diff --git a/main.py b/main.py
index f2d7051..2ff3538 100644
--- a/main.py
+++ b/main.py
@@ -64,6 +64,11 @@ from routers import (
     conversational_ops,
     ux_analytics,
     sr_auto_review,
+    alert_rules,
+    search as search_router,
+    sr_chat,
+    inventory,
+    system as system_router,
 )
 
 
@@ -375,6 +380,7 @@ from routers import (
 app.include_router(autodiscovery.router)        # CMDB SSH 자동 발견
 app.include_router(snmp_discovery.router)       # SNMP 네트워크 장비 발견
 app.include_router(dependency_map.router)       # 서비스 의존성 자동 매핑
+app.include_router(inventory.router)            # #62 부품 재고 (/api/inventory/parts — config_inventory보다 먼저 등록)
 app.include_router(config_inventory.router)     # 서버 구성 인벤토리 자동 수집
 app.include_router(nlquery.router)              # Text-to-SQL 자연어 쿼리
 app.include_router(op_assistant.router)         # 대화형 운영 어시스턴트
@@ -517,6 +523,13 @@ app.include_router(data_governance.router)        # 데이터 거버넌스 (PII
 app.include_router(harness_builder.router)        # 하네스 빌더 (노코드 에이전트 생성·실행·스킬)
 app.include_router(tmux_sessions.router)          # tmux 세션 관리 (영속터미널·공유·명령전송)
 
+# ── 모바일 100기능 백엔드 API ────────────────────────────────────────────────
+app.include_router(alert_rules.router)            # #45 알림 규칙 CRUD
+app.include_router(search_router.router)           # #50 통합 검색
+app.include_router(sr_chat.router)                 # #98 SR 채팅 (REST + WebSocket)
+app.include_router(system_router.router)           # #77 시스템 정보/릴리즈 노트
+app.include_router(approvals.changes_router)       # #68 변경 달력 (/api/changes)
+
 
 # ── 개방망 보안 헤더 미들웨어 ────────────────────────────────────────────────
 @app.middleware("http")
diff --git a/models.py b/models.py
index fc1cd68..880055e 100644
--- a/models.py
+++ b/models.py
@@ -7153,3 +7153,123 @@ class TmuxCommand(Base):
     command    = Column(Text)
     sent_by    = Column(String(100))
     created_at = Column(DateTime, default=func.now())
+
+
+# ════════════════════════════════════════════════════════════════════════════════
+# ── 모바일 100기능 백엔드 모델 (Mobile API) ─────────────────────────────────────
+# ════════════════════════════════════════════════════════════════════════════════
+
+class AlertRule(Base):
+    """알림 규칙 — 서버/서비스/SR 지표 임계치 기반 노코드 알림 정의 (#45)."""
+    __tablename__ = "tb_alert_rule"
+
+    id          = Column(Integer, primary_key=True, index=True)
+    tenant_id   = Column(String(50), nullable=False, index=True)
+    target_type = Column(String(20), nullable=False)   # server | service | sr
+    target_id   = Column(String(100))
+    metric      = Column(String(30), nullable=False)   # cpu | memory | disk | sla
+    threshold   = Column(Float, nullable=False)
+    operator    = Column(String(5), default=">")        # > | < | =
+    channel     = Column(String(20), default="inapp")   # push | inapp | sms
+    enabled     = Column(Boolean, default=True)
+    created_by  = Column(String(100))
+    created_at  = Column(DateTime, default=func.now())
+    updated_at  = Column(DateTime, default=func.now(), onupdate=func.now())
+
+
+class InventoryPart(Base):
+    """부품 재고 — 현장 서비스 교체 부품 관리 (#62)."""
+    __tablename__ = "tb_inventory_part"
+
+    id           = Column(Integer, primary_key=True, index=True)
+    tenant_id    = Column(String(50), nullable=False, index=True)
+    name         = Column(String(200), nullable=False)
+    model        = Column(String(100))
+    quantity     = Column(Integer, default=0)
+    min_quantity = Column(Integer, default=1)
+    location     = Column(String(200))
+    created_at   = Column(DateTime, default=func.now())
+    updated_at   = Column(DateTime, default=func.now(), onupdate=func.now())
+
+
+class SRChatMessage(Base):
+    """SR 채팅 메시지 — SR별 실시간 협업 대화 (#98)."""
+    __tablename__ = "tb_sr_chat_message"
+
+    id         = Column(Integer, primary_key=True, index=True)
+    task_id    = Column(String(30), nullable=False, index=True)   # SRRequest.sr_id
+    sender_id  = Column(String(100), nullable=False)
+    content    = Column(Text, nullable=False)
+    msg_type   = Column(String(20), default="text")   # text | image | sr_update
+    read_by    = Column(Text)   # JSON list of usernames who read
+    created_at = Column(DateTime, default=func.now(), index=True)
+
+
+class SRSubscription(Base):
+    """SR 구독/팔로우 — 사용자가 SR 변경 알림을 받도록 구독 (#14)."""
+    __tablename__ = "tb_sr_subscription"
+
+    id         = Column(Integer, primary_key=True, index=True)
+    task_id    = Column(String(30), nullable=False, index=True)   # SRRequest.sr_id
+    username   = Column(String(100), nullable=False, index=True)
+    created_at = Column(DateTime, default=func.now())
+
+
+class SRRating(Base):
+    """SR 완료 만족도 평가 (#53)."""
+    __tablename__ = "tb_sr_rating"
+
+    id         = Column(Integer, primary_key=True, index=True)
+    task_id    = Column(String(30), nullable=False, index=True)
+    rater      = Column(String(100), nullable=False)
+    score      = Column(Integer, nullable=False)   # 1~5
+    comment    = Column(Text)
+    created_at = Column(DateTime, default=func.now())
+
+
+class SRSignature(Base):
+    """현장 전자서명 — 작업 완료 현장 확인 서명 (#70)."""
+    __tablename__ = "tb_sr_signature"
+
+    id            = Column(Integer, primary_key=True, index=True)
+    task_id       = Column(String(30), nullable=False, index=True)
+    signed_by     = Column(String(100), nullable=False)
+    signature_b64 = Column(Text, nullable=False)   # base64 PNG 서명 데이터
+    created_at    = Column(DateTime, default=func.now())
+
+
+class SRCheckin(Base):
+    """현장 체크인 — 엔지니어 현장 도착 GPS 기록 (#93)."""
+    __tablename__ = "tb_sr_checkin"
+
+    id         = Column(Integer, primary_key=True, index=True)
+    task_id    = Column(String(30), nullable=False, index=True)
+    username   = Column(String(100), nullable=False)
+    lat        = Column(Float)
+    lng        = Column(Float)
+    created_at = Column(DateTime, default=func.now())
+
+
+class UserDevice(Base):
+    """등록 디바이스 — 모바일 앱 디바이스/푸시 토큰 관리 (#33)."""
+    __tablename__ = "tb_user_device"
+
+    id           = Column(Integer, primary_key=True, index=True)
+    username     = Column(String(100), nullable=False, index=True)
+    device_name  = Column(String(150))
+    device_type  = Column(String(30))   # android | ios | web
+    push_token   = Column(String(300))
+    last_seen_at = Column(DateTime, default=func.now())
+    created_at   = Column(DateTime, default=func.now())
+
+
+class LoginEvent(Base):
+    """보안 이벤트 로그 — 로그인 성공/실패/디바이스 등록 등 (#34)."""
+    __tablename__ = "tb_login_event"
+
+    id          = Column(Integer, primary_key=True, index=True)
+    username    = Column(String(100), index=True)
+    event_type  = Column(String(40), nullable=False)   # LOGIN_SUCCESS | LOGIN_FAIL | DEVICE_ADDED | ...
+    detail      = Column(Text)
+    ip_addr_hash= Column(String(64))   # SHA-256, 원본 미저장
+    created_at  = Column(DateTime, default=func.now(), index=True)
diff --git a/routers/alert_rules.py b/routers/alert_rules.py
new file mode 100644
index 0000000..b2c3c79
--- /dev/null
+++ b/routers/alert_rules.py
@@ -0,0 +1,198 @@
+"""
+알림 규칙 CRUD API (모바일 기능 #45).
+
+엔드포인트:
+  GET    /api/alert-rules/            — 내 알림 규칙 목록 (tenant 필터)
+  POST   /api/alert-rules/            — 알림 규칙 생성
+  PUT    /api/alert-rules/{id}        — 알림 규칙 수정
+  DELETE /api/alert-rules/{id}        — 알림 규칙 삭제
+  PATCH  /api/alert-rules/{id}/toggle — 활성/비활성 토글
+
+AlertRule: target_type(server/service/sr), metric(cpu/memory/disk/sla),
+           threshold, operator(>/</=), channel(push/inapp/sms), enabled
+"""
+from __future__ import annotations
+
+from datetime import datetime
+from typing import List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel, ConfigDict, field_validator
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from core.auth import get_current_user
+from database import get_db
+from models import AlertRule, User
+
+router = APIRouter(prefix="/api/alert-rules", tags=["Alert Rules"])
+
+_VALID_TARGET = {"server", "service", "sr"}
+_VALID_METRIC = {"cpu", "memory", "disk", "sla"}
+_VALID_OPERATOR = {">", "<", "="}
+_VALID_CHANNEL = {"push", "inapp", "sms"}
+
+
+def _tenant_of(user: User) -> str:
+    """사용자의 테넌트 식별자 — inst_code 우선, 없으면 username 단위 격리."""
+    return user.inst_code or f"user:{user.username}"
+
+
+class AlertRuleCreate(BaseModel):
+    target_type: str
+    target_id: Optional[str] = None
+    metric: str
+    threshold: float
+    operator: str = ">"
+    channel: str = "inapp"
+    enabled: bool = True
+
+    @field_validator("target_type")
+    @classmethod
+    def _v_target(cls, v: str) -> str:
+        if v not in _VALID_TARGET:
+            raise ValueError(f"target_type은 {_VALID_TARGET} 중 하나여야 합니다.")
+        return v
+
+    @field_validator("metric")
+    @classmethod
+    def _v_metric(cls, v: str) -> str:
+        if v not in _VALID_METRIC:
+            raise ValueError(f"metric은 {_VALID_METRIC} 중 하나여야 합니다.")
+        return v
+
+    @field_validator("operator")
+    @classmethod
+    def _v_op(cls, v: str) -> str:
+        if v not in _VALID_OPERATOR:
+            raise ValueError(f"operator는 {_VALID_OPERATOR} 중 하나여야 합니다.")
+        return v
+
+    @field_validator("channel")
+    @classmethod
+    def _v_ch(cls, v: str) -> str:
+        if v not in _VALID_CHANNEL:
+            raise ValueError(f"channel은 {_VALID_CHANNEL} 중 하나여야 합니다.")
+        return v
+
+
+class AlertRuleUpdate(BaseModel):
+    target_type: Optional[str] = None
+    target_id: Optional[str] = None
+    metric: Optional[str] = None
+    threshold: Optional[float] = None
+    operator: Optional[str] = None
+    channel: Optional[str] = None
+    enabled: Optional[bool] = None
+
+
+class AlertRuleOut(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    target_type: str
+    target_id: Optional[str]
+    metric: str
+    threshold: float
+    operator: str
+    channel: str
+    enabled: bool
+    created_by: Optional[str]
+    created_at: Optional[datetime]
+
+
+@router.get("/", response_model=List[AlertRuleOut])
+async def list_alert_rules(
+    enabled: Optional[bool] = None,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """내 테넌트의 알림 규칙 목록."""
+    q = select(AlertRule).where(AlertRule.tenant_id == _tenant_of(current_user))
+    if enabled is not None:
+        q = q.where(AlertRule.enabled == enabled)
+    q = q.order_by(AlertRule.created_at.desc())
+    rows = (await db.execute(q)).scalars().all()
+    return rows
+
+
+@router.post("/", response_model=AlertRuleOut, status_code=201)
+async def create_alert_rule(
+    payload: AlertRuleCreate,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    rule = AlertRule(
+        tenant_id=_tenant_of(current_user),
+        target_type=payload.target_type,
+        target_id=payload.target_id,
+        metric=payload.metric,
+        threshold=payload.threshold,
+        operator=payload.operator,
+        channel=payload.channel,
+        enabled=payload.enabled,
+        created_by=current_user.username,
+    )
+    db.add(rule)
+    await db.commit()
+    await db.refresh(rule)
+    return rule
+
+
+async def _get_owned_rule(rule_id: int, db: AsyncSession, user: User) -> AlertRule:
+    rule = await db.get(AlertRule, rule_id)
+    if not rule or rule.tenant_id != _tenant_of(user):
+        raise HTTPException(404, "알림 규칙을 찾을 수 없습니다.")
+    return rule
+
+
+@router.put("/{rule_id}", response_model=AlertRuleOut)
+async def update_alert_rule(
+    rule_id: int,
+    payload: AlertRuleUpdate,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    rule = await _get_owned_rule(rule_id, db, current_user)
+    data = payload.model_dump(exclude_unset=True)
+    # 유효성 검증
+    if "target_type" in data and data["target_type"] not in _VALID_TARGET:
+        raise HTTPException(422, f"target_type은 {_VALID_TARGET} 중 하나여야 합니다.")
+    if "metric" in data and data["metric"] not in _VALID_METRIC:
+        raise HTTPException(422, f"metric은 {_VALID_METRIC} 중 하나여야 합니다.")
+    if "operator" in data and data["operator"] not in _VALID_OPERATOR:
+        raise HTTPException(422, f"operator는 {_VALID_OPERATOR} 중 하나여야 합니다.")
+    if "channel" in data and data["channel"] not in _VALID_CHANNEL:
+        raise HTTPException(422, f"channel은 {_VALID_CHANNEL} 중 하나여야 합니다.")
+    for k, v in data.items():
+        setattr(rule, k, v)
+    rule.updated_at = datetime.now()
+    await db.commit()
+    await db.refresh(rule)
+    return rule
+
+
+@router.delete("/{rule_id}", status_code=204)
+async def delete_alert_rule(
+    rule_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    rule = await _get_owned_rule(rule_id, db, current_user)
+    await db.delete(rule)
+    await db.commit()
+
+
+@router.patch("/{rule_id}/toggle", response_model=AlertRuleOut)
+async def toggle_alert_rule(
+    rule_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """알림 규칙 활성/비활성 토글."""
+    rule = await _get_owned_rule(rule_id, db, current_user)
+    rule.enabled = not rule.enabled
+    rule.updated_at = datetime.now()
+    await db.commit()
+    await db.refresh(rule)
+    return rule
diff --git a/routers/approvals.py b/routers/approvals.py
index 00f9efd..119fb2e 100644
--- a/routers/approvals.py
+++ b/routers/approvals.py
@@ -34,6 +34,66 @@ async def _write_audit(db: AsyncSession, sr_id: str, actor: str, action: str, de
     ))
 
 
+class DelegateByUsernameRequest(BaseModel):
+    delegate_to: str          # 대리 결재자 username
+    from_date: str            # ISO date
+    to_date: str              # ISO date
+    reason: Optional[str] = None
+
+
+@router.post("/delegate")
+async def delegate_global(
+    body: DelegateByUsernameRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """기간 기반 대리 결재 위임 — 현재 사용자의 대기 결재를 일괄 위임 (#65).
+
+    주의: 이 라우트는 POST /{sr_id} 보다 먼저 정의되어야 'delegate'가
+    sr_id 경로 변수로 잘못 매칭되지 않는다.
+    """
+    try:
+        from_dt = datetime.fromisoformat(body.from_date)
+        to_dt = datetime.fromisoformat(body.to_date)
+    except ValueError:
+        raise HTTPException(422, "from_date / to_date는 ISO 날짜 형식이어야 합니다.")
+    if to_dt < from_dt:
+        raise HTTPException(422, "to_date는 from_date 이후여야 합니다.")
+
+    delegate_user = (await db.execute(
+        select(User).where(User.username == body.delegate_to)
+    )).scalars().first()
+    if not delegate_user:
+        raise HTTPException(404, f"대리 결재자 '{body.delegate_to}'를 찾을 수 없습니다.")
+
+    pending = (await db.execute(
+        select(ApprovalFlow).where(
+            ApprovalFlow.approver == current_user.username,
+            ApprovalFlow.result == ApprovalResult.PENDING,
+        )
+    )).scalars().all()
+
+    delegated = 0
+    for apv in pending:
+        apv.delegate_to = delegate_user.id
+        apv.delegate_until = to_dt
+        delegated += 1
+    if pending:
+        await _write_audit(
+            db, pending[0].sr_id, current_user.username, "APPROVAL_DELEGATED_BULK",
+            f"대리 결재 → {delegate_user.username} ({body.from_date}~{body.to_date}) "
+            f"| {delegated}건 | 사유: {body.reason or ''}"
+        )
+    await db.commit()
+    return {
+        "delegate_to": delegate_user.username,
+        "from_date": body.from_date,
+        "to_date": body.to_date,
+        "delegated_count": delegated,
+        "message": f"{delegated}건의 결재가 위임되었습니다.",
+    }
+
+
 @router.get("/{sr_id}", response_model=List[ApprovalOut])
 async def list_approvals(sr_id: str, db: AsyncSession = Depends(get_db),
                          _u: User = Depends(get_current_user)):
@@ -245,3 +305,99 @@ async def extend_deadline(
         "new_deadline":  body.new_deadline,
         "message":       "승인 마감이 연장되었습니다.",
     }
+
+
+# ════════════════════════════════════════════════════════════════════════════════
+# ── 모바일 100기능: 다단계 승인 현황 ────────────────────────────────────────────
+# ════════════════════════════════════════════════════════════════════════════════
+
+@router.get("/{approval_id}/stages")
+async def approval_stages(
+    approval_id: int,
+    db: AsyncSession = Depends(get_db),
+    _u: User = Depends(get_current_user),
+):
+    """다단계 승인 현황 — 동일 SR의 모든 승인 단계를 순서대로 반환 (#67)."""
+    apv = await db.get(ApprovalFlow, approval_id)
+    if not apv:
+        raise HTTPException(404, "승인 레코드를 찾을 수 없습니다.")
+
+    rows = (await db.execute(
+        select(ApprovalFlow).where(ApprovalFlow.sr_id == apv.sr_id)
+        .order_by(ApprovalFlow.created_at, ApprovalFlow.id)
+    )).scalars().all()
+
+    stages = []
+    for level, r in enumerate(rows, start=1):
+        stages.append({
+            "level": level,
+            "approval_id": r.id,
+            "approver": r.approver,
+            "status": r.result,
+            "approved_at": r.decided_at.isoformat() if r.decided_at else None,
+            "delegate_to": r.delegate_to,
+            "signed": bool(r.signature),
+        })
+    return {"sr_id": apv.sr_id, "stages": stages, "total_stages": len(stages)}
+
+
+# ════════════════════════════════════════════════════════════════════════════════
+# ── 변경 달력 (#68) — /api/changes/calendar ─────────────────────────────────────
+# ════════════════════════════════════════════════════════════════════════════════
+
+changes_router = APIRouter(prefix="/api/changes", tags=["changes"])
+
+
+@changes_router.get("/calendar")
+async def changes_calendar(
+    month: str,   # YYYY-MM
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """변경 달력 — 해당 월 날짜별 변경(SR) 목록 (#68)."""
+    try:
+        year, mon = month.split("-")
+        year_i, mon_i = int(year), int(mon)
+        if not (1 <= mon_i <= 12):
+            raise ValueError()
+    except (ValueError, AttributeError):
+        raise HTTPException(422, "month는 YYYY-MM 형식이어야 합니다.")
+
+    from datetime import date as _date
+    start = _date(year_i, mon_i, 1)
+    end = _date(year_i + (1 if mon_i == 12 else 0),
+                1 if mon_i == 12 else mon_i + 1, 1)
+    start_dt = datetime(start.year, start.month, start.day)
+    end_dt = datetime(end.year, end.month, end.day)
+
+    # CHANGE / DEPLOY 유형 SR을 변경으로 취급, created_at 기준 그룹핑
+    from models import SRType
+    q = select(SRRequest).where(
+        SRRequest.created_at >= start_dt,
+        SRRequest.created_at < end_dt,
+    )
+    # CUSTOMER 기관 필터
+    from models import UserRole
+    if current_user.role == UserRole.CUSTOMER and current_user.inst_code:
+        from models import Institution as _Inst
+        inst = (await db.execute(
+            select(_Inst).where(_Inst.inst_code == current_user.inst_code)
+        )).scalars().first()
+        q = q.where(SRRequest.inst_id == (inst.id if inst else -1))
+
+    srs = (await db.execute(q.order_by(SRRequest.created_at))).scalars().all()
+
+    by_date: dict = {}
+    for s in srs:
+        if not s.created_at:
+            continue
+        key = s.created_at.date().isoformat()
+        by_date.setdefault(key, []).append({
+            "sr_id": s.sr_id,
+            "title": s.title,
+            "sr_type": s.sr_type,
+            "status": s.status,
+            "priority": s.priority,
+        })
+
+    return {"month": month, "calendar": by_date, "total": len(srs)}
diff --git a/routers/auth.py b/routers/auth.py
index 5ee96c8..ba79216 100644
--- a/routers/auth.py
+++ b/routers/auth.py
@@ -10,7 +10,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from core.auth import (create_access_token, get_current_user, hash_password,
                        verify_password, MAX_FAILED_ATTEMPTS, LOCKOUT_MINUTES)
 from database import get_db
-from models import User
+from models import User, UserDevice, LoginEvent, Institution
 
 router = APIRouter(prefix="/api/auth", tags=["auth"])
 
@@ -453,6 +453,158 @@ async def admin_user_lock_status(
     }
 
 
+# ════════════════════════════════════════════════════════════════════════════════
+# ── 모바일 100기능: 디바이스 / 보안 이벤트 / 네트워크 상태 / 기관 전환 ───────────
+# ════════════════════════════════════════════════════════════════════════════════
+
+class DeviceRegister(BaseModel):
+    device_name: Optional[str] = None
+    device_type: Optional[str] = None   # android | ios | web
+    push_token: Optional[str] = None
+
+
+class SwitchTenantRequest(BaseModel):
+    tenant_id: str   # 전환 대상 inst_code
+
+
+@router.get("/devices")
+async def list_devices(
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """등록 디바이스 목록 (#33)."""
+    rows = (await db.execute(
+        select(UserDevice).where(UserDevice.username == current_user.username)
+        .order_by(UserDevice.last_seen_at.desc())
+    )).scalars().all()
+    return [
+        {
+            "id": d.id,
+            "device_name": d.device_name,
+            "device_type": d.device_type,
+            "last_seen_at": d.last_seen_at.isoformat() if d.last_seen_at else None,
+            "created_at": d.created_at.isoformat() if d.created_at else None,
+        }
+        for d in rows
+    ]
+
+
+@router.post("/devices", status_code=201)
+async def register_device(
+    body: DeviceRegister,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """디바이스 등록/갱신 (#33)."""
+    dev = UserDevice(
+        username=current_user.username,
+        device_name=body.device_name,
+        device_type=body.device_type,
+        push_token=body.push_token,
+        last_seen_at=datetime.now(),
+    )
+    db.add(dev)
+    db.add(LoginEvent(username=current_user.username, event_type="DEVICE_ADDED",
+                      detail=f"{body.device_type or '?'} / {body.device_name or '?'}"))
+    await db.commit()
+    await db.refresh(dev)
+    return {"id": dev.id, "message": "디바이스가 등록되었습니다."}
+
+
+@router.delete("/devices/{device_id}", status_code=204)
+async def unregister_device(
+    device_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """디바이스 등록 해제 (#33)."""
+    dev = await db.get(UserDevice, device_id)
+    if not dev or dev.username != current_user.username:
+        raise HTTPException(404, "디바이스를 찾을 수 없습니다.")
+    await db.delete(dev)
+    db.add(LoginEvent(username=current_user.username, event_type="DEVICE_REMOVED",
+                      detail=f"device_id={device_id}"))
+    await db.commit()
+
+
+@router.get("/events")
+async def list_security_events(
+    limit: int = 50,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """보안 이벤트 로그 — 로그인 이력/실패/디바이스 변경 등 (#34)."""
+    rows = (await db.execute(
+        select(LoginEvent).where(LoginEvent.username == current_user.username)
+        .order_by(LoginEvent.created_at.desc())
+        .limit(min(limit, 200))
+    )).scalars().all()
+    return [
+        {
+            "id": e.id,
+            "event_type": e.event_type,
+            "detail": e.detail,
+            "created_at": e.created_at.isoformat() if e.created_at else None,
+        }
+        for e in rows
+    ]
+
+
+@router.get("/network-status")
+async def network_status(
+    current_user: User = Depends(get_current_user),
+):
+    """접속 경로 상태 — VPN / 개방망 / 내부망 (#37)."""
+    import os as _os
+    mode = _os.environ.get("GUARDIA_NETWORK_MODE", "internal")
+    if mode == "open":
+        via, level = "opennet", 2
+    elif mode == "vpn":
+        via, level = "vpn", 2
+    else:
+        via, level = "internal", 3   # 내부망이 가장 신뢰 수준 높음
+    return {
+        "via": via,
+        "level": level,
+        "username": current_user.username,
+        "checked_at": datetime.now().isoformat(),
+    }
+
+
+@router.post("/switch-tenant")
+async def switch_tenant(
+    body: SwitchTenantRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """기관 전환 — 새 inst_code로 전환 후 새 JWT 발급 (#33/멀티기관)."""
+    inst = (await db.execute(
+        select(Institution).where(Institution.inst_code == body.tenant_id)
+    )).scalars().first()
+    if not inst:
+        raise HTTPException(404, "전환 대상 기관을 찾을 수 없습니다.")
+
+    # CUSTOMER는 자기 기관으로만 제한, ADMIN/PM/ENGINEER는 자유 전환
+    from models import UserRole
+    if current_user.role == UserRole.CUSTOMER and current_user.inst_code != body.tenant_id:
+        raise HTTPException(403, "해당 기관으로 전환할 권한이 없습니다.")
+
+    token = create_access_token({
+        "sub": current_user.username,
+        "role": current_user.role,
+        "tenant": body.tenant_id,
+    })
+    db.add(LoginEvent(username=current_user.username, event_type="TENANT_SWITCH",
+                      detail=f"→ {body.tenant_id}"))
+    await db.commit()
+    return {
+        "access_token": token,
+        "token_type": "bearer",
+        "tenant_id": body.tenant_id,
+        "inst_name": inst.inst_name,
+    }
+
+
 # ── OAuth2 소셜 로그인 ────────────────────────────────────────────────────────
 
 @router.get("/oauth/providers")
diff --git a/routers/inventory.py b/routers/inventory.py
new file mode 100644
index 0000000..1723ce9
--- /dev/null
+++ b/routers/inventory.py
@@ -0,0 +1,171 @@
+"""
+부품 재고 API (모바일 기능 #62).
+
+  GET  /api/inventory/parts                — 부품 목록 (tenant 필터)
+  GET  /api/inventory/parts/{id}           — 부품 상세
+  POST /api/inventory/parts                — 부품 등록
+  POST /api/inventory/parts/{id}/request   — 부품 요청 → SR 자동 생성
+"""
+from __future__ import annotations
+
+from datetime import datetime
+from typing import List, Optional
+from uuid import uuid4
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel, ConfigDict
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from core.auth import get_current_user
+from database import get_db
+from models import Institution, InventoryPart, SRRequest, SRStatus, SRType, User
+
+router = APIRouter(prefix="/api/inventory", tags=["Inventory"])
+
+
+def _tenant_of(user: User) -> str:
+    return user.inst_code or f"user:{user.username}"
+
+
+class PartCreate(BaseModel):
+    name: str
+    model: Optional[str] = None
+    quantity: int = 0
+    min_quantity: int = 1
+    location: Optional[str] = None
+
+
+class PartOut(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    name: str
+    model: Optional[str]
+    quantity: int
+    min_quantity: int
+    location: Optional[str]
+    low_stock: bool = False
+
+
+class PartRequest(BaseModel):
+    quantity: int = 1
+    reason: Optional[str] = None
+    target_server: Optional[str] = None
+
+
+def _to_out(p: InventoryPart) -> dict:
+    return {
+        "id": p.id,
+        "name": p.name,
+        "model": p.model,
+        "quantity": p.quantity,
+        "min_quantity": p.min_quantity,
+        "location": p.location,
+        "low_stock": (p.quantity or 0) <= (p.min_quantity or 0),
+    }
+
+
+@router.get("/parts", response_model=List[PartOut])
+async def list_parts(
+    low_stock_only: bool = False,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """내 테넌트의 부품 목록."""
+    q = select(InventoryPart).where(
+        InventoryPart.tenant_id == _tenant_of(current_user)
+    ).order_by(InventoryPart.name)
+    rows = (await db.execute(q)).scalars().all()
+    out = [_to_out(p) for p in rows]
+    if low_stock_only:
+        out = [p for p in out if p["low_stock"]]
+    return out
+
+
+@router.post("/parts", response_model=PartOut, status_code=201)
+async def create_part(
+    payload: PartCreate,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    part = InventoryPart(
+        tenant_id=_tenant_of(current_user),
+        name=payload.name,
+        model=payload.model,
+        quantity=payload.quantity,
+        min_quantity=payload.min_quantity,
+        location=payload.location,
+    )
+    db.add(part)
+    await db.commit()
+    await db.refresh(part)
+    return _to_out(part)
+
+
+async def _get_owned_part(part_id: int, db: AsyncSession, user: User) -> InventoryPart:
+    part = await db.get(InventoryPart, part_id)
+    if not part or part.tenant_id != _tenant_of(user):
+        raise HTTPException(404, "부품을 찾을 수 없습니다.")
+    return part
+
+
+@router.get("/parts/{part_id}", response_model=PartOut)
+async def get_part(
+    part_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    part = await _get_owned_part(part_id, db, current_user)
+    return _to_out(part)
+
+
+@router.post("/parts/{part_id}/request", status_code=201)
+async def request_part(
+    part_id: int,
+    payload: PartRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """부품 요청 → SR 자동 생성."""
+    part = await _get_owned_part(part_id, db, current_user)
+    if payload.quantity < 1:
+        raise HTTPException(422, "요청 수량은 1 이상이어야 합니다.")
+
+    # 소속 기관 id 매핑 (있으면)
+    inst_id = None
+    if current_user.inst_code:
+        inst = (await db.execute(
+            select(Institution).where(Institution.inst_code == current_user.inst_code)
+        )).scalars().first()
+        if inst:
+            inst_id = inst.id
+
+    sr_id = f"SR-{datetime.now().strftime('%Y%m%d')}-{str(uuid4())[:6].upper()}"
+    desc = (
+        f"부품 요청\n"
+        f"- 부품명: {part.name}\n"
+        f"- 모델: {part.model or '-'}\n"
+        f"- 요청수량: {payload.quantity}\n"
+        f"- 보관위치: {part.location or '-'}\n"
+        f"- 사유: {payload.reason or '-'}"
+    )
+    sr = SRRequest(
+        sr_id=sr_id,
+        inst_id=inst_id,
+        sr_type=SRType.OTHER,
+        title=f"[부품요청] {part.name} x{payload.quantity}",
+        description=desc,
+        status=SRStatus.RECEIVED,
+        requested_by=current_user.username,
+        target_server=payload.target_server,
+    )
+    db.add(sr)
+    await db.commit()
+    return {
+        "sr_id": sr_id,
+        "part_id": part.id,
+        "part_name": part.name,
+        "requested_quantity": payload.quantity,
+        "message": "부품 요청 SR이 생성되었습니다.",
+    }
diff --git a/routers/search.py b/routers/search.py
new file mode 100644
index 0000000..58cca15
--- /dev/null
+++ b/routers/search.py
@@ -0,0 +1,138 @@
+"""
+통합 검색 API (모바일 기능 #50).
+
+  GET /api/search/?q={query}&types=sr,server,kb,institution
+
+SR, 서버(CMDB), KB 문서, 기관을 동시에 검색하여 타입별 결과를 반환.
+보안: 서버 결과는 ServerOut 안전 필드만 반환(ip_addr/ssh_user/os_pw_enc 제외).
+      CUSTOMER 역할은 자신의 기관 SR/서버만 조회.
+"""
+from __future__ import annotations
+
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import select, or_
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from core.auth import get_current_user
+from database import get_db
+from models import (
+    Institution, KBDocument, Server, SRRequest, User, UserRole,
+)
+
+router = APIRouter(prefix="/api/search", tags=["Search"])
+
+_PER_TYPE_LIMIT = 5
+
+
+async def _customer_inst_id(user: User, db: AsyncSession) -> Optional[int]:
+    """CUSTOMER 역할이면 소속 기관 id 반환, 아니면 None."""
+    if user.role == UserRole.CUSTOMER and user.inst_code:
+        inst = (await db.execute(
+            select(Institution).where(Institution.inst_code == user.inst_code)
+        )).scalars().first()
+        return inst.id if inst else -1
+    return None
+
+
+@router.get("/")
+async def global_search(
+    q: str = Query(..., min_length=1, description="검색어"),
+    types: str = Query("sr,server,kb,institution", description="콤마 구분 검색 대상"),
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SR + 서버 + KB + 기관 통합 검색."""
+    wanted = {t.strip() for t in types.split(",") if t.strip()}
+    if not wanted:
+        raise HTTPException(422, "types에 최소 하나의 검색 대상을 지정하세요.")
+
+    like = f"%{q}%"
+    results: dict = {}
+    cust_inst_id = await _customer_inst_id(current_user, db)
+
+    # ── SR 검색 ──────────────────────────────────────────────────────────
+    if "sr" in wanted:
+        sr_q = select(SRRequest).where(
+            or_(SRRequest.title.ilike(like),
+                SRRequest.description.ilike(like),
+                SRRequest.sr_id.ilike(like))
+        )
+        if cust_inst_id is not None:
+            sr_q = sr_q.where(SRRequest.inst_id == cust_inst_id)
+        sr_q = sr_q.order_by(SRRequest.created_at.desc()).limit(_PER_TYPE_LIMIT)
+        srs = (await db.execute(sr_q)).scalars().all()
+        results["sr"] = [
+            {
+                "sr_id": s.sr_id,
+                "title": s.title,
+                "status": s.status,
+                "priority": s.priority,
+                "sr_type": s.sr_type,
+            }
+            for s in srs
+        ]
+
+    # ── 서버(CMDB) 검색 — 자격증명 필드 절대 제외 ──────────────────────────
+    if "server" in wanted:
+        srv_q = select(Server).where(
+            or_(Server.server_name.ilike(like),
+                Server.server_role.ilike(like),
+                Server.os_type.ilike(like))
+        )
+        if cust_inst_id is not None:
+            srv_q = srv_q.where(Server.inst_id == cust_inst_id)
+        srv_q = srv_q.limit(_PER_TYPE_LIMIT)
+        servers = (await db.execute(srv_q)).scalars().all()
+        results["server"] = [
+            {
+                "id": s.id,
+                "server_name": s.server_name,
+                "server_role": s.server_role,
+                "os_type": s.os_type,
+                "inst_id": s.inst_id,
+                # ip_addr / ssh_user / os_pw_enc 절대 미포함
+            }
+            for s in servers
+        ]
+
+    # ── KB 검색 ──────────────────────────────────────────────────────────
+    if "kb" in wanted:
+        kb_q = select(KBDocument).where(
+            or_(KBDocument.title.ilike(like),
+                KBDocument.symptoms.ilike(like),
+                KBDocument.tags.ilike(like))
+        ).limit(_PER_TYPE_LIMIT)
+        kbs = (await db.execute(kb_q)).scalars().all()
+        results["kb"] = [
+            {
+                "doc_id": k.doc_id,
+                "title": k.title,
+                "category": k.category,
+                "tags": k.tags,
+            }
+            for k in kbs
+        ]
+
+    # ── 기관 검색 ────────────────────────────────────────────────────────
+    if "institution" in wanted:
+        inst_q = select(Institution).where(
+            or_(Institution.inst_name.ilike(like),
+                Institution.inst_code.ilike(like))
+        )
+        if cust_inst_id is not None and cust_inst_id != -1:
+            inst_q = inst_q.where(Institution.id == cust_inst_id)
+        inst_q = inst_q.limit(_PER_TYPE_LIMIT)
+        insts = (await db.execute(inst_q)).scalars().all()
+        results["institution"] = [
+            {
+                "id": i.id,
+                "inst_code": i.inst_code,
+                "inst_name": i.inst_name,
+            }
+            for i in insts
+        ]
+
+    total = sum(len(v) for v in results.values())
+    return {"query": q, "total": total, "results": results}
diff --git a/routers/sr_chat.py b/routers/sr_chat.py
new file mode 100644
index 0000000..4b4dc29
--- /dev/null
+++ b/routers/sr_chat.py
@@ -0,0 +1,280 @@
+"""
+SR 채팅방 API + WebSocket (모바일 기능 #98).
+
+  WS   /ws/sr-chat/{sr_id}?token={jwt}  — SR별 실시간 채팅
+  POST /api/sr-chat/{sr_id}/messages    — 메시지 전송 (REST)
+  GET  /api/sr-chat/{sr_id}/messages    — 메시지 이력
+  POST /api/sr-chat/{sr_id}/read        — 읽음 처리
+
+메시지 타입: text | image | sr_update
+"""
+from __future__ import annotations
+
+import json
+import logging
+from datetime import datetime
+from typing import Dict, List, Optional, Set
+
+from fastapi import (
+    APIRouter, Depends, HTTPException, Query, WebSocket, WebSocketDisconnect,
+)
+from pydantic import BaseModel, ConfigDict
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from core.auth import get_current_user
+from database import get_db, SessionLocal
+from models import SRChatMessage, SRRequest, User
+
+logger = logging.getLogger(__name__)
+router = APIRouter(tags=["SR Chat"])
+
+_VALID_MSG_TYPE = {"text", "image", "sr_update"}
+
+
+# ── WebSocket 연결 관리 (SR방별 그룹) ─────────────────────────────────────────
+class _ChatRooms:
+    def __init__(self) -> None:
+        # { sr_id: set(WebSocket) }
+        self._rooms: Dict[str, Set[WebSocket]] = {}
+
+    def join(self, sr_id: str, ws: WebSocket) -> None:
+        self._rooms.setdefault(sr_id, set()).add(ws)
+
+    def leave(self, sr_id: str, ws: WebSocket) -> None:
+        room = self._rooms.get(sr_id)
+        if room:
+            room.discard(ws)
+            if not room:
+                self._rooms.pop(sr_id, None)
+
+    async def broadcast(self, sr_id: str, payload: dict) -> None:
+        room = self._rooms.get(sr_id)
+        if not room:
+            return
+        msg = json.dumps(payload, ensure_ascii=False)
+        dead = []
+        for ws in list(room):
+            try:
+                await ws.send_text(msg)
+            except Exception:
+                dead.append(ws)
+        for ws in dead:
+            room.discard(ws)
+
+
+rooms = _ChatRooms()
+
+
+# ── 스키마 ────────────────────────────────────────────────────────────────────
+class ChatMessageCreate(BaseModel):
+    content: str
+    msg_type: str = "text"
+
+
+class ChatMessageOut(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    task_id: str
+    sender_id: str
+    content: str
+    msg_type: str
+    created_at: Optional[datetime]
+
+
+# ── 헬퍼 ──────────────────────────────────────────────────────────────────────
+async def _ensure_sr(sr_id: str, db: AsyncSession) -> SRRequest:
+    sr = (await db.execute(
+        select(SRRequest).where(SRRequest.sr_id == sr_id)
+    )).scalars().first()
+    if not sr:
+        raise HTTPException(404, "SR을 찾을 수 없습니다.")
+    return sr
+
+
+async def _save_message(db: AsyncSession, sr_id: str, sender: str,
+                        content: str, msg_type: str) -> SRChatMessage:
+    if msg_type not in _VALID_MSG_TYPE:
+        raise HTTPException(422, f"msg_type은 {_VALID_MSG_TYPE} 중 하나여야 합니다.")
+    if not content or not content.strip():
+        raise HTTPException(422, "메시지 내용이 비어 있습니다.")
+    m = SRChatMessage(
+        task_id=sr_id,
+        sender_id=sender,
+        content=content,
+        msg_type=msg_type,
+        read_by=json.dumps([sender], ensure_ascii=False),
+    )
+    db.add(m)
+    await db.commit()
+    await db.refresh(m)
+    return m
+
+
+# ── REST: 메시지 전송 ─────────────────────────────────────────────────────────
+@router.post("/api/sr-chat/{sr_id}/messages", response_model=ChatMessageOut, status_code=201)
+async def send_message(
+    sr_id: str,
+    payload: ChatMessageCreate,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SR 채팅 메시지 전송 (REST). 연결된 WebSocket 구독자에게도 브로드캐스트."""
+    await _ensure_sr(sr_id, db)
+    m = await _save_message(db, sr_id, current_user.username,
+                            payload.content, payload.msg_type)
+    await rooms.broadcast(sr_id, {
+        "type": "message",
+        "id": m.id,
+        "task_id": sr_id,
+        "sender_id": m.sender_id,
+        "content": m.content,
+        "msg_type": m.msg_type,
+        "created_at": m.created_at.isoformat() if m.created_at else None,
+    })
+    return m
+
+
+# ── REST: 메시지 이력 ─────────────────────────────────────────────────────────
+@router.get("/api/sr-chat/{sr_id}/messages", response_model=List[ChatMessageOut])
+async def list_messages(
+    sr_id: str,
+    skip: int = 0,
+    limit: int = 100,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SR 채팅 메시지 이력 (오래된 순)."""
+    await _ensure_sr(sr_id, db)
+    rows = (await db.execute(
+        select(SRChatMessage)
+        .where(SRChatMessage.task_id == sr_id)
+        .order_by(SRChatMessage.created_at.asc())
+        .offset(skip).limit(min(limit, 500))
+    )).scalars().all()
+    return rows
+
+
+# ── REST: 읽음 처리 ───────────────────────────────────────────────────────────
+@router.post("/api/sr-chat/{sr_id}/read")
+async def mark_read(
+    sr_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """현재 사용자가 SR 채팅의 모든 메시지를 읽음 처리."""
+    await _ensure_sr(sr_id, db)
+    rows = (await db.execute(
+        select(SRChatMessage).where(SRChatMessage.task_id == sr_id)
+    )).scalars().all()
+    updated = 0
+    for m in rows:
+        try:
+            readers = json.loads(m.read_by) if m.read_by else []
+        except Exception:
+            readers = []
+        if current_user.username not in readers:
+            readers.append(current_user.username)
+            m.read_by = json.dumps(readers, ensure_ascii=False)
+            updated += 1
+    await db.commit()
+    return {"sr_id": sr_id, "marked_read": updated, "reader": current_user.username}
+
+
+# ── WebSocket: 실시간 채팅 ────────────────────────────────────────────────────
+async def _authenticate_ws(token: str, db: AsyncSession) -> Optional[User]:
+    if not token:
+        return None
+    try:
+        from core.auth import SECRET_KEY, ALGORITHM
+        from jose import jwt
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        if payload.get("mfa_pending"):
+            return None
+        username = payload.get("sub")
+        if not username:
+            return None
+        user = (await db.execute(
+            select(User).where(User.username == username)
+        )).scalars().first()
+        return user if (user and user.is_active) else None
+    except Exception:
+        return None
+
+
+@router.websocket("/ws/sr-chat/{sr_id}")
+async def sr_chat_ws(
+    websocket: WebSocket,
+    sr_id: str,
+    token: str = Query(..., description="JWT access_token"),
+    db: AsyncSession = Depends(get_db),
+):
+    """SR별 실시간 채팅 WebSocket."""
+    user = await _authenticate_ws(token, db)
+    if not user:
+        await websocket.close(code=4001, reason="인증 실패: 유효한 토큰이 필요합니다.")
+        return
+
+    # SR 존재 확인
+    sr = (await db.execute(
+        select(SRRequest).where(SRRequest.sr_id == sr_id)
+    )).scalars().first()
+    if not sr:
+        await websocket.close(code=4004, reason="SR을 찾을 수 없습니다.")
+        return
+
+    await websocket.accept()
+    rooms.join(sr_id, websocket)
+    await websocket.send_text(json.dumps({
+        "type": "connected",
+        "sr_id": sr_id,
+        "username": user.username,
+        "server_time": datetime.now().isoformat(),
+    }, ensure_ascii=False))
+
+    try:
+        while True:
+            raw = await websocket.receive_text()
+            try:
+                data = json.loads(raw)
+            except Exception:
+                await websocket.send_text(json.dumps(
+                    {"type": "error", "message": "JSON 형식이 아닙니다."},
+                    ensure_ascii=False))
+                continue
+
+            if data.get("type") == "ping":
+                await websocket.send_text(json.dumps(
+                    {"type": "pong", "server_time": datetime.now().isoformat()},
+                    ensure_ascii=False))
+                continue
+
+            content = (data.get("content") or "").strip()
+            msg_type = data.get("msg_type", "text")
+            if not content or msg_type not in _VALID_MSG_TYPE:
+                await websocket.send_text(json.dumps(
+                    {"type": "error", "message": "content 또는 msg_type이 올바르지 않습니다."},
+                    ensure_ascii=False))
+                continue
+
+            # DB 저장 (독립 세션) + 구독자에게 브로드캐스트
+            async with SessionLocal() as _db:
+                m = await _save_message(_db, sr_id, user.username, content, msg_type)
+                payload = {
+                    "type": "message",
+                    "id": m.id,
+                    "task_id": sr_id,
+                    "sender_id": m.sender_id,
+                    "content": m.content,
+                    "msg_type": m.msg_type,
+                    "created_at": m.created_at.isoformat() if m.created_at else None,
+                }
+            await rooms.broadcast(sr_id, payload)
+
+    except WebSocketDisconnect:
+        pass
+    except Exception as exc:
+        logger.debug("SR 채팅 WS 오류: sr=%s err=%s", sr_id, exc)
+    finally:
+        rooms.leave(sr_id, websocket)
diff --git a/routers/system.py b/routers/system.py
new file mode 100644
index 0000000..1f4e872
--- /dev/null
+++ b/routers/system.py
@@ -0,0 +1,92 @@
+"""
+시스템 정보 API (모바일 기능 #77).
+
+  GET /api/system/release-notes  — 버전별 릴리즈 노트 목록
+  GET /api/system/version        — 현재 버전 정보
+
+릴리즈 노트는 정적 정의(코드 내장)로 제공한다.
+"""
+from __future__ import annotations
+
+from typing import List, Optional
+
+from fastapi import APIRouter, Depends
+from pydantic import BaseModel
+
+from core.auth import get_current_user
+from models import User
+
+router = APIRouter(prefix="/api/system", tags=["System"])
+
+CURRENT_VERSION = "2.0.0"
+
+# 최신 → 과거 순서
+_RELEASE_NOTES: List[dict] = [
+    {
+        "version": "2.0.0",
+        "date": "2026-06-06",
+        "changes": [
+            "모바일 100기능 백엔드 API 추가 (알림규칙·통합검색·SR채팅·부품재고)",
+            "SR 에스컬레이션/구독/만족도/현장서명/체크인 지원",
+            "보안 이벤트 로그 및 디바이스 관리 추가",
+            "다단계 승인 현황 및 변경 달력 API 추가",
+        ],
+        "breaking_changes": [],
+    },
+    {
+        "version": "1.5.0",
+        "date": "2026-06-01",
+        "changes": [
+            "CI/CD 배포 트리거 연동",
+            "tmux 세션 관리·하네스 빌더 추가",
+            "AI-SOC·데이터 거버넌스 영역 확장",
+        ],
+        "breaking_changes": [],
+    },
+    {
+        "version": "1.0.0",
+        "date": "2026-05-20",
+        "changes": [
+            "GUARDiA ITSM 정식 출시",
+            "SR 라이프사이클·CMDB·KB·SLA·승인 워크플로우",
+        ],
+        "breaking_changes": [],
+    },
+]
+
+
+class ReleaseNote(BaseModel):
+    version: str
+    date: str
+    changes: List[str]
+    breaking_changes: List[str] = []
+
+
+@router.get("/release-notes", response_model=List[ReleaseNote])
+async def list_release_notes(
+    since: Optional[str] = None,
+    _u: User = Depends(get_current_user),
+):
+    """버전별 릴리즈 노트 목록 (최신순). since 지정 시 해당 버전 이후만."""
+    notes = _RELEASE_NOTES
+    if since:
+        # since 버전 이후(미포함)만 반환
+        filtered = []
+        for n in notes:
+            if n["version"] == since:
+                break
+            filtered.append(n)
+        notes = filtered
+    return notes
+
+
+@router.get("/version")
+async def get_version(_u: User = Depends(get_current_user)):
+    """현재 버전 정보."""
+    latest = _RELEASE_NOTES[0] if _RELEASE_NOTES else None
+    return {
+        "name": "GUARDiA ITSM",
+        "version": CURRENT_VERSION,
+        "latest_release_date": latest["date"] if latest else None,
+        "release_count": len(_RELEASE_NOTES),
+    }
diff --git a/routers/tasks.py b/routers/tasks.py
index 0e7d8cf..dc82067 100644
--- a/routers/tasks.py
+++ b/routers/tasks.py
@@ -13,7 +13,8 @@ from core.events import broadcast
 from database import get_db
 from models import (
     AuditLog, Institution, SRCreate, SROut, SRRequest, SRStatus,
-    SRStatusUpdate, SRType, User, compute_log_hash
+    SRStatusUpdate, SRType, User, compute_log_hash,
+    SRSubscription, SRRating, SRSignature, SRCheckin,
 )
 
 router = APIRouter(prefix="/api/tasks", tags=["tasks"])
@@ -507,3 +508,301 @@ async def bulk_sr_action(
         "results": results,
     }
 
+
+# ════════════════════════════════════════════════════════════════════════════════
+# ── 모바일 100기능: SR 액션 + 통계 ──────────────────────────────────────────────
+# ════════════════════════════════════════════════════════════════════════════════
+
+class EscalateRequest(BaseModel):
+    reason: Optional[str] = None
+    escalate_to: Optional[str] = None   # 미지정 시 온콜 에스컬레이션 체인 사용
+
+
+class RatingRequest(BaseModel):
+    score: int
+    comment: Optional[str] = None
+
+
+class SignatureRequest(BaseModel):
+    signature_base64: str
+
+
+class SlaExceptionRequest(BaseModel):
+    reason: str
+    new_deadline: str   # ISO datetime/date
+
+
+class CheckinRequest(BaseModel):
+    lat: float
+    lng: float
+
+
+async def _get_sr(sr_id: str, db: AsyncSession) -> SRRequest:
+    sr = (await db.execute(
+        select(SRRequest).where(SRRequest.sr_id == sr_id)
+    )).scalars().first()
+    if not sr:
+        raise HTTPException(404, detail="SR을 찾을 수 없습니다.")
+    return sr
+
+
+@router.post("/{sr_id}/escalate")
+async def escalate_task(
+    sr_id: str,
+    payload: EscalateRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SR 에스컬레이션 — 상위 담당자로 재배정 + 알림 (#8)."""
+    from models import UserRole
+    if current_user.role == UserRole.CUSTOMER:
+        raise HTTPException(403, "에스컬레이션 권한이 없습니다.")
+
+    sr = await _get_sr(sr_id, db)
+
+    target = payload.escalate_to
+    if not target:
+        # 온콜 에스컬레이션 체인에서 대상 도출 시도
+        try:
+            from core.oncall_rotate import get_current_oncall
+            sched = await get_current_oncall(db)
+            if sched:
+                target = sched.escalation_to or sched.backup_engineer or sched.engineer
+        except Exception:
+            target = None
+
+    sr.escalated_at = datetime.now()
+    sr.escalated_to = target
+    if target:
+        sr.assigned_to = target
+    sr.updated_at = datetime.now()
+    await _write_audit(db, sr_id, current_user.username, "SR_ESCALATED",
+                       f"에스컬레이션 → {target or '미정'} | 사유: {payload.reason or ''}")
+    await db.commit()
+    await broadcast("sla_escalated", {
+        "sr_id": sr_id, "escalated_to": target, "by": current_user.username,
+    })
+    return {
+        "sr_id": sr_id,
+        "escalated_to": target,
+        "escalated_at": sr.escalated_at.isoformat(),
+        "message": f"'{target or '대상 미정'}'(으)로 에스컬레이션되었습니다.",
+    }
+
+
+@router.post("/{sr_id}/subscribe")
+async def toggle_subscribe(
+    sr_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SR 구독/팔로우 토글 (#14)."""
+    await _get_sr(sr_id, db)
+    existing = (await db.execute(
+        select(SRSubscription).where(
+            SRSubscription.task_id == sr_id,
+            SRSubscription.username == current_user.username,
+        )
+    )).scalars().first()
+
+    if existing:
+        await db.delete(existing)
+        await db.commit()
+        return {"sr_id": sr_id, "subscribed": False, "message": "구독을 해제했습니다."}
+
+    sub = SRSubscription(task_id=sr_id, username=current_user.username)
+    db.add(sub)
+    await db.commit()
+    return {"sr_id": sr_id, "subscribed": True, "message": "구독했습니다."}
+
+
+@router.post("/{sr_id}/rating", status_code=201)
+async def rate_task(
+    sr_id: str,
+    payload: RatingRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """완료 SR 만족도 평가 (#53)."""
+    if not (1 <= payload.score <= 5):
+        raise HTTPException(422, "score는 1~5 범위여야 합니다.")
+    sr = await _get_sr(sr_id, db)
+    if sr.status != SRStatus.COMPLETED:
+        raise HTTPException(400, "완료된 SR만 평가할 수 있습니다.")
+
+    rating = SRRating(
+        task_id=sr_id, rater=current_user.username,
+        score=payload.score, comment=payload.comment,
+    )
+    db.add(rating)
+    await _write_audit(db, sr_id, current_user.username, "SR_RATED",
+                       f"만족도 {payload.score}점")
+    await db.commit()
+    await db.refresh(rating)
+    return {"sr_id": sr_id, "score": payload.score, "rating_id": rating.id}
+
+
+@router.post("/{sr_id}/signature", status_code=201)
+async def save_signature(
+    sr_id: str,
+    payload: SignatureRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """현장 전자서명 저장 (#70)."""
+    if not payload.signature_base64 or len(payload.signature_base64) < 10:
+        raise HTTPException(422, "signature_base64 데이터가 올바르지 않습니다.")
+    await _get_sr(sr_id, db)
+
+    sig = SRSignature(
+        task_id=sr_id, signed_by=current_user.username,
+        signature_b64=payload.signature_base64,
+    )
+    db.add(sig)
+    await _write_audit(db, sr_id, current_user.username, "SR_SIGNED", "현장 서명 등록")
+    await db.commit()
+    await db.refresh(sig)
+    return {"sr_id": sr_id, "signature_id": sig.id, "signed_by": current_user.username}
+
+
+@router.post("/{sr_id}/sla-exception")
+async def request_sla_exception(
+    sr_id: str,
+    payload: SlaExceptionRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """SLA 예외 승인 요청 — SLA 마감 연장 요청 (#94)."""
+    sr = await _get_sr(sr_id, db)
+    try:
+        new_dl = datetime.fromisoformat(payload.new_deadline)
+    except ValueError:
+        raise HTTPException(422, "new_deadline은 ISO 날짜/시간 형식이어야 합니다.")
+
+    old_dl = sr.sla_deadline
+    sr.sla_deadline = new_dl
+    sr.sla_breached = False
+    sr.updated_at = datetime.now()
+    await _write_audit(db, sr_id, current_user.username, "SLA_EXCEPTION_REQUESTED",
+                       f"SLA 마감 {old_dl} → {new_dl} | 사유: {payload.reason}")
+    await db.commit()
+    return {
+        "sr_id": sr_id,
+        "old_deadline": old_dl.isoformat() if old_dl else None,
+        "new_deadline": new_dl.isoformat(),
+        "reason": payload.reason,
+        "message": "SLA 예외(마감 연장)가 적용되었습니다.",
+    }
+
+
+@router.post("/{sr_id}/checkin", status_code=201)
+async def checkin_task(
+    sr_id: str,
+    payload: CheckinRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """현장 체크인 — GPS 좌표 기록 (#93)."""
+    if not (-90 <= payload.lat <= 90) or not (-180 <= payload.lng <= 180):
+        raise HTTPException(422, "좌표 값이 올바르지 않습니다.")
+    await _get_sr(sr_id, db)
+
+    chk = SRCheckin(
+        task_id=sr_id, username=current_user.username,
+        lat=payload.lat, lng=payload.lng,
+    )
+    db.add(chk)
+    await _write_audit(db, sr_id, current_user.username, "SR_CHECKIN",
+                       f"현장 체크인 ({payload.lat}, {payload.lng})")
+    await db.commit()
+    await db.refresh(chk)
+    return {
+        "sr_id": sr_id,
+        "checkin_id": chk.id,
+        "lat": payload.lat,
+        "lng": payload.lng,
+        "checked_in_at": chk.created_at.isoformat() if chk.created_at else None,
+    }
+
+
+@router.get("/stats/mine")
+async def my_sr_stats(
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """내 SR 처리 통계 — total / closed / avg_resolve_hours / sla_met_rate (#3)."""
+    rows = (await db.execute(
+        select(SRRequest).where(SRRequest.assigned_to == current_user.username)
+    )).scalars().all()
+
+    total = len(rows)
+    terminal = {SRStatus.COMPLETED, SRStatus.REJECTED, SRStatus.FAILED_ROLLBACK}
+    closed_rows = [r for r in rows if r.status in terminal]
+    closed = len(closed_rows)
+
+    # 평균 해결 시간 (완료 건의 created_at→updated_at)
+    completed = [r for r in rows if r.status == SRStatus.COMPLETED
+                 and r.created_at and r.updated_at]
+    avg_hours = 0.0
+    if completed:
+        secs = sum((r.updated_at - r.created_at).total_seconds() for r in completed)
+        avg_hours = round(secs / len(completed) / 3600, 2)
+
+    # SLA 준수율 (마감 시각이 있는 건 중 미위반 비율)
+    sla_rows = [r for r in rows if r.sla_deadline is not None]
+    sla_met = len([r for r in sla_rows if not r.sla_breached])
+    sla_met_rate = round(sla_met / len(sla_rows) * 100, 1) if sla_rows else 100.0
+
+    return {
+        "username": current_user.username,
+        "total": total,
+        "closed": closed,
+        "open": total - closed,
+        "avg_resolve_hours": avg_hours,
+        "sla_met_rate": sla_met_rate,
+    }
+
+
+@router.get("/stats/by-institution")
+async def stats_by_institution(
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """기관별 SR 현황 비교 (#4). CUSTOMER는 자기 기관만."""
+    from models import UserRole
+
+    q = select(SRRequest)
+    cust_inst_id = None
+    if current_user.role == UserRole.CUSTOMER and current_user.inst_code:
+        inst = (await db.execute(
+            select(Institution).where(Institution.inst_code == current_user.inst_code)
+        )).scalars().first()
+        cust_inst_id = inst.id if inst else -1
+        q = q.where(SRRequest.inst_id == cust_inst_id)
+
+    srs = (await db.execute(q)).scalars().all()
+
+    # 기관 이름 매핑
+    insts = (await db.execute(select(Institution))).scalars().all()
+    name_map = {i.id: i.inst_name for i in insts}
+
+    terminal = {SRStatus.COMPLETED, SRStatus.REJECTED, SRStatus.FAILED_ROLLBACK}
+    agg: dict = {}
+    for s in srs:
+        key = s.inst_id
+        bucket = agg.setdefault(key, {
+            "inst_id": key,
+            "inst_name": name_map.get(key, "미지정"),
+            "total": 0, "closed": 0, "open": 0, "sla_breached": 0,
+        })
+        bucket["total"] += 1
+        if s.status in terminal:
+            bucket["closed"] += 1
+        else:
+            bucket["open"] += 1
+        if s.sla_breached:
+            bucket["sla_breached"] += 1
+
+    result = sorted(agg.values(), key=lambda x: x["total"], reverse=True)
+    return {"institutions": result, "count": len(result)}
+