diff --git a/src/application/services/trash_service.rs b/src/application/services/trash_service.rs
index 5892f962..aa09dc32 100644
--- a/src/application/services/trash_service.rs
+++ b/src/application/services/trash_service.rs
@@ -662,22 +662,25 @@ impl TrashUseCase for TrashService {
     async fn empty_trash_for_drive(&self, user_id: Uuid, drive_id: Uuid) -> Result<()> {
         // Per-drive trash empty — the Drive group-by on `/trash` exposes
         // this as a per-row affordance so multi-drive owners can clear
-        // one drive without touching the others. Refuses with
-        // `NotFound` (anti-enum) when the caller lacks Delete on the
-        // named drive — same shape as the user-facing drive listing
-        // would emit for an unknown id.
-        let allowed = self.drives_with_delete_for(user_id).await?;
-        if !allowed.contains(&drive_id) {
-            tracing::info!(
-                target: "audit",
-                event = "trash.empty_drive_rejected",
-                reason = "no_delete_on_drive",
-                user_id = %user_id,
-                drive_id = %drive_id,
-                "👮🏻‍♂️ refused per-drive empty — caller lacks Delete on this drive",
-            );
-            return Err(DomainError::not_found("Drive", drive_id.to_string()));
-        }
+        // one drive without touching the others.
+        //
+        // Route through `authz.require(Delete, Drive)` so the denial
+        // shape stays consistent with every other write verb: 403 when
+        // the caller has Read on the drive (viewer/editor holding no
+        // Delete), 404 when they don't (anti-enum). Before 2026-07-16
+        // this method rolled its own `drives_with_delete_for` check +
+        // hardcoded `NotFound` — that predated the graduated-denial
+        // engine change and returned 404 unconditionally even for a
+        // Viewer who could see the drive in `/api/drives`. The engine
+        // now emits `authz.denied` with `visibility="visible"|"hidden"`
+        // and the standard mapping renders it as 403 or 404.
+        self.authz
+            .require(
+                Subject::User(user_id),
+                Permission::Delete,
+                Resource::Drive(drive_id),
+            )
+            .await?;
         info!("Emptying trash for drive {} (user {})", drive_id, user_id);
         self.clear_trash_in(&[drive_id], user_id).await
     }
diff --git a/src/interfaces/nextcloud/uploads_handler.rs b/src/interfaces/nextcloud/uploads_handler.rs
index 194b9c8a..d4761c47 100644
--- a/src/interfaces/nextcloud/uploads_handler.rs
+++ b/src/interfaces/nextcloud/uploads_handler.rs
@@ -6,7 +6,7 @@ use axum::{
 use std::sync::Arc;
 use uuid::Uuid;
 
-use crate::application::ports::file_ports::{FileRetrievalUseCase, FileUploadUseCase};
+use crate::application::ports::file_ports::FileUploadUseCase;
 use crate::application::ports::storage_ports::StorageUsagePort;
 use crate::common::di::AppState;
 use crate::common::mime_detect::filename_from_path;
@@ -402,8 +402,6 @@ async fn handle_assemble(
         .map_err(|e| AppError::internal_error(format!("Failed to list chunks: {}", e)))?;
 
     let upload_service = &state.applications.file_upload_service;
-    let file_service = &state.applications.file_retrieval_service;
-    let folder_service = &state.applications.folder_service;
 
     // Path-based lookups below scope by `drive_id`. The NC session's
     // chroot is always populated for path-scoped handlers (see
@@ -433,64 +431,41 @@ async fn handle_assemble(
     .await?;
     let content_type = ingested.content_type.clone();
 
-    // Check if file exists (update vs create).
-    let existing = file_service
-        .get_file_by_path(&internal_path, drive_id)
-        .await;
-
-    let etag: Option<String> = if existing.is_ok() {
-        let dto = upload_service
-            .update_file_streaming_with_perms(
-                &internal_path,
-                drive_id,
-                ingested.stored(),
-                &content_type,
-                oc_mtime,
-                user.id,
-            )
-            .await
-            .map_err(|e| AppError::internal_error(format!("Failed to update file: {}", e)))?;
-
-        Some(dto.etag)
-    } else {
-        // New-file branch: resolve the parent folder by path and register
-        // the file row against the already-ingested blob.
-        let (parent_sub, filename) = match dest_subpath.rsplit_once('/') {
-            Some((p, n)) => (p, n),
-            None => ("", dest_subpath.as_str()),
-        };
-        let parent_internal =
-            crate::interfaces::nextcloud::webdav_handler::nc_to_internal_path(chroot, parent_sub)?;
-        let parent_internal = parent_internal.trim_end_matches('/');
-
-        use crate::application::ports::folder_ports::FolderUseCase;
-        let parent_folder = match folder_service
-            .get_folder_by_path(parent_internal, drive_id)
-            .await
-        {
-            Ok(folder) => folder,
-            Err(e) => {
-                discard_ingested(&state.core.dedup_service, &ingested).await;
-                return Err(AppError::internal_error(format!(
-                    "Parent folder lookup failed: {}",
-                    e
-                )));
-            }
-        };
-
-        let dto = upload_service
-            .upload_file_streaming(
-                filename.to_string(),
-                Some(parent_folder.id),
-                content_type.to_string(),
-                ingested.stored(),
-                user.id,
-            )
-            .await
-            .map_err(|e| AppError::internal_error(format!("Failed to create file: {}", e)))?;
-
-        Some(dto.etag)
+    // AuthZ audit #12 (2026-07-12): the previous shape branched on
+    // file existence — `update_file_streaming_with_perms` on the
+    // overwrite path (correct), plain `upload_file_streaming` on
+    // the create path (NO `authz.require`). Viewer/Commenter on a
+    // shared drive could MKCOL → PUT chunks → MOVE and land a
+    // brand-new file, skipping the `Create`-on-parent-folder gate.
+    //
+    // `update_file_streaming_with_perms` handles both branches
+    // atomically: `Update` on the existing file OR `Create` on the
+    // parent folder / drive root (per the service's own internal
+    // fork). Funneling everything through the one method also
+    // deletes the duplicated parent-folder lookup that used to
+    // live here.
+    //
+    // AuthZ audit #2 (2026-07-12): route DomainError through
+    // `AppError::from` so authz denials keep the graduated 403/404
+    // shape instead of collapsing into 500.
+    let dto = match upload_service
+        .update_file_streaming_with_perms(
+            &internal_path,
+            drive_id,
+            ingested.stored(),
+            &content_type,
+            oc_mtime,
+            user.id,
+        )
+        .await
+    {
+        Ok(dto) => dto,
+        Err(e) => {
+            discard_ingested(&state.core.dedup_service, &ingested).await;
+            return Err(AppError::from(e));
+        }
     };
+    let etag: Option<String> = Some(dto.etag);
 
     // Cleanup session.
     let _ = nc.chunked_uploads.cleanup(&user.username, upload_id).await;
diff --git a/tests/api/trash_per_drive.hurl b/tests/api/trash_per_drive.hurl
index f8cd89d0..4b0fbdeb 100644
--- a/tests/api/trash_per_drive.hurl
+++ b/tests/api/trash_per_drive.hurl
@@ -190,8 +190,12 @@ HTTP 404
 
 # ─────────────────────────────────────────────────────────────
 # Step 9 — Provision a Viewer of the shared drive (`tpd_viewer`),
-#          then assert the per-drive empty refuses for Viewer / Editor
-#          / non-member callers. Each refusal is 404 (anti-enum).
+#          then assert the per-drive empty refuses for Viewer /
+#          Editor / non-member callers. Graduated denial (see
+#          [[project_authz_require_graduated_denial]]): the Viewer
+#          and Editor tests get 403 because they hold Read on the
+#          drive; the non-member fallback keeps the 404 anti-enum
+#          shape (no Read = no existence oracle).
 # ─────────────────────────────────────────────────────────────
 POST {{base_url}}/api/admin/users
 Authorization: Bearer {{admin_token}}
@@ -249,17 +253,19 @@ Authorization: Bearer {{owner_token}}
 HTTP 204
 
 
-# Test 4 — Viewer cannot empty the drive's trash.
+# Test 4 — Viewer cannot empty the drive's trash. Viewer has Read
+#          on the drive → graduated denial returns 403.
 DELETE {{base_url}}/api/trash/drive/{{shared_drive_id}}
 Authorization: Bearer {{viewer_token}}
 
-HTTP 404
+HTTP 403
 
 
 # ─────────────────────────────────────────────────────────────
 # Step 10 — Test 5: Editor cannot either.
 #           Promote tpd_viewer to Editor; same refusal. Confirms
-#           `Delete` isn't in the Editor bundle.
+#           `Delete` isn't in the Editor bundle. Editor has Read →
+#           graduated denial returns 403.
 # ─────────────────────────────────────────────────────────────
 PATCH {{base_url}}/api/drives/{{shared_drive_id}}/members/user/{{viewer_user_id}}
 Authorization: Bearer {{owner_token}}
@@ -272,7 +278,7 @@ HTTP 200
 DELETE {{base_url}}/api/trash/drive/{{shared_drive_id}}
 Authorization: Bearer {{viewer_token}}
 
-HTTP 404
+HTTP 403
 
 
 # ─────────────────────────────────────────────────────────────
@@ -315,6 +321,74 @@ HTTP 200
 jsonpath "$.items[*].drive_id" contains "{{shared_drive_id}}"
 
 
+# ─────────────────────────────────────────────────────────────
+# Step 11b — Regression pin for AuthZ audit #10 (2026-07-12).
+#            `POST /api/trash/{id}/restore` and `DELETE /api/trash/{id}`
+#            once did `err_str.contains("not found")` to decide "already
+#            gone" vs real failure — an authz denial (which returns a
+#            `NotFound`-shaped DomainError to preserve anti-enum on the
+#            listing side) matched the substring and got synthesised
+#            into a 200 `{"success": true}` response. Response lied;
+#            no mutation happened.
+#
+#            Post-fix: both handlers route through
+#            `AppError::from(e).into_response()`, so authz denials
+#            surface as the graduated 403 / 404 shape and body is
+#            never a success envelope.
+#
+#            The Editor (from Step 10 promotion) holds Read on the
+#            canary — graduated denial returns 403 with a
+#            `AccessDenied`-shape body, NOT a success envelope. If a
+#            future refactor reintroduces the substring hack this
+#            assertion trips before it lands in prod.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/trash/resources
+Authorization: Bearer {{viewer_token}}
+
+HTTP 200
+[Captures]
+# The shared drive's trash holds exactly one item at this point (the
+# canary owner trashed after Step 9), so `$.items[0]` is unambiguous
+# — no filter needed. `TrashResourceItemDto` wraps the underlying
+# resource in `.resource` (untagged File | Folder | Drive enum) and
+# the trash key equals the original resource id (see
+# `storage.trash_items` view), so `.resource.id` is exactly what
+# `POST /api/trash/{id}/restore` and `DELETE /api/trash/{id}` accept.
+# The `[?(...)]` + `nth 0` shape (see the sibling
+# feedback_hurl_jsonpath_filter_empty memory) collapses on a single
+# match and returns a scalar hurl can't index, so we avoid it here.
+canary_trash_id: jsonpath "$.items[0].resource.id"
+
+
+POST {{base_url}}/api/trash/{{canary_trash_id}}/restore
+Authorization: Bearer {{viewer_token}}
+
+HTTP 403
+[Asserts]
+body not contains "\"success\":true"
+
+
+DELETE {{base_url}}/api/trash/{{canary_trash_id}}
+Authorization: Bearer {{viewer_token}}
+
+HTTP 403
+[Asserts]
+body not contains "\"success\":true"
+
+
+# The canary is still there — the two Editor attempts didn't mutate.
+GET {{base_url}}/api/trash/resources
+Authorization: Bearer {{owner_token}}
+
+HTTP 200
+[Asserts]
+# Owner sees TWO trash items at this point — the shared drive's
+# canary (from Step 9) plus their personal drive's leftover from
+# Step 4 (owner emptied only the shared drive's trash at Step 6).
+# `contains` avoids depending on the sort order between them.
+jsonpath "$.items[*].resource.id" contains "{{canary_trash_id}}"
+
+
 # ─────────────────────────────────────────────────────────────
 # Step 12 — Cleanup: drop the canary, then the shared drive itself
 #           (D3b's delete-drive guard refuses non-empty drives, so