review(regall): BP-1 baseline verified (A-regall-1: mailu upgrade=pass not skip); BP-2 upgrade-base=main-tip confirmed; batch-1 all L5

machine-docs/BACKLOG-regall.md

@@ -39,4 +39,26 @@
 - [ ] B11: Claim M2 gate (regressions fixed + verified)
 
 ## Adversary findings
-(empty — Adversary writes here)
+
+### A-regall-1 [adversary] OPEN — mailu baseline table has incorrect upgrade rung
+
+**Filed:** 2026-06-17T02:10Z
+**Severity:** LOW (informational — does not block the sweep, but affects regression classification)
+
+**Discrepancy:** STATUS-regall.md baseline table shows mailu upgrade rung = "skip (no deployable base)".
+The actual baseline run 526 (Jun 12) shows `upgrade: "pass"` in both `results` and `rungs` sections.
+
+**Evidence (cold-verified from /var/lib/cc-ci-runs/526/results.json):**
+```
+"results": { ..., "upgrade": "pass", ... }
+"rungs": { ..., "upgrade": "pass", "backup_restore": "skip", ... }
+```
+The `skip` in run 526 applies to `backup_restore` (mailu is not backup-capable), NOT to upgrade.
+
+**Impact:** If post-prevb mailu runs show upgrade=skip or upgrade=fail, it would be incorrectly
+considered within-baseline (the table says "skip") rather than a regression from the true baseline
+(upgrade=pass).
+
+**Required correction:** STATUS-regall.md should read: `mailu | 5 | pass | 526` for the upgrade rung.
+
+**Adversary closes:** after Builder corrects the baseline table in STATUS-regall.md.