S00-003: Record blocked task and remediation handoff

Changes: Preserve incomplete work and blocker metadata for S00-003. This checkpoint does not mark implementation accepted.
Validation: Session ended with status blocked.
Blocker: Stanza 12.22.1 browser HMAC sha-512 fails RFC 4231 Test Case 1: wrong 64-byte block selection. SCRAM-SHA-512 derives that hyphenated algorithm; private algorithm mutation/vendor patches are unsupported. Parent cannot attest browser strongest-mechanism compatibility from Node-only success.

Task: S00-003
Agent: auto-protocol-dcdf92cd067e
Role: protocol
Action: claim
Status: blocked

Task title: Проверить XMPP WSS/auth библиотеку

planning/tasks/S00-003.md

@@ -5,7 +5,7 @@
 - Этап: S00
 - Оператор: protocol
 - Reviewer: qa
-- Зависимости: S00-001, S00-002, S00-017, S00-018
+- Зависимости: S00-001, S00-002, S00-017, S00-018, S00-019
 - Требования: ACC-004, NET-003, NET-004
 
 ## Один результат

planning/tasks/S00-019.md

@@ -0,0 +1,61 @@
+# S00-019: Validate browser-compatible SCRAM-SHA-512 through a public mechanism API
+
+- Remediation для: S00-003; root: S00-003; depth: 1
+
+> Generated from planning/tasks.json; status is in state/tasks.json.
+
+- Этап: S00
+- Оператор: crypto
+- Reviewer: security
+- Зависимости: S00-001, S00-002, S00-017, S00-018
+- Требования: ACC-004, NET-003, NET-004
+
+## Один результат
+
+One isolated runnable independently reviewed browser-compatible SCRAM-SHA-512 integration uses vetted existing crypto through a supported public mechanism API and validates proof/server-final without vendor/private-field patching or custom primitives.
+
+## Разрешённые пути
+
+- `experiments/0002-xmpp-library/sha512-validation/**`
+- `docs/decisions/0002-xmpp-sha512-validation.md`
+
+Не изменять другие modules, shared contracts или spec snapshots без изменения плана. Stem без расширения разрешает принятые stack-specific extensions и focused test рядом.
+
+## Прочитать
+
+- docs/WEB_PROFILE.md
+- docs/ARCHITECTURE.md
+- docs/CONTRACTS.md
+- docs/TESTING.md
+- roles/protocol.md
+- docs/decisions/README.md
+- state/blockers/S00-019.md
+
+## Шаги
+
+1. Read original blocker, accepted stack/SASL ADR and pinned browser implementation/public APIs.
+2. Reproduce the HMAC alias defect and evaluate an existing vetted mechanism/backend or candidate with primary docs, exact pins, license and browser/API checks.
+3. Implement only isolated SCRAM-SHA-512 integration via supported public APIs using existing cryptographic code; retain fail-closed mutual authentication and real absence of channel binding.
+4. Run fixed known vectors and full exchange positive/negative checks against the browser-resolved backend; preserve evidence, limitations and handoff for independent security review.
+
+## Приёмка
+
+1. RFC SHA-512 known vectors match using actual browser-compatible crypto backend, including algorithm spelling and varied key lengths.
+2. Full SCRAM-SHA-512 client proof and verified server-final agree with an independent existing implementation/fixed externally derived vector; missing/forged/premature final fails without authentication/restart.
+3. Integration uses public mechanism APIs, correct SCRAM-SHA-512 wire name, no private-field/vendor patch, invented binding, custom primitives or plaintext downgrade.
+4. Runnable pinned fixture experiment and browser bundle/backend evidence permit independent review; no parent WSS/library selection/shared contract work.
+
+## Focused checks
+
+1. Reproduce original browser sha-512 HMAC mismatch.
+2. Fixed SHA-512/HMAC known vectors including long keys using selected browser backend.
+3. Full SCRAM-SHA-512 verified exchange and forged/missing/out-of-order server-final rejection.
+4. Exact dependency/license/API/browser checks and repeatable clean install/bundle plus focused suite.
+
+## Блокер и завершение запуска
+
+Для всех ролей scope — только эта задача. При блокере создать issue JSON по state/ISSUE_TEMPLATE.json, вызвать escalate с текущим ID/role/agent, проверить status=blocked и resolution_task, затем немедленно завершить запуск. Не решать blocker и не выбирать следующую задачу самому. Новый агент назначается runner. Правки metadata через CLI — единственное исключение scope.
+
+## Передача
+
+Сохранить evidence/handoff; submit → review и завершить запуск. Reviewer также выполняет только эту задачу, включая обязательное escalate при блокере.