fix: commit cover DB pointer before mutating the old blob

put_cover/delete_cover mutated storage before the DB pointer, so a transient DB
failure could leave the row pointing at a deleted blob. Reorder to
put->set-DB->delete-old and clear-DB->delete-blob, so a failure only orphans a
blob, never dangles the pointer. Happy path covered by the 16 existing cover tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/Cargo.lock

@@ -1558,7 +1558,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
 
 [[package]]
 name = "mangalord"
-version = "0.128.15"
+version = "0.128.16"
 dependencies = [
  "anyhow",
  "argon2",

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.128.15"
+version = "0.128.16"
 edition = "2021"
 default-run = "mangalord"
 

backend/src/api/mangas.rs

@@ -409,6 +409,17 @@ async fn put_cover(
     let old_key = repo::manga::get(&state.db, id).await?.cover_image_path;
     let new_key = format!("mangas/{}/cover.{}", id, img.ext);
     state.storage.put(&new_key, &img.bytes).await?;
+    // Cover keys are reused (mangas/{id}/cover.{ext}), so a same-extension
+    // replacement overwrites the blob at an existing key — drop any thumbnails
+    // cached for it so we don't serve a stale variant of the old cover.
+    crate::api::files::purge_thumbnails(state.storage.as_ref(), &new_key).await;
+
+    // Commit the DB pointer to the new blob BEFORE removing the old one. If we
+    // deleted the old blob first and this write then failed, the row would point
+    // at a deleted blob (a cover that 404s) and the new blob would be orphaned.
+    // Ordering it first means a failure here leaves the row pointing at the
+    // still-present old blob; only a harmless orphan (new blob) can result.
+    repo::manga::set_cover_image_path(&state.db, id, &new_key, img.bytes.len() as i64).await?;
 
     if let Some(prev) = old_key.as_deref() {
         if prev != new_key {
@@ -423,12 +434,6 @@ async fn put_cover(
             crate::api::files::purge_thumbnails(state.storage.as_ref(), prev).await;
         }
     }
-    // Cover keys are reused (mangas/{id}/cover.{ext}), so a same-extension
-    // replacement overwrites the blob at an existing key — drop any thumbnails
-    // cached for it so we don't serve a stale variant of the old cover.
-    crate::api::files::purge_thumbnails(state.storage.as_ref(), &new_key).await;
-
-    repo::manga::set_cover_image_path(&state.db, id, &new_key, img.bytes.len() as i64).await?;
     Ok(Json(repo::manga::get_detail(&state.db, id).await?))
 }
 
@@ -446,12 +451,15 @@ async fn delete_cover(
     }
     require_can_edit(&state, id, user.id, admin_via_session(&session)).await?;
     if let Some(key) = repo::manga::get(&state.db, id).await?.cover_image_path {
+        // Clear the DB pointer BEFORE deleting the blob, so a storage-delete
+        // failure can't leave the row pointing at a removed blob. A failure
+        // after the clear only orphans the blob (harmless).
+        repo::manga::clear_cover_image_path(&state.db, id).await?;
         match state.storage.delete(&key).await {
             Ok(()) | Err(StorageError::NotFound) => {}
             Err(e) => return Err(e.into()),
         }
         crate::api::files::purge_thumbnails(state.storage.as_ref(), &key).await;
-        repo::manga::clear_cover_image_path(&state.db, id).await?;
     }
     Ok(Json(repo::manga::get_detail(&state.db, id).await?))
 }

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.128.15",
+  "version": "0.128.16",
   "private": true,
   "type": "module",
   "scripts": {