[Doc] Fix several places for dpsk v4 cookbook (#25506)

docs_new/cookbook/autoregressive/DeepSeek/DeepSeek-V4.mdx

@@ -120,7 +120,7 @@ The generator currently picks values on the **conservative** side (mirroring an
 **Hopper (H200) note**
 
 We provide two different options for running DeepSeek-V4 models on Hopper devices (H200)
-- Original FP4 checkpoints: To run original FP4 checkpoints, apply the w4a16 MoE kernels (marlin) as in interactive command generator. For this option we only support TP method. Complete Pro model can be run on a single H200 node with this option.
+- Original FP4 checkpoints: To run original FP4 checkpoints, we provide two different options for w4a16 MoE kernels: Marlin (`--moe-runner-backend marlin`) and Flashinfer (`--moe-runner-backend flashinfer_mxfp4). For this variant we only support Tensor Parallelism. Complete Pro model can be run on a single H200 node with this option.
 - Converted FP8 checkpoints: We also provide pre-converted FP8 checkpoints (`sgl-project/DeepSeek-V4-Flash-FP8`, `sgl-project/DeepSeek-V4-Pro-FP8`), which support more parallelism and features.
 
 PD-Disagg recipes on H200 may require `docker run --privileged --ulimit memlock=-1`
@@ -128,6 +128,26 @@ PD-Disagg recipes on H200 may require `docker run --privileged --ulimit memlock=
 can discover the IB HCAs; without IB exposure mooncake silently falls back to
 TCP, which can lead to garbled KV transfer on large checkpoints.
 
+**MegaMoE**
+
+MegaMoE fuses expert dispatch + GEMM into a single kernel for higher throughput
+on MoE layers. To enable it, use the **MegaMoE** toggle in the
+[command generator above](#3-model-deployment) — the generator will swap
+`--moe-a2a-backend deepep` for `--moe-a2a-backend megamoe` and add the
+relevant env vars automatically.
+
+
+Two variants are exposed:
+- **W4A8** — default MegaMoE kernel (FP4 weights, FP8 activations).
+- **W4A4** — adds `SGLANG_OPT_DEEPGEMM_MEGA_MOE_USE_FP4_ACTS=1` and
+  `SGLANG_OPT_DEEPGEMM_MEGA_MOE_USE_MXF4_KIND=1` to run the custom W4A4
+  kernel (FP4 activations). Higher throughput with negligible accuracy drop
+  (~89.5 GPQA on Pro).
+
+Notes:
+- MegaMoE is **not** supported on Hopper (H100 / H200) nor on the `low-latency` / `cp` settings. When running MegaMoE, don't set `--moe-runner-backend` manually.
+- Adjust `SGLANG_OPT_DEEPGEMM_MEGA_MOE_NUM_MAX_TOKENS_PER_RANK` based on your workload and memory usage. Setting higher number of tokens for MegaMoE requires more HBM space. (recommended: 4096 for balanced, 8320 for max-throughput).
+
 **GB300 PD-Disagg cross-pod MNNVL**
 
 On some GB300 clusters with cross-pod KV transfer over NVLink, mooncake may

docs_new/src/snippets/autoregressive/deepseek-v4-deployment.jsx

@@ -96,6 +96,15 @@ export const DeepSeekV4Deployment = () => {
   const MARLIN_HARDWARE = new Set(["h200-fp4", "h100"]);
   const MARLIN_LABEL = { "h200-fp4": "H200 (FP4)", h100: "H100 (FP4)" };
 
+  // MegaMoE is only supported on Blackwell with DeepEP-based recipes
+  // (balanced / max-throughput / pd-disagg). It's disabled on Hopper
+  // (H100 / H200 / H200-FP4) and on low-latency / cp recipes.
+  const MEGAMOE_UNSUPPORTED_RECIPES = new Set(["low-latency", "cp"]);
+  const MEGAMOE_UNSUPPORTED_HARDWARE = new Set(["h100", "h200", "h200-fp4"]);
+  const isMegamoeUnsupported = (vals) =>
+    MEGAMOE_UNSUPPORTED_HARDWARE.has(vals.hardware) ||
+    MEGAMOE_UNSUPPORTED_RECIPES.has(vals.recipe);
+
   const resolveItems = (option, vals) => {
     if (option.name === "recipe" && vals && MARLIN_HARDWARE.has(vals.hardware)) {
       return option.items.map((it) =>
@@ -104,6 +113,14 @@ export const DeepSeekV4Deployment = () => {
           : it
       );
     }
+    if (option.name === "megamoe" && vals && isMegamoeUnsupported(vals)) {
+      const reason = MEGAMOE_UNSUPPORTED_HARDWARE.has(vals.hardware)
+        ? "MegaMoE is only supported on Blackwell"
+        : "MegaMoE is not supported on this recipe";
+      return option.items.map((it) =>
+        it.id === "disabled" ? it : { ...it, disabled: true, disabledReason: reason }
+      );
+    }
     return option.items;
   };
 
@@ -151,6 +168,15 @@ export const DeepSeekV4Deployment = () => {
       ) {
         next.recipe = "low-latency";
       }
+      // Switching to a hardware/recipe combo that doesn't support MegaMoE
+      // while w4a8 / w4a4 is selected: fall back to disabled.
+      if (
+        (optionName === "hardware" || optionName === "recipe") &&
+        next.megamoe !== "disabled" &&
+        isMegamoeUnsupported(next)
+      ) {
+        next.megamoe = "disabled";
+      }
       return next;
     });
   };