diff --git a/01.workspace/heave/examples/using_filters.rs b/01.workspace/heave/examples/using_filters.rs
index 6654d91..f74f2f4 100644
--- a/01.workspace/heave/examples/using_filters.rs
+++ b/01.workspace/heave/examples/using_filters.rs
@@ -55,7 +55,7 @@ fn main() {
     // Define the path for the SQLite database file.
     let db_path = "./using_filters.sqlite3";
     // Create a new `Catalog` instance with the specified database path.
-    let mut catalog = Catalog::new(db_path);
+    let catalog = Catalog::new(db_path);
     // Initialize the catalog, which sets up the database.
     catalog.init().unwrap();
     // Create some component instances.
diff --git a/01.workspace/heave/examples/working_with_many_types.rs b/01.workspace/heave/examples/working_with_many_types.rs
index 11a8454..d512081 100644
--- a/01.workspace/heave/examples/working_with_many_types.rs
+++ b/01.workspace/heave/examples/working_with_many_types.rs
@@ -98,7 +98,7 @@ fn main() -> Result<(), FailedTo> {
 
     // 1. Initialize and Persist Data
     println!("== 1. Storing different product types ==");
-    let mut catalog = Catalog::new(db_path);
+    let catalog = Catalog::new(db_path);
     catalog.init()?;
 
     let products_to_add = vec![
diff --git a/01.workspace/heave/src/imp/catalog_insert_many.rs b/01.workspace/heave/src/imp/catalog_insert_many.rs
index b65513c..6c7bc06 100644
--- a/01.workspace/heave/src/imp/catalog_insert_many.rs
+++ b/01.workspace/heave/src/imp/catalog_insert_many.rs
@@ -19,7 +19,7 @@ impl Catalog {
     ///
     /// Returns `Err(FailedTo)` if any of the underlying `upsert` operations fail.
     /// This could be due to issues like an object not having a valid ID.
-    pub fn insert_many(&mut self, objects: Vec<impl EAV>) -> Result<(), FailedTo> {
+    pub fn insert_many(&self, objects: Vec<impl EAV>) -> Result<(), FailedTo> {
         for object in objects {
             self.upsert(object)?;
         }
diff --git a/01.workspace/heave/src/imp/catalog_load.rs b/01.workspace/heave/src/imp/catalog_load.rs
index ce26f06..8754ee0 100644
--- a/01.workspace/heave/src/imp/catalog_load.rs
+++ b/01.workspace/heave/src/imp/catalog_load.rs
@@ -23,7 +23,7 @@ impl Catalog {
     ///
     /// Returns `Err(FailedTo::LoadFromDB)` if there is an issue loading entities
     /// from the database.
-    pub fn load<T>(&mut self) -> Result<(), FailedTo>
+    pub fn load<T>(&self) -> Result<(), FailedTo>
     where
         T: EAV,
     {
diff --git a/01.workspace/heave/src/tst/catalog_get_by.rs b/01.workspace/heave/src/tst/catalog_get_by.rs
index dfa67ac..d0dc440 100644
--- a/01.workspace/heave/src/tst/catalog_get_by.rs
+++ b/01.workspace/heave/src/tst/catalog_get_by.rs
@@ -11,7 +11,7 @@ mod tests {
     }
     #[test]
     fn get_by_finds_item() {
-        let mut catalog = catalog("get_by_finds_item");
+        let catalog = catalog("get_by_finds_item");
         let item1 = Item {
             id: "1".to_string(),
             name: "one".to_string(),
@@ -33,7 +33,7 @@ mod tests {
     }
     #[test]
     fn get_by_returns_none_when_no_match() {
-        let mut catalog = catalog("get_by_returns_none_when_no_match");
+        let catalog = catalog("get_by_returns_none_when_no_match");
         let item1 = Item {
             id: "1".to_string(),
             name: "one".to_string(),
@@ -51,7 +51,7 @@ mod tests {
     }
     #[test]
     fn get_by_multiple_matches() {
-        let mut catalog = catalog("get_by_multiple_matches");
+        let catalog = catalog("get_by_multiple_matches");
         let item1 = Item {
             id: "1".to_string(),
             name: "match".to_string(),
diff --git a/01.workspace/heave/src/tst/catalog_insert_many.rs b/01.workspace/heave/src/tst/catalog_insert_many.rs
index 50857de..6545418 100644
--- a/01.workspace/heave/src/tst/catalog_insert_many.rs
+++ b/01.workspace/heave/src/tst/catalog_insert_many.rs
@@ -4,7 +4,7 @@ mod tests {
     #[test]
     fn insert_many_should_add_all_entities() {
         // 'insert_many()': Should add all provided entities to the 'items' map.
-        let mut catalog = Catalog::new("dummy.db");
+        let catalog = Catalog::new("dummy.db");
         let items = vec![
             Item {
                 id: "item-1".to_string(),
diff --git a/01.workspace/heave/src/tst/catalog_integration.rs b/01.workspace/heave/src/tst/catalog_integration.rs
index bff5d8e..7c9e815 100644
--- a/01.workspace/heave/src/tst/catalog_integration.rs
+++ b/01.workspace/heave/src/tst/catalog_integration.rs
@@ -43,7 +43,7 @@ mod tests {
             std::fs::remove_file(path).unwrap();
         }
         // 1. 'init' -> 'insert_many' -> 'persist'
-        let mut catalog1 = Catalog::new(db_path);
+        let catalog1 = Catalog::new(db_path);
         catalog1.init().unwrap();
         let items_to_insert = vec![
             Item {
@@ -68,7 +68,7 @@ mod tests {
         let _ = catalog1.insert_many(items_to_insert.clone());
         catalog1.persist().unwrap();
         // 2. new catalog -> 'load_by_class' -> 'list_by_class'
-        let mut catalog2 = Catalog::new(db_path);
+        let catalog2 = Catalog::new(db_path);
         catalog2.load::<Item>().unwrap();
         let mut loaded_items: Vec<Item> = catalog2
             .list::<Item>()
diff --git a/01.workspace/heave/src/tst/catalog_load_by_class.rs b/01.workspace/heave/src/tst/catalog_load_by_class.rs
index 55f0089..a113fe7 100644
--- a/01.workspace/heave/src/tst/catalog_load_by_class.rs
+++ b/01.workspace/heave/src/tst/catalog_load_by_class.rs
@@ -35,7 +35,7 @@ mod tests {
         let _ = catalog1.upsert(item2.clone());
         catalog1.persist().unwrap();
         // 2. Create a new catalog and load the items by class
-        let mut catalog2 = Catalog::new(db_path);
+        let catalog2 = Catalog::new(db_path);
         let result = catalog2.load::<Item>();
         assert!(result.is_ok());
         // 3. Verify that all items of that class were loaded
@@ -84,7 +84,7 @@ mod tests {
         let _ = catalog1.upsert(item_in_db.clone());
         catalog1.persist().unwrap();
         // 2. Create a new catalog with a different in-memory version of the same item.
-        let mut catalog2 = Catalog::new(db_path);
+        let catalog2 = Catalog::new(db_path);
         let item_in_memory = Item {
             id: "item-1".to_string(),
             subclass: Some("subitem".to_string()),
@@ -128,7 +128,7 @@ mod tests {
             std::fs::remove_file(path).unwrap();
         }
         // 1. Create an empty, initialized database.
-        let mut catalog = Catalog::new(db_path);
+        let catalog = Catalog::new(db_path);
         catalog.init().unwrap();
         // 2. Attempt to load from the empty DB.
         let result = catalog.load::<Item>();
@@ -164,7 +164,7 @@ mod tests {
         // Using a directory as a path should cause a failure.
         let invalid_path = "target/test_dbs/a_directory_for_load_class_fail";
         std::fs::create_dir_all(invalid_path).unwrap();
-        let mut catalog = Catalog::new(invalid_path);
+        let catalog = Catalog::new(invalid_path);
         // Attempt to load from the invalid path.
         let result = catalog.load::<Item>();
         assert!(result.is_err());
diff --git a/01.workspace/heave/src/tst/catalog_load_by_filter.rs b/01.workspace/heave/src/tst/catalog_load_by_filter.rs
index 90b1919..d546d68 100644
--- a/01.workspace/heave/src/tst/catalog_load_by_filter.rs
+++ b/01.workspace/heave/src/tst/catalog_load_by_filter.rs
@@ -10,7 +10,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -57,7 +57,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -96,7 +96,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -183,7 +183,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -230,7 +230,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -277,7 +277,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -324,7 +324,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -383,7 +383,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -430,7 +430,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -489,7 +489,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -536,7 +536,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -595,7 +595,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -642,7 +642,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -701,7 +701,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -783,7 +783,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -845,7 +845,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -917,7 +917,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -980,7 +980,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1042,7 +1042,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1080,7 +1080,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1117,7 +1117,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1152,7 +1152,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1189,7 +1189,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1224,7 +1224,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1261,7 +1261,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1296,7 +1296,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1333,7 +1333,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
@@ -1368,7 +1368,7 @@ mod tests {
         if path.exists() {
             std::fs::remove_file(path).unwrap();
         }
-        let mut catalog_setup = Catalog::new(db_path);
+        let catalog_setup = Catalog::new(db_path);
         catalog_setup.init().unwrap();
         let items = vec![
             Item {
diff --git a/01.workspace/heave/src/tst/catalog_persist.rs b/01.workspace/heave/src/tst/catalog_persist.rs
index fb3be35..df027e5 100644
--- a/01.workspace/heave/src/tst/catalog_persist.rs
+++ b/01.workspace/heave/src/tst/catalog_persist.rs
@@ -166,7 +166,7 @@ mod tests {
         let _ = catalog_setup.upsert(item_to_keep.clone());
         catalog_setup.persist().unwrap();
         // 2. Manipulation: Load the data and perform mixed operations.
-        let mut catalog_ops = Catalog::new(db_path);
+        let catalog_ops = Catalog::new(db_path);
         catalog_ops.load::<Item>().unwrap(); // Load all items
         // A new item to be inserted.
         let item_to_add = Item {
@@ -196,7 +196,7 @@ mod tests {
         // 3. Execution: Persist all the changes in one go.
         catalog_ops.persist().unwrap();
         // 4. Verification: Load into a new catalog and check the final state of the DB.
-        let mut catalog_verify = Catalog::new(db_path);
+        let catalog_verify = Catalog::new(db_path);
         catalog_verify.load::<Item>().unwrap();
         // Check total count
         assert_eq!(catalog_verify.len().unwrap(), 3);
diff --git a/01.workspace/heave/src/tst/catalog_thread_safety.rs b/01.workspace/heave/src/tst/catalog_thread_safety.rs
index c1d2c3e..4e119e9 100644
--- a/01.workspace/heave/src/tst/catalog_thread_safety.rs
+++ b/01.workspace/heave/src/tst/catalog_thread_safety.rs
@@ -39,7 +39,7 @@ mod tests {
         let total_items = catalog.with_items(|items| Ok(items.len())).unwrap();
         assert_eq!(total_items, 1000);
         catalog.persist().unwrap();
-        let mut new_catalog = Catalog::new(db_path);
+        let new_catalog = Catalog::new(db_path);
         new_catalog.load::<Item>().unwrap();
         let total_items_after_load = new_catalog.with_items(|items| Ok(items.len())).unwrap();
         assert_eq!(total_items_after_load, 1000);