config: retire the hidden global fallbacks and the mamba-extra-buffer instance reads (#34080)

python/sglang/srt/runtime_context.py

@@ -1383,3 +1383,26 @@ def reset_context() -> None:
     _CONTEXT.resources = Resources()
     _CONTEXT.forward = ForwardFlags()
     set_global_dwdp_manager(None)
+
+
+def mamba_extra_buffer_enabled() -> bool:
+    """Whether the mamba radix cache keeps its extra state buffer.
+
+    A predicate over two published leaves (``memory.disable_radix_cache`` and
+    ``exec.mamba.mamba_radix_cache_strategy``), so it reads the bags rather
+    than the startup record — the ``ServerArgs`` member of the same name is the
+    pre-publish equivalent used inside the resolution pipeline.
+    """
+    return (
+        get_memory().disable_radix_cache is False
+        and get_exec().mamba.mamba_radix_cache_strategy
+        in ("extra_buffer", "extra_buffer_lazy")
+    )
+
+
+def mamba_extra_buffer_lazy_enabled() -> bool:
+    """The lazy variant of :func:`mamba_extra_buffer_enabled`."""
+    return (
+        get_memory().disable_radix_cache is False
+        and get_exec().mamba.mamba_radix_cache_strategy == "extra_buffer_lazy"
+    )