server: support GptOss in TP engine + benchmark script

- tp_engine.rs: TpModel enum dispatches between Qwen3 and GptOss based on
  config.is_moe(). Server auto-detects model type on startup.
- tools/run_gpt_oss_bench.sh: one-click benchmark comparing xserv (TP=2)
  vs llama.cpp (BF16 GGUF) on GSM8K quality + speed

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tools/bench_gpt_oss.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+# Benchmark gpt-oss-20b: xserv (TP=2) vs llama.cpp (BF16 GGUF)
+# Runs GSM8K 200 problems on both systems and produces a comparison report.
+#
+# Usage: ./tools/bench_gpt_oss.sh [--quality-limit N]
+set -e
+
+REMOTE="dash5"
+REMOTE_DIR="/opt/wjh/projects/xserv"
+MODEL_DIR="/opt/wjh/models/gpt-oss-20b-bf16"
+GGUF="/opt/wjh/models/gpt-oss-20b-gguf/gpt-oss-20b-bf16.gguf"
+LLAMA_BIN="$REMOTE_DIR/third_party/llama.cpp/build/bin/llama-server"
+XSERV_BIN="$REMOTE_DIR/target/release/xserv-server"
+
+QUALITY_LIMIT="${1:-200}"
+XSERV_PORT=18080
+LLAMA_PORT=18090
+
+echo "=== gpt-oss-20b Benchmark: xserv vs llama.cpp ==="
+echo "Quality limit: $QUALITY_LIMIT problems"
+echo ""
+
+# Sync project first
+LOCAL_DIR="$(cd "$(dirname "$0")/.." && pwd)"
+echo "Syncing project..."
+rsync -az --exclude target --exclude .git --exclude bench-out \
+    "$LOCAL_DIR/" "$REMOTE:$REMOTE_DIR/" >/dev/null
+
+# Build on remote
+echo "Building xserv..."
+ssh $REMOTE "cd $REMOTE_DIR && source /etc/profile && \
+    if [ -d /usr/local/cuda-12.9 ]; then export CUDA_HOME=/usr/local/cuda-12.9; else export CUDA_HOME=/usr/local/cuda; fi && \
+    export PATH=\$CUDA_HOME/bin:\$PATH && \
+    cargo build --release 2>&1 | tail -3"
+
+echo ""
+echo "=== Starting servers ==="
+
+# Start llama.cpp server (GPU 2-3, BF16 GGUF needs ~42GB → use 2 GPUs)
+echo "Starting llama-server (GPU 2,3)..."
+ssh $REMOTE "CUDA_VISIBLE_DEVICES=2,3 nohup $LLAMA_BIN \
+    -m $GGUF --port $LLAMA_PORT -ngl 999 -c 4096 --n-gpu-layers 999 \
+    > /tmp/llama-gptoss.log 2>&1 &"
+sleep 5
+
+# Start xserv server (GPU 0,1, TP=2)
+echo "Starting xserv-server (GPU 0,1, TP=2)..."
+ssh $REMOTE "CUDA_VISIBLE_DEVICES=0,1 nohup $XSERV_BIN $MODEL_DIR \
+    --port $XSERV_PORT --tp 2 --max-batch 1 --max-seq-len 4096 \
+    > /tmp/xserv-gptoss.log 2>&1 &"
+sleep 10
+
+# Wait for servers to be ready
+echo "Waiting for servers..."
+for i in $(seq 1 30); do
+    XSERV_OK=$(ssh $REMOTE "curl -s http://localhost:$XSERV_PORT/health 2>/dev/null" || echo "")
+    LLAMA_OK=$(ssh $REMOTE "curl -s http://localhost:$LLAMA_PORT/health 2>/dev/null" || echo "")
+    if [ -n "$XSERV_OK" ] && [ -n "$LLAMA_OK" ]; then
+        echo "Both servers ready!"
+        break
+    fi
+    sleep 2
+done
+
+echo ""
+echo "=== Running GSM8K benchmark ($QUALITY_LIMIT problems) ==="
+
+# Run quality benchmark
+ssh $REMOTE "cd $REMOTE_DIR && python3 -m tools.bench.runner \
+    --xserv-base-url http://localhost:$XSERV_PORT \
+    --xserv-model-id gpt-oss-20b \
+    --llama-base-url http://localhost:$LLAMA_PORT \
+    --suite quality \
+    --quality-limit $QUALITY_LIMIT \
+    --max-seq-len 4096" 2>&1
+
+echo ""
+echo "=== Running speed benchmark ==="
+
+ssh $REMOTE "cd $REMOTE_DIR && python3 -m tools.bench.runner \
+    --xserv-base-url http://localhost:$XSERV_PORT \
+    --xserv-model-id gpt-oss-20b \
+    --llama-base-url http://localhost:$LLAMA_PORT \
+    --suite speed \
+    --max-seq-len 4096" 2>&1
+
+# Cleanup
+echo ""
+echo "=== Cleaning up ==="
+ssh $REMOTE "pkill -f 'llama-server.*18090' 2>/dev/null; pkill -f 'xserv-server.*18080' 2>/dev/null" || true
+
+echo "Done! Results in bench-out/"