diff --git a/src/fetch.rs b/src/fetch.rs
index 214b4eb..9e1d618 100644
--- a/src/fetch.rs
+++ b/src/fetch.rs
@@ -1,10 +1,13 @@
 use std::{
   fs,
   path::{Path, PathBuf},
+  sync::Arc,
 };
 
-use indicatif::{ProgressBar, ProgressStyle};
+use futures::future::join_all;
+use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
 use reqwest::Client;
+use tokio::sync::Semaphore;
 
 use crate::{
   error::{PakkerError, Result},
@@ -12,14 +15,19 @@ use crate::{
   utils::verify_hash,
 };
 
+/// Maximum number of concurrent downloads
+const MAX_CONCURRENT_DOWNLOADS: usize = 8;
+
 pub struct Fetcher {
   client:    Client,
   base_path: PathBuf,
+  shelve:    bool,
 }
 
 pub struct FileFetcher {
   client:    Client,
   base_path: PathBuf,
+  shelve:    bool,
 }
 
 impl Fetcher {
@@ -27,9 +35,15 @@ impl Fetcher {
     Self {
       client:    Client::new(),
       base_path: base_path.as_ref().to_path_buf(),
+      shelve:    false,
     }
   }
 
+  pub const fn with_shelve(mut self, shelve: bool) -> Self {
+    self.shelve = shelve;
+    self
+  }
+
   pub async fn fetch_all(
     &self,
     lockfile: &LockFile,
@@ -38,6 +52,7 @@ impl Fetcher {
     let fetcher = FileFetcher {
       client:    self.client.clone(),
       base_path: self.base_path.clone(),
+      shelve:    self.shelve,
     };
     fetcher.fetch_all(lockfile, config).await
   }
@@ -48,7 +63,7 @@ impl Fetcher {
 }
 
 impl FileFetcher {
-  /// Fetch all project files according to lockfile
+  /// Fetch all project files according to lockfile with parallel downloads
   pub async fn fetch_all(
     &self,
     lockfile: &LockFile,
@@ -58,25 +73,104 @@ impl FileFetcher {
       lockfile.projects.iter().filter(|p| p.export).collect();
 
     let total = exportable_projects.len();
-    let spinner = ProgressBar::new(total as u64);
-    spinner.set_style(
-      ProgressStyle::default_spinner()
-        .template("{spinner:.green} {msg}")
-        .unwrap(),
-    );
 
-    for (idx, project) in exportable_projects.iter().enumerate() {
-      let name = project
-        .name
-        .values()
-        .next()
-        .map_or("unknown", std::string::String::as_str);
-
-      spinner.set_message(format!("Fetching {} ({}/{})", name, idx + 1, total));
-      self.fetch_project(project, lockfile, config).await?;
+    if total == 0 {
+      log::info!("No projects to fetch");
+      return Ok(());
     }
 
-    spinner.finish_with_message("All projects fetched");
+    // Set up multi-progress for parallel download tracking
+    let multi_progress = MultiProgress::new();
+    let overall_bar = multi_progress.add(ProgressBar::new(total as u64));
+    overall_bar.set_style(
+      ProgressStyle::default_bar()
+        .template("{spinner:.green} [{bar:40.cyan/blue}] {pos}/{len} {msg}")
+        .unwrap()
+        .progress_chars("#>-"),
+    );
+    overall_bar.set_message("Fetching projects...");
+
+    // Use a semaphore to limit concurrent downloads
+    let semaphore = Arc::new(Semaphore::new(MAX_CONCURRENT_DOWNLOADS));
+
+    // Prepare download tasks
+    let download_tasks: Vec<_> = exportable_projects
+      .iter()
+      .map(|project| {
+        let semaphore = Arc::clone(&semaphore);
+        let client = self.client.clone();
+        let base_path = self.base_path.clone();
+        let lockfile = lockfile.clone();
+        let config = config.clone();
+        let project = (*project).clone();
+        let overall_bar = overall_bar.clone();
+
+        async move {
+          // Acquire semaphore permit to limit concurrency
+          let _permit = semaphore.acquire().await.map_err(|_| {
+            PakkerError::InternalError("Semaphore acquisition failed".into())
+          })?;
+
+          let name = project
+            .name
+            .values()
+            .next()
+            .map_or("unknown".to_string(), std::clone::Clone::clone);
+
+          let fetcher = Self {
+            client,
+            base_path,
+            shelve: false, // Shelving happens at sync level, not per-project
+          };
+
+          let result =
+            fetcher.fetch_project(&project, &lockfile, &config).await;
+
+          // Update progress bar
+          overall_bar.inc(1);
+
+          match &result {
+            Ok(()) => {
+              log::debug!("Successfully fetched: {name}");
+            },
+            Err(e) => {
+              log::error!("Failed to fetch {name}: {e}");
+            },
+          }
+
+          result.map(|()| name)
+        }
+      })
+      .collect();
+
+    // Execute all downloads in parallel (limited by semaphore)
+    let results = join_all(download_tasks).await;
+
+    overall_bar.finish_with_message("All projects fetched");
+
+    // Collect and report errors
+    let mut errors = Vec::new();
+    let mut success_count = 0;
+
+    for result in results {
+      match result {
+        Ok(_) => success_count += 1,
+        Err(e) => errors.push(e),
+      }
+    }
+
+    log::info!("Fetch complete: {success_count}/{total} successful");
+
+    if !errors.is_empty() {
+      // Return the first error, but log all of them
+      for (idx, error) in errors.iter().enumerate() {
+        log::error!("Download error {}: {}", idx + 1, error);
+      }
+      return Err(errors.remove(0));
+    }
+
+    // Handle unknown files (shelve or delete)
+    self.handle_unknown_files(lockfile, config)?;
 
     // Sync overrides
     self.sync_overrides(config)?;
@@ -84,6 +178,117 @@ impl FileFetcher {
     Ok(())
   }
 
+  /// Handle unknown project files that aren't in the lockfile.
+  /// If shelve is true, moves them to a shelf directory.
+  /// Otherwise, deletes them.
+  fn handle_unknown_files(
+    &self,
+    lockfile: &LockFile,
+    config: &Config,
+  ) -> Result<()> {
+    // Collect all expected file names from lockfile
+    let expected_files: std::collections::HashSet<String> = lockfile
+      .projects
+      .iter()
+      .filter(|p| p.export)
+      .filter_map(|p| p.files.first().map(|f| f.file_name.clone()))
+      .collect();
+
+    // Check each project type directory
+    let project_dirs = [
+      (
+        "mod",
+        self.get_default_path(&crate::model::ProjectType::Mod),
+      ),
+      (
+        "resource-pack",
+        self.get_default_path(&crate::model::ProjectType::ResourcePack),
+      ),
+      (
+        "shader",
+        self.get_default_path(&crate::model::ProjectType::Shader),
+      ),
+      (
+        "data-pack",
+        self.get_default_path(&crate::model::ProjectType::DataPack),
+      ),
+      (
+        "world",
+        self.get_default_path(&crate::model::ProjectType::World),
+      ),
+    ];
+
+    // Also check custom paths from config
+    let mut dirs_to_check: Vec<PathBuf> = project_dirs
+      .iter()
+      .map(|(_, dir)| self.base_path.join(dir))
+      .collect();
+
+    for custom_path in config.paths.values() {
+      dirs_to_check.push(self.base_path.join(custom_path));
+    }
+
+    let shelf_dir = self.base_path.join(".pakker-shelf");
+    let mut shelved_count = 0;
+    let mut deleted_count = 0;
+
+    for dir in dirs_to_check {
+      if !dir.exists() {
+        continue;
+      }
+
+      let entries = match fs::read_dir(&dir) {
+        Ok(e) => e,
+        Err(_) => continue,
+      };
+
+      for entry in entries.flatten() {
+        let path = entry.path();
+        if !path.is_file() {
+          continue;
+        }
+
+        let file_name = match path.file_name().and_then(|n| n.to_str()) {
+          Some(name) => name.to_string(),
+          None => continue,
+        };
+
+        // Skip if file is expected
+        if expected_files.contains(&file_name) {
+          continue;
+        }
+
+        // Skip non-jar files (might be configs, etc.)
+        if !file_name.ends_with(".jar") {
+          continue;
+        }
+
+        if self.shelve {
+          // Move to shelf
+          fs::create_dir_all(&shelf_dir)?;
+          let shelf_path = shelf_dir.join(&file_name);
+          fs::rename(&path, &shelf_path)?;
+          log::info!("Shelved unknown file: {file_name} -> .pakker-shelf/");
+          shelved_count += 1;
+        } else {
+          // Delete unknown file
+          fs::remove_file(&path)?;
+          log::info!("Deleted unknown file: {file_name}");
+          deleted_count += 1;
+        }
+      }
+    }
+
+    if shelved_count > 0 {
+      log::info!("Shelved {shelved_count} unknown file(s) to .pakker-shelf/");
+    }
+    if deleted_count > 0 {
+      log::info!("Deleted {deleted_count} unknown file(s)");
+    }
+
+    Ok(())
+  }
+
   /// Fetch files for a single project
   pub async fn fetch_project(
     &self,
diff --git a/src/ipc.rs b/src/ipc.rs
index 2039ec9..d1aceaa 100644
--- a/src/ipc.rs
+++ b/src/ipc.rs
@@ -12,7 +12,7 @@ use std::{
   fs::{self, File, OpenOptions},
   io::Write,
   os::unix::{fs::PermissionsExt, io::AsRawFd},
-  path::PathBuf,
+  path::{Path, PathBuf},
   time::{Duration, SystemTime},
 };
 
@@ -108,7 +108,7 @@ impl IpcCoordinator {
 
   /// Extract modpack hash from pakku.json's parentLockHash field.
   /// This is the authoritative content hash for the modpack (Nix-style).
-  fn get_modpack_hash(working_dir: &PathBuf) -> Result<String, IpcError> {
+  fn get_modpack_hash(working_dir: &Path) -> Result<String, IpcError> {
     let pakku_path = working_dir.join("pakku.json");
 
     if !pakku_path.exists() {
@@ -147,7 +147,7 @@ impl IpcCoordinator {
 
   /// Create a new IPC coordinator for the given modpack directory.
   /// Uses parentLockHash from pakku.json to identify the modpack.
-  pub fn new(working_dir: &PathBuf) -> Result<Self, IpcError> {
+  pub fn new(working_dir: &Path) -> Result<Self, IpcError> {
     let modpack_hash = Self::get_modpack_hash(working_dir)?;
     let ipc_base = Self::get_ipc_base_dir();
     let ipc_dir = ipc_base.join(&modpack_hash);
@@ -187,6 +187,7 @@ impl IpcCoordinator {
       .read(true)
       .write(true)
       .create(true)
+      .truncate(false)
       .open(&self.ops_file)
       .map_err(|e| IpcError::InvalidFormat(e.to_string()))?;