diff --git a/benchmarks/single_node/agentic/dsv4_fp4_b300_sglang_mtp.sh b/benchmarks/single_node/agentic/dsv4_fp4_b300_sglang_mtp.sh
index fc917052c7..6187389c39 100755
--- a/benchmarks/single_node/agentic/dsv4_fp4_b300_sglang_mtp.sh
+++ b/benchmarks/single_node/agentic/dsv4_fp4_b300_sglang_mtp.sh
@@ -127,10 +127,21 @@ if [ "$DP_ATTENTION" = "true" ]; then
     )
     MEM_FRACTION_STATIC=0.95
     if [ "$CONC" -ge 512 ]; then
-        # Leave room for FlashInfer's transient MoE workspace at the DEP8 tail.
-        MEM_FRACTION_STATIC=0.94
+        # DEP8 c512: MegaMoE FP4-activation A2A (same DeepGEMM path as the
+        # vLLM amxf4 recipe) plus a larger per-step prefill budget so the
+        # 5,677-request warmup finishes inside the job budget. The DSV4
+        # indexer's fp32 MQA logits transient scales with the per-rank chunk
+        # and has no budget cap in this image, so static memory must stay at
+        # 0.85 (the only value that has completed c512 end to end).
+        PARALLEL_ARGS+=(--moe-a2a-backend megamoe)
+        export SGLANG_OPT_DEEPGEMM_MEGA_MOE_USE_FP4_ACTS=1
+        export SGLANG_OPT_DEEPGEMM_MEGA_MOE_USE_MXF4_KIND=1
+        export SGLANG_OPT_DEEPGEMM_MEGA_MOE_NUM_MAX_TOKENS_PER_RANK=16384
+        MEM_FRACTION_STATIC=0.85
+        CHUNKED_PREFILL_SIZE=131072
+    else
+        CHUNKED_PREFILL_SIZE=16384
     fi
-    CHUNKED_PREFILL_SIZE=16384
 else
     PARALLEL_ARGS+=(
         --moe-runner-backend flashinfer_mxfp4
@@ -143,6 +154,9 @@ MODEL_ARGS=(
     --page-size 256
     --disable-shared-experts-fusion
 )
+if [ "$DP_ATTENTION" = "true" ] && [ "$CONC" -ge 512 ]; then
+    MODEL_ARGS+=(--enable-deepseek-v4-fp4-indexer)
+fi
 
 # AgentX concurrency counts live session trees, not individual requests.
 # Allow subagent fan-out to exceed CONC without clipping request bursts.
@@ -240,6 +254,23 @@ wait_for_ready \
 
 if [ "$USE_SGLANG_ROUTER" = "true" ]; then
     echo "Starting SGLang router on port $PORT for $TP DP ranks..."
+    # Wave hardening, gated on the pinned router's flag surface: bounded
+    # retries with backoff absorb transient upstream failures during the
+    # cache-hit flood so a single 5xx cannot abort a root warmup request,
+    # no circuit breaker (its fast-fail window can strike root requests),
+    # and idle-pool pruning drops connections before the server's 900 s
+    # keep-alive closes them under us.
+    ROUTER_HARDENING_ARGS=(--disable-retries)
+    ROUTER_HELP="$("${SGLANG_ROUTER_CMD[@]}" --help 2>&1 || true)"
+    if grep -q -- "--retry-max-retries" <<<"$ROUTER_HELP"; then
+        ROUTER_HARDENING_ARGS=(--retry-max-retries 8 --retry-initial-backoff-ms 250 --retry-max-backoff-ms 4000)
+    fi
+    if grep -q -- "--disable-circuit-breaker" <<<"$ROUTER_HELP"; then
+        ROUTER_HARDENING_ARGS+=(--disable-circuit-breaker)
+    fi
+    if grep -q -- "--pool-idle-timeout-secs" <<<"$ROUTER_HELP"; then
+        ROUTER_HARDENING_ARGS+=(--pool-idle-timeout-secs 300)
+    fi
     "${SGLANG_ROUTER_CMD[@]}" \
         --worker-urls "http://localhost:$SGLANG_BACKEND_PORT" \
         --policy consistent_hashing \
@@ -252,7 +283,7 @@ if [ "$USE_SGLANG_ROUTER" = "true" ]; then
         --connect-timeout-secs 900 \
         --request-timeout-secs 14400 \
         --disable-health-check \
-        --disable-retries > "$ROUTER_LOG" 2>&1 &
+        "${ROUTER_HARDENING_ARGS[@]}" > "$ROUTER_LOG" 2>&1 &
     ROUTER_PID=$!
     echo "Router PID: $ROUTER_PID"
     wait_for_ready \
diff --git a/configs/nvidia-master.yaml b/configs/nvidia-master.yaml
index 28dd645600..b0e6ae49e0 100644
--- a/configs/nvidia-master.yaml
+++ b/configs/nvidia-master.yaml
@@ -1173,6 +1173,25 @@ dsv4-fp4-b300-sglang-agentic-hicache-mtp:
       - { tp: 4, ep: 4, dp-attn: true, kv-offloading: dram, kv-offload-backend: { name: hicache }, spec-decoding: mtp, conc-list: [32, 40, 48, 56, 64, 72, 80, 88, 96, 128], router: { name: sglang-router, version: "0.3.2" } }
       - { tp: 8, ep: 8, dp-attn: true, kv-offloading: none, spec-decoding: mtp, conc-list: [52, 72, 100, 128, 144, 196, 512], router: { name: sglang-router, version: "0.3.2" } }
 
+# Test-only DEP8 c512 arm on the current sglang nightly: HiCache host offload
+# behind the DP-attention arm (the running set saturates the GPU KV pool at
+# c512, so follow-up prefix reuse needs the host tier), MegaMoE FP4-activation
+# A2A, and 16384-token/rank prefill chunks. Not intended to replace the
+# v0.5.17 entry above.
+dsv4-fp4-b300-sglang-agentic-hicache-mtp-nightly:
+  image: lmsysorg/sglang:nightly-dev-cu13-20260818-c0b6474b
+  model: deepseek-ai/DeepSeek-V4-Pro
+  model-prefix: dsv4
+  runner: cluster:b300-nv
+  precision: fp4
+  framework: sglang
+  multinode: false
+  scenarios:
+    agentic-coding:
+    - dram-utilization: 0.80
+      search-space:
+      - { tp: 8, ep: 8, dp-attn: true, kv-offloading: dram, kv-offload-backend: { name: hicache }, spec-decoding: mtp, conc-list: [512], router: { name: sglang-router, version: "0.3.2" } }
+
   # DeepSeek-V4-Pro on B300 with EAGLE/MTP speculative decoding. Recipe is
   # selected inside benchmarks/single_node/dsv4_fp4_b300_sglang_mtp.sh by
   # DP_ATTENTION:
diff --git a/perf-changelog.yaml b/perf-changelog.yaml
index 999f674b76..6c0ba8f07e 100644
--- a/perf-changelog.yaml
+++ b/perf-changelog.yaml
@@ -6203,3 +6203,11 @@
   description:
     - "Add new B200 multi-node configs with PP2, DCP8"
   pr-link: https://github.com/SemiAnalysisAI/InferenceX/pull/2672
+
+- config-keys:
+    - dsv4-fp4-b300-sglang-agentic-hicache-mtp-nightly
+  scenario-type:
+    - agentic-coding
+  description:
+    - "Test-only: measure sglang nightly on B300 AgentX DEP8 c512 with HiCache DRAM offload, MegaMoE FP4-activation A2A, 131072-token chunked prefill, and mem-fraction 0.85."
+  pr-link: https://github.com/SemiAnalysisAI/InferenceX/pull/2680