                let error_message = match db.update_metadata(file_meta.id, &audio_meta) {
+                    Ok(()) => {
+                        imported += 1;
+                        None
+                    }
+                    Err(e) => Some(e.to_string()),
+                };
+
+                let progress = ImportProgress {
+                    imported,
+                    total,
+                    current_file: Some(entry.virtual_path),
+                    error_message,
+                };
+
+                if tx.send(Ok(progress)).await.is_err() {
+                    break;
+                }
+            }
+        });
+
+        Ok(Response::new(ReceiverStream::new(rx)))
+    }
+}
+
+/// Entry from import file (CSV or JSON).
+#[derive(Debug, Clone, serde::Deserialize)]
+struct ImportEntry {
+    virtual_path: String,
+    #[serde(default)]
+    title: Option<String>,
+    #[serde(default)]
+    artist: Option<String>,
+    #[serde(default)]
+    album: Option<String>,
+    #[serde(default)]
+    album_artist: Option<String>,
+    #[serde(default)]
+    genre: Option<String>,
+    #[serde(default)]
+    year: Option<u32>,
+    #[serde(default)]
+    track: Option<u32>,
+    #[serde(default)]
+    disc: Option<u32>,
+    #[serde(default)]
+    date: Option<String>,
+    #[serde(default)]
+    composer: Option<String>,
+    #[serde(default)]
+    comment: Option<String>,
+}
+
+impl ImportEntry {
+    fn to_audio_meta(&self) -> AudioMeta {
+        AudioMeta {
+            title: self.title.clone(),
+            artist: self.artist.clone(),
+            album: self.album.clone(),
+            album_artist: self.album_artist.clone(),
+            genre: self.genre.clone(),
+            year: self.year,
+            track: self.track,
+            disc: self.disc,
+            duration_ms: None,
+            bitrate: None,
+            sample_rate: None,
+            format: musicfs_core::AudioFormat::Unknown,
+            track_total: None,
+            disc_total: None,
+            date: self.date.clone(),
+            composer: self.composer.clone(),
+            comment: self.comment.clone(),
+            lyrics: None,
+            copyright: None,
+            compilation: None,
+            artist_sort: None,
+            album_artist_sort: None,
+            album_sort: None,
+            title_sort: None,
+            mb_recording_id: None,
+            mb_album_id: None,
+            mb_artist_id: None,
+            mb_album_artist_id: None,
+            mb_release_group_id: None,
+            replaygain_track_gain: None,
+            replaygain_track_peak: None,
+            replaygain_album_gain: None,
+            replaygain_album_peak: None,
+            channels: None,
+            bits_per_sample: None,
+            encoder: None,
+        }
+    }
+}
+
+/// Parse CSV content into ImportEntry list.
+fn parse_csv_entries(content: &str) -> Result<Vec<ImportEntry>, String> {
+    let mut reader = csv::Reader::from_reader(content.as_bytes());
+    let mut entries = Vec::new();
+
+    for result in reader.deserialize() {
+        let entry: ImportEntry = result.map_err(|e| format!("CSV parse error: {}", e))?;
+        entries.push(entry);
+    }
+
+    Ok(entries)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::proto::musicfs::v1::BatchUpdateItem;
+    use musicfs_core::{AudioFormat, OriginId};
+    use std::path::Path;
+    use std::time::UNIX_EPOCH;
+    use tempfile::TempDir;
+    use tokio_stream::StreamExt;
+
+    fn create_test_db() -> (TempDir, Arc<Database>) {
+        let dir = TempDir::new().unwrap();
+        let db = Arc::new(Database::open_memory().unwrap());
+        (dir, db)
+    }
+
+    fn insert_test_file(db: &Database, vpath: &str) -> FileId {
+        let real_path = format!("/music{}", vpath);
+        db.upsert_file(
+            &OriginId::from("local"),
+            Path::new(&real_path),
+            &VirtualPath::new(vpath),
+            &AudioMeta {
+                title: Some("Test Track".to_string()),
+                artist: Some("Test Artist".to_string()),
+                album: Some("Test Album".to_string()),
+                format: AudioFormat::Flac,
+                ..Default::default()
+            },
+            UNIX_EPOCH,
+            1000,
+        )
+        .unwrap()
+    }
+
+    #[tokio::test]
+    async fn test_get_metadata_success() {
+        let (_dir, db) = create_test_db();
+        let vpath = "/Artist/Album/Track.flac";
+        insert_test_file(&db, vpath);
+
+        let service = MetadataServiceImpl::new(db);
+        let request = Request::new(GetMetadataRequest {
+            virtual_path: vpath.to_string(),
+        });
+
+        let response = service.get_metadata(request).await.unwrap();
+        let meta = response.into_inner();
+
+        assert_eq!(meta.title, Some("Test Track".to_string()));
+        assert_eq!(meta.artist, Some("Test Artist".to_string()));
+        assert_eq!(meta.album, Some("Test Album".to_string()));
+    }
+
+    #[tokio::test]
+    async fn test_get_metadata_not_found() {
+        let (_dir, db) = create_test_db();
+        let service = MetadataServiceImpl::new(db);
+
+        let request = Request::new(GetMetadataRequest {
+            virtual_path: "/nonexistent.flac".to_string(),
+        });
+
+        let result = service.get_metadata(request).await;
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().code(), tonic::Code::NotFound);
+    }
+
+    #[tokio::test]
+    async fn test_get_metadata_empty_path() {
+        let (_dir, db) = create_test_db();
+        let service = MetadataServiceImpl::new(db);
+
+        let request = Request::new(GetMetadataRequest {
+            virtual_path: String::new(),
+        });
+
+        let result = service.get_metadata(request).await;
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().code(), tonic::Code::InvalidArgument);
+    }
+
+    #[tokio::test]
+    async fn test_update_metadata_success() {
+        let (_dir, db) = create_test_db();
+        let vpath = "/Artist/Album/Track.flac";
+        let file_id = insert_test_file(&db, vpath);
+
+        let service = MetadataServiceImpl::new(db.clone());
+        let request = Request::new(UpdateMetadataRequest {
+            file_id: file_id.0,
+            title: Some("Updated Title".to_string()),
+            artist: Some("Updated Artist".to_string()),
+            ..Default::default()
+        });
+
+        let response = service.update_metadata(request).await.unwrap();
+        let result = response.into_inner();
+
+        assert!(result.success);
+        assert!(result.error_message.is_none());
+
+        let meta = db.get_file_metadata_row(file_id).unwrap();
+        assert_eq!(meta.title, Some("Updated Title".to_string()));
+        assert_eq!(meta.artist, Some("Updated Artist".to_string()));
+    }
+
+    #[tokio::test]
+    async fn test_update_metadata_invalid_id() {
+        let (_dir, db) = create_test_db();
+        let service = MetadataServiceImpl::new(db);
+
+        let request = Request::new(UpdateMetadataRequest {
+            file_id: 0,
+            title: Some("Title".to_string()),
+            ..Default::default()
+        });
+
+        let result = service.update_metadata(request).await;
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().code(), tonic::Code::InvalidArgument);
+    }
+
+    #[tokio::test]
+    async fn test_clear_overlay_success() {
+        let (_dir, db) = create_test_db();
+        let vpath = "/Artist/Album/Track.flac";
+        let file_id = insert_test_file(&db, vpath);
+
+        let service = MetadataServiceImpl::new(db.clone());
+        let request = Request::new(ClearOverlayRequest { file_id: file_id.0 });
+
+        let response = service.clear_overlay(request).await.unwrap();
+        let result = response.into_inner();
+
+        assert!(result.success);
+        assert!(result.error_message.is_none());
+
+        let meta = db.get_file_metadata_row(file_id).unwrap();
+        assert!(meta.title.is_none());
+        assert!(meta.artist.is_none());
+    }
+
+    #[tokio::test]
+    async fn test_clear_overlay_invalid_id() {
+        let (_dir, db) = create_test_db();
+        let service = MetadataServiceImpl::new(db);
+
+        let request = Request::new(ClearOverlayRequest { file_id: -1 });
+
+        let result = service.clear_overlay(request).await;
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().code(), tonic::Code::InvalidArgument);
+    }
+
+    #[tokio::test]
+    async fn test_batch_update_metadata() {
+        let (_dir, db) = create_test_db();
+        let file_id1 = insert_test_file(&db, "/Track1.flac");
+        let file_id2 = insert_test_file(&db, "/Track2.flac");
+
+        let service = MetadataServiceImpl::new(db.clone());
+        let request = Request::new(BatchUpdateRequest {
+            items: vec![
+                BatchUpdateItem {
+                    file_id: file_id1.0,
+                    metadata: Some(UpdateMetadataRequest {
+                        file_id: file_id1.0,
+                        title: Some("Batch Title 1".to_string()),
+                        ..Default::default()
+                    }),
+                },
+                BatchUpdateItem {
+                    file_id: file_id2.0,
+                    metadata: Some(UpdateMetadataRequest {
+                        file_id: file_id2.0,
+                        title: Some("Batch Title 2".to_string()),
+                        ..Default::default()
+                    }),
+                },
+            ],
+        });
+
+        let response = service.batch_update_metadata(request).await.unwrap();
+        let mut stream = response.into_inner();
+
+        let mut progress_count = 0;
+        while let Some(Ok(result)) = stream.next().await {
+            progress_count += 1;
+            assert!(result.error_message.is_none());
+        }
+
+        assert_eq!(progress_count, 2);
+
+        let meta1 = db.get_file_metadata_row(file_id1).unwrap();
+        assert_eq!(meta1.title, Some("Batch Title 1".to_string()));
+
+        let meta2 = db.get_file_metadata_row(file_id2).unwrap();
+        assert_eq!(meta2.title, Some("Batch Title 2".to_string()));
+    }
+
+    #[tokio::test]
+    async fn test_import_metadata_empty_path() {
+        let (_dir, db) = create_test_db();
+        let service = MetadataServiceImpl::new(db);
+
+        let request = Request::new(ImportMetadataRequest {
+            source_path: String::new(),
+            format: None,
+        });
+
+        let result = service.import_metadata(request).await;
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().code(), tonic::Code::InvalidArgument);
+    }
+
+    #[test]
+    fn test_parse_csv_entries() {
+        let csv_content = r#"virtual_path,title,artist,album
+/Track1.flac,Title 1,Artist 1,Album 1
+/Track2.flac,Title 2,Artist 2,Album 2"#;
+
+        let entries = parse_csv_entries(csv_content).unwrap();
+        assert_eq!(entries.len(), 2);
+        assert_eq!(entries[0].virtual_path, "/Track1.flac");
+        assert_eq!(entries[0].title, Some("Title 1".to_string()));
+        assert_eq!(entries[1].virtual_path, "/Track2.flac");
+        assert_eq!(entries[1].artist, Some("Artist 2".to_string()));
+    }
+
+    #[test]
+    fn test_import_entry_to_audio_meta() {
+        let entry = ImportEntry {
+            virtual_path: "/test.flac".to_string(),
+            title: Some("Test".to_string()),
+            artist: Some("Artist".to_string()),
+            album: None,
+            album_artist: None,
+            genre: Some("Rock".to_string()),
+            year: Some(2024),
+            track: Some(1),
+            disc: None,
+            date: None,
+            composer: None,
+            comment: None,
+        };
+
+        let meta = entry.to_audio_meta();
+        assert_eq!(meta.title, Some("Test".to_string()));
+        assert_eq!(meta.artist, Some("Artist".to_string()));
+        assert_eq!(meta.genre, Some("Rock".to_string()));
+        assert_eq!(meta.year, Some(2024));
+        assert_eq!(meta.track, Some(1));
+    }
+}