diff --git a/src/application/services/file_upload_service.rs b/src/application/services/file_upload_service.rs
index a6ac8209..f3eb48f7 100644
--- a/src/application/services/file_upload_service.rs
+++ b/src/application/services/file_upload_service.rs
@@ -353,16 +353,24 @@ impl FileUploadService {
     /// the target drive is `kind='personal'`, so a shared-drive upload
     /// still doesn't touch any user envelope.
     fn maybe_update_storage_usage(&self, file: &FileDto, caller_id: Uuid) {
+        self.apply_storage_usage_delta(file.size as i64, &file.folder_id, caller_id);
+    }
+
+    /// Same as [`Self::maybe_update_storage_usage`] but takes an explicit
+    /// `delta` instead of assuming "whole file size" — the overwrite path
+    /// (`update_file_streaming_with_perms`) needs `new_size - old_size`,
+    /// not the new size added a second time on top of what the old
+    /// content already contributed.
+    fn apply_storage_usage_delta(&self, delta: i64, folder_id: &Option<String>, caller_id: Uuid) {
         let Some(storage_service) = &self.storage_usage_service else {
             return;
         };
-        let delta = file.size as i64;
+        if delta == 0 {
+            return;
+        }
 
         let owner = Some(caller_id);
-        let folder = file
-            .folder_id
-            .as_deref()
-            .and_then(|s| Uuid::parse_str(s).ok());
+        let folder = folder_id.as_deref().and_then(|s| Uuid::parse_str(s).ok());
 
         // Per-user delta — only when the target drive is `kind='personal'`.
         // The user envelope (`auth.users.storage_quota_bytes`) caps the SUM
@@ -496,6 +504,7 @@ impl FileUploadUseCase for FileUploadService {
                 )
                 .await?;
 
+            let old_size = file.size();
             let file_id = file.id().to_string();
             let (new_hash, updated_at) = self
                 .file_write
@@ -531,6 +540,11 @@ impl FileUploadUseCase for FileUploadService {
                 DomainError::internal_error("FileUpload", format!("rebuild entity: {e}"))
             })?;
             let dto = FileDto::from(updated);
+            self.apply_storage_usage_delta(
+                blob.size as i64 - old_size as i64,
+                &dto.folder_id,
+                caller_id,
+            );
             if let Some(hook) = &self.file_lifecycle_hook {
                 hook.on_file_updated(&file_id, &dto.content_hash, content_type);
             }
@@ -603,6 +617,7 @@ impl FileUploadUseCase for FileUploadService {
             )
             .await?;
         let dto = FileDto::from(created);
+        self.maybe_update_storage_usage(&dto, caller_id);
         if let Some(hook) = &self.file_lifecycle_hook {
             hook.on_file_created(&dto.id, &dto.content_hash, content_type, is_new_blob);
         }
diff --git a/tests/api/nc_webdav_quota_properties.hurl b/tests/api/nc_webdav_quota_properties.hurl
index 928f14c4..99775a07 100644
--- a/tests/api/nc_webdav_quota_properties.hurl
+++ b/tests/api/nc_webdav_quota_properties.hurl
@@ -120,8 +120,10 @@ ncq_root_folder_id: jsonpath "$.root_folder_id"
 # ─────────────────────────────────────────────────────────────
 PROPFIND {{base_url}}/remote.php/dav/files/{{ncq_nc_username}}~{{ncq_root_folder_id}}/
 Depth: 0
+[Options]
+variable: ncq_composite_user={{ncq_nc_username}}~{{ncq_root_folder_id}}
 [BasicAuth]
-{{ncq_nc_username}}~{{ncq_root_folder_id}}: {{ncq_nc_password}}
+{{ncq_composite_user}}: {{ncq_nc_password}}
 
 HTTP 207
 [Asserts]
@@ -135,8 +137,10 @@ xpath "number(//*[local-name()='quota-available-bytes'])" == 500
 # ─────────────────────────────────────────────────────────────
 PUT {{base_url}}/remote.php/dav/files/{{ncq_nc_username}}~{{ncq_root_folder_id}}/quota-probe.txt
 Content-Type: text/plain
+[Options]
+variable: ncq_composite_user={{ncq_nc_username}}~{{ncq_root_folder_id}}
 [BasicAuth]
-{{ncq_nc_username}}~{{ncq_root_folder_id}}: {{ncq_nc_password}}
+{{ncq_composite_user}}: {{ncq_nc_password}}
 ```
 32-byte-ish payload for nc
 ```
@@ -144,10 +148,18 @@ Content-Type: text/plain
 HTTP 201
 
 
+# The drive-usage bump is fire-and-forget on a tokio task (see
+# `file_upload_service.rs::maybe_update_storage_usage`), so retry
+# until `used_bytes` catches up — same shape as `drive_quota.hurl`
+# Step 5.
 PROPFIND {{base_url}}/remote.php/dav/files/{{ncq_nc_username}}~{{ncq_root_folder_id}}/
 Depth: 0
+[Options]
+variable: ncq_composite_user={{ncq_nc_username}}~{{ncq_root_folder_id}}
+retry: 10
+retry-interval: 200ms
 [BasicAuth]
-{{ncq_nc_username}}~{{ncq_root_folder_id}}: {{ncq_nc_password}}
+{{ncq_composite_user}}: {{ncq_nc_password}}
 
 HTTP 207
 [Asserts]
diff --git a/tests/api/webdav_quota_properties.hurl b/tests/api/webdav_quota_properties.hurl
index e7d48f93..d092578f 100644
--- a/tests/api/webdav_quota_properties.hurl
+++ b/tests/api/webdav_quota_properties.hurl
@@ -203,10 +203,18 @@ Content-Type: text/plain
 HTTP 201
 
 
+# The drive-usage bump is fire-and-forget on a tokio task (see
+# `file_upload_service.rs::maybe_update_storage_usage`), so the SQL
+# UPDATE may not have landed yet when the PUT above returned. Retry
+# the PROPFIND until `used_bytes` catches up — same shape as
+# `drive_quota.hurl` Step 5.
 PROPFIND {{base_url}}/webdav/@drive/{{wq_drive_id}}/
 Authorization: Bearer {{wq_owner_token}}
 Depth: 0
 Content-Type: application/xml; charset=utf-8
+[Options]
+retry: 10
+retry-interval: 200ms
 ```
 <?xml version="1.0" encoding="utf-8"?>
 <D:propfind xmlns:D="DAV:">