diff --git a/server/server_mgmt.go b/server/server_mgmt.go
index 5d3e6d1..b851ca7 100644
--- a/server/server_mgmt.go
+++ b/server/server_mgmt.go
@@ -1530,10 +1530,11 @@ func skillRelPath(file string) (string, string) {
 	if strings.HasPrefix(file, "/") || strings.Contains(file, "//") {
 		return "", "invalid path: must be relative with no empty segments"
 	}
-	// 4. Normalize and final safety re-check after Clean.
-	//    filepath.Clean removes redundant separators and resolves single dots.
-	clean := filepath.Clean(file)
-	if clean == "." || filepath.IsAbs(clean) || strings.HasPrefix(clean, "..") {
+	// 4. Normalize as a URL/API path, not as a host filesystem path. API paths
+	//    always use '/', including when ARTEX runs on Windows. Filesystem calls
+	//    below accept this canonical form through filepath.Join.
+	clean := path.Clean(file)
+	if clean == "." || path.IsAbs(clean) || strings.HasPrefix(clean, "..") {
 		return "", "invalid path"
 	}
 	return clean, ""
@@ -1554,6 +1555,10 @@ func walkSkillFiles(root string) ([]string, error) {
 		if relErr != nil || rel == "." {
 			return nil
 		}
+		// The file list is an HTTP API contract consumed by a frontend that splits
+		// paths on '/'. filepath.Rel uses '\\' on Windows, so normalize before the
+		// value leaves the backend.
+		rel = filepath.ToSlash(rel)
 		if d.IsDir() {
 			entries = append(entries, rel+"/")
 		} else {
diff --git a/server/skill_upload_test.go b/server/skill_upload_test.go
index 81756b2..563a89e 100644
--- a/server/skill_upload_test.go
+++ b/server/skill_upload_test.go
@@ -64,6 +64,33 @@ func TestSkillRelPath(t *testing.T) {
 	}
 }
 
+func TestWalkSkillFilesUsesSlashSeparatedAPIPaths(t *testing.T) {
+	root := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(root, "scripts", "helpers"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "scripts", "helpers", "run.py"), []byte("pass\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	entries, err := walkSkillFiles(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []string{"scripts/", "scripts/helpers/", "scripts/helpers/run.py"}
+	if len(entries) != len(want) {
+		t.Fatalf("walkSkillFiles() = %q, want %q", entries, want)
+	}
+	for i := range want {
+		if entries[i] != want[i] {
+			t.Errorf("walkSkillFiles()[%d] = %q, want %q", i, entries[i], want[i])
+		}
+		if strings.Contains(entries[i], `\`) {
+			t.Errorf("walkSkillFiles()[%d] contains a Windows separator: %q", i, entries[i])
+		}
+	}
+}
+
 type nopWriteCloser struct{ io.Writer }
 
 func (nopWriteCloser) Close() error { return nil }