diff --git a/test/manual/test_tokenizer_manager.py b/test/manual/test_tokenizer_manager.py
index 04115fb99..9525fedbb 100644
--- a/test/manual/test_tokenizer_manager.py
+++ b/test/manual/test_tokenizer_manager.py
@@ -14,7 +14,7 @@ python3 -m unittest test_tokenizer_manager.TestTokenizerManagerIntegration
 import unittest
 from unittest.mock import Mock, patch
 
-from sglang.srt.managers.tokenizer_manager import TokenizerManager
+from sglang.srt.managers.tokenizer_manager import InputFormat, TokenizerManager
 from sglang.srt.server_args import PortArgs, ServerArgs
 from sglang.test.test_utils import DEFAULT_SMALL_MODEL_NAME_FOR_TEST
 
@@ -42,7 +42,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             text, is_cross_encoder=False
         )
-        self.assertEqual(result, "single_string")
+        self.assertEqual(result, InputFormat.SINGLE_STRING)
 
     def test_detect_single_string_cross_encoder_disabled(self):
         """Test single string with cross_encoder disabled still returns single_string."""
@@ -50,7 +50,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             text, is_cross_encoder=True
         )
-        self.assertEqual(result, "single_string")
+        self.assertEqual(result, InputFormat.SINGLE_STRING)
 
     def test_detect_batch_strings(self):
         """Test detection of batch string inputs."""
@@ -58,7 +58,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=False
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
     def test_detect_batch_strings_cross_encoder_disabled(self):
         """Test batch strings with cross_encoder disabled."""
@@ -66,7 +66,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
     def test_detect_cross_encoder_single_pair(self):
         """Test detection of cross-encoder single pair."""
@@ -74,7 +74,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "cross_encoder_pairs")
+        self.assertEqual(result, InputFormat.CROSS_ENCODER_PAIRS)
 
     def test_detect_cross_encoder_multiple_pairs(self):
         """Test detection of cross-encoder multiple pairs."""
@@ -82,7 +82,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "cross_encoder_pairs")
+        self.assertEqual(result, InputFormat.CROSS_ENCODER_PAIRS)
 
     def test_detect_cross_encoder_disabled_with_pairs(self):
         """Test pairs with cross_encoder disabled should return batch_strings."""
@@ -90,7 +90,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=False
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
     def test_detect_empty_list(self):
         """Test detection with empty list."""
@@ -98,7 +98,7 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
     def test_detect_malformed_cross_encoder_pairs(self):
         """Test malformed cross-encoder pairs (not length 2)."""
@@ -106,13 +106,13 @@ class TestInputFormatDetection(unittest.TestCase):
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
         texts = [["query", "doc", "extra"]]  # Three elements, not a pair
         result = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(result, "batch_strings")
+        self.assertEqual(result, InputFormat.BATCH_STRINGS)
 
 
 class TestTokenizerInputPreparation(unittest.TestCase):
@@ -135,20 +135,24 @@ class TestTokenizerInputPreparation(unittest.TestCase):
     def test_prepare_single_string_input(self):
         """Test preparation of single string input."""
         text = "Hello world"
-        result = self.tokenizer_manager._prepare_tokenizer_input(text, "single_string")
+        result = self.tokenizer_manager._prepare_tokenizer_input(
+            text, InputFormat.SINGLE_STRING
+        )
         self.assertEqual(result, ["Hello world"])
 
     def test_prepare_batch_strings_input(self):
         """Test preparation of batch strings input."""
         texts = ["Hello", "World", "Test"]
-        result = self.tokenizer_manager._prepare_tokenizer_input(texts, "batch_strings")
+        result = self.tokenizer_manager._prepare_tokenizer_input(
+            texts, InputFormat.BATCH_STRINGS
+        )
         self.assertEqual(result, ["Hello", "World", "Test"])
 
     def test_prepare_cross_encoder_pairs_input(self):
         """Test preparation of cross-encoder pairs input."""
         texts = [["query1", "doc1"], ["query2", "doc2"]]
         result = self.tokenizer_manager._prepare_tokenizer_input(
-            texts, "cross_encoder_pairs"
+            texts, InputFormat.CROSS_ENCODER_PAIRS
         )
         self.assertEqual(result, [["query1", "doc1"], ["query2", "doc2"]])
 
@@ -156,15 +160,15 @@ class TestTokenizerInputPreparation(unittest.TestCase):
         """Test preparation of single cross-encoder pair."""
         texts = [["query text", "document text"]]
         result = self.tokenizer_manager._prepare_tokenizer_input(
-            texts, "cross_encoder_pairs"
+            texts, InputFormat.CROSS_ENCODER_PAIRS
         )
         self.assertEqual(result, [["query text", "document text"]])
 
-    def test_prepare_unknown_input_format(self):
-        """Test preparation with unknown input format falls back to returning as-is."""
+    def test_prepare_batch_strings_input_format_passthrough(self):
+        """Batch strings should pass through unchanged."""
         texts = ["test"]
         result = self.tokenizer_manager._prepare_tokenizer_input(
-            texts, "unknown_format"
+            texts, InputFormat.BATCH_STRINGS
         )
         self.assertEqual(result, ["test"])
 
@@ -193,7 +197,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "single_string", original_batch_size=1
+                input_ids,
+                token_type_ids,
+                InputFormat.SINGLE_STRING,
+                original_batch_size=1,
             )
         )
 
@@ -207,7 +214,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "cross_encoder_pairs", original_batch_size=1
+                input_ids,
+                token_type_ids,
+                InputFormat.CROSS_ENCODER_PAIRS,
+                original_batch_size=1,
             )
         )
 
@@ -221,7 +231,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "batch_strings", original_batch_size=2
+                input_ids,
+                token_type_ids,
+                InputFormat.BATCH_STRINGS,
+                original_batch_size=2,
             )
         )
 
@@ -235,7 +248,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "cross_encoder_pairs", original_batch_size=2
+                input_ids,
+                token_type_ids,
+                InputFormat.CROSS_ENCODER_PAIRS,
+                original_batch_size=2,
             )
         )
 
@@ -251,7 +267,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "single_string", original_batch_size=1
+                input_ids,
+                token_type_ids,
+                InputFormat.SINGLE_STRING,
+                original_batch_size=1,
             )
         )
 
@@ -265,7 +284,10 @@ class TestTokenizerResultExtraction(unittest.TestCase):
 
         result_input_ids, result_token_type_ids = (
             self.tokenizer_manager._extract_tokenizer_results(
-                input_ids, token_type_ids, "single_string", original_batch_size=1
+                input_ids,
+                token_type_ids,
+                InputFormat.SINGLE_STRING,
+                original_batch_size=1,
             )
         )
 
@@ -298,7 +320,7 @@ class TestTokenizerManagerIntegration(unittest.TestCase):
         input_format = self.tokenizer_manager._detect_input_format(
             text, is_cross_encoder=False
         )
-        self.assertEqual(input_format, "single_string")
+        self.assertEqual(input_format, InputFormat.SINGLE_STRING)
 
         # Step 2: Prepare input
         tokenizer_input = self.tokenizer_manager._prepare_tokenizer_input(
@@ -329,7 +351,7 @@ class TestTokenizerManagerIntegration(unittest.TestCase):
         input_format = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=True
         )
-        self.assertEqual(input_format, "cross_encoder_pairs")
+        self.assertEqual(input_format, InputFormat.CROSS_ENCODER_PAIRS)
 
         # Step 2: Prepare input
         tokenizer_input = self.tokenizer_manager._prepare_tokenizer_input(
@@ -358,7 +380,7 @@ class TestTokenizerManagerIntegration(unittest.TestCase):
         input_format = self.tokenizer_manager._detect_input_format(
             texts, is_cross_encoder=False
         )
-        self.assertEqual(input_format, "batch_strings")
+        self.assertEqual(input_format, InputFormat.BATCH_STRINGS)
 
         # Step 2: Prepare input
         tokenizer_input = self.tokenizer_manager._prepare_tokenizer_input(