[RL] support weight reload for low-bit rollout (#9650)

Co-authored-by: Hecate0821 <hec4te0821@gmail.com>
Co-authored-by: eternally-z <zzywzj@gmail.com>
Co-authored-by: Wilboludriver <wilbolu@outlook.com>
Co-authored-by: Wilbolu <81792854+Wilboludriver@users.noreply.github.com>
Co-authored-by: Ke Bao <ispobaoke@gmail.com>

python/sglang/srt/server_args.py

@@ -79,6 +79,7 @@ LOAD_FORMAT_CHOICES = [
     "gguf",
     "bitsandbytes",
     "layered",
+    "flash_rl",
     "remote",
     "remote_instance",
 ]
@@ -250,6 +251,7 @@ class ServerArgs:
     skip_tokenizer_init: bool = False
     load_format: str = "auto"
     model_loader_extra_config: str = "{}"
+    rl_quant_profile: Optional[str] = None  # For flash_rl load format
     trust_remote_code: bool = False
     context_length: Optional[int] = None
     is_embedding: bool = False
@@ -2169,6 +2171,12 @@ class ServerArgs:
             "This will be passed to the model loader corresponding to the chosen load_format.",
             default=ServerArgs.model_loader_extra_config,
         )
+        parser.add_argument(
+            "--rl-quant-profile",
+            type=str,
+            default=ServerArgs.rl_quant_profile,
+            help="Path to the FlashRL quantization profile. Required when using --load-format flash_rl.",
+        )
         parser.add_argument(
             "--trust-remote-code",
             action="store_true",