diff --git "a/claudetool/onstart/testdata/Makefile-\346\227\245\346\234\254\350\252\236" "b/claudetool/onstart/testdata/Makefile-\346\227\245\346\234\254\350\252\236"
new file mode 100644
index 0000000..c78f45a
--- /dev/null
+++ "b/claudetool/onstart/testdata/Makefile-\346\227\245\346\234\254\350\252\236"
@@ -0,0 +1,10 @@
+# Makefile with Japanese characters in filename
+# This should be categorized as a build file
+
+all:
+	echo "Building with Japanese characters in Makefile name"
+
+clean:
+	rm -f *.o
+
+.PHONY: all clean
diff --git "a/claudetool/onstart/testdata/caf\303\251.js" "b/claudetool/onstart/testdata/caf\303\251.js"
new file mode 100644
index 0000000..6cd53e3
--- /dev/null
+++ "b/claudetool/onstart/testdata/caf\303\251.js"
@@ -0,0 +1,2 @@
+// JavaScript file with French accent in filename
+console.log('Hello from café.js');
diff --git "a/claudetool/onstart/testdata/readme-espa\303\261ol.md" "b/claudetool/onstart/testdata/readme-espa\303\261ol.md"
new file mode 100644
index 0000000..4232509
--- /dev/null
+++ "b/claudetool/onstart/testdata/readme-espa\303\261ol.md"
@@ -0,0 +1,8 @@
+# README Español
+
+This is a documentation file with Spanish characters in the filename.
+
+## Características
+
+- Soporte para Unicode
+- Caracteres españoles en nombres de archivo
diff --git "a/claudetool/onstart/testdata/subdir/claude.\355\225\234\352\265\255\354\226\264.md" "b/claudetool/onstart/testdata/subdir/claude.\355\225\234\352\265\255\354\226\264.md"
new file mode 100644
index 0000000..ab36b92
--- /dev/null
+++ "b/claudetool/onstart/testdata/subdir/claude.\355\225\234\352\265\255\354\226\264.md"
@@ -0,0 +1,8 @@
+# Claude Guidance with Korean Characters
+
+This file should be categorized as a guidance file since it starts with 'claude-' and ends with '.md'.
+
+## 지침
+
+- 한국어 문자 지원
+- 파일 이름에 유니코드 사용
diff --git "a/claudetool/onstart/testdata/\303\234bung.html" "b/claudetool/onstart/testdata/\303\234bung.html"
new file mode 100644
index 0000000..afc66ab
--- /dev/null
+++ "b/claudetool/onstart/testdata/\303\234bung.html"
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>German Umlaut Test</title>
+</head>
+<body>
+    <h1>Übung HTML File</h1>
+    <p>This HTML file has German umlaut characters in the filename.</p>
+</body>
+</html>
diff --git "a/claudetool/onstart/testdata/\321\200\321\203\321\201\321\201\320\272\320\270\320\271.py" "b/claudetool/onstart/testdata/\321\200\321\203\321\201\321\201\320\272\320\270\320\271.py"
new file mode 100644
index 0000000..8110369
--- /dev/null
+++ "b/claudetool/onstart/testdata/\321\200\321\203\321\201\321\201\320\272\320\270\320\271.py"
@@ -0,0 +1,2 @@
+# Python file with Russian characters in filename
+print('Hello from русский.py')
diff --git "a/claudetool/onstart/testdata/\346\265\213\350\257\225\346\226\207\344\273\266.go" "b/claudetool/onstart/testdata/\346\265\213\350\257\225\346\226\207\344\273\266.go"
new file mode 100644
index 0000000..30a3d59
--- /dev/null
+++ "b/claudetool/onstart/testdata/\346\265\213\350\257\225\346\226\207\344\273\266.go"
@@ -0,0 +1,6 @@
+// Package test with Chinese characters in filename
+package test
+
+func TestFunction() {
+	// This is a test file with Chinese characters in the filename
+}
diff --git "a/claudetool/onstart/testdata/\360\237\232\200rocket.md" "b/claudetool/onstart/testdata/\360\237\232\200rocket.md"
new file mode 100644
index 0000000..6140a51
--- /dev/null
+++ "b/claudetool/onstart/testdata/\360\237\232\200rocket.md"
@@ -0,0 +1,8 @@
+# README with Emoji in filename
+
+This is a documentation file with an emoji character in the filename.
+
+## Features
+
+- Unicode support
+- Emoji in filenames