Add trace length bucket tuning support

configs/examples/dash0_qwen27b_tight_slo_baseline_proposal.json

@@ -0,0 +1,28 @@
+{
+  "observation": "The incumbent should start from the known launch-safe qwen3.5-27b serving recipe on dash0 before asking the LLM to optimize throughput above that baseline.",
+  "diagnosis": "This model uses a long-context hybrid stack and fp8 quantization. The safest first measurement is to preserve the existing warmup, hybrid-model, chunked-prefill, and prefix-caching behavior from run_qwen27b.sh, while keeping a conservative sequence cap.",
+  "config_patch": {
+    "env_patch": {
+      "VLLM_ATTENTION_BACKEND": "FLASH_ATTN",
+      "VLLM_ENABLE_TORCH_COMPILE": "1",
+      "VLLM_USE_FLASHINFER_SAMPLER": "0",
+      "VLLM_ENABLE_MODEL_RUNNER_WARMUP": "1"
+    },
+    "flag_patch": {
+      "tensor-parallel-size": 4,
+      "gpu-memory-utilization": 0.9,
+      "block-size": 64,
+      "max-num-batched-tokens": 8192,
+      "max-num-seqs": 16,
+      "enable-prefix-caching": true,
+      "enable-chunked-prefill": true,
+      "disable-cascade-attn": true
+    }
+  },
+  "expected_effects": [
+    "Launch-safe baseline aligned with the current hand-tuned qwen27b recipe while using all 4 visible H20 GPUs",
+    "Reliable first incumbent under the tighter TTFT and TPOT SLO",
+    "Clear trial history for the LLM to propose a higher-throughput follow-up patch"
+  ],
+  "why_not_previous_failures": "This baseline intentionally avoids speculative new kernels or batching spikes before we have an incumbent under the new SLO."
+}