cascade: zil interleaved scheme = exact gradients at all depths (cos 1.0000 L6-24, trajectory 0.9998+); casc_ep_train zil trainer; naive-relaxation depth failure documented

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

1 files changed, 20 insertions, 0 deletions

diff --git a/docs/campaign/CASCADE_ABLATION_PLAN.md b/docs/campaign/CASCADE_ABLATION_PLAN.md
index 5c10dd9..c480c11 100644
--- a/docs/campaign/CASCADE_ABLATION_PLAN.md
+++ b/docs/campaign/CASCADE_ABLATION_PLAN.md
@@ -26,6 +26,26 @@ The looped-EP precedent multiplier was ~230× BP; the K-frontier decides whether
 
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+## STATUS 2026-07-09 (same day): Tier 0 CLOSED GREEN via the zil scheme; C1 running
+
+- **Naive relaxation FAILS at depth** (the B1-lite sweep): jacobi K=40·L → cos 0.82 (L6) / 0.67 (L12)
+  / 0.53 (L24), shrink dying 0.41→0.28; gsf/gsr with small-η+momentum no better; β-insensitive
+  (0.01/0.03/0.1 identical) ⟹ binding error = RELAXATION INCOMPLETENESS, not Taylor bias.
+  warp2.0 catastrophic (cos 0.11) under naive descent.
+- **Two implementation traps found:** (1) NBT-normalized energy made γ=1 actually γ=1/128;
+  (2) plain γ=1 reverse sweep WITHOUT interleaved reads contaminates e_l with J_l·δ_{l−1}
+  (same β-order as the signal) — final-state readout is directionally ruined (cos 0.30@L6).
+- **The fix = zil scheme (interleaved reverse sweep):** update z_l (γ=1, SUM units) then read
+  θ_l IMMEDIATELY (e_l = −β·δ_l exact at the feedforward point; δ-recursion has NO linearization
+  error). Single phase, β cancels exactly. **Results: cos = 1.0000 at L=6/12/24; io gate 0.9999;
+  warp2.0 → 1.0000; real-trajectory ckpts (casc_bp6 s0→s4000) → 0.9998–1.0000. A0.1/A0.2/A0.3 all
+  green.** Honest framing: zil is numerically BP restructured as per-layer local two-factor energy
+  reads (no global backward graph); the EQUILIBRIUM mode (jacobi/CG to convergence) remains the
+  physically-meaningful EP column — priced expensive by the sweep, CG/preconditioning is the B2 job,
+  and it is the analog-hardware rung (E-tier).
+- **C1 money run LAUNCHED:** casc_ep6 (zil, seed 0) vs casc_bp6 (BP twin, best 2.9746@4k) —
+  step-0 CE bit-identical (true twin). 107 GPU3.
+
 ## Tier 0 — gate hardening (probe-scale, hours, no training)  → K1
 
 | ID | question | design | decision rule |