diff --git a/src/application/ports/folder_ports.rs b/src/application/ports/folder_ports.rs
index dfae242e..76b2c6f0 100644
--- a/src/application/ports/folder_ports.rs
+++ b/src/application/ports/folder_ports.rs
@@ -44,11 +44,8 @@ pub trait FolderUseCase: Send + Sync + 'static {
     /// folder (docs/plan/drive.md §10). Pre-D0 the wrapper name
     /// embedded the username and made the path globally unique;
     /// post-D0 the caller_id filter is required.
-    async fn get_folder_by_path(
-        &self,
-        path: &str,
-        user_id: Uuid,
-    ) -> Result<FolderDto, DomainError>;
+    async fn get_folder_by_path(&self, path: &str, user_id: Uuid)
+    -> Result<FolderDto, DomainError>;
 
     /// Lists folders within a parent folder
     async fn list_folders(&self, parent_id: Option<&str>) -> Result<Vec<FolderDto>, DomainError>;
diff --git a/src/infrastructure/repositories/pg/drive_pg_repository.rs b/src/infrastructure/repositories/pg/drive_pg_repository.rs
index 12a60424..f02079b4 100644
--- a/src/infrastructure/repositories/pg/drive_pg_repository.rs
+++ b/src/infrastructure/repositories/pg/drive_pg_repository.rs
@@ -127,14 +127,12 @@ impl DriveRepository for DrivePgRepository {
         .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.folder", e))?;
 
         // 3. Close the other side of the circular reference.
-        sqlx::query(
-            r#"UPDATE storage.drives SET root_folder_id = $1 WHERE id = $2"#,
-        )
-        .bind(folder_id)
-        .bind(drive_id)
-        .execute(&mut *tx)
-        .await
-        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.wire", e))?;
+        sqlx::query(r#"UPDATE storage.drives SET root_folder_id = $1 WHERE id = $2"#)
+            .bind(folder_id)
+            .bind(drive_id)
+            .execute(&mut *tx)
+            .await
+            .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.wire", e))?;
 
         // 4. Owner role_grant — the caller becomes the drive's sole
         //    owner (single-user invariant on personal drives, §2).
diff --git a/src/interfaces/api/handlers/webdav_handler.rs b/src/interfaces/api/handlers/webdav_handler.rs
index ea9f8343..e6b535fd 100644
--- a/src/interfaces/api/handlers/webdav_handler.rs
+++ b/src/interfaces/api/handlers/webdav_handler.rs
@@ -1208,7 +1208,10 @@ async fn handle_mkcol(
         }
         accumulated_path.push_str(segment);
 
-        match folder_service.get_folder_by_path(&accumulated_path, user.id).await {
+        match folder_service
+            .get_folder_by_path(&accumulated_path, user.id)
+            .await
+        {
             Ok(existing) => {
                 parent_id = Some(existing.id);
             }
@@ -1443,7 +1446,9 @@ async fn handle_move(
             let move_dto = crate::application::dtos::folder_dto::MoveFolderDto {
                 parent_id: if dest_parent_path.is_empty() {
                     None
-                } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path, user.id).await
+                } else if let Ok(parent) = folder_service
+                    .get_folder_by_path(dest_parent_path, user.id)
+                    .await
                 {
                     assert_owner(
                         parent.owner_id.as_deref(),
@@ -1644,7 +1649,10 @@ async fn handle_copy(
 
     let target_parent_id = if dest_parent_path.is_empty() {
         None
-    } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path, user.id).await {
+    } else if let Ok(parent) = folder_service
+        .get_folder_by_path(dest_parent_path, user.id)
+        .await
+    {
         assert_owner(
             parent.owner_id.as_deref(),
             &user.id.to_string(),
diff --git a/src/interfaces/nextcloud/basic_auth_middleware.rs b/src/interfaces/nextcloud/basic_auth_middleware.rs
index 726e786f..6fe930bb 100644
--- a/src/interfaces/nextcloud/basic_auth_middleware.rs
+++ b/src/interfaces/nextcloud/basic_auth_middleware.rs
@@ -168,22 +168,31 @@ pub async fn basic_auth_middleware(
             };
 
             // ── Resolve chroot from the Basic Auth drive marker ─────
-            // No marker → user's home folder. With a marker →
+            // No marker → caller's default personal drive's root folder
+            // (post-D0 every internal user has one — provisioned by the
+            // lifecycle hook via the atomic four-write transaction in
+            // §3 of docs/plan/drive.md). With a marker →
             // `get_folder_with_perms` enforces per-folder access (404
             // anti-enumeration on miss / no-read). Today this is the
             // sole chroot source; tomorrow it'll come from the
             // app-password row instead.
+            //
+            // Pre-D0 this lookup name-matched `"My Folder - <username>"`
+            // against the user's root folders; that broke after the
+            // wrapper was renamed to `"Personal"` and shared across all
+            // users — name-matching was the wrong axis. The drive lookup
+            // is the right one: name-independent, secondary-drive-safe.
             use crate::application::ports::folder_ports::FolderUseCase;
+            use crate::domain::repositories::drive_repository::DriveRepository;
             let chroot = match drive_marker.as_deref() {
                 None => {
-                    let expected = format!("My Folder - {}", current_user.username);
-                    match state
-                        .applications
-                        .folder_service
-                        .list_folders_with_perms(None, current_user.id)
-                        .await
-                    {
-                        Ok(folders) => folders.into_iter().find(|f| f.name == expected),
+                    match state.drive_repo.find_default_for_user(current_user.id).await {
+                        Ok(drive_with_name) => state
+                            .applications
+                            .folder_service
+                            .get_folder(&drive_with_name.drive.root_folder_id.to_string())
+                            .await
+                            .ok(),
                         Err(_) => None,
                     }
                 }