From f31e9ccfd5ff81eb82b78466a787c2be0bff4330 Mon Sep 17 00:00:00 2001 From: Gahow Wang Date: Mon, 15 Jun 2026 16:57:53 +0800 Subject: [PATCH] Record Stop-A boundary-guard A/B: correct verdict, ~38% replay saved With the guard enabled the binary search recovers best sampling_u=0.078125 (rate 2.30 req/s), identical to the full-replay baseline. The guard fired on exactly the one feasibility-knee probe (0.08594, re-measured full -> infeasible); the other three probes truncated to ~45-50%. Net ~38% replay saved on the trial with no peak-rate overestimate. Stop-A + boundary guard is safe to enable. Co-Authored-By: Claude Opus 4.8 --- .../stop-a-validation-20260615.md | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/docs/harness-ablation/stop-a-validation-20260615.md b/docs/harness-ablation/stop-a-validation-20260615.md index 4a9db5e..1ef4d7e 100644 --- a/docs/harness-ablation/stop-a-validation-20260615.md +++ b/docs/harness-ablation/stop-a-validation-20260615.md @@ -79,6 +79,31 @@ L-C-A converges. It targets exactly this knee case at low extra cost (it only extends replay on probes sitting on the feasibility boundary). Recommend adding it as a small Stop-A enhancement before enabling Stop-A in production studies. +## 4. SLO-boundary guard (implemented + validated) + +Added `trace.adaptive_stop.boundary_delta` (default 0.02): when a truncated probe's +measured pass-rate lands within ±δ of the SLO target, re-measure on the full window +and use that verdict. Re-ran the same config with `adaptive_stop` enabled +(τ=0.9, τ_c=0.90, δ=0.02): + +| threshold | feasible | pass | selected | replayed | boundary_extended | +| --- | --- | --- | --- | --- | --- | +| 0.06250 | True | 1.000 | 1086 | 487 (45%) | — | +| 0.09375 | False | 0.444 | 1656 | 822 (50%) | — | +| 0.07812 | True | 0.994 | 1378 | 682 (49%) | — | +| 0.08594 | **False** | 0.947 | 1523 | **1523 (100%)** | **True** | + +Result: best feasible `sampling_u=0.078125` (rate 2.30 req/s) — **identical to the +full-replay baseline**. The guard fired on exactly the one knee probe and +re-measured it to the correct infeasible verdict; the other three probes truncated +to ~45–50%. Net replayed 3514/5643 requests ≈ **38% replay saved on this trial +while recovering the correct peak rate** (no one-step overestimate). + +**Conclusion: Stop-A with the boundary guard is correct (verdict matches full +replay) and still saves replay time. Safe to enable.** Configs: +`dash0_qwen30b_a3b_stopA_fulldata.json` (OFF baseline) and +`dash0_qwen30b_a3b_stopA_on.json` (ON). + ## Repro ```