diff --git a/components/object/upload-picker.tsx b/components/object/upload-picker.tsx
index a9d0b4a..0051ad2 100644
--- a/components/object/upload-picker.tsx
+++ b/components/object/upload-picker.tsx
@@ -8,6 +8,7 @@ import { Progress } from "@/components/ui/progress"
 import { useAddUploadFiles, useTaskPanelOpen } from "@/contexts/task-context"
 import { formatBytes } from "@/lib/functions"
 import { useMessage } from "@/lib/feedback/message"
+import { buildUploadObjectKey, normalizeUploadPrefix } from "@/lib/object-upload"
 import { RiDeleteBinLine, RiFileAddLine, RiFolderAddLine, RiUploadCloudLine } from "@remixicon/react"
 import { useVirtualizer } from "@tanstack/react-virtual"
 import * as React from "react"
@@ -228,7 +229,7 @@ export function ObjectUploadPicker({
     }
   }, [canUpload, onShowChange, show])
 
-  const effectivePrefix = editablePrefix.replace(/\/$/, "") || ""
+  const effectivePrefix = normalizeUploadPrefix(editablePrefix)
 
   const ensureCapacity = React.useCallback(
     (incoming: number): boolean => {
@@ -416,7 +417,7 @@ export function ObjectUploadPicker({
     try {
       const tasks = items.map(({ relativePath, file }) => ({
         file,
-        key: effectivePrefix ? `${effectivePrefix}/${relativePath}` : relativePath,
+        key: buildUploadObjectKey(effectivePrefix, relativePath),
       }))
       const batchSize = 50
       let processed = 0
diff --git a/lib/object-upload.js b/lib/object-upload.js
new file mode 100644
index 0000000..3f9ea0b
--- /dev/null
+++ b/lib/object-upload.js
@@ -0,0 +1,9 @@
+export function normalizeUploadPrefix(prefix) {
+  return prefix.trim().replace(/^\/+/, "").replace(/\/+$/, "")
+}
+
+export function buildUploadObjectKey(prefix, relativePath) {
+  const normalizedPrefix = normalizeUploadPrefix(prefix)
+  const normalizedRelativePath = relativePath.replace(/^\/+/, "")
+  return normalizedPrefix ? `${normalizedPrefix}/${normalizedRelativePath}` : normalizedRelativePath
+}
diff --git a/lib/object-upload.ts b/lib/object-upload.ts
new file mode 100644
index 0000000..1195fd4
--- /dev/null
+++ b/lib/object-upload.ts
@@ -0,0 +1,9 @@
+export function normalizeUploadPrefix(prefix: string): string {
+  return prefix.trim().replace(/^\/+/, "").replace(/\/+$/, "")
+}
+
+export function buildUploadObjectKey(prefix: string, relativePath: string): string {
+  const normalizedPrefix = normalizeUploadPrefix(prefix)
+  const normalizedRelativePath = relativePath.replace(/^\/+/, "")
+  return normalizedPrefix ? `${normalizedPrefix}/${normalizedRelativePath}` : normalizedRelativePath
+}
diff --git a/tests/lib/object-upload.test.js b/tests/lib/object-upload.test.js
new file mode 100644
index 0000000..dcc4d64
--- /dev/null
+++ b/tests/lib/object-upload.test.js
@@ -0,0 +1,21 @@
+import test from "node:test"
+import assert from "node:assert/strict"
+import { buildUploadObjectKey, normalizeUploadPrefix } from "../../lib/object-upload.js"
+
+test("normalizeUploadPrefix removes leading and trailing slashes", () => {
+  assert.equal(normalizeUploadPrefix("/Normal/"), "Normal")
+  assert.equal(normalizeUploadPrefix("//Normal//"), "Normal")
+})
+
+test("buildUploadObjectKey avoids leading slash when prefix starts with slash", () => {
+  assert.equal(buildUploadObjectKey("/Normal/", "file.txt"), "Normal/file.txt")
+})
+
+test("buildUploadObjectKey keeps nested relative paths under the normalized prefix", () => {
+  assert.equal(buildUploadObjectKey("Normal/", "folder/file.txt"), "Normal/folder/file.txt")
+})
+
+test("buildUploadObjectKey uses relative path when prefix is empty or slash only", () => {
+  assert.equal(buildUploadObjectKey("", "file.txt"), "file.txt")
+  assert.equal(buildUploadObjectKey("/", "file.txt"), "file.txt")
+})