Fix RuntimeEndpoint.select method (#1495)

python/sglang/lang/backend/runtime_endpoint.py

@@ -244,7 +244,8 @@ class RuntimeEndpoint(BaseBackend):
                 "temperature": 0,
             },
             "return_logprob": True,
-            "logprob_start_len": max(prompt_len - 2, 0),  # for token healing
+            "return_text_in_logprobs": True,
+            "logprob_start_len": prompt_len - 2,  # For token healing
         }
         obj = self._generate_http_request(s, data)
 
@@ -254,6 +255,17 @@ class RuntimeEndpoint(BaseBackend):
         input_token_logprobs = [r["meta_info"]["input_token_logprobs"] for r in obj]
         output_token_logprobs = [r["meta_info"]["output_token_logprobs"] for r in obj]
 
+        # Remove extra token if no token healing occurred
+        for i in range(len(input_token_logprobs)):
+            healed_token_str = input_token_logprobs[i][0][-1]
+            healed_token_logprob = input_token_logprobs[i][0][0]
+            if s.text_.endswith(healed_token_str):
+                normalized_prompt_logprobs[i] = (
+                    normalized_prompt_logprobs[i] * len(input_token_logprobs[i])
+                    - healed_token_logprob
+                ) / (len(input_token_logprobs[i]) - 1)
+                input_token_logprobs[i] = input_token_logprobs[i][1:]
+
         # Compute unconditional logprobs if required
         if choices_method.requires_unconditional_logprobs:
             input_ids = [[el[1] for el in subl] for subl in input_token_logprobs]