[8.9b] Root-diff triage and the L1–L5 all-green verdict on the build to be soaked

[rootwarp]

Plan reference: plan/glamsterdam-2026-09-05/issues/08-phase-8-network-soak-and-observability.md · Issue 8.9b

Description

Triage every root that moved at the new tag and run all five KAT layers to a verdict. The verdict is binary: all green names the exact build 8.8 will soak; anything else blocks 8.8 until fixed and re-run (D26). The readiness record is 8.10's, after the soak.

Implementation Notes

• Each changed root gets a verdict: spec change (record and re-baseline with the spec citation) or rs-vc defect (issue in the owning phase). Never a silent re-baseline.
• If L1 fails at the new tag, ADR-001 (adopt libssz =0.3.0) reopens and the ADR-007 hand-roll is the fallback; ADR-007 confines the swap to rvc_gloas::merkle, so container declarations do not move. Stop and raise the reversal rather than absorbing it into this issue's points.
• Write the per-layer results and the commit SHA of the build that passed into the Decision Log; 8.8 soaks that SHA and 8.10 records it. A fix to any layer produces a new SHA and re-runs this issue; the soak (if started) restarts.
• 3 points is the triage-plus-record floor, justified by the unbounded diff surface; it is not a budget for an ADR-001 reversal.

Acceptance Criteria

• L1–L5 all green at the new tag on one named commit SHA — the only outcome that unblocks 8.8. A failure is recorded with a verdict and an owning issue and leaves 8.8 blocked; it never satisfies this criterion (D26).
• Every root that changed versus the previous tag appears in the Decision Log (plan/glamsterdam-2026-09-05/project-plan.md:129) with its verdict and citation; no root re-baselined without one.
• kat_policy.rs green with zero new EXEMPTIONS.
• The Decision Log entry names the passing commit SHA and the tag; 8.8's snapshots reference it.
• If L1 failed, an ADR-001 reversal issue exists and is linked; this issue does not perform the swap and 8.8 stays blocked.

Testing Notes

re-run the full KAT set on the regenerated vectors; mainnet preset nightly, minimal in CI.

Points: 3 · Type: spike · Priority: P0 · Scope: 1.5 days — unbounded above this if L1 fails (see risks) · Blocked by: #340 · Blocks: #339