docs(dcy-010): confirm-req-implemented — REQ-046/048/049/050/051 Implemented, REQ-047 Approved 유지(Step2 결재대기), BAT-020 release-candidate

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VHtM5Ws1HKCKQ4JGi6GRb5

docs/srs/Non-Functional/req-051_broker-credential-security-isolation.md

@@ -1,6 +1,6 @@
 # REQ-051: 브로커 인증정보 보안 격리 — service-token 전용·web 토큰 차단
 
-- Status: Approved
+- Status: Implemented
 - Type: Non-Functional
 - Priority: High
 - Owner: Justin Ko
@@ -94,3 +94,33 @@
 - Date: 2026-06-28
 - Author: 팀장(Claude)
 - confirm-req: `Proposed` → `Approved`. dcy-010 NFR-1/2/3 흡수 적절(동일 엔드포인트 보안속성). service-token 전용·web 토큰 차단·타 엔드포인트 credential 미노출(AC-5)·로그 비노출(AC-8)·degrade(AC-6/7) testable. REQ-049와 동일 batch 권고. blocker 없음.
+
+### CHG-20260628-03
+- Date: 2026-06-28
+- Author: 팀장(Claude)
+
+#### Change Summary
+- confirm-req-implemented: `Approved` → `Implemented`. PR #17 머지(mergeCommit d4acfd4), BAT-020, QC PASS-WITH-NOTES(blocker 0), 테스트 통과.
+
+#### Intent
+- BAT-020 delivery(PR #17 머지)에서 보안 격리(service-token 전용, web 토큰 차단, 타 엔드포인트 credential 미노출, graceful degrade) 구현 및 AC-1~8 테스트 통과가 확인되어 Implemented로 전환한다.
+
+#### Acceptance Criteria Delta
+- Added: 없음
+- Updated: 없음
+- Removed: 없음
+
+#### Impacted Area Delta
+- 없음 (상태 전환만)
+
+#### Delivery Trace Delta
+- Batches: BAT-020 (PR #17, mergeCommit d4acfd4)
+- Releases: 미정
+
+#### Revalidation Impact
+- Reverification Needed: no
+- Existing Implementation Invalidated: no
+- Status Recommendation: implemented
+
+#### Validation Plan
+- BAT-020 verification 문서 및 QC PASS-WITH-NOTES 결과(blocker 0)로 AC-1~8 근거 확보됨.