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: S00-003 cannot attest parser limits: Stanza 12.22.1 exposes no resource bounds and its persistent WebSocket parser accepts large/deep XML and reassembles incomplete documents across separate input messages.

Task: S00-003
Agent: auto-protocol-902594b44429
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
+- Зависимости: S00-001, S00-002, S00-017, S00-018
 - Требования: ACC-004, NET-003, NET-004
 
 ## Один результат

planning/tasks/S00-018.md

@@ -0,0 +1,62 @@
+# S00-018: Validate bounded standalone XML ingress for the XMPP candidate
+
+- Remediation для: S00-003; root: S00-003; depth: 1
+
+> Generated from planning/tasks.json; status is in state/tasks.json.
+
+- Этап: S00
+- Оператор: protocol
+- Reviewer: security
+- Зависимости: S00-001, S00-002, S00-017
+- Требования: ACC-004, NET-003, NET-004
+
+## Один результат
+
+One isolated runnable and independently reviewed ingress experiment enforces explicit finite XML resource limits and standalone text XML per WebSocket message before unsafe accumulation/import, through a supported library integration path.
+
+## Разрешённые пути
+
+- `experiments/0002-xmpp-library/parser-validation/**`
+- `docs/decisions/0002-xmpp-parser-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/S00-018.md
+
+## Шаги
+
+1. Read original blocker evidence, bounded probe, shipped parser/transport APIs and RFC 7395 framing; reproduce the stock failure with finite synthetic input.
+2. Choose and document a supported ingress integration using vetted existing XML parsing; keep limits experiment-local, do not implement a handwritten security XML parser or patch ignored vendor sources.
+3. Enforce byte/depth/element/attribute budgets and complete single-document text-message framing before unbounded tree/import work; reject invalid input terminally and clear attempt state.
+4. Add valid boundary and adversarial fixtures including incomplete messages, multiple roots, oversized tokens/attributes, deep XML, malformed XML and binary messages; verify rejection causes no stanza delivery or retained cross-message state.
+5. Record exact dependencies/licenses/browser API constraints if adding packages, runnable commands/results and limitations, then submit for independent security review.
+
+## Приёмка
+
+1. Explicit finite byte/depth/element/attribute budgets are enforced before uncontrolled accumulation/import; boundary-valid stanza still parses with actual library behavior.
+2. Each WebSocket message is one complete standalone text XML document; incomplete/multiple-root/binary input is rejected and cannot be revived by a later message.
+3. Original large/deep/cross-message failure categories are rejected under documented local limits without post-import-only checks, vendor patch or TLS/CORS bypass.
+4. One supported integration path and cleanup/reset behavior are demonstrated by runnable actual ingress tests; no production shared contract, auth policy or product limit change.
+
+## Focused checks
+
+1. Positive boundary-valid framed stanza using the actual candidate registry/parser and ingress integration.
+2. Original bounded probe categories exceed local budgets or fail framing and produce terminal rejection without stanza emission.
+3. Malformed/unfinished/multiple-root/binary/oversized-token/attribute/depth/element cases; no cross-message retained state or late revival.
+4. Fresh attempt/reset accepts valid input; dependency pin/license/API and scope inspection.
+
+## 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.