RESULT 37: ride fails at 72M (beta-scaled damage through beta-independent guards -> weight poisoning); crown-3 relaunched as fw72m_plain from s50000; ride-v2 design lessons

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014FAPDWQ49M5Ye3NpTndTpn

1 files changed, 23 insertions, 0 deletions

diff --git a/docs/campaign/CASCADE_ABLATION_PLAN.md b/docs/campaign/CASCADE_ABLATION_PLAN.md
index 6c38ce1..e6c10ad 100644
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+++ b/docs/campaign/CASCADE_ABLATION_PLAN.md
@@ -568,6 +568,29 @@ direction), not training-under-fault; wave-2 = co-training with faults injected
 
 
 
+### RESULT 37 (2026-07-17): RIDE FAILS AT 72M — weight poisoning via permissive guards during beta surfing; crown-3 relaunched as PLAIN from the clean ckpt.
+Timeline (fw72m_ride): healthy surf to ~48k; at 72M the governor never found the 42M-style smooth
+hover — beta banged between 1.5e-4 and 1.85e-2 (rho-hat is noisy/laggy at this scale). ~54k:
+first skip jolt (4->17). By 60k beta was PINNED at the cap floor (1.5e-4) yet nearly every step
+drift-rejected at K=8 — relaxation diverging at 20x smaller beta than had been stable for 50k
+steps => the WEIGHT STATE itself was sharpened/poisoned, not a beta-level wall. Mechanism: at
+big beta, displacement (and any semi-diverged garbage) scales with beta, but the drift-accept
+threshold (0.5) is beta-INDEPENDENT — near-threshold accepts during 1e-2-scale surfing carry
+beta-scaled damage into the weights. 42M never showed this because its window is so wide the
+excursions stayed benign. CE never recovered (val 3.77 -> 4.0-4.2, best frozen 3.5797); training
+deadlocked (governor cannot cure a state disease by lowering beta).
+INTERVENTION: killed at ~75k; relaunched as fw72m_plain from the last clean ckpt (s50000,
+skips=3 era): plain estimator, FIXED bf_late 3e-3@0, bcap 0.9 defensive-only (ride=1.0).
+Resume health: val 3.7354, zero skips, cos 0.9965. ETA ~15h.
+LESSONS (ride-v2 design, to be tuned on cheap probes, NEVER on crown runs):
+(a) beta-scaled accept threshold (drift_max ~ f(beta)) or update-norm clip during high-beta;
+(b) climb hysteresis: after any wall contact, cooldown + re-climb at a fraction of the last
+    stable beta (no immediate re-surf);
+(c) rho-hat smoothing (EMA) before governor decisions — the raw per-step meter is too noisy at
+    72M; (d) hard beta_ride headroom set from the last-known stable beta, not a fixed 30x.
+Status: ride stays VALIDATED at 42M (RESULT 35); at 72M it is a failed-first-attempt with a
+diagnosed mechanism — an honest boundary datum for the governor line, not a retraction of it.
+
 ### RESULT 36 (2026-07-17): PRE-REGISTRATION — ride seed campaign + fw72m_ride crown-3 + the BP-fairness note.
 User call: "多跑几条 ride, 在 72M 跑 ride — 说不定真比 BP 好, 因为我们没扫 BP 的最佳 setting."
 Launched: