feat(unified-memory): byte-budget sizing, feasibility floor, and a conservation verifier (#35158)

Co-authored-by: Caihua Li <caihua.li@bytedance.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Cheng Wan <cheng.wan@radixark.ai>

python/sglang/srt/model_executor/pool_configurator.py

@@ -71,6 +71,13 @@ class MemoryPoolConfig:
 
     mem_fraction_static: Optional[float] = None
 
+    # Unified pool only: the PROFILED byte budget for the token-granular
+    # sub-pools. Set, the factories size the buffer from it directly instead of
+    # re-summing ratio-derived token counts, which keeps the re-sum's floor
+    # losses out of the buffer; the token counts stay boot labels / conserve
+    # caps. None on the token-capped path -- a user token cap IS the budget.
+    unified_total_bytes: Optional[int] = None
+
     def __post_init__(self):
         if self.max_total_num_tokens <= 0:
             msg = "Not enough memory. Please try to increase --mem-fraction-static."