[Refactor] Tidy server_args.py section grouping and drop unused alias (#32496)

python/sglang/srt/server_args.py

@@ -132,30 +132,6 @@ LOAD_FORMAT_CHOICES = [
 
 # TODO: this list should likely contain only methods that support online quantization, or that support using custom quantization classes compatible with a given `quant_method` in config.json.
 # Some of the choices here do NOT support online quantization.
-# Attention backends whose kernels read the chunked prefix-cache layout.
-# Out-of-tree platforms may extend this list (via
-# add_chunked_prefix_cache_attention_backend) before ServerArgs construction;
-# the chunked-prefix gate is evaluated during resolution.
-CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS = [
-    "flashinfer",
-    "fa3",
-    "fa4",
-    "flashmla",
-    "cutedsl_mla",
-    "cutlass_mla",
-    "trtllm_mla",
-    "tokenspeed_mla",
-]
-
-
-def add_chunked_prefix_cache_attention_backend(backend_name):
-    if backend_name not in CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS:
-        CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS.append(backend_name)
-        logger.info(
-            f"Added {backend_name} to CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS."
-        )
-
-
 QUANTIZATION_CHOICES = [
     "awq",
     "fp8",  # MOE + linear online quantization.
@@ -194,9 +170,6 @@ QUANTIZATION_CHOICES = [
     "humming",
 ]
 
-
-SPECULATIVE_DRAFT_MODEL_QUANTIZATION_CHOICES = QUANTIZATION_CHOICES
-
 ATTENTION_BACKEND_CHOICES = [
     # Common
     "triton",
@@ -227,6 +200,21 @@ ATTENTION_BACKEND_CHOICES = [
     "intel_xpu",
 ]
 
+# Attention backends whose kernels read the chunked prefix-cache layout.
+# Out-of-tree platforms may extend this list (via
+# add_chunked_prefix_cache_attention_backend) before ServerArgs construction;
+# the chunked-prefix gate is evaluated during resolution.
+CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS = [
+    "flashinfer",
+    "fa3",
+    "fa4",
+    "flashmla",
+    "cutedsl_mla",
+    "cutlass_mla",
+    "trtllm_mla",
+    "tokenspeed_mla",
+]
+
 DETERMINISTIC_ATTENTION_BACKEND_CHOICES = [
     "ascend",
     "fa3",
@@ -372,6 +360,10 @@ def add_attention_backend_choices(choices):
     ATTENTION_BACKEND_CHOICES.extend(choices)
 
 
+def add_chunked_prefix_cache_attention_backend(backend_name):
+    CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS.append(backend_name)
+
+
 def add_deterministic_attention_backend_choices(choices):
     DETERMINISTIC_ATTENTION_BACKEND_CHOICES.extend(choices)
 
@@ -2140,7 +2132,7 @@ class ServerArgs:
         Optional[str],
         Arg(
             help="The quantization method for speculative model.",
-            choices=SPECULATIVE_DRAFT_MODEL_QUANTIZATION_CHOICES,
+            choices=QUANTIZATION_CHOICES,
         ),
         NS("spec"),
     ] = None
@@ -2203,6 +2195,7 @@ class ServerArgs:
         NS("spec"),
     ] = None
 
+    # -------------------------------------------------------------------------
     # Speculative decoding (ngram)
     # -------------------------------------------------------------------------
     speculative_ngram_min_bfs_breadth: A[
@@ -3336,6 +3329,9 @@ class ServerArgs:
         NS("exec.features"),
     ] = False
 
+    # -------------------------------------------------------------------------
+    # Weight cache
+    # -------------------------------------------------------------------------
     weight_cache_mode: A[
         str,
         Arg(