diff --git a/crates/pinakes-core/src/import.rs b/crates/pinakes-core/src/import.rs
index 6d3c657..27046e2 100644
--- a/crates/pinakes-core/src/import.rs
+++ b/crates/pinakes-core/src/import.rs
@@ -498,10 +498,14 @@ fn collect_import_result(
       tracing::warn!(path = %path.display(), error = %e, "failed to import file");
       results.push(Err(e));
     },
-    Err(e) => {
-      tracing::error!(error = %e, "import task panicked");
+    Err(join_err) => {
+      if join_err.is_panic() {
+        tracing::error!(error = %join_err, "import task panicked");
+      } else {
+        tracing::warn!(error = %join_err, "import task was cancelled");
+      }
       results.push(Err(PinakesError::InvalidOperation(format!(
-        "import task panicked: {e}"
+        "import task failed: {join_err}"
       ))));
     },
   }
diff --git a/crates/pinakes-core/src/storage/postgres.rs b/crates/pinakes-core/src/storage/postgres.rs
index e0caeee..f9d2a43 100644
--- a/crates/pinakes-core/src/storage/postgres.rs
+++ b/crates/pinakes-core/src/storage/postgres.rs
@@ -4295,6 +4295,11 @@ impl StorageBackend for PostgresBackend {
     &self,
     metadata: &crate::model::BookMetadata,
   ) -> Result<()> {
+    if metadata.media_id.0.is_nil() {
+      return Err(PinakesError::Database(
+        "upsert_book_metadata: media_id must not be nil".to_string(),
+      ));
+    }
     let mut client = self
       .pool
       .get()
diff --git a/crates/pinakes-core/src/storage/sqlite.rs b/crates/pinakes-core/src/storage/sqlite.rs
index c377d9e..cfe08c9 100644
--- a/crates/pinakes-core/src/storage/sqlite.rs
+++ b/crates/pinakes-core/src/storage/sqlite.rs
@@ -1116,7 +1116,8 @@ impl StorageBackend for SqliteBackend {
             parent_id.map(|p| p.to_string()),
             now.to_rfc3339(),
           ],
-        )?;
+        )
+        .map_err(crate::error::db_ctx("create_tag", &name))?;
         drop(db);
         Tag {
           id,
@@ -1192,7 +1193,8 @@ impl StorageBackend for SqliteBackend {
           .lock()
           .map_err(|e| PinakesError::Database(e.to_string()))?;
         let changed = db
-          .execute("DELETE FROM tags WHERE id = ?1", params![id.to_string()])?;
+          .execute("DELETE FROM tags WHERE id = ?1", params![id.to_string()])
+          .map_err(crate::error::db_ctx("delete_tag", id))?;
         drop(db);
         if changed == 0 {
           return Err(PinakesError::TagNotFound(id.to_string()));
@@ -1214,7 +1216,11 @@ impl StorageBackend for SqliteBackend {
         db.execute(
           "INSERT OR IGNORE INTO media_tags (media_id, tag_id) VALUES (?1, ?2)",
           params![media_id.0.to_string(), tag_id.to_string()],
-        )?;
+        )
+        .map_err(crate::error::db_ctx(
+          "tag_media",
+          format!("{media_id} x {tag_id}"),
+        ))?;
       }
       Ok(())
     })
@@ -1232,7 +1238,11 @@ impl StorageBackend for SqliteBackend {
         db.execute(
           "DELETE FROM media_tags WHERE media_id = ?1 AND tag_id = ?2",
           params![media_id.0.to_string(), tag_id.to_string()],
-        )?;
+        )
+        .map_err(crate::error::db_ctx(
+          "untag_media",
+          format!("{media_id} x {tag_id}"),
+        ))?;
       }
       Ok(())
     })
@@ -1323,7 +1333,8 @@ impl StorageBackend for SqliteBackend {
             now.to_rfc3339(),
             now.to_rfc3339(),
           ],
-        )?;
+        )
+        .map_err(crate::error::db_ctx("create_collection", &name))?;
         drop(db);
         Collection {
           id,
@@ -1406,7 +1417,8 @@ impl StorageBackend for SqliteBackend {
         let changed = db
           .execute("DELETE FROM collections WHERE id = ?1", params![
             id.to_string()
-          ])?;
+          ])
+          .map_err(crate::error::db_ctx("delete_collection", id))?;
         drop(db);
         if changed == 0 {
           return Err(PinakesError::CollectionNotFound(id.to_string()));
@@ -1440,7 +1452,11 @@ impl StorageBackend for SqliteBackend {
             position,
             now.to_rfc3339(),
           ],
-        )?;
+        )
+        .map_err(crate::error::db_ctx(
+          "add_to_collection",
+          format!("{collection_id} <- {media_id}"),
+        ))?;
       }
       Ok(())
     })
@@ -1463,7 +1479,11 @@ impl StorageBackend for SqliteBackend {
           "DELETE FROM collection_members WHERE collection_id = ?1 AND \
            media_id = ?2",
           params![collection_id.to_string(), media_id.0.to_string()],
-        )?;
+        )
+        .map_err(crate::error::db_ctx(
+          "remove_from_collection",
+          format!("{collection_id} <- {media_id}"),
+        ))?;
       }
       Ok(())
     })
@@ -1863,20 +1883,27 @@ impl StorageBackend for SqliteBackend {
         let db = conn
           .lock()
           .map_err(|e| PinakesError::Database(e.to_string()))?;
-        let tx = db.unchecked_transaction()?;
+        let ctx = format!("{} media x {} tags", media_ids.len(), tag_ids.len());
+        let tx = db
+          .unchecked_transaction()
+          .map_err(crate::error::db_ctx("batch_tag_media", &ctx))?;
         // Prepare statement once for reuse
         let mut stmt = tx.prepare_cached(
           "INSERT OR IGNORE INTO media_tags (media_id, tag_id) VALUES (?1, ?2)",
-        )?;
+        )
+        .map_err(crate::error::db_ctx("batch_tag_media", &ctx))?;
         let mut count = 0u64;
         for mid in &media_ids {
           for tid in &tag_ids {
-            let rows = stmt.execute(params![mid, tid])?;
+            let rows = stmt
+              .execute(params![mid, tid])
+              .map_err(crate::error::db_ctx("batch_tag_media", &ctx))?;
             count += rows as u64; // INSERT OR IGNORE: rows=1 if new, 0 if existed
           }
         }
         drop(stmt);
-        tx.commit()?;
+        tx.commit()
+          .map_err(crate::error::db_ctx("batch_tag_media", &ctx))?;
         count
       };
       Ok(count)
@@ -2695,7 +2722,7 @@ impl StorageBackend for SqliteBackend {
         let id_str = id.0.to_string();
         let now = chrono::Utc::now();
         let role_str = serde_json::to_string(&role).map_err(|e| {
-          PinakesError::Database(format!("failed to serialize role: {e}"))
+          PinakesError::Serialization(format!("failed to serialize role: {e}"))
         })?;
 
         tx.execute(
@@ -2714,7 +2741,7 @@ impl StorageBackend for SqliteBackend {
         let user_profile = if let Some(prof) = profile.clone() {
           let prefs_json =
             serde_json::to_string(&prof.preferences).map_err(|e| {
-              PinakesError::Database(format!(
+              PinakesError::Serialization(format!(
                 "failed to serialize preferences: {e}"
               ))
             })?;
@@ -2796,7 +2823,9 @@ impl StorageBackend for SqliteBackend {
           if let Some(ref r) = role {
             updates.push("role = ?");
             let role_str = serde_json::to_string(r).map_err(|e| {
-              PinakesError::Database(format!("failed to serialize role: {e}"))
+              PinakesError::Serialization(format!(
+                "failed to serialize role: {e}"
+              ))
             })?;
             params.push(Box::new(role_str));
           }
@@ -2814,7 +2843,7 @@ impl StorageBackend for SqliteBackend {
         if let Some(prof) = profile {
           let prefs_json =
             serde_json::to_string(&prof.preferences).map_err(|e| {
-              PinakesError::Database(format!(
+              PinakesError::Serialization(format!(
                 "failed to serialize preferences: {e}"
               ))
             })?;
@@ -2966,7 +2995,9 @@ impl StorageBackend for SqliteBackend {
         PinakesError::Database(format!("failed to acquire database lock: {e}"))
       })?;
       let perm_str = serde_json::to_string(&permission).map_err(|e| {
-        PinakesError::Database(format!("failed to serialize permission: {e}"))
+        PinakesError::Serialization(format!(
+          "failed to serialize permission: {e}"
+        ))
       })?;
       let now = chrono::Utc::now();
       db.execute(
@@ -5055,6 +5086,11 @@ impl StorageBackend for SqliteBackend {
     &self,
     metadata: &crate::model::BookMetadata,
   ) -> Result<()> {
+    if metadata.media_id.0.is_nil() {
+      return Err(PinakesError::Database(
+        "upsert_book_metadata: media_id must not be nil".to_string(),
+      ));
+    }
     let conn = Arc::clone(&self.conn);
     let media_id_str = metadata.media_id.to_string();
     let isbn = metadata.isbn.clone();