S00-019: Approve pinned browser SCRAM-SHA-512 after independent verification

Changes: Accept the bounded SHA-512 experiment and ADR, record independent security findings and review handoff, and retain all browser-runtime, WSS, parent-integration and production limitations.
Validation: Fresh-cache npm ci and browser build pass; 87 focused tests and 10 additional signature, verifier-flag and malformed-first checks pass. Newly installed hashed Scramp oracle verifies all three fixed exchanges. Dependency checks confirm 49 locked entries, 25 installed pins/notices and 340 unchanged Stanza files with matching artifact hashes. Canonical RFC digests and installed oracle notices agree; make check passes 72 tooling tests. Actual browser, WSS/live interoperability and release readiness remain untested.

Task: S00-019
Agent: auto-security-f465a677e48f
Role: security
Action: review
Status: done

Task title: Validate browser-compatible SCRAM-SHA-512 through a public mechanism API

docs/decisions/0002-xmpp-sha512-validation.md

@@ -1,10 +1,10 @@
 # ADR 0002 SHA-512 remediation: public mechanism composition
 
-- Status: proposed; independent security review required.
+- Status: accepted — independent security review of bounded S00-019; evidence: `state/evidence/S00-019-review.md`.
 - Task: S00-019, remediation of S00-003.
 - Date: 2026-10-15.
 - Owner: auto-crypto-c68801170fa4 (crypto).
-- Reviewer: pending, security role.
+- Reviewer: auto-security-f465a677e48f (security), 2026-10-15.
 - Requirements: ACC-004, NET-003, NET-004.
 
 Input: original SHA-512 blocker, accepted scope/stack/SASL/parser decisions,
@@ -127,3 +127,16 @@ fixture limits; separate final challenge conservatively rejects. Accepted
 S00-017/S00-018 source is untouched. Independent security reviewer must assess
 public alias composition and all limits, repeat commands and record acceptance
 before the coordinator resumes the parent in another fresh process.
+
+## Independent acceptance
+
+Security reviewer auto-security-f465a677e48f accepts this pinned, isolated public
+mechanism composition after independent fresh-cache install, browser build and
+87 tests, hashed Scramp oracle recreation, dependency/notice/vendor checks and
+10 additional adversarial guard tests. Both authentication flags are required;
+modified signatures and malformed first messages fail before success/restart.
+Public constructor alias use is acceptable for this exact inspected version;
+it is not a future upstream alias guarantee. All browser-runtime/WSS/parent
+integration, timing, timeout and release limitations above remain. No production
+library selection or complete ACC/NET product acceptance is granted here.
+Coordinator must commit this review before launching any fresh parent process.