diff --git a/core/src/document/manager.rs b/core/src/document/manager.rs
index c17ac5d..29c7b0a 100644
--- a/core/src/document/manager.rs
+++ b/core/src/document/manager.rs
@@ -3,10 +3,10 @@
 //
 // Document Manager – single entry point via SessionCommand.
 
-use crate::document::command::SessionCommand;
 use crate::document::loader::{load_document, scan_directory_into};
-use crate::document::session::{CollectionKind, SessionData};
-use crate::document::store;
+use crate::document::session::command::SessionCommand;
+use crate::document::session::data::{CollectionKind, SessionData};
+use crate::document::session::store;
 use crate::document::DocumentContent;
 use crate::error::Error;
 use log::warn;
@@ -38,6 +38,7 @@ impl Default for DocumentManager {
 }
 
 impl DocumentManager {
+    #[must_use]
     pub fn new() -> Self {
         Self::default()
     }
@@ -87,11 +88,13 @@ impl DocumentManager {
     }
 
     /// Read-only access to a session by name.
+    #[must_use]
     pub fn session(&self, name: &str) -> Option<&SessionData> {
         self.sessions.iter().find(|s| s.name == name)
     }
 
     /// Read-only access to the active session.
+    #[must_use]
     pub fn active_session(&self) -> Option<&SessionData> {
         let name = self.active_session_name.as_deref()?;
         self.sessions.iter().find(|s| s.name == name)
@@ -118,7 +121,7 @@ impl DocumentManager {
     fn open_session_file(&mut self, path: &Path) {
         match store::load_sessions(path) {
             Ok(mut loaded) => {
-                for session in loaded.iter_mut() {
+                for session in &mut loaded {
                     match session.kind {
                         CollectionKind::DirectoryBrowser => {
                             if let Some(dir) = session.path.clone() {
@@ -214,29 +217,23 @@ impl DocumentManager {
         source_index: usize,
         target_index: usize,
     ) {
-        let item = match self.session(source_name) {
-            Some(s) => match s.items.get(source_index) {
+        let item = if let Some(s) = self.session(source_name) {
+            match s.items.get(source_index) {
                 Some(item) => item.clone(),
                 None => return,
-            },
-            None => {
-                self.state = DocumentState::Error(Error::Session(format!(
-                    "Source session '{}' not found",
-                    source_name
-                )));
-                return;
             }
+        } else {
+            self.state = DocumentState::Error(Error::Session(format!(
+                "Source session '{source_name}' not found"
+            )));
+            return;
         };
 
-        let target = match self.session(target_name) {
-            Some(s) => s,
-            None => {
-                self.state = DocumentState::Error(Error::Session(format!(
-                    "Target session '{}' not found",
-                    target_name
-                )));
-                return;
-            }
+        let Some(target) = self.session(target_name) else {
+            self.state = DocumentState::Error(Error::Session(format!(
+                "Target session '{target_name}' not found"
+            )));
+            return;
         };
 
         if target.kind != CollectionKind::DocumentCollection {
@@ -262,18 +259,23 @@ impl DocumentManager {
     }
 
     fn remove_document(&mut self, index: usize) {
-        let session = match self.active_session_mut() {
-            Some(s) => s,
+        // Check kind before taking a mutable borrow on the session, so that
+        // self.state can be set without conflicting borrows.
+        match self.active_session().map(|s| s.kind.clone()) {
             None => return,
-        };
-
-        if session.kind != CollectionKind::DocumentCollection {
-            self.state = DocumentState::Error(Error::Session(
-                "Can only remove from a DocumentCollection".to_string(),
-            ));
-            return;
+            Some(CollectionKind::DirectoryBrowser) => {
+                self.state = DocumentState::Error(Error::Session(
+                    "Can only remove from a DocumentCollection".to_string(),
+                ));
+                return;
+            }
+            Some(CollectionKind::DocumentCollection) => {}
         }
 
+        let Some(session) = self.active_session_mut() else {
+            return;
+        };
+
         if index >= session.items.len() {
             return;
         }