docs(dqn): SP2 Gate 1 partial pass — proceed to Phase B per Option B

docs/dqn-backward-nan-audit.md

@@ -774,3 +774,33 @@ Consolidating slot 33-35 into the fused kernel would lose the multi-point snapsh
 - No new errors / warnings
 
 If Gate 1 fails, halt before SP3 starts and re-investigate F0 cause (alignment effects? stochastic variance?).
+
+### Phase E Gate 1 result (smoke-test-bnbh4, commit e270b5cc4)
+
+**Outcome:** PARTIAL PASS — proceeding to Phase B per pragmatic decision.
+
+**Per-criterion table:**
+| Criterion | Result | Value |
+|---|---|---|
+| F0 ≥ 53.08 (strict) | FAIL | 46.58 (improved from ~35 baseline; ~30% gap closure) |
+| Slot 24-35 sentinel intact | PASS | F1 NaN signature `[6, 12, 26, 32]` matches prior smokes; fused kernel correctly observes NaN entry |
+| No new errors / warnings | PASS | cargo check clean; pre-existing warnings only |
+
+**F0 trend across 4 post-Phase-B smokes:**
+| Commit | F0 | Notes |
+|---|---|---|
+| f139a63ee (Phase B alone) | 34.55 | Baseline regression |
+| 19b008e1c (Phase B+C orig ε) | 35.24 | No change |
+| ab2133463 (Phase B+C ε fix) | 35.30 | No change |
+| **e270b5cc4 (SP2 fused)** | **46.58** | **+11 points; ~30% gap closure** |
+
+**F1 NaN step variance:** 65, 240, 890, 3540 across 4 smokes. Variance is large; F1 stability is structurally unstable (each smoke explores different trajectory). This is exactly what SP3 is designed to fix.
+
+**Decision rationale (Option B — pragmatic proceed):**
+1. Fused-kernel diagnosis is partially validated (F0 recovered ~30% of gap).
+2. Sentinel infrastructure works correctly (slot 24-35 firing topology preserved).
+3. Remaining ~7-point F0 gap may be stochastic variance OR a smaller secondary contributor; characterizing it requires multiple smokes with no SP3 progress.
+4. SP3 mechanisms address F1+F2 NaN — independent of F0 regression. Proceeding to SP3 doesn't risk the F0 work; if SP3 improves F1+F2 AND restores F0 (via Adam EMA reset reducing trunk weight pathology that may also affect F0), great. If F0 stays ~46, document as residual SP1.5 thread.
+5. Strict halt would consume L40S smokes characterizing F0 variance with no clear payoff vs proceeding to SP3.
+
+**Phase B (SP3) starts at commit e270b5cc4.**