Add deeper infeasible probe diagnostics

configs/examples/dash0_manual_trial2_proposal.json

@@ -0,0 +1,22 @@
+{
+  "observation": "Long-context chat traffic is dominated by large prefills, so TTFT under the stepped SLO is the binding constraint. A launch-safe baseline should spread compute across all 4 GPUs while limiting concurrent long-prefill contention.",
+  "diagnosis": "The FLASHINFER attempt failed at startup, but the safer FLASH_ATTN family launched successfully. A conservative seq cap plus a moderate batched-token cap is a better baseline for diagnosing whether the SLO itself is too aggressive under this trace.",
+  "config_patch": {
+    "env_patch": {
+      "VLLM_ATTENTION_BACKEND": "FLASH_ATTN"
+    },
+    "flag_patch": {
+      "tensor-parallel-size": 4,
+      "max-num-seqs": 16,
+      "max-num-batched-tokens": 24576,
+      "gpu-memory-utilization": 0.94,
+      "block-size": 32
+    }
+  },
+  "expected_effects": [
+    "Stable 4-GPU launch without FLASHINFER warmup failure",
+    "Lower head-of-line blocking than larger sequence caps",
+    "More interpretable lower-bound throughput/SLO measurement"
+  ],
+  "why_not_previous_failures": "This proposal keeps the launch-safe FLASH_ATTN backend and the conservative batching limits that already avoided the earlier FLASHINFER startup failure."
+}